JPH0550553A - Manufacture of composite vibration dampening material excellent in spot weldability - Google Patents

Abstract

PURPOSE:To obtain the composite vibration-dampening material excellent in weldability, vibration-dampening property and spot weldability by a method in which when the intermediate layer composed of thermoplastic resin, crosslinking agent and conductive material are clamped between two metallic sheets and are stuck mutually under heating, the gel molecular fraction of the resin on the metallic sheet before being mutually stuck under heating, is limited to at most specified value. CONSTITUTION:The resin composition composed of thermoplastic resin and crosslinking agent is prepared, and at least one surface to be laminated of a metallic sheet, and preferably both surfaces to be laminated thereof are directly coated with said resin composition and conductive filler, and then they are heated at room temperature or at the temperature of 100-200 deg.C and solvent is removed. Then, continuously or after said materials have been left as they are, they are laminated under heating, and thus composite vibration-dampening material is produced, The gel molecular fraction of the resin on the metallic sheet before being mutually stuck under heating is limited to at most 70%, and more preferably to at most 60%. If is exceeds 70%, the weldability is reduced. Thus, since conductive metallic powder, carbon and solvent, etc., may be easily added to the resin composition, the vibration-dampening material capable of spot welding is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite damping material,
More specifically, it relates to a composite vibration damping material having excellent spot weldability and shear adhesive strength.

[0002]

2. Description of the Related Art Reflecting the recent world-oriented environment, interest in noise and vibration, which are one of environmental problems, is increasing, and many efforts are being made to solve this problem. With regard to noise, in particular, with regard to automobile noise, related bills such as the Noise Control Law have been embodied and have been implemented. Therefore, development of materials for noise prevention is active. Against this background, materials having a vibration-damping effect are required, and among them, a composite vibration-damping material in which an intermediate resin layer made of a viscoelastic resin is interposed between two metal plates is attracting attention as a noise / vibration preventing agent. Has been done. This composite type vibration damping material is one in which the intermediate resin layer converts the vibration applied to the metal plate into heat energy, and can be widely used in the automobile industry, the civil engineering construction industry, the electrical machinery industry and the like. For example, building materials such as engine oil pans, stairs, doors, floor materials, roof materials, motors,
It is being used or considered for use as a compressor.

Generally, the damping performance of such a composite damping material (hereinafter referred to as damping material) depends on the performance of the intermediate resin layer. Then, this damping performance is expressed by the loss coefficient (η)
Η has a characteristic of showing a peak at a certain temperature, and it is most effective to use the damping material in the vicinity of this peak characteristic temperature. As the intermediate resin layer of the damping material,
Conventionally, polyurethane (JP-A 47-19277), polyester (JP-A 50-143880), polyamide (JP-A 51-79146), polyisobutylene (JP-A 54-4)
3251), ethylene / α-olefin (JP-A-55-8)
4655), EVA (JP-A-57-34949), cross-linked polyolefin (JP-A-59-152487), polyvinyl acetal (JP-A-60-88149), and the like are being studied. It is known that asphalt, synthetic rubber, acrylic adhesive, epoxy resin and the like also have vibration damping performance.

The resin applied to such an intermediate resin layer is generally a thermoplastic resin as described above. However, if these are applied as they are as the intermediate resin layer of the vibration damping material, there arises a problem in baking performance (heat resistance during baking coating). Therefore, in a general vibration damping material, an adhesive property and a baking property are improved by adding a cross-linking agent corresponding to these thermoplastic resins to impart thermosetting property.

Further, the damping material is pressed, bent,
Since it undergoes processing such as drawing processing, it is required to have an adhesive strength that can withstand these processing. Such a damping material having an intermediate resin layer composed of a thermoplastic resin and a cross-linking agent is generally prepared by dissolving the resin as described above in a solvent corresponding thereto to prepare a mixed solution containing the cross-linking agent. It is manufactured by applying this mixed solution on a metal plate, laminating similar metal plates with the coated surface inside, and thermocompressing the laminated body. According to this method, the damping performance peak temperature can be adjusted to some extent by adjusting the amount of the cross-linking agent added to the mixed solution, and since the intermediate resin layer is a thermosetting type, the adhesive performance and baking performance are improved. Can be made

Further, the spot weldability is an important characteristic required for the composite type vibration damping material. Since the composite type vibration damping material sandwiches the resin having no conductivity as the intermediate layer, the two metal plates are insulated. Various attempts have been made to impart spot weldability to such composite vibration damping materials. Iron, graphite, in the intermediate resin layer
An attempt to add conductivity by blending particles such as a silicon alloy (JP-A-56-31540, JP-A-58-160141, JP-B-SHO)
No. 60-25232), and a combination of spiral conductors (JP-A-58-14).
No. 2844), blending of metal fibers (Japanese Patent Laid-Open No. 58-142845), weldable clad steel plate (Japanese Patent Laid-Open No. 56-136291) in which irregularities are formed and bonded on the bonding surface of the steel plate, bonding surface Formation of projections of the same metal by thermal spraying on the surface (Japanese Patent Laid-Open No. 62-227741)
Various attempts have been made such as limiting the ratio of the particle diameter of the metal filler to the thickness of the intermediate resin layer.

[0007]

The present situation is that none of the composite type vibration damping materials satisfying all of the adhesive performance, the vibration damping performance and the spot welding performance required above has been found yet. In particular, regarding the spot weldability, the approaches such as the shape of the metal filler, the particle size, and the processing of the metal plate are the main ones, and the approach from the resin side is rarely made.

In view of this point of view, it is an object of the present invention to propose a method for producing a composite vibration damping material in which the spot welding performance is improved by the approach from the resin side without impairing the adhesion performance and the vibration damping performance. It is a thing.

[0009]

According to the present invention, when an intermediate layer composed of a thermoplastic resin, a cross-linking agent and a conductive substance is sandwiched between two metal plates and heat-bonded, the heat-bonded metal plate before heat-bonding is used. The method for producing a composite damping material is characterized in that the gel fraction of the resin is adjusted to 70% or less. First,
The constituent components of the resin composition used in the composite vibration damping material of the present invention will be sequentially described.

The thermoplastic resin may be a thermoplastic resin having a glass transition temperature of −30 ° C. or higher and having a functional group capable of reacting with a crosslinking agent, but a saturated copolyester resin is preferable. The saturated copolyester refers to the following compounds. That is, aromatic dibasic acids such as dimethyl terephthalic acid, terephthalic acid, isophthalic acid, phthalic acid, succinic acid, glutaric acid, adipic acid, β-methyladipic acid, pimelic acid, 1,6-hexanedicarboxylic acid, One or more kinds of aliphatic dibasic acids such as azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, and hexadecanedicarboxylic acid; and ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,5-pentanediol, 3-methylpentanediol, 1,3-hexanediol, 1,6-hexanediol, 1, 4-
Polyester or caprolactone synthesized from one or more of glycols such as cyclohexanediol, hydrogenated bisphenol A, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, polytetramethylene glycol, and their residue-forming derivatives. It is a more synthetic polyester.

The method for synthesizing the saturated copolyester resin is as follows. That is, the saturated copolyester resin used in the present invention can be synthesized by a conventional method. Specifically, it is synthesized by the esterification reaction of the above-mentioned dibasic acid and glycol and the subsequent transesterification reaction while distilling off excess glycol at high temperature under reduced pressure, or polyethylene terephthalate, polysynthesized in advance. Butylene terephthalate and the like may be depolymerized in the presence of the desired dibasic acid and excess glycol, and similarly synthesized by a transesterification reaction.

The polymerization catalyst is tetra-n-butoxytitanium,
It is appropriately selected from ordinary catalysts composed of metal salts such as zinc acetate, antimony trioxide and potassium titanate oxalate. The second essential constituent is a cross-linking agent, and a cross-linking agent suitable when using a saturated copolyester resin is a polyvalent isocyanate compound. The polyvalent isocyanate compound used in the present invention is a polyvalent isocyanate compound having two or more isocyanate groups in the molecule.
4-tolylene diisocyanate, 2,6-tolylene diisocyanate (usually TDI), methylene-bis-4-phenyl isocyanate (usually MDI), polymethylene polyphenyl polyisocyanate or polyol modified M
MDI derivatives such as DI, carbodiimide modified MDI,
Hexamethylene diisocyanate (usually HDI) and its derivatives, isophorone diisocyanate (usually IPD)
I) and its derivatives, TDI-based adduct polyisocyanates obtained by adding TDI to trimethylolpropane, etc., such as commercially available products Coronate L, HL (above,
Nihon Polyurethane), Dismofen L, Dismodur N (Sumitomo Bayer Urethane), and MDI diisocyanates include Millionate MTL-C (manufactured by Nippon Polyurethane Co.). In addition, polymerized polyisocyanates that have been reacted in advance, for example, commercially available products such as Sprasec 3240, 3250, Coronate 2030, 2031 (Japan Polyurethane), Dismodur IL, HL (Sumitomo Bayer Urethane), isocyanate masked blocks with caprolactam, etc. Examples thereof include doisocyanate and a terminal isocyanate prepolymer obtained by previously reacting a low molecular weight polyether with the above-mentioned polyvalent isocyanate.

In the present invention, any of these can be used as the polyvalent isocyanate compound, but adduct polyisocyanate and polymerized polyisocyanate are preferable from the viewpoint of improving the adhesiveness. The resin component of the present invention is
As described above, the amount ratio is such that the isocyanate group of the polyvalent isocyanate compound is equivalent to 1 equivalent of the hydroxyl group in the saturated copolyester resin calculated from the number average molecular weight.
A quantity ratio of 0.5 to 10 equivalents is preferable. If the amount is less than 0.5 equivalent, the cohesive force of the obtained viscoelastic resin is extremely small, which may cause problems such as deviation during molding and peeling. On the other hand, when 10 equivalents or more are used, the vibration damping performance of the obtained viscoelastic resin is significantly reduced.

Examples of additives that can be used in combination are polyester resins other than thermoplastic polyester resins, acrylic resins having terminal hydroxyl groups, bisphenol epoxy resins, epoxy resins such as cresol novolac epoxy resins, styrene resins, α-methylstyrene resins. Styrene resin such as, terpene resin, terpene phenol resin,
Rosin-based resins, hydrocarbon-based resins, aromatic-based resins, tackifying resins such as phenolic resins, polyalkylene glycol polyester-based plasticizers, melamine resins, organofunctional silanes (commonly known as silane coupling agents), peroxides, etc. And a metal salt such as n-butyltin dilaurate, an amine-based or glycol-based isocyanate curing catalyst, and a chain extender.

Further, as the filler, calcium carbonate,
Inorganic fillers such as talc and hard seal can be used, and as the solvent, toluene, MEK, acetone, xylene and the like can be used. Further, by adding a conductive solid substance as a filler to the resin composition to impart conductivity, a damping material having a viscoelastic resin obtained from the resin composition as an intermediate layer can be spot-welded. To do. As the conductive solid substance used for this purpose,
Metal substances such as iron, stainless steel, zinc, copper, tin, nickel, aluminum, and brass processed into powder, flakes, fibers, and wires, and plated metal such as copper or nickel, and carbon The conductive carbon substances such as black, graphite and carbon fiber may be used alone or in combination of two or more. In addition, as the conductive substance, it is preferable to select a metal substance in order to exhibit good conductivity.

When the conductive substance is in the form of powder, its maximum thickness is, and when it is in the form of fibers or wires, its maximum diameter is its representative length (L). In order to develop better conductivity,
The ratio (L / T) between the representative length (L) and the thickness (T) of the viscoelastic resin obtained from the resin composition having a conductive substance is 0.5.
It is preferable to use the above, preferably 0.8 or more. If the L / T ratio is less than 0.5, the spot welding performance of the vibration damping material having the viscoelastic resin as the intermediate layer is deteriorated.

Further, the filling amount of the conductive substance is preferably such that the viscoelastic resin obtained from the resin composition containing the conductive substance occupies 0.5 to 10% by volume. If it is less than 0.5% by volume, the spot welding performance of the damping material having the viscoelastic resin as the intermediate layer is low, and if it exceeds 10% by volume, the spot weldability is sufficiently satisfied. This is not preferable because the adhesiveness between them and the damping performance of the damping material are reduced.

The layer thickness of the intermediate resin layer is determined in relation to the plate thickness of the metal plate to be composited, but is generally about 20 to 150 μm. If it is less than 20 μm, the vibration damping performance is insufficient, and it is 150 μm.
If it exceeds the above range, it may cause misalignment during molding. The metal plate applied to the vibration damping material is not particularly limited, and any of cold-rolled steel plate, chromate-treated steel plate, zinc-based plated steel plate, surface-treated steel plate such as phosphate-treated steel plate, copper plate, aluminum plate, stainless plate, etc. Or a coiled original plate or a cut plate. The plate thickness is not particularly limited, but it is 0.3 in consideration of moldability and shape retention.
It is preferably about 2 mm.

A typical example of the composite type vibration damping material of the present invention is one in which a viscoelastic resin is sandwiched as an intermediate resin layer between the two metal plates, but in addition to this, it has a multilayer structure. Those etc. are also included in the present invention. Next, a preferred method for producing the composite damping material of the present invention will be described. The composite damping material of the present invention is a resin composition comprising a thermoplastic resin and a cross-linking agent, and the resin composition and the conductive filler are directly applied to at least one of the metal plates, preferably to the laminated surface of both. After coating and heating at room temperature or preferably at a temperature of 100 ° C. or more and 200 ° C. or less to distill off the solvent, it is heated or laminated and adhered continuously or after standing.

In the present invention, the gel fraction of the resin on the metal plate before heat bonding is limited to 70% or less. More preferably
It is less than 60%. If it exceeds 70%, spot weldability deteriorates. The gel fraction can be adjusted by changing the heating temperature or the heating time in the heating step before heat bonding.

The method of applying the liquid resin composition onto the metal plate is not particularly limited, but a roll coater, a spray, a curtain flow coater, a doctor knife coater and the like are preferable. The lamination adhesion temperature is usually the same as the resin composition.
It suffices that heating at 130 to 250 ° C. is applied, and a contact time of about 2 seconds to 2 minutes in the case of a hot press and about 0.5 to 10 seconds in the case of a heating roll. Alternatively, the metal plates may be heated to the same temperature in advance and laminated and bonded by a cooling press or a cooling roll.

A solvent can be added to the resin composition used in the present invention, and in that case, since it can be applied to the metal plate in a liquid state, the adhesion between the metal plate and the intermediate layer can be enhanced,
It is possible to prevent gas entrapment. Further, in order to facilitate the addition of conductive metal powder, carbon, etc. added to the damping material of the present invention for the purpose of imparting spot weldability to the resin composition used in the present invention, the resin composition Although it is preferable to add a solvent to the product, conductive metal powder, carbon, a solvent, etc. can be easily added to the resin composition used in the present invention. Can be easily obtained.

In addition, the composite type vibration damping material of the present invention has a characteristic that a predetermined adhesiveness can be obtained immediately after the adhesion, and in the production thereof, it is produced under the same condition as the case of using a usual thermoplastic resin. However, the intermediate layer has a feature that it exhibits heat resistance equal to or higher than the bonding temperature.

[0024]

[Operation] In the present invention, since the gel fraction of the resin on the metal plate before heat bonding is limited to 70% or less, it is possible to improve the spot weldability without impairing the bonding performance and the vibration damping performance. It was The reason is considered as follows. A metal filler is added to the intermediate resin layer for the purpose of imparting spot weldability. Examples of the method for dispersing the metal filler include a method in which the metal filler is added and mixed in the resin solution and applied on the metal plate, and a method in which the resin filler is applied on the metal plate and then the metal filler is dispersed. Also in this case, the metal plates are bonded by thermocompression bonding. At that time, the metal filler dispersed in the resin is deformed to some extent by pressurization. When the gel fraction of the resin is high, the resin does not have fluidity, and thus the contact area between the metal filler and the metal plate is prevented from increasing in the process of deforming the metal filler. Furthermore, since the resin does not have fluidity, the resin layer is deformed by pressurization and returns to its original thickness when pressure is removed, whereas the metal filler is deformed by pressure and is removed even when pressure is removed. , Its thickness is almost unchanged. Therefore, the resin layer becomes thicker than the deformed metal filler. Due to the above reasons, the spot weldability deteriorates when the gel fraction at the time of pressure bonding is high.

If the gel fraction of the resin before heat-bonding is 70% or less, the above problem does not occur and a damping material having good spot weldability can be obtained.

[0026]

EXAMPLES The present invention will be specifically described below based on examples. Moreover, the damping material was manufactured by the following method and evaluated. (1) Physical properties of the thermoplastic polyester resin used The glass transition temperature, softening temperature and number average molecular weight of the resin were measured by the following methods.

Measurement of glass transition temperature Using a thermoplastic polyester resin as a 1 mm thick sheet, the dynamic elastic modulus (E ') is measured by a viscoelasticity spectrum meter (10 Hz), and the temperature at which the elastic modulus begins to decrease is defined as the glass transition temperature. And Measurement of softening temperature According to JIS K 2531, measurement was made by R & B softening point, and the temperature was defined as softening temperature.

Measurement of number average molecular weight A thermoplastic polyester resin was dissolved in tetrahydrofuran and measured by liquid chromatography to calculate the number average molecular weight in terms of polystyrene. (2) Preparation of resin composition A thermoplastic polyester resin was dissolved in a mixed solvent of toluene and MEK (1/1 by weight ratio) so as to have a solid content (hereinafter abbreviated as NV) of 30%, and a polyvalent polyvalent crosslinking agent. As an isocyanate compound, Coronate 2030 [NV = 50%, NCOwt% =
7.7%, manufactured by Nippon Polyurethane Industry Co., Ltd.] was added and mixed in an amount of 3 parts by weight with respect to 100 parts by weight of the thermoplastic polyester resin solution to obtain a resin composition. (3) Manufacture of composite vibration damping material As a metal plate, cold rolled steel plate (SPCC-S) with a thickness of 0.8 mm
D) was used after degreasing.

The resin composition was applied to one side of the steel sheet by a doctor knife coater so that the thickness after drying was about 25 μm. Immediately after that, the average particle size was 70μ by gravure roll.
Ni powder of m was uniformly dispersed so as to be 2 vol% with respect to the resin volume, and air-dried. Similarly, the resin composition was applied to another steel plate and air-dried without spraying the Ni powder.
These two steel plates are heated and dried in an oven (200 ° C), the solvent is distilled off, and the steel plates with resin layers are stacked with the resin layer side facing inward, and a heat roll (200 ° C, linear pressure 10 kgf / cm ) And heat-bonded to obtain a damping material. The gel fraction was adjusted by changing the heating time in the oven in order to change the gel fraction during bonding. (4) Performance evaluation test Adhesive strength Shear adhesive strength (SAS) based on JIS K 6850 test method
Was measured at room temperature at a tension rate of 5 mm / min.

Gel Fraction The soluble fraction of the resin on the steel sheet which was gelled by heat drying was removed by the Soxhlet extraction method (reflux for 1 hour), and the weight ratio before and after extraction was taken as the gel fraction. Spot welding test CF type, 3.2mm diameter Cu-Cr electrode is used as an electrode.
4 energizing cycles, current 4kA, pressurizing load 100kgf
Under these conditions, 100 spots were made, and the number of spot welding success spots per 100 spots was defined as the spot welding success rate (%). The initial resistance value of spot welding represents the resistance value of the first cycle of energization.

Example 1 An equivalence ratio of 60 moles of terephthalic acid residue, 40 moles of adipic acid residue, 60 moles of ethylene glycol residue and 40 moles of 1,6-hexanediol residue having a number average molecular weight of 15,000,
A saturated polyester resin having a glass transition temperature of -25 ° C was synthesized by a conventional method. This polyester is toluene, MEK
It was dissolved in a solvent having a weight ratio of 1/1 to a solid content (NV) of 25% to obtain a resin solution. Coronate 2030 [NV = 50%, NCO content 7.7%, manufactured by Nippon Polyurethane Industry Co., Ltd.], which is a polyvalent isocyanate compound, was used as a crosslinking agent.

A degreased cold-rolled steel sheet having a thickness of 0.8 mm was used as a metal plate constituting the composite type vibration damping material, and the composite type vibration damping material was produced according to the above manufacturing method. With respect to the obtained composite vibration damping material, a spot welding performance test, a shear adhesive strength (SAS) test, and a gel fraction were measured under the above conditions.
The results are shown in FIGS. The vibration damping performance was well above the desired level, although not particularly mentioned.

[0033]

Industrial Applicability According to the present invention, a composite type vibration damping material having excellent spot weldability and shear adhesive strength can be stably manufactured industrially. Therefore, the composite vibration damping material having excellent performance, which can be used in the automobile field and the like, can be stably provided.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between a gel fraction at the time of bonding and a spot welding success rate.

FIG. 2 is a graph showing the relationship between the gel fraction at the time of bonding and the shear adhesive strength.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location C08G 18/02 NDQ 8620-4J // B23K 11/11 543 9265-4E F16F 15/02 Q 9138- 3J (72) Inventor Hidetaka Sugibe 1 Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Technical Research Division

Claims (2)

[Claims] 1. When sandwiching an intermediate layer composed of a thermoplastic resin, a cross-linking agent and a conductive substance between two metal plates and performing heat bonding, the gel fraction of the resin on the metal plates before heat bonding is determined.
A method for producing a composite vibration damping material, which comprises adjusting the content to 70% or less. 2. The method for producing a composite vibration damping material according to claim 1, wherein the thermoplastic resin is a saturated copolyester resin and the crosslinking agent is a polyvalent isocyanate compound.