JPH04336239A - Damping structure for vehicle - Google Patents

Abstract

PURPOSE:To impart high damping properties, rigidity and heat insulating properties to a panel over a wide temp. range so as to follow the uneven surface of the panel in the structure bonded to the vibration substrate such as the floor panel of a vehicle. CONSTITUTION:A semi-gelled spacer sheet formed from a composition consisting of a liquid epoxy resin, a coreactive curing agent, a foaming agent, a surfactant and a rubber elastomer or a thermoplastic resin is laminated to the under surface of a damping sheet composed of a viscoelastic material and the formed laminate is placed on a panel uneven steel plate shown by Fig 1, integrally welded thereto in a heat-drying process of panel painting and foamed.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a vibration damping structure for a vehicle, which is integrated by fusion molding onto a substrate that easily vibrates, such as a floor panel, dash panel, wheel house, ceiling panel, etc. of a vehicle. be.

0002

BACKGROUND OF THE INVENTION Vibration substrates such as floor panels, dash panels, wheel houses, ceiling panels, etc. of vehicles are often fused with a heat-fusible damping material containing asphalt as a main component. In addition, in recent years, restraint-type vibration damping has been developed by providing metal sheets such as steel plates and aluminum plates as restraining materials on the top surface of asphalt-based vibration damping materials, or by laminating thermosetting resins such as epoxy resins, diallyl phthalate resins, and acrylic resins. Efforts are also being made to improve the vibration damping performance of the structure. Furthermore, recently, attempts have been made to improve the damping performance by foaming a damping material whose main component is asphalt. However, these damping structures have the following problems. In other words, in a double-layer damping structure in which the vibration of a vibrating board is damped only with a heat-adhesive damping sheet mainly composed of asphalt, etc., in order to improve its damping performance, it is necessary to increase the thickness. This results in the inconvenience of increasing the weight of the vehicle. In addition, we made this asphalt-based damping material foamable,
Techniques for suppressing the weight increase have recently begun to be widely used, but the improvement in damping performance within a practical weight range is not significant. In addition, in order to tightly adhere a highly rigid metal sheet to the heat-adhesive vibration damping material using a metal sheet such as a steel plate or aluminum plate as a restraining material on the asphalt-based vibration damping material, for example, a highly rigid vibration base such as a steel plate is used. mechanically fixed to,
Alternatively, it is necessary to fix by a method such as screwing using bolts or the like. However, since the floor panels of vehicles are generally press-formed into an uneven shape to provide rigidity, it is necessary to form the restraining metal sheet into a complementary shape, which requires an extra process. Another problem is that it is not easy to correctly position the device at a predetermined position during installation.

[0003] In addition, there is a method in which an uncured thermosetting resin is placed on a vibration damping material and cured during the drying process of the coating and used as a restraining material, and a thermoplastic resin using a tackifier resin as a base material. Another method is to use the resin as a restraining material by placing the resin on the damping material and heat-sealing it during the coating drying process. Although the method of using these hard resin materials as a restraint material is certainly effective in improving vibration damping performance, it still does not involve a significant increase in weight from the perspective of reducing noise in the interior of a modern vehicle. The current situation is that the improvement in vibration damping performance when using a resin restraint material within a practical range is becoming insufficient.

0004

[Problems to be Solved by the Invention] In order to solve these problems, the present inventors first added a liquid epoxy resin and a heat-activated type to a composition consisting of a vinyl chloride resin for paste, a plasticizer, a foaming agent, etc. We have proposed a so-called vibration damping structure with a thermosetting foam spacer (Japanese Patent Application No. 2-75495), which uses a foamable semi-gelled sheet containing a hardening agent as a spacer, and has excellent vibration damping and a lightweight structure. However, since the composition contains vinyl chloride resin, there is a problem that the resin may thermally decompose at high temperatures, such as those used in the electrodeposition coating process in automobile production lines. Ta. Under these circumstances, the present invention provides a vehicle structure that is lightweight and provides high vibration damping performance, and also provides:
The object of the present invention is to provide a vibration damping structure with a thermosetting foam spacer having a composition that has good heat resistance and can withstand, for example, an electrodeposition coating process.

[0005]

[Means for Solving the Problems] According to the present invention, rubber,
In a two-layer structure consisting of a damping sheet (2) made of a viscoelastic material such as asphalt and a spacer sheet (1) made of a foamable thermosetting resin sheet sandwiched between a vehicle vibration substrate, the spacer sheet (1) ) is (A) an epoxy resin 10 having one or more epoxy groups in one molecule.
0 parts by weight, (B) coreactive curing agent for epoxy resin 0.5
~20 parts by weight, (C) cracked gas temperature 100~220°C
0.5 to 20 parts by weight of blowing agent, (D) surfactant 0.0
5 to 5 parts by weight, and (E) a rubber elastic material that is insoluble in the epoxy resin at room temperature and can be mixed and dispersed with the epoxy resin at a temperature of 80 to 150°C, or a halogen-free material that is insoluble in the epoxy resin at room temperature. Not contained, average particle size 150μ
contains 10 to 200 parts by weight of at least one selected from powdered thermoplastic resins of not more than m, and the blowing agent (
A vehicle characterized in that the sheet is semi-gelled by heating at a temperature below the decomposition gas generation temperature of C), and the adhesive surfaces of these sheets and panels fuse together and foam as a result of heating. A vibration damping structure is provided.

The present invention also provides a structure for a vehicle that is capable of imparting excellent vibration damping performance within a range where the weight of the vehicle is small by integrating the structure with a vibration substrate of the vehicle. It is something. Furthermore, for this type of vehicle structure, it is necessary to adhere to the uneven vibrating substrate by heat treatment during the drying process such as painting, and to complete the reaction, foaming, and fusion of each layer, and at a relatively high temperature. However, a material with preferable properties that exhibits less deterioration in physical properties is required, and the structure according to the present invention satisfies these requirements.

[0007] Each constituent layer related to the present invention will be explained below. The spacer sheet (1) used in the present invention is made of a foamable thermosetting resin sheet, and its desirable properties as a spacer in a vibration damping structure for a vehicle are that it is lightweight, has high rigidity, has little change in physical properties due to temperature changes, and is dry when painted. It is closely attached and fixed to the uneven vibrating substrate during the process, and moreover, it has a high-magnification foaming effect during this process. In the spacer composition of the present invention, the liquid epoxy resin used as component (A) contains one or more epoxy groups in the molecule, and examples of such resins include (i) bisphenol A, bisphenol Glycidyl ethers based on F or resorcinol, ■Polyglycidyl ethers of phenolic novolac resins or cresol novolac resins, ■Glycidyl ethers of hydrogenated bisphenol A, ■Glycidylamine type, ■Linear aliphatic epoxide type, phthalic acid, hexahydro Among the glycidyl ethers of phthalic acid or tetrahydrophthalic acid, preferable epoxy equivalents include those having an epoxy equivalent of 100 to 300. These liquid epoxy resins may be used alone or in combination of two or more,
In addition, in order to impart toughness to the resulting foam, phenol A added with ethylene oxide or propylene oxide is added.
Flexible epoxy resins such as type epoxy resin, dimer acid type epoxy resin, and epoxy-modified NBR may be used in combination.

In the spacer composition of the present invention, a co-reactive curing agent for epoxy resin is used as component (B). The curing agent preferably has an exothermic peak temperature in the range of 100 to 200°C in combination with the epoxy resin, and examples of such curing agents include dicyandiamide, 4,4,'-diaminodiphenylsulfone, 2-n - imidazole derivatives such as heptadecylimidazole, isophthalic acid dihydrazide, N,N-dialkylthiourea derivatives, acid anhydrides such as tetrahydrophthalic anhydride, isophorone diamine, m-phenylene diamine, N-aminoethylpiperazine, trifluorocarbon Examples include boric acid complex compounds and trisdimethylaminomethylphenol. These curing agents may be used alone or in combination of two or more, and the amount added is 0 to 100 parts by weight of the epoxy resin as the component (A).
．． It is in the range of 5 to 20 parts by weight. If this amount is less than 0.5 parts by weight, curing will be insufficient and the rigidity of the foam will be insufficient;
If the amount exceeds 0 parts by weight, the rigidity of the foam will not improve in proportion to the amount, which will be economically disadvantageous. The curing temperature here refers to the temperature of the medium at which the heat generated by curing reaches its peak when the mixture of epoxy resin and curing agent at room temperature is heated in an oil bath, heater, etc. In addition, preferred combinations and amounts of epoxy resin and curing agent depending on the heating conditions can be easily determined by testing in advance. In the present invention, in addition to the curing agent of component (B), if necessary, curing accelerators such as alcohol, phenol, mercaptan, dimethylurea, aliphatic, imidazole, monuron, chlorotoluene, etc. etc. can be used.

In the spacer composition of the present invention, component (C) has a decomposition gas generation temperature of 100 to 220°C.
A high-temperature decomposition type blowing agent of °C is used. As such a high temperature decomposition type foaming agent, an organic foaming agent, an inorganic foaming agent, a high temperature expansion type microcapsule, etc. can be used. If the decomposition gas generation temperature is below 100°C, foaming may begin during the processing of semi-gel sheets, which will be described later, or gas may escape due to insufficient melting of the resin during foaming in the heating furnace, and the foaming ratio may not be large. Or it is difficult to obtain a homogeneous foam. Further, if the temperature exceeds 220° C., the processing temperature of the composition becomes high and the resin deteriorates, making it difficult to obtain a foam of good quality. Examples of such organic blowing agents include azodicarbonamide, p-toluenesulfonylhydrazide, dinitrosopentamethylenetetramine,
Examples include 4,4'-oxybisbenzenesulfonyl hydrazide. The decomposition temperature of these organic blowing agents can be adjusted by adding urea, zinc compounds, lead compounds, etc.
Can be easily adjusted. Examples of inorganic blowing agents include sodium hydrogen carbonate and sodium borohydride, and examples of high-temperature expansion microcapsules include those obtained by encapsulating low-boiling hydrocarbons with vinylidene chloride resin.

[0010] In the present invention, any of the above-mentioned organic blowing agents, inorganic blowing agents, and high-temperature expansion type microcapsules can be used, but organic blowing agents are suitable from the viewpoint of expansion ratio and economical efficiency. . Further, these blowing agents may be used alone or in combination of two or more. The amount added is selected within the range of 0.5 to 15 parts by weight per 100 parts by weight of the liquid epoxy resin (A). If this amount is less than 0.5 parts by weight, foaming will be insufficient, and if it exceeds 15 parts by weight, the expansion ratio will not improve in proportion to the amount, and problems such as roughened foam cells will often occur. In order to obtain a dense foam having a uniform cell diameter and a rigid cell membrane, it is advantageous for the particles of the blowing agent to have a small particle size, for example, 0.1 to 0.6 mm, preferably 0.
In order to obtain a foam having a cell diameter of around 3 mm, the particle diameter is preferably 20 μm or less, preferably 10 μm or less, and uniform. In the present invention, a foaming accelerator can be used in addition to the foaming agent, if necessary. Examples of foam accelerators include calcium stearate, barium stearate, sodium and potassium compounds,
Examples include urea.

In the spacer composition of the present invention, a surfactant is used as component (D). This surfactant has the role of improving the cell structure. Examples of the surfactant include alkyl sulfate salts such as sodium lauryl sulfate and sodium myristyl sulfate, alkylaryl sulfonates such as sodium dodecylbenzenesulfonate and potassium dodecylbenzenesulfonate, sodium dioctylsulfosuccinate, Preferred examples include sulfosuccinic acid ester salts such as sodium dihexyl sulfosuccinate, fatty acid salts such as ammonium laurate and potassium stearate, anionic surfactants such as polyoxyethylene aryl sulfate ester salts and rosinate salts. In addition, sorbitan esters such as sorbitan monooleate and polyoxyethylene sorbitan monostearate, nonionic surfactants such as polyoxyethylene ethers, polyoxyethylene alkylphenyl ethers, and polyoxyethylene alkyl esters, cetylpyridinium chloride, Cationic surfactants such as cetyltrimethylammonium bromide can also be used. These surfactants may be used alone or in combination of two or more. The amount added is selected within the range of 0.05 to 5 parts by weight, preferably 0.2 to 3 parts by weight, per 100 parts by weight of the liquid epoxy resin (A). If it is less than 0.05 parts by weight, it cannot play the role of improving the cell structure, and even if it is more than 3 parts by weight,
Considering the amount, the stability of the cell is not improved, and in some cases, it may cause discoloration due to decomposition during heating. When the rubber elastic body or thermoplastic resin used as component (E) is in powder form, the method for adding the surfactant is as follows:
It is advantageous to use it by spraying it in advance so that it can be dried and adsorbed uniformly.

(E) of the spacer composition of the present invention
As a component, a rubber elastic body or a halogen-free thermoplastic resin that is insoluble in the epoxy resin (A) at room temperature and can be mixed and dispersed with the epoxy resin at a temperature of 80 to 150°C can be used. In this case, the rubber elastic body can be not only solid but also viscous liquid, while the thermoplastic resin composition has an average particle size of 150 μm.
It is necessary to use a powder with a size of less than m. When the composition is heated to 150°C or higher, this rubber elastic body or thermoplastic resin melts to form a homogeneous affinity with the epoxy resin of component (A), and maintains the melt viscosity of the composition stably. Examples of such materials include rubber elastic bodies such as chloroprene rubber, butadiene-acrylonitrile rubber, carboxyl-modified butadiene-acrylonitrile rubber, epoxy-modified butadiene-acrylonitrile rubber, butadiene rubber, isoprene rubber, etc.
Vinyl acetate copolymer, polyphenylene ether, ethylene-vinyl alcohol copolymer, acrylonitrile-styrene copolymer, polyamide, polyvinyl butyral,
Examples include polyvinyl acetal, polymethyl methacrylate, acrylonitrile-butadiene-styrene copolymer, methyl methacrylate-butadiene-styrene copolymer, polystyrene, and the like. These may be used alone or in combination of two or more. Said (
Component E) has the function of adjusting the melt viscosity of the composition and also has the function of improving the toughness of the obtained foam. The amount of component (E) added is selected within the range of 10 to 200 parts by weight per 100 parts by weight of the liquid epoxy resin of component (A). It depends on the type of rubber elastic material or halogen-free thermoplastic resin added, but if it is less than 10 parts by weight, there is no function to adjust the melt viscosity or to improve the toughness of the foam, and on the other hand, if it is more than 200 parts by weight, this will not work. However, depending on the type of rubber elastic body or thermoplastic resin, disadvantages arise in that the expansion ratio of the foam does not improve or the rigidity of the foam decreases.

In the composition of the present invention, it is important to balance the affinity between the epoxy resin as the component (A) and the rubber elastic material and thermoplastic resin as the component (E). It is necessary to appropriately select the particle size, amount added, etc. In particular, in terms of affinity balance, a system in which polymers are completely compatible with each other during melting is not desirable;
It is desirable to be in a stable dispersed mixture state. Therefore, depending on the combination of polymers, it is desirable to add a plasticizer to increase the mutual affinity and adjust the affinity between the polymers. This plasticizer also has the function of adjusting melt viscosity, and examples of the plasticizer include phthalate esters such as dioctyl phthalate and dibutyl phthalate, phosphate esters such as tricresyl phosphate, dioctyl adipate, etc. Further, conventionally known fatty acid esters such as adipic acid condensates of ethylene glycol, trimellitic acid esters, glycolic acid esters, chlorinated paraffins, and alkylbenzenes can be used.

[0014] In the composition of the present invention, an epoxy resin diluent may be added as necessary for the purpose of facilitating initial mixing, increasing the amount of fillers, etc. added. Examples of the diluent include reactive diluents such as butyl glycidyl ether, allyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, persatic acid glycidyl ether, dibutyl phthalate, dioctyl phthalate, butyl benzyl phthalate, tricresyl phosphatate, etc. Mention may be made of non-reactive diluents such as phate, acetyltributyl citrate, aromatic process oil, pine oil, 2,2,4-trimethyl-1,3-pentadiol isobutyrate. A thixotropic agent or a filler may be added to the composition of the present invention, as necessary, for the purpose of adjusting coating properties such as processability and viscosity, or increasing the amount to reduce costs. etc. may be added. Examples of the thixotropic agents include silicic acid-based agents such as anhydrous silicic acid and hydrous silicic acid, bentonite-based agents such as organic bentonite, asbestos-based agents such as Cylodex, and organic agents such as dibenzylidene sorbitol. In addition, examples of fillers include calcium carbonate, mica, talc, kaolin clay, celite, asbestos, perlite, baryta,
Silica, silica sand, flaky graphite, dolomite limestone, gypsum,
Examples include aluminum powder.

The spacer composition of the present invention contains the essential components (A), (B), (C), (D) and (E) and various additive components used as desired. It can be adjusted using a quantitative method, for example, a planetary mixer, kneader, roll, Henschel mixer, etc. The spacer composition of the present invention prepared in this manner has a melt viscosity of 2.5 x 103 to 5 x 104 dP at the decomposition gas generation temperature of the blowing agent contained therein.
a. It is preferably in the range of s. If the melt viscosity is outside the above range, it will be difficult to obtain a foam with a good appearance, an expansion ratio of 5 times or more, and an average cell diameter of 0.5 mm or less. Further, in the structure of the present invention, this spacer composition is used in the form of a semi-gelled sheet. That is, the prepared composition is preformed into a sheet at a temperature below the decomposition temperature of the blowing agent,
After that, the vibration damping sheet (2) is laminated, and the next heating step, for example, the coating drying step, is carried out at 120°C to 200°C.
It is foamed and cured by crosslinking of the epoxy resin. The expansion ratio of the spacer sheet (1) is 2 to 30 times, preferably 5 to 10 times. A foam with a foaming ratio of 2 times or less can of course function as a spacer, but this is not the purpose of the present invention from the viewpoint of light weight, and if the foaming ratio is 30 times or more, the strength of the foam cells will be insufficient and the vehicle will be damaged. There may be problems with durability depending on where it is used. The thickness of the spacer sheet after foaming is 1 to 50 mm, preferably 3 to 30 mm.
It is. If it is less than 1 mm, it will not function effectively as a spacer, and if it is more than 50 mm, it will become impractical in vehicle applications, which is the purpose of the present invention, because the interior space of the vehicle will become narrow and heating processes such as drying processes will be difficult. In this case, homogeneous foaming properties cannot be obtained.

The vibration damping sheet (2) made of a viscoelastic material applied to the present invention is not particularly limited in type, such as rubber, resin, or asphalt. It is necessary to consider the required qualities such as thermal adhesion, uneven vibration substrate, and excellent vibration damping performance. Asphalt-based damping materials, butyl rubber-based damping materials, and the like are suitable in view of meeting these requirements and considering cost, lightness, etc. The thickness of such a damping sheet is 10 mm or less,
The thickness is preferably 2 mm or less. In the case of a thickness of 10 mm or more, the weight becomes extremely large, which is not the main purpose of the present invention. Further, there is no particular lower limit to the thickness. This is because, since the structure of the present invention is a damping structure with a spacer, the damping sheet (2) can sufficiently exhibit its function even if it is thin, although it depends on the thickness of the spacer sheet (1). To manufacture such a structure according to the present invention, each layer of the spacer sheet (1) and the vibration damping sheet (2) is individually placed on the vibration substrate of the vehicle, and the vibration substrate and the spacer sheet are heated during a coating drying process. Sheet (1) and damping sheet (2)
It is also possible to fuse the two sheets together and form them into a foam, simultaneously making them follow the irregularities of the vibrating board, or by laminating two layers of each sheet in advance and fusing them to the panel in a heating process such as a painting drying process. It may also be made to follow the foaming and irregularities of the panel.

[0017]

Effects of the Invention The vibration damping structure for a vehicle according to the present invention is placed on a vibration substrate such as a floor panel or a dash panel of a vehicle, foams the spacer sheet (1) by heating, and foams the vibration damping sheet (2). ) and the vibrating substrate can be firmly fixed, and the uneven shape of the vibrating substrate can be followed. The structure obtained in this way has a vibration damping structure with a spacer that is rigid, has good heat resistance, and has a dense cell structure with a high expansion ratio in the spacer, so it exhibits excellent vibration damping performance over a wide temperature range. Not only is it suitable as a material for reducing noise inside a vehicle, but it also provides rigidity to the vehicle body panel and provides a structure with excellent heat insulation properties.

[0018]

[Examples] The present invention will be explained below with reference to Examples and Comparative Examples. The materials and test methods used for the test are as follows. I. Test materials ■ Vibration board: 0.8 mm thick steel plate ■ Spacer sheet A spacer composition was mixed in a Hobart mixer for 20 minutes at the compounding ratio shown in Table 1 below to create it, and then coated on release paper to a predetermined thickness. . This was heated at 120° C. for 100 seconds to create a semi-gelled sheet.

[0019]

[Table 1]

■ Damping material sheet Asphalt-based vibration damping sheet (product name Melsheet
(manufactured by Nippon Tokushu Toyo) Material code - F Asphalt-based foam vibration damping sheet (trade name: Foam Melsheet, manufactured by Nippon Tokushu Toyo) Material code - G Thickness was adjusted in advance to a predetermined value using a hot press.

II. Test method Spacer sheet and vibration damping sheet each 15 x 300
A damping structure was created by combining the steel plates with a thickness of 0.8 mm and a thickness of 0.8 mm, and the rigidity ratio of each structure was measured at 20, 40, and 60°C. For lamination and foaming of each layer, each layer was placed on a steel plate and then heat treated in an oven at 150° C. for 30 minutes. The loss coefficient was calculated from the half width at the resonance point of the mechanical impedance, and the loss coefficient at 200 Hz was determined by interpolation. Note that the measurement frequency is 1 to 1000 Hz.

[0022]Followability to uneven shapes was determined by cutting out the above-mentioned spacer sheet and damping sheet materials to a width of 20 mm and a length of 250 mm.
A heating test was conducted in an oven on a steel plate having an uneven shape shown in a side view and a wave height of 7.8 mm so as to be perpendicular to the wave shape, and the followability was observed. The heating conditions are the same as in the case of bonding. The rating is "○" if the product is in close contact with no gaps, "△" if there is a slight gap but no problem in use, and "" if there is a gap remaining that poses a problem in use.
The uniformity of the foamed cells was determined by observing the appearance, and the uniformity of the foamed cells was determined by observing the appearance.
They were classified into different levels and the foaming ratio was measured. Table 2 shows the results of the following examples and foaming properties, and Table 3 shows the results of the comparative examples.

[0023]

[Table 2]

[0024]

[Table 3]

From the above results, as shown in Table 2, Examples 1 to 5 had good foaming properties, vibration damping properties (loss coefficient), and unevenness followability, and were especially excellent in loss coefficient. This fully satisfies the vibration damping performance required by the structure. On the other hand, in Comparative Examples 1 to 7, as shown in Table 3, the structures of Comparative Examples 1 and 2 had extremely poor foaming properties, and the structures of Comparative Example 2 had poor vibration damping properties. Furthermore, the structures of Comparative Examples 3 to 7 had significantly poor loss coefficients.

[Brief explanation of the drawing]

FIG. 1 is a front view and a side view of a steel plate used in a followability test.

Claims (1)

[Claims] [Claim 1] A spacer sheet (1) made of a foamable thermosetting resin sheet sandwiched between a vibration damping sheet (2) made of a viscoelastic material such as rubber or asphalt and a vehicle vibration substrate.
In the two-layer structure, the spacer sheet (1) contains (A) 100 parts by weight of an epoxy resin having one or more epoxy groups in one molecule, and (B) 0 parts by weight of a co-reactive curing agent for epoxy resin. .5 to 20 parts by weight, (C) 0.5 to 20 parts by weight of a blowing agent with a cracked gas temperature of 100 to 220°C;
(D) 0.05 to 5 parts by weight of a surfactant, and (E) a rubber elastic body that is insoluble in the epoxy resin at room temperature and can be mixed and dispersed with the epoxy resin at a temperature of 80 to 150°C; The decomposed gas of the blowing agent (C) contains 10 to 200 parts by weight of at least one kind selected from powdered thermoplastic resins that are insoluble in the epoxy resin, do not contain halogen, and have an average particle size of 150 μm or less, and A vibration damping structure for a vehicle, which is a sheet that is semi-gelled by heating at a temperature below the generation temperature, and the adhesive surfaces of these sheets and panels are integrally fused and foamed by heating. .