JPH058727B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vibration-damping material made of a low-foaming polyurethane elastomer having a three-layer structure of dense-coarse-fine layers.

High-speed tracks such as the Tohoku Shinkansen generally have a structure as shown in Figure 1. In other words, 1 is a rail, 2 is a ballast, 3 is a concrete sleeper, and 4 is a concrete roadbed. It is installed through.

Conventionally, rubber-like elastic bodies mainly made of natural rubber and synthetic rubber have been known as the above-mentioned vibration-proofing materials.
For example, it is used to prevent the rotational or reciprocating vibrations of compressor presses from being transmitted onto the supporting floor. Such vibration isolating rubber transmits vibration energy from a vibration source to a rubber-like elastic body, and achieves vibration isolation through the vibration transmission blocking effect and internal loss caused by the deformation of the elastic body. When the displacement due to vibration between the source and the support member is only in one axis direction, that is, in the direction of gravitational acceleration, the vibration isolation effect can be easily achieved by simply inserting vibration isolating rubber between the vibration source and the support member. I can do it.

However, when conventional anti-vibration rubber is used in a confined space where it cannot be freely deformed, as shown in the recess 5 in Figure 1, it becomes apparently hard and has little vibration reduction effect, making it practical for practical use. It was not suitable for In other words, vibration isolating materials mainly made of natural rubber and synthetic rubber have a dense structure, so they are difficult to change volume, and when free deformation (volume deformation) is restricted, the spring constant increases and the It could not be used because the anti-vibration function would be lost.

The present inventors, in Japanese Patent Application Laid-Open No. 58-23819,
In place of conventional vibration-proof rubber, we proposed the following vibration-proof material made of low-foam polyurethane elastomer as a high-load vibration-proof material that can withstand use on high-speed tracks. This is (a) an organic polyisocyanate, (b) an average number of functional groups of 2.5 to 3.5, and a number average molecular weight of 4,500 to 4,500.
A bulk density of 0.3 to 0.9 g/cm ³ obtained by reacting a polyether polyol of 8500 and (c) a side chain extender in a ratio such that the NCO index is 90 to 110 in the presence of water as a blowing agent. It is an anti-vibration material.

For example, in the case of a urethane elastomer with a bulk density of 0.58 g/cm ³ , this anti-vibration material can be compressed under free deformation with a plate of 10 cm x 10 cm x 25 mm by 4% - 10
The spring constant per unit area between % strains was 4.2 Kg/cm ³ , but when compressed in a restrained state that causes volumetric compression, the spring constant was 5.5 Kg/cm ³ , an increase of only 1.30 times. It has significantly better vibration-proofing performance than conventional products (for example, in a vibration-proofing material made mainly of chloroprene rubber measuring 20cm on a side and 25mm on a side, the spring constant is 4 times higher in a similar compression test). have

However, even such a slight change in the spring constant cannot be ignored when supporting a vibration source under a high load such as in the high-speed orbit.
In practice, by providing a notch (0.5 to 50%, preferably 2 to 20% of the bottom area of the base body) as shown by the dotted line P in FIG. 1, volume changes can be absorbed by the notch P. However, there was a problem in that changes in the spring constant had to be suppressed, which required troublesome construction work.

As a result of various studies conducted by the present inventors in view of the above-mentioned problems, it was found that when reacting the three components (a) to (c), such as the organic polyisocyanate and polyether polyol, using a blowing agent, a blowing agent can be used instead of water. By using Freon gas with a boiling point of 40 to 70°C, the resulting low-foam polyurethane elastomer has a three-layer structure of dense-coarse-dense, and even under high loads with restricted free deformation. We have discovered that the change in spring constant is extremely small and has excellent vibration damping performance, leading to the present invention.

That is, the vibration damping material made of the low-foam polyurethane elastomer according to the present invention has a three-layer structure in which the density changes continuously or continuously from the middle layer to the surface layer, i.e., dense-coarse-fine, with the dense layer near the surface layer. It is characterized by its structure.

The vibration-proof material with such a three-layer structure is
(a) Organic polyisocyanate, (b) average number of functional groups
A polyether polyol having a number average molecular weight of 2.5 to 3.5 and a number average molecular weight of 4500 to 8500, and (c) a chain extender,
It is produced by reacting in the presence of trichlorotrifluoroethane as a foaming agent at a rate that gives an NCO index of 90 to 110.

As shown in FIG. 2, the vibration damping material according to the present invention has a three-layer structure with a dense layer 7 in the middle and dense layers 8 on both sides, and the ratio of the thickness of the dense layer 8 to the sparse layer 7. , or the rate of change in bulk density from the loosely dense layer 7 to the dense layer 8 varies depending on the boiling point of the halogenated hydrocarbon gas used, the cooling conditions by the mold 10 around the vibration isolating material 9, etc., but the overall bulk The density is
0.3-0.9 g/cm ³ of urethane elastomer is used. That is, if the bulk density is smaller than this, the load bearing capacity will be extremely low, while if it is 0.9 g/cm ³ or more, it will be susceptible to volume changes due to slight compression.

FIG. 3 is a graph showing the vibration isolation effect of the vibration isolating material according to the present invention and the conventional product. In contrast to curve A showing the conventional product, curve B showing the product of the present invention transmits vibration by reducing the spring constant. The peak of is shifted to the lower cycle side, and the transmissibility is lower than 1, indicating that the vibration isolation effect is excellent.

The present invention will be explained in more detail below.

The urethane elastomer used in the present invention is
It is formed from a composition comprising a polyhydric alcohol with an average functionality of 2.5 to 3.5 and a number average molecular weight of 4,500 to 8,500, an organic polyisocyanate, a urethanization catalyst, a chain extender, a blowing agent, and a foam stabilizer. If the functionality of the polyhydric alcohol is less than 2.5, the compression set of the resulting urethane elastomer, which is an important property as a vibration-proof material, will increase, making it unsuitable. When the number of functional groups in the polyhydric alcohol exceeds 3.5, the resulting elastomer tends to become extremely hard and there is a greater risk of breakage due to vibration compression. The preferred number of functional groups is in the range of 2.8 to 3.3. When the number average molecular weight of the polyhydric alcohol is 4500 or less, only a urethane elastomer with particularly low vibrational energy absorption properties can be obtained. This is thought to be because the density of chemical crosslinking points becomes high and the behavior approaches that of a perfect elastic body. On the other hand, if the number average molecular weight is 8,500 or more, the elastic properties of the obtained urethane elastomer will decrease, plastic deformation will easily occur, and compression set will particularly increase, which is not preferable. The preferred number average molecular weight range of the polyhydric alcohol is from 4,500 to 6,500.

Further, in the present invention, it is essential to use a chain extender in order to obtain a good vibration-proof elastomer. The chain extender reacts with the isocyanate to form a hard segment mainly consisting of hydrogen bonds through urethane bonds or urea bonds, and becomes an important factor governing the properties of the elastic body.

According to the research conducted by the present inventors, in the case of the combination with the polyhydric alcohol described above, the amount of the bifunctional sedation extender in the elastomer composition is expressed as a molar concentration with respect to the unit weight of the urethane elastomer obtained. 0.2×10 ^-4 mol/gr. to 1.0×10 ^-5 mol/
It was found that a range of gr. If the concentration is lower than this, the chain lengthening effect will not be sufficient, and the strength of the resulting low-foamed elastomer will be extremely low, making it difficult to put it to practical use. Also, 1.0×10 ^-5 mol/gr.＋
At higher concentrations, the number of hydrogen-hydrogen bonds increases;
Although the strength of the resulting elastomer is improved, it becomes an extremely hard elastomer and, as a fatal defect, compression set and glide compression fatigue properties deteriorate. This is considered to indicate that when used in applications that are subject to repeated compressive stress, such as vibration isolating materials, it is undesirable for the density of physical crosslinking points, such as hydrogen bonds, to increase.

The vibration damping material of the present invention has a bulk density of 0.3 to 0.9 by using trichlorotrifluoroethane.
g/cm ³ , a three-layer structure of dense-coarse-fine structure can be obtained. If it is lower than 40°C, foaming will vary, and if it exceeds 70°C, it will be difficult to control not only foaming but also the reaction temperature. Conventionally, a low boiling point Freon gas such as trichloromonofluoromethane (boiling point 23.82°C) has been used as a blowing agent, but in this case, only a bulk density that is almost uniform throughout can be obtained, and the present invention The desired three-layer structure of dense-coarse-fine structure cannot be obtained. By making the surface layer denser, mechanical strength and durability are improved, and by creating a dense layer in the middle, compressive deformation due to high loads can be easily absorbed, eliminating the need for conventional cutouts. performance is significantly improved.

Examples of polyhydric alcohols used in the present invention include addition polymerization of oxyalkylene compounds such as ethylene oxide and propylene oxide to low-molecular-weight polyhydric alcohols such as glycerin and trimethylolpropane, or low-molecular-weight active hydrogen compounds such as ethylenediamine. , so-called polyether polyols, etc. can be used. Similarly, polyester polyols, hydroxy-terminated liquid polybutadiene, etc. can also be used.

As the polyisocyanate, those commonly used for urethane elastomers can be used. For example, 4,4'-diphenylmethane diisocyanate, naphthylene diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, etc. can be mentioned, and mixtures of two or more of these can also be used.

Moreover, the polyisocyanate can also be used as a precursor precondensed with the polyhydric alcohol. In any case, the amount of polyisocyanate used depends on the active hydrogen-containing component (polyhydric alcohol, chain extender, etc.) that should react with the isocyanate residue,
It is possible to vary the stoichiometric amount or within a range of about ±10% thereof, that is, within a range of 90 to 110% of the NCO index.

As the chain lengthening agent, a relatively low molecular weight substantially difunctional compound such as diol/diamine is used, such as ethylene diglycol, propylene glycol, propanediol, butanediol, methylene bis(0- (dichloroaniline), hydroquinone, hydroxyethylequinone ether, etc.

The urethanization catalysts used are those used in normal urethanization reactions, that is, tertiary amine compounds, finite metal compounds, etc., such as triethylenediamine, diaza-bicycloundecene, N-methylmorpholine, N,N -dimethylethanolamine, tin octylate, dibutyltin laurinate, and the like. The amount of catalyst used can vary widely depending on the desired reaction rate, but it is necessary to adjust the amount as appropriate depending on the amount of foamed urethane elastomer and atmospheric conditions (temperature, humidity, etc.). It is easy to select. In any case, in order for the urethane elastomer of the present invention to function as a vibration damping material, it has a spring constant per unit area of at least about 1 Kg/cm ³ or more, particularly preferably from 3 Kg/cm ³ to 10 Kg/cm It is desirable that it be in the range of ³ . Values in this range can be obtained by appropriately selecting the composition and bulk density of the urethane elastomer when the thickness is about 5 to 100 mm, which is commonly used as a vibration damping layer. Of course, increasing the bulk density also increases the spring constant, and polyhydric alcohols with high molecular weight, polyhydric alcohols with a low number of functional groups, and low crosslinking density have the advantage of lowering the spring constant and providing strong adhesion. Normally, vibration isolators must be able to reliably transmit the vibrations from the vibration source, block the vibrations, and absorb them within the vibration isolator, so the adhesive properties described above are a huge advantage in practical terms. .

In other words, the urethane coating layer exhibits an excellent effect when it is integrally molded and foamed to the base and is brought into close contact with the base, and it is also molded separately from the base and then brought into close contact with the base to fix the vibration source and achieve a vibration-proofing effect. It is possible to demonstrate this effectively. That is, it may be adhered to the bottom of the base using an adhesive, or a method may be adopted in which a box-shaped urethane elastomer body is molded and the base is inserted into it.

In the present invention, a base body having a urethane elastomer coating layer is fitted into a recess on the floor surface where a vibration source is to be set, but this recess may be previously formed in the floor surface or may have a urethane elastomer coating layer. The base body may be formed by installing the base body on a smooth floor surface and then filling the sides with concrete, asphalt, or the like. It is also possible to temporarily lift the coated substrate off the floor and then fill its bottom and sides with concrete, asphalt, or the like. Furthermore, it is also possible to form a recess in advance between the base body having no coating layer and the floor surface, inject the urethane elastomer into the recess, and perform foam molding. In this case, the urethane elastomer is integrally molded on both the base and the supporting floor surface, and it is possible to obtain the effect of strong adhesion.

The vibration-proofing material of the present invention can be used for vibration-proofing in all industrial fields or for the purpose of soundproofing associated therewith. For example, possible applications include installing it on the bottom of a metal punching press, installing it on the underside of a compressor, providing vibration isolation for air conditioning equipment installed on the floor, and using it for vibration isolation on railway tracks.

The invention will now be illustrated by examples.

Example 1 A urethane elastomer coating layer with a thickness of 30 mm was formed on five sides of a concrete base having a size of 500 x 500 x 300 mm by integral molding with the concrete base and a foaming method. The urethane elastomer has the following composition and the density of the coating layer is 0.70g/
^cm3 . Composition of urethane elastomer (Liquid A) Polyether polyol 100.0 Ethylene glycol 3.0 Trichlorotrifluoroethane 0.35 Foam stabilizer 0.50 Triethylenediamine 0.20 (Liquid B) Polyisocyanate/polyol precursor condensate
Isocyanate index 100 Number average molecular weight 6500 Glycerin/propylene oxide/ethylene oxide copolymer adduct Silicone surfactant Isocyanate-terminated precursor condensate of polyether polyol with 4,4'-diphenylmethane diisocyanate Amount of residual isocyanate 16% (weight) ) Both solutions A and B were quickly mixed and injected into the space formed by surrounding the 5 sides of the concrete base with iron plates, and the base and urethane elastomer were bonded at the same time as foaming, and the iron plates were removed after about 2 hours.

This base was installed in a 330 mm deep recess formed on the floor (the bottom of the recess was a smooth concrete surface), and then concrete was poured around the base up to the floor level. After the concrete had completely hardened, a friction press was installed on top of the base, and the press and base were connected by bolts embedded in the base. The total weight of the press is approximately 500Kg and the press capacity is 2 tons.

The press was operated and the vibration acceleration of the floor surface measured at a distance of approximately 3 meters was approximately 55 dB.
When a similar type of press is installed on a 500mm x 500mm x 30mm floor with a vibration-proofing layer such as chloroprene rubber embedded in it, the vibration acceleration of the floor can be measured in the same way and approx.
It was 66dB.

Example 2 A urethane elastomer with the same composition as in Example 1, a bulk density of 0.60 g/cm ³ and a thickness of 25 mm was applied to the bottom and sides of a 1000 x 500 x 50 mm concrete plate-like base as a rubber adhesive. I pasted it with This coated base was fitted into a 75 mm deep recess provided in the concrete floor. A 20 horsepower air compressor was installed on the top of the base and was fastened with bolts embedded in the base concrete. The weight of the air compressor is approximately 1
The urethane elastomer used was 4 tons.
Spring constant per unit area between % and 10% strain is 8Kg/cm ³
showed the value of

The air compressor was operated and the vibration acceleration of the floor surface measured at a point approximately 3 meters away was 65 dB.
For comparison, the above air compressor was installed directly on a concrete floor and the vibration acceleration was similarly measured, and the result showed a value of 83 dB.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the structure of a high-speed track used to explain the present invention, FIG. 2 is a cross-sectional model diagram showing an example of the vibration isolating material according to the present invention, and FIG. 3 is a diagram showing the vibration isolating material according to the present invention. It is a graph showing the vibration isolation characteristics of a conventional product. 1: Rail, 2: Ballast, 3: Concrete, 4: Sleepers, 6: Anti-vibration material, 7: Rough (sparse)
Lamina densa, 8: Lamina densa.

Claims (1)

[Scope of Claims] 1. A vibration-damping material made of a urethane elastomer whose density changes continuously or intermittently from the intermediate layer to the surface layer, with a dense layer near the surface layer, comprising: (a) an organic polyisocyanate; (b) ) average number of functional groups is
2.5 to 3.5 and a number average molecular weight of 4,500 to 8,500 polyether polyol and (c) 0.2 x 10 ^-4 mol/gr. to 1.0
10 ^-5 mol/gr. of a bifunctional anti-vibration extender is reacted in the presence of trichlorotrifluoroethane as a blowing agent at a rate such that the NCO index is 90 to 110. material.