JPH0412841A - Damping steel plate - Google Patents

Abstract

PURPOSE:To secure high bonding strength as a whole even when the bonding strength to a metal is insufficient in the case of use in a car, a machine or a building by holding a damping resin layer composed of a resin composition containing a specific essential component between metal plates through the adhesive resin layers based on an epoxy resin preliminarily applied to the metal plates. CONSTITUTION:Thin adhesive resin layers are preliminarily formed to the surfaces of metal plates holding a resin having high damping capacity therebetween and the resin having high damping capacity is bonded to the metal plates using the resin layers as interface layers. As the resin for the interface layers, a resin composition based on an epoxy resin excellent in the adhesiveness to the metal plates is used. The resin composition having damping properties contains 10-50 pts.wt. of a bisphenol A type epoxy resin, 20-70 pts.wt. of liquid NBR having functional groups at both terminals thereof and 5-60 pts.wt. of a long chain epoxy resin and a curing agent or long chain curing agent for an epoxy resin as essential components so that three kinds of the components become 100 pts.wt. in total.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to the structure of a vibration damping steel plate, and more specifically, its use as a structural member or part of a structure such as an automobile, machine, or building. The present invention relates to a vibration damping steel plate that has vibration damping properties in a wide temperature range from low to high temperatures and has excellent formability during pressing, and is used as an intermediate layer in vibration damping materials for composite structures.

(Prior art) In machines and equipment that generate vibration or noise, metal plates, etc., have viscoelasticity for the purpose of preventing or reducing the generation of vibration or noise in the metal covers, or preventing resonance. A composite damping material with a laminated structure sandwiching an intermediate layer is used.

This composite vibration damping material is being studied or used for automobile oil pans, engine covers, wheelhouses, stoppers for transportation equipment, home appliances, and other structural members of metal processing machines.

Generally, the performance of such a composite vibration damping material depends on the performance of the viscoelastic body that constitutes the intermediate layer. Conventionally, as viscoelastic resin compositions constituting such an intermediate layer, polyester resins (Japanese Patent Laid-Open No. 50143880), resin compositions in which a plasticizer is added to polyester (Japanese Patent Laid-Open No. 50143880) have been used.
-93770), polyamide resin (JP-A-56-
159160), ethylene vinyl acetate copolymer (
JP-A-57-34949), copolymer of isocyanate prepolymer and vinyl monomer (JP-A-52-34949),
28554), etc. are known. Since these resins perform vibration damping using a single glass transition temperature (Tg), it is difficult to perform vibration damping over a wide temperature range.

The present inventors have already proposed a resin composition that exhibits excellent vibration damping properties in a wide temperature range from low to high temperatures, and disclosed this in Japanese Patent Application No. 1-328197.

(Problems to be Solved by the Invention) Due to their characteristics, these resins are required to have not only vibration damping ability but also adhesive ability with steel plates. However, its workability is not sufficient, and although there is no particular problem in simple folding or simple drawing, there are problems such as peeling when processing into shapes such as complex drawing or 180 degree bending such as hem flanges. may occur. In this case, not only the vibration damping performance deteriorates due to the separation of the two metal plates, but also problems such as corrosion of the metal on the peeled surface occur.

There is a conflict between the adhesion or adhesion to the base material and the damping performance. That is, in order to improve vibration damping performance at room temperature, it is necessary to lower the glass transition point of the resin to room temperature or lower, but there is a problem that lowering the glass transition point tends to reduce shear strength. That is, when processing a metal plate, shearing force is applied to the resin due to the deformation of the metal plate.

The resin needs to follow the deformation, but if the shear strength is low, the ability to follow it is insufficient, which means that the adhesive force with the metal will eventually become weak. This tendency is remarkable in viscoelastic compositions.

(Means for Solving the Problems) As a result of intensive studies regarding the above-mentioned problems, the present inventors found that the metal surface is thinly covered with a resin layer having a high glass transition point, and this resin layer sandwiches a resin with high vibration damping properties. It was discovered that by adopting this structure, high adhesive strength can be ensured as a whole, and the present invention was completed.

In other words, the vibration damping steel plate of the present invention has a thin adhesive resin layer formed in advance on the metal surface sandwiching the resin with high vibration damping ability, and this resin layer is used as an interface layer to connect the resin with high vibration damping ability. It is characterized by increasing adhesive strength without reducing vibration damping ability by bonding metal to metal. As the resin for the interfacial layer required for this purpose, a resin composition whose main component is an epoxy resin that has excellent adhesion to metals is used. In reality, the resin for the interface layer is preferably a resin in the same series as the resin responsible for vibration damping, but since epoxy resins can be modified in various ways, it is relatively easy to introduce the necessary resin skeleton.

In the present invention, the resin composition having vibration damping properties includes (A) 10 to 50 parts by weight of bisphenol A epoxy resin, (B) 20 to 70 parts by weight of liquid NBR having functional groups at both ends, and (C) long chain Epoxy resins and curing agents for epoxy resins,
Or, it contains 5 to 60 parts by weight of a long chain curing agent for epoxy resin as an essential component, and the total of these three components is 100 parts by weight.
This is a resin composition containing part by weight of the resin composition as an essential component.

(for production) The reason for limiting these compositions is as follows.

The bisphenol A type epoxy resin as component (A) is an epoxy resin derived from epichlorohydrin, and there are many types ranging from liquid to solid, and any of them can be used. The purpose of blending this resin is to increase the loss coefficient at relatively high temperatures, and the blending amount is 10 to 50%.
Parts by weight. If it is less than 10 parts by weight, the loss coefficient in the high temperature section will decrease, and if it is more than 50 parts by weight, the crosslinking density of the entire system will increase and Tg will shift to the high temperature side, making it impossible to ensure damping properties at low temperatures. .

Component (B) is a liquid NBR (acrylonitrile-butadiene copolymer) having functional groups at both ends, and the functional groups include a carboxyl group, an amino group, and a hydroxyl group. These liquid rubbers usually have a glass transition temperature below 0"C and serve to increase the loss coefficient below 0°C of the present resin composition. Therefore, component (A) basically has a glass transition temperature below 0"C. If there is no phase separation, it cannot be put to practical use. For example, NBR that is copolymerized with acrylic acid to have a functional group on the side chain has good compatibility with component (A), so the Tg of NBR is It shifts to the high temperature side and cannot ensure damping performance on the low temperature side.The blending amount is 20 to 7
0 parts by weight is preferable; if it is less than 20 parts by weight, the loss coefficient at low temperatures will decrease, and if it is more than 70 parts by weight, the vibration damping properties at high temperatures will decrease and the adhesion to metal will decrease, making it difficult to press. There is a risk that problems such as peeling may occur during processing.

(The long-chain epoxy resin and the curing agent for epoxy resin of the C component, or the long-chain curing agent for epoxy resin are at least selected from the group consisting of dimer acid-modified epoxy resin, oil-modified epoxy resin, and polyglycol type epoxy resin. Any type of epoxy resin or a curing agent whose terminal end is modified with a functional group that reacts with an epoxy group is sufficient, and the role of this resin is to appropriately dissolve components (A) and (B). In other words, if only components (A) and (B) are used, it is possible to ensure vibration damping properties in the low and high temperature ranges due to phase separation, but damping properties in the medium temperature range are not sufficient. Therefore, by blending component (C), the loss coefficient (tan δ) of the dynamic viscoelasticity of the resin composition can be made flat while maintaining a high value from a low temperature range to a high temperature range, Therefore, the vibration damping property has less temperature dependence and a high value can be obtained.The blending amount is preferably 5 to 60 parts by weight, and if it is less than 5 parts by weight, component (8) and (
Since component B) cannot be properly compatible and the effect of blending component (C) cannot be obtained, the loss coefficient at medium humidity will decrease, and if the amount exceeds 60 parts by weight, it will be at low temperature or high temperature side. As well as the vibration damping properties of the material are reduced, the adhesion to metal is also reduced, which may cause problems such as peeling during press working.

The dimer acid-modified epoxy resin is an epoxy resin derived from a long chain dimer acid having 10 to 20 carbon atoms, and includes, for example, an epoxy resin derived from a linoleic acid dimer and epichlorohydrin. Oil-modified epoxy resins are obtained by epoxidizing the double bonds of vegetable oils, and include, for example, castor oil-modified epoxy resins and soybean-modified epoxy resins. Examples of polyglycol-type modified epoxy resins include epoxy resins produced by reacting polyethylene glycol, polypropylene glycol, and epichlorohydrin. These epoxy resins may be used alone or in a mixed form.

There are no particular restrictions on the curing agent for epoxy resin, but from the viewpoint of productivity, it is preferable to use a heat-activated curing agent for epoxy resin. The curing agent for heat-activated epoxy resins may be anything as long as it exhibits a curing effect upon heating, such as dicyandiamide, 4,4'-diaminodiphenylsulfone, imidazole derivatives such as 2-n-heptadecyl imidazole, adipine, etc. Examples include hydrazide derivatives such as acid dihydrazide, N,N-dialkyl urea derivatives, and the like.

The resin composition having vibration damping properties used in the present invention is the above (A).
In addition to containing ~(C) as an essential component, if necessary, fillers such as calcium carbonate, carbon, and silica, metal powders such as aluminum, zinc, and nickel, thickeners such as fine silica powder, and surfactants. etc. can be used in combination.

(Example) The invention will be illustrated by the following examples and comparative examples.

1 to 12, 1 to 3 An adhesive resin layer consisting of a resin with good adhesive properties shown in Table 1 was applied to the surfaces of two cold rolled steel plates with a thickness of 0.4 mm, and the vibration damping ability was A vibration-damping resin layer made of a resin with a high temperature is sandwiched between the heat press (200"c, 3 minutes, 1 kg/cm2
) to obtain composite damping materials of Examples 1 to 12 and Comparative Examples 1 to 3 having a thickness of 0.410.0510.4 mm.

A 150 x 150 mm plate was cut out from these damping materials to serve as a test piece, and as shown in Figure 1, each test piece was cut 180 degrees along a line L = 30 mm from one side of the test piece 1 along a round bar with a diameter of 10 mm. A bending test was conducted. The minimum diameter at which no peeling occurred was determined by this 180 degree bending test. The results are also shown in Table 1.

The symbols of the adhesive resin composition are as follows.

A: Immediately after applying a room temperature curable resin prepared by mixing 100 parts by weight of Epicoat 828 (manufactured by Yuka Shell Epoxy, bisphenol A type epoxy resin) and 40 parts by weight of modified polyamine EH-220 (manufactured by Asahi Denka Kogyo), a viscoelastic layer is applied. If it gets caught.

A1: When a viscoelastic layer was sandwiched 1 hour after applying A.

A2: After coating A, it was cured by heating at 140°C for 1 hour, and then a viscoelastic layer was sandwiched.

B: Epicoat 828 (manufactured by Yuka Shell Epoxy) 100
Heavy duty Nihiker CTBN1300x8 (Ube Industries type,
When a viscoelastic layer is sandwiched immediately after coating a thermosetting resin containing 10 parts by weight of NBR containing terminal carboxyl groups and 5 parts by weight of dicyandiamide.

B1: After coating B, it was cured by heating at 170°C for 5 minutes, and then a viscoelastic layer was sandwiched.

B2: After coating B, it was cured by heating at 180° C. for 1 hour, and then a viscoelastic layer was sandwiched.

C: When epoxy cationic electrodeposition coating U600 (manufactured by Nippon Paint) was applied and cured by heating at 170°C for 20 minutes, after which a viscoelastic layer was sandwiched.

D: Polybutadiene-based anion electrodeposition coating (NOF type)
After heating and curing at 170″C for 20 minutes, a viscoelastic layer was sandwiched.

E: When using Durasteel R (manufactured by Shinjo Tetsu, a surface-treated steel plate whose surface is nickel plated and coated with a 2 to 3 μm thick epoxy resin layer).

Further, the symbols of the resin compositions having vibration damping properties are as follows.

χ: ACR epoxy R80 (manufactured by N.C.R.,
bisphenol A type epoxy resin) 25 parts by weight,
Liquid NBR with carboxyl groups at both ends (CTBNI
300X13, Ube Industries type) 50 parts by weight, and 5L20
Thermosetting resin Y: 50 parts by weight of Epicoat 828 (manufactured by Yuka Shell Epoxy), which is a mixture of 25 parts by weight of G (manufactured by intermediary oil and fat, epoxy resin derived from dibasic acid) and 3 parts by weight of dicyandiamide; Liquid NBR (C
TBN1300X13, manufactured by Ube Industries) 50 parts by weight,
UL20DH (Made by Intermediate Oil Co., Ltd., acid hydrazine hardener) 1
25 parts by weight of thermosetting resin Yl Epicoat 828 (manufactured by Yuka Shell Epoxy) mixed with 4 parts by weight, and liquid NBR (C
TBN1300X13, manufactured by Ube Industries) 75 parts by weight,
The damping performance was measured when the thermosetting resin compositions X, Y, and Yl, each containing 7 parts by weight of tlL20 Kano (manufactured by Intermediate Oil Co., Ltd.), were sandwiched between the steel plates. In the measurement, the relationship between loss coefficient and temperature at a vibration frequency of 500 Hz was determined using mechanical impedance. The results are shown in Figure 2.

In the damping steel plate of the present invention, the thickness of the adhesive resin layer serving as the interface layer is not particularly limited, but from the viewpoint of adhesive strength and workability, it is more effective to be thinner than thinner, and 1 to 5 μm is preferable. The reason for this is that if the interface layer is thick, it may not be able to follow the strain caused by processing. Therefore, an effective method is to apply a thin layer of resin that will become an interface layer and then sandwich a resin with a high vibration damping effect, and the coated surface may be the resin side with a high vibration damping effect or the metal side.

However, if the resin having a high vibration damping effect is in the form of a paste or a thermosetting resin, it is preferable to apply it to the metal surface side. Furthermore, even when applied to a metal surface, if the resin layer is thin and uncured, it may mix with the resin, which has a high vibration damping effect, and it may not be possible to form the interfacial layer that is a feature of the present invention. It is necessary to semi-cure or completely cure the material before inserting a damping resin layer made of a resin with a high damping effect.

The resin composition for vibration damping materials of the present invention can be used in the form of a sheet or film by a conventional method, but it can also be used in the form of a paste. For example, if a solid epoxy resin is used as the component (A), it will become a semi-solid resin composition that can be easily formed into a sheet or film, so it can be molded using a roll or press. Furthermore, even in the paste state, it is applied to the base material and preheated to a semi-cured state to the extent that the adhesiveness is not impaired.
It can be used by a method such as stacking another base material, forming a sandwich, and bonding by heating and curing. The thermal bonding conditions at this time are press molding, continuous molding with rolls, etc., with a pressure of 0.1 to 200 to the surface of the pressure crab metal plate.
kg/cm", temperature: The reaction temperature of the epoxy resin is preferably 150 to 250° C. 1 hour: 1 to 60 minutes. In any case, an appropriate processing method may be adopted depending on the properties of the resin composition. It is not particularly stipulated.

The vibration damping resin composition of the present invention can be used for various inorganic and organic base materials, but is particularly preferably used as a vibration damping steel plate in the form of a so-called plate having a metal base material. used. In this case, the thickness of the steel plate sandwiching the resin composition is 0.3 to 10 mm, and the thickness of the damping resin layer is 0.3 to 10 mm.
．． It is preferably about 0.01 to 3 mm.

(Effects of the Invention) As we have seen above, according to the present invention, there is no direct adhesion between the resin with vibration damping properties and the metal, so even resins with low adhesion ability to metal can be used. This effect can be obtained. This means that there are fewer restrictions on resins that have vibration damping properties. In other words, the composite damping steel sheet of the present invention has the effect that workability is ensured even if the adhesive strength with metal is somewhat insufficient, as long as the resin exhibits damping properties in a wide temperature range from low to high temperatures. can get. In this way, the composite vibration damping material of the present invention exhibits excellent damping properties in a wide temperature range from low to high temperatures, has good workability at room temperature, and can be formed by cold working etc. using a known method. It can be used for various purposes such as interior and exterior parts of automobiles, civil engineering and construction materials, industrial materials, machinery, and equipment.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the 180-degree bending test method for damping steel plates. Figure 2 shows the loss coefficient and temperature variation of damping steel plates using resin compositions with damping properties used in Examples and Comparative Examples. It is a curve diagram showing a relationship.

Claims (1)

[Scope of Claims] In a damping steel plate formed by sandwiching a resin with high vibration damping ability between one or two metal plates, an adhesive made of a resin composition containing an epoxy resin as a main component and applied in advance onto the metal plate. A vibration damping resin layer made of a resin with high vibration damping ability is sandwiched between the vibration damping resin layers, and the vibration damping resin layer contains the following components (A) 10 to 50 parts by weight of a bisphenol A type epoxy resin and ( B) 20 to 70 parts by weight of liquid NBR having functional groups at both ends; (C) long-chain epoxy resin and curing agent for epoxy resin;
Alternatively, a vibration-damping steel plate comprising a resin composition containing 5 to 60 parts by weight of a long-chain curing agent for epoxy resin as an essential component.