JPH0679840B2 - Multi-layer heat-resistant damping material - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layer heat-resistant damping material which is mainly applied to a high temperature portion such as a floor portion above an exhaust pipe of an automobile.

[0002]

2. Description of the Related Art As a conventional vehicle vibration damping material, a bituminous material is used as a binder component, and various fillers such as powdery fillers and fibrous fillers are dispersed and kneaded into this, and processed into a sheet. However, it was cut and constructed according to the shapes of the floor, door, dash, etc. of the vehicle.

On the other hand, it is an urgent task to reduce the emission concentration of nitrogen oxides and carbon oxides by the highly efficient combustion of exhaust gas from automobiles due to the heightened environmental problems. The temperature of the exhaust gas passing through the exhaust pipe is higher than in the past.

Therefore, in the conventional damping material, the damping material applied to the upper portion of the exhaust pipe and its peripheral portion is softened by the high temperature exhaust gas generated when the engine is rotated at high speed, and the damping material is damped. At the same time as the performance deteriorates, the carpet laid on the upper layer of the vibration damping material may be contaminated with the bituminous material. In addition, it was completely unpredictable in terms of imparting rigidity to the surface of the fusion-bonded steel sheet by thermal softening of the damping material.

For this reason, it is the current situation that no vibration countermeasure can be taken by a damping material containing a bituminous substance as a main component in a high temperature portion of the vehicle.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to improve the heat resistance of a vibration damping material, and to have a higher vibration damping performance in at least a temperature range than conventional bituminous vibration damping materials. Moreover, it has high rigidity even in high temperature range,
It is to develop a heat-resistant damping material.

[0007]

As a solution to this problem, the inventors of the present invention have conducted extensive studies and as a result, found that 90 parts by weight of 1,2 bond was added to the composition of the conventional damping material mainly composed of bituminous material. % Or more, average molecular weight 100,000 to 200,000, crystallinity 10
40% of polybutadiene is mixed at a weight mixing ratio of bituminous material and polybutadiene of 0: 100 to 50:50, and a crosslinking curing reaction is carried out with a curing agent such as sulfur or peroxide. The heat resistance, which was only about 100 ° C, improved to 180 ° C, and J at 20 ° C
The spring hardness test specified by IS K6301 has a hardness of 50 to 98 and an elastic modulus of 10 ⁵ to 10 ¹¹ dy.
By applying a hot melt adhesive of ne / cm ² , the damping performance is superior over the conventional bituminous damping material in each temperature range, and it also has high rigidity in the high temperature range. I found it. Furthermore, when the hot-melt adhesive is applied to the damping material according to the present invention, the hot-melt adhesive is applied to the fusion-bonding surface of the damping material to the steel plate in an amount of 5 to 100 mm.
By applying 80 to 90% of the entire fusion-bonded surface of the vibration damping material in a band shape with a width of 5 to 30 mm, the vibration damping material and the steel plate surface can be blistered by bubbles during heat fusion. It was found that the situation in which the adhesiveness of No. 1 becomes poor can be prevented and good adhesiveness is realized. The details will be described below centering on the composition.

It is desirable that the polybutadiene mixed with the bituminous substance basically has a syndiotactic structure.
Further, there are 1,2-bond and 1,4-bond, and these two types are mixed in an appropriate ratio, but the product usable in the present invention is that the 1,2-bond is 90% by weight of the total amount. It is mandatory to include at least%. If the content of the 1,2 bond is less than 90%, rubbery properties appear in the physical properties when heat-cured, resulting in a decrease in rigidity, which is not preferable. Even if the average molecular weight or the crystallinity deviates, compatibility with a bituminous material, vibration damping performance, a problem in the shape-following property to the vibration-damped surface during heating, etc. may occur, and the object of the present invention may be achieved. Absent.

As the bituminous material which can be used in the present invention, any one such as straight asphalt, blown asphalt, semi-blown asphalt, rubber modified asphalt, and mixed asphalt of two or more of these can be used, but the bituminous material is not always used. It is not essential, and if the problems of steel plate adhesion, cost, etc. are solved, it is better not to mix bituminous substances from the viewpoint of high rigidity.

The weight mixing ratio of the bituminous material and the polybutadiene is 0.5 to 0.5 for the bituminous material and 0.5 to 0.5 for the polybutadiene.
Mandatory to be 1.0. When the bituminous material exceeds 0.5, high rigidity of the vibration damping material cannot be obtained, and when polybutadiene is less than 0.5, sufficient heat resistance may not be obtained and sufficient high rigidity may not be obtained. .

As the filler which can be used in the present invention, powdery filler containing pigments such as calcium carbonate, barium sulfate, talc and clay, animal material such as wool, plant material such as waste paper, synthetic fiber, glass Various fibrous fillers made from minerals such as the above can be arbitrarily used. The use of a flaky filler such as mica, graphite or mica is preferable because it improves the vibration damping property. The use of hollow fillers such as plastic balloons, glass balloons, silica balloons, and shirasu balloons is preferable because it contributes to weight reduction of the damping material. Coloring pigments such as carbon black can also be used as appropriate.

The hot melt adhesive contains a thermoplastic synthetic polymer as a main component, and a wax, a plasticizer, a tackifier, an antioxidant, a filler and the like as a modifier are appropriately mixed therein. % Solids adhesive. The thermoplastic synthetic polymer used is ethyl cellulose, vinyl acetate resin and its derivatives, polyethylene, ethylene-vinyl acetate copolymer, butyl methacrylic resin, polystyrene and copolymer, polyisobutylene, petroleum resin, polypropylene, polyamide resin, polyester. Resin etc. are used.

The hot melt adhesive is nontoxic and safe in operation since it does not contain any solvent, and does not require a drying device. It has a short solidification time and a quick rise in adhesive strength.
Due to its excellent characteristics such as almost no shrinkage due to% solid content and infinite storage time, it is widely used in the packaging industry and especially for adhering impermeable surfaces such as plastic films and metal foils. Is.

When the hot melt adhesive is applied, it is heated to a temperature at which the hot melt adhesive can be applied by a dedicated applicator and applied, but it is solidified at the same time as it is cooled to room temperature. However, when heated, it is reactivated by heat and has adhesive properties again.

The hot melt adhesive which can be used in the present invention has a hardness of 50 to 98 by a spring type hardness test specified in JIS K6301 at 20 ° C.
It is essential that the elastic modulus is 10 ⁵ to 10 ¹¹ dyne / cm ² . If the hardness is less than 50, the adhesiveness may develop at normal temperature when the temperature is high such as in summer. In such a case, the damping materials coated with the adhesive are stacked and adhered to each other during storage and transportation. There is a problem that a so-called blocking phenomenon occurs. Also, hardness 98
When it exceeds the above range, the adhesive layer formed by the hot melt adhesive is likely to be broken, which is not preferable, and besides, there is a fear that sufficient damping property is not exhibited and the damping property is not improved. Also,
The value of the elastic modulus of the hot melt adhesive at room temperature close to that of the vibration damping material is advantageous for improving the vibration damping property. That is, the elastic modulus of the hot melt adhesive itself at room temperature is 1
It is preferably 0 ⁵ to 10 ¹¹ dyne / cm ² and 10 ⁹
Particularly preferred is one having a concentration of -10 ¹⁰ dyne / cm ² . 10 ⁵
If the elastic modulus is less than dyne / cm ^2, the adhesive layer of the vibration damping material is too soft, and the vibration damping property may deteriorate.
On the other hand, when the elastic modulus exceeds 10 ¹¹ dyne / cm ² , the hardness is conversely too hard, and the strain for converting the vibration energy generated on the vibration-suppressed surface into the heat energy does not occur. There is a risk that it will not be demonstrated.

The amount of the hot melt adhesive applied to the damping material is preferably 0.1 to 0.4 kg / m ² . 0.1 kg
If it is less than / m ² , sufficient adhesion cannot be obtained and 0.4
Even if the coating amount is more than kg / m ² , the adhesion cannot be improved in proportion to the coating amount, which is rather disadvantageous in terms of cost.

There is no obstacle to adding other rubber component of polybutadiene or synthetic resin component to the damping material of the present invention. As the rubber component, natural rubber, styrene-butadiene rubber, butyl rubber, neoprene rubber, acrylonitrile-butadiene rubber, synthetic rubber such as chloroprene rubber, and recycled rubber can be appropriately selected and used. Petroleum resin, polyethylene, polypropylene,
It can be appropriately selected and used from ethylene-vinyl acetate copolymer and the like.

It is also possible to use a plasticizer such as process oil, DOP or DBP in order to give the damping material flexibility.

In order to crosslink and cure the polybutadiene, it is necessary to add an appropriate amount of sulfur and peroxide as a curing agent. When sulfur is blended, it is desirable to further add a vulcanization accelerator such as thiurams and thiazole. As the peroxide, dicumyl peroxide, TBPB,
1,1 bis (t-butylperoxy) 3,3,5-trimethylcyclohexane and the like can be used.

Other additives that can be used include quick lime that absorbs moisture to prevent blistering of the damping material, and diazoaminobenzole for foaming by utilizing the heat when the damping material is heat-fused. , Foaming agents such as azoisobutyl nitrile and benzol sulfohydrazide, and foaming aids such as urea and its derivatives and thermosetting resins. When blending the foaming agent, it is necessary to mix at a temperature not higher than the decomposition temperature of the foaming agent.

In order to manufacture the heat-resistant vibration damping material for vehicles according to the present invention, a bituminous material is heated and melted, polybutadiene is mixed with this, and other various fillers and additives are added and mixed, followed by dispersion kneading. A conventionally known mixing and dispersing machine such as an open kneader, a vacuum kneader, an attritor, a high-speed agitator with blades, or two or three rolls can be used. The blended mixture is processed into a sheet by a calender roll to have a constant thickness. Furthermore, it cuts into the required shape according to the construction part of the vehicle. Apply a proper amount of hot melt adhesive to the damping material with a special applicator and cool to room temperature to obtain a multilayer damping material.

When the hot-melt adhesive is applied to the damping material, if the hot-melt adhesive is applied to the entire fusion-bonded surface, blisters will be generated on the damping material when bubbles are generated, which causes troubles in the parts to be attached in the subsequent process. In addition, the vibration damping property deteriorates. In order to prevent such a situation, the hot-melt adhesive is not applied to the entire fusion-bonded surface of the damping material, and the width of 5-10
It is applied in a band shape with an application interval of 0 mm and an application interval of 5 to 30 mm, so that 50 to 9
The coating area is 5%. Preferably, width 20-60m
m, spacing 5-20 mm, more preferably width 30-
The distance is 50 mm and the distance is 5 to 10 mm.

[0023]

EXAMPLES In order to understand the present invention, examples will be described below. Needless to say, the present invention is not limited to the examples below.

[0024]

Example 1 10 parts by weight of straight asphalt (manufactured by Idemitsu Petrochemical Co., Ltd.), 90% by weight of polybutadiene = 1,2 bond, average molecular weight 110,000, crystallinity 20% (manufactured by Japan Synthetic Rubber Co., Ltd.) 20 parts by weight , 50 parts by weight of precipitated calcium carbonate (manufactured by Maruo Calcium Co., Ltd.), 1 part by weight of sulfur, and 0.2 parts by weight of thiazole are melt-mixed in a heatable vacuum kneader, and a calender roll has a thickness of 2 mm. age,
0.3 kg / m ^{2 of a} vinyl acetate hot melt adhesive was applied to this with a dedicated applicator at a pitch of a coating width of 30 mm and an uncoated width of 6 mm, and cooled to room temperature to obtain a vibration damping material 1.

[0025]

Example 2 Polybutadiene = 1,2 bond 90% by weight
Containing, average molecular weight 110,000, crystallinity 20% (manufactured by Japan Synthetic Rubber Co., Ltd.) 30 parts by weight, precipitated calcium carbonate (manufactured by Maruo Calcium Co.) 50 parts by weight, sulfur 1 part by weight, thiazole 0.2 part by weight Melt and mix with a possible vacuum kneader, and use a calender roll to make a damping material with a thickness of 2 mm.
A vinyl acetate hot melt adhesive was applied to this with a dedicated applicator at a coating width of 30 mm and an uncoated width of 6 mm at 0.3 kg / m ² and cooled to room temperature to obtain a vibration damping material 2.

[0026]

[Comparative example] Blown asphalt (made by Idemitsu Petrochemical Co., Ltd.)
30 parts by weight, 50 parts by weight of precipitated calcium carbonate (made by Maruo Calcium Co., Ltd.), and 5 parts by weight of mica are melt-mixed by a heatable vacuum kneader and calendered to 2.5 mm.
The damping material 3 having a thickness of 3 is used.

[0027]

【Test method】

(1) Heat resistance evaluation test Damping material 1 to damping material 3 were placed on a 0.8 mm thick dull steel plate, heated at 140 ° C for 30 minutes, and heat-sealed to the steel plate.
Cool it to room temperature, lay a cloth on the damping material, and
A load of g is applied to heat under a predetermined temperature condition, the load is removed, and after cooling, the cloth is peeled off and the degree of contamination on the cloth is observed.

(2) Vibration damping test Similar to the heat resistance test, a test piece was prepared by heating and fusing at 140 ° C. for 30 minutes and cooling to room temperature, and using the resonance method (Japanese Society for Acoustic Materials "Noise Countermeasure Handbook" 438). Loss coefficient η at each temperature of 20 ° C., 40 ° C. and 60 ° C. It is said that the larger the value of η, the higher the vibration damping effect, and that if η is 0.05 or more, the vibration damping effect is obtained.

(3) Bending Rigidity Ratio Test Similar to the heat resistance test, a test piece prepared by heating and fusing at 140 ° C. for 30 minutes and cooling to room temperature was used as a resonance method (“Noise Countermeasure Handbook” 438 published by Japan Acoustical Materials Association). The secondary resonance frequency f at each temperature of 20 ° C., 40 ° C., and 60 ° C. is calculated by the following method, and B _{0 is} the bending rigidity of the substrate (0.8 mm steel plate), and B is the bending rigidity of the substrate and the damping material. At this time, the bending rigidity ratio B ₀ / B is obtained by B ₀ / B = (f / f ₀ ) ² (m ₀ + m / m ₀ ). However, f: substrate + damping material secondary resonance frequency f ₀ : substrate secondary resonance frequency m: damping material surface weight m ₀ : substrate surface weight

[0030]

【result】

[0031]

[0032]

[0033]

EFFECTS OF THE INVENTION The heat-resistant damping material for vehicles according to the present invention exhibits remarkably excellent heat resistance as compared with the conventional damping material mainly containing bituminous substances. This damping material is conventionally softened due to high temperature to reduce its damping property, and it can also be used in places where there is a risk of contaminating carpets and the like, which not only prevents contamination of interior materials. However, it is superior in vibration damping performance and bending rigidity ratio in each temperature range to conventional vibration damping materials, and can greatly contribute to vehicle vibration damping. Further, the improvement of the rigidity of the vehicle steel plate has a favorable effect on the maneuverability of the automobile.

Claims (2)

[Claims] 1. A heat-sealing type vibration damping material containing bituminous material as a main component, comprising a bituminous material, polybutadiene, and a filler.
Bituminous matter: Polybutadiene weight mixing ratio of 0: 100
˜50: 50, polybutadiene contains 90% by weight or more of 1,2 bond and has an average molecular weight of 100,000 to 200,000 and a crystallinity of 10 to 40%.
The hardness according to the spring type hardness test specified by SK6301 is 50 to 98 and the elastic modulus is 10 ⁵ to 10 ¹¹ dyn.
A multilayer heat-resistant damping material, characterized by being applied with a hot melt adhesive having an e / cm ² . 2. A hot-melt adhesive is applied to the fusion-bonded surface of a steel sheet in a strip shape with a width of 5 to 100 mm at intervals of 5 to 30 mm.
The multilayer heat resistant vibration damping material according to claim 1, wherein 80% to 90% of the entire fused surface of the vibration damping material is applied.