JPS6185430A - Vibration-damping material and its production - Google Patents

Abstract

PURPOSE:To provide the titled material having extremely small spring constant and excellent vibration-damping property, useful for the vibration-damping of railroad, etc., and composed of a foamed polyurethane elastomer having low degree of expansion and having a structure characterized by the density varying from the intermediate layer toward the surface layer, and having dense layers near the surface. CONSTITUTION:The objective material is composed of a foamed polyurethane elastomer having low degree of expansion, and having three-layered structure consisting of a dense layer 8, a porous layer 7 and a dense layer 8, i.e. having dense layers at the surface region, wherein the density varies continuously or discontinuously from the intermediate layer toward the surface layers. The foam can be produced by reacting (A) an organic polyisocyanate with (B) a polyether polyol having an average number of functional groups of 2.5-3.5 and a number-average molecular weight of 4,500-8,500, and (C) a chain extender at a ratio to give an NCO index of 90-110, in the presence of (D) freon gas having a boiling point of 40-70 deg.C as a foaming agent.

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 and dense, and a method for producing the same.

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 pallast, 3 is a concrete sleeper, and 4 is a concrete roadbed, and the concrete sleeper 3 has a vibration-proofing material (coating layer) 6 in a recess 5 formed in the roadbed 4. It is installed via 几.

Conventionally, rubber-like elastic materials mainly made of natural rubber or synthetic rubber have been known as the above-mentioned vibration-proofing materials, and are used, for example, to completely prevent the rotational or reciprocating vibrations of compressor presses from being transmitted to the supporting floor. It's cold. Such anti-vibration rubber transmits the vibration energy from the vibration source to a rubber-like elastic body, and achieves complete vibration isolation through the vibration transmission blocking effect and internal loss caused by the deformation of the elastic body. 2
When the displacement due to vibration between the supporting members is only in one axis direction, that is, in the direction of gravitational acceleration, the vibration isolating effect can be easily achieved by simply inserting the vibration isolating rubber between the entire vibration source and the supporting member.

However, in conventional anti-vibration rubber, as shown in the recess 5 in FIG.
When used in the '7 state, it becomes apparently hard and has little vibration reduction effect, making it unsuitable for practical use.
4. In other words, vibration isolating materials mainly made of natural rubber or synthetic rubber have a dense structure, so it is difficult to induce volume changes, and the spring constant increases when free deformation (volume deformation) is restrained f′. It could not be used because the anti-photo protection function was essentially lost.

In Japanese Patent Application Laid-Open No. 58-23819, the present inventors proposed a vibration-proofing material made of the following low-foam polyurethane elastomer as a high-load vibration-proofing material that can withstand use on high-speed tracks in place of conventional vibration-proofing rubber. Proposed. This material is (a) 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, and (c) a side chain extender 'i,
At a ratio where the NOO index is 90 to 110, the bulk density obtained by reacting in the presence of water as a blowing agent is 0.3.
~Q, 9? /crA vibration isolating material.

For example, in the case of a urethane elastomer with a bulk density of 0.58 F/-, this vibration-proof material has a size of 10 cm x 10 cm x
When compressing a 25-sized plate under free deformation, the Nonone constant per unit area between 4 chips and 10% strain is 4.2 kv.
/i, but when compressed in a restrained state that causes this n1 volumetric compression, the 6-ne constant was 5.5 h/cJ, an increase of only 1.30 times, compared to conventional products (for example, 20 cm per side).
In the case of a vibration damping material mainly made of chloroprene rubber that is 1n square and 25 pieces thick, the spring constant will be four times as high in a similar compression test. )
Vibration isolation performance that is significantly better than that of have

However, even such a slight change in the Nonone constant cannot be ignored when supporting a vibration source under a high load such as in the high-speed orbit, and when implementing it, the dotted line P in Fig. By providing all the notches (0.5 to 50 inches, preferably 2 to 20% of the bottom area of the base body) as shown, volume changes can be absorbed by the notches P and changes in the spring constant can be suppressed. Therefore, there was a problem in that it required troublesome construction work.

The present inventor has conducted various studies in view of the above problem, and has found that when reacting the three components (a) to (c), such as the organic polyinsyanate and polyether polyol, using a blowing agent, it is possible to By using 7 Leon gas with a boiling point of 40 to 70°C instead, the resulting low-foaming polyurethane elastomer has a three-layer structure of dense phase and dense structure, and can withstand high loads with restricted free deformation. The inventors have discovered that the change in Nonone's constant is extremely small even under various conditions, and that the material has excellent f'LfC vibration damping performance, leading to the present invention.

That is, in the vibration damping material made of the low-foam polyurethane elastomer according to the present invention, the density is continuous from the intermediate layer to the surface layer, and the density changes from dense to coarse to dense, that is, from the dense layer to the dense layer near the surface layer. It is characterized by its three-layer structure.

The anti-vibration material having a three-layer structure is made of (a) an organic polyisocyanate, and (b) an average number of functional groups of 2.5 to 2.
3.5 and a number average molecular weight of 4.500 to 8.500, and (c) a chain extender, N
It is produced by reacting it in the presence of 7 Leon gas having a boiling point of 40 to 70°C as a blowing agent at a rate such that the CO index is 90 to 110.

As shown in FIG. 2, the vibration damping material according to the present invention has a three-layer structure in which the intermediate layer is a dense layer 11 and the surface layer on both sides is dense Nj8, and the ratio of the thickness of the dense layer 8 to the sparse layer 7, or The rate of bulk density change from the sparse layer 7 to the dense layer 8 is used as 7
Although it varies depending on the boiling point of Leon gas and the cooling conditions of the mold 10 around the vibration-proofing material 9, the overall bulk density is 0.
．． A urethane elastomer of 3 to 0.9 t/d is used. That is, if the bulk density is less than n, the load bearing capacity will be extremely low, while if it is 0.9 f/I 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.The curve ILs8, which shows the product of the present invention, shows the curved line showing the conventional product, and the curve shows the curved line showing the product of the present invention. As a result, the peak of vibration transmission moves to the lower cycle side, and the transmission ratio becomes lower than 1, indicating that the vibration isolation effect is excellent.

The present invention will be explained in more detail below.

The urethane distomer used in the present invention has an average functionality of 2.5 to 3.5, a number average molecular weight of 4,500 to 8,500, a polyhydric alcohol (8ν polyisocyanate, a urethanization catalyst, a chain extender, Formed from a composition consisting of a blowing agent and a foam stabilizer.The functionality of the polyhydric alcohol is 2.
．． If it is less than 5, the compression set of the resulting urethane elastomer, which is an important property as a vibration damping material, becomes large and is not suitable. When the number of functional groups in the polyhydric alcohol exceeds 3.5 gold, the obtained elastomer tends to become extremely hard and the risk of breakage due to vibration compression increases.

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, Vi
In particular, only urethane elastomers with low absorption characteristics for imaging energy can be obtained. It is thought that this fL is due to an increase in the density of chemical crosslinking points, which approaches the behavior 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 polyhydric alcohol is 4500
~6500.

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 incyanate to form a hard segment mainly composed of hydrogen bonds through urethane bonds or urea bonds, and becomes an important factor controlling the overall 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 chain extender in the elastomer composition is determined based on the unit weight of the urethane distomer obtained. Expressed in molar concentration, 0.2 x 10-
'mol/gr, to 1. OX 10-'mo
It has been found that the range of l/gr is suitable.

Since the chain lengthening effect is not sufficient at concentrations lower than this,
The strength of the resulting low-foaming nidistomer is extremely low, making it difficult to put it to practical use. Also, 1. OX 10 mol/gr.

At higher concentrations, the number of hydrogen bonds increases, so the strength of the resulting elastomer improves, but it becomes an extremely hard elastomer and, as a fatal defect, compression set and repeated compression fatigue properties deteriorate. Does this mean that when used in applications that are subject to repeated compressive stress, such as vibration-proofing materials, it is undesirable for the density of physical crosslinking points, such as hydrogen bonding, to increase? I'm thinking of a book to show you.

The vibration damping material of the present invention has a bulk density of 0.3 to 0.9 by using Freon gas with a boiling point of 40 to 70°C, such as trichlorotrifluoroethane, dibromotetrafluoroethane, and tetrachlorodifluoroethane. /cJ,
A three-layer structure of dense, coarse and dense is obtained. If the temperature is lower than 40°C, foaming will be irregular, 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 gas such as trichloromonofluoromethane (boiling point 23.82°C) has been used as a blowing agent, but in this case, only a bulk density with a uniform overall density can be obtained. First, it is difficult to obtain the three-layer structure of dense, coarse, and dense, which is the object of the present invention. By making the surface layer denser, mechanical strength and durability are improved, and by making the middle layer denser and denser, compressive deformation due to high loads can be absorbed without burying, eliminating the need for conventional cutouts. Workability is significantly improved.

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

As the polyincyanate, those which are not normally 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. Regardless of the amount of polyisocyanate used, the amount of active hydrogen-containing components (polyhydric alcohol,
(chain extender, etc.) in a stoichiometrically equivalent amount or ±1
Within the range of about 0%, that is, the NOO index is 90 to 1
It is possible to vary it within a range of 10%.

As chain extenders, substantially difunctional compounds of relatively low molecular weight, such as diols and diamines, are used. 0
--) chloroaniline), hydroquinone, hydroxyethylquinone ether, and the like.

Urethane-forming catalysts include those not used in ordinary urethane-forming reactions, that is, tertiary amine compounds, finite metal compounds, etc., such as triethylenediamine, diaza-bicycloundecene, N-methylmorpholine, Examples include N,N-dimethylethanolamine, tin octylate, and dibutyltin laurate. The amount of catalyst used can vary widely depending on the desired reaction rate, but it is necessary to adjust the amount i depending on the amount of urethane distomer foamed and the atmospheric conditions (temperature, humidity, etc.). It is easy to select. Since the urethane disstomer of the present invention functions as a vibration damping material no matter how many times it is layered, the spring constant per unit area has a value of at least about 1 yen/- or more, and preferably 3 yen/- in percent. ~10 gin/d
It is desirable that it be within the range of . Values in this range can be obtained by appropriately selecting the composition and bulk density of the urethane disstomer when the thickness is about 5 to 100+a+, which is not commonly used as a vibration damping layer. Of course, the higher the bulk density, the higher the spring constant, and a polyhydric alcohol with a high molecular weight, a polyhydric alcohol with a low number of functional groups, and a low crosslinking density have the advantage of having a low spring constant and strong adhesion.

Normally, vibration isolators need to reliably transmit and reduce the vibrations from the vibration source, block the vibrations, and absorb them inside the vibration isolator, so the adhesive properties described above are a huge advantage in practical terms. Become.

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 also provides an anti-vibration effect by fixing the vibration source by molding it separately from the base and then bringing it into close contact with the base. It can be used effectively. That is, it may be adhered to the bottom of the base body using an adhesive, or a method may be adopted in which a box-shaped urethane elastomer body is molded and the base body is inserted into this.

In the present invention, the substrate having the urethane entomer coating layer is used as the vibration source. It is fitted into a recess on the floor surface to be set, but this recess is either pre-formed in the floor surface, or the substrate with the urethane nystomer coating layer is installed on a smooth floor surface and then placed on its side. It may be formed by covering the entire part with concrete, asphalt, etc. It is also possible to temporarily lift the coated substrate from the floor and then cover 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 layer to be coated and the floor surface, inject the urethane distomer into the recess, and perform foam molding. In this case, the urethane distomer is integrally molded on both the base and the supporting floor surface, and the effect of strong adhesion can be obtained.

The vibration-proofing material of the present invention can be used for vibration-proofing purposes in all industrial fields or for soundproofing associated with ovens.

For example, applications such as installation on the bottom of a metal punching press, installation on the underside of a compressor, vibration isolation for air conditioning equipment installed on the floor, and use for vibration isolation on railway tracks are being considered. Ru.

Next, the present invention will be fully illustrated by examples.

Example 1 A urethane distomer covering layer having a thickness of 30 mm was formed on five sides of a 500 x 500 x 300 concrete base by integral molding with the concrete base and foaming method. The urethane elastomer having the following composition was used and the f'Lfc coating layer had a density of 0.70 f/cd.

□ Composition of urethane elastomer Polyether polyol ■ 100.0
? ”-y-v7f +) Near -/l/
3.0 Trichlorotrifluoroethane
0.358 Foam stabilizer■
0.50 triethylenediamine
0.20 Polyisocyanate/Isocyanate ■ Number average molecule -11
-6500 Chrycerin/propylene oxide/ethylene oxide copolymer adduct ■ Silicone surfactant ■ 4.4'-diphenylmethane diisocyanate ■
Incyanate-terminated precondensation product of polyether polyol (inocyanate amount 16% C weight: It)
Quickly mix A and Bw liquids and place 5 on the concrete base.
Inject it into the space created by surrounding the surface with iron plates.

At the same time as foaming, the base and urethane elastomer were bonded together, and after about 2 hours, the iron plate was removed.

A recess with a depth of 330 mm was formed on the anvil surface of this base (the bottom of the recess was a smooth concrete surface), and then concrete 1 was poured around the base up to the level of the floor surface.The concrete hardened completely. After that, a friction press was installed on the top of the base, and the press and base were connected by bolts embedded in the base.The total weight of the press was approximately 500 yen.
It is a station with a press capacity of 2 tons.

The press was operated and the vibration acceleration of the floor surface at a distance of about 3 m was measured, and the result was about 55 dB.

When the same type of press FR500x500wmx30 is installed on the floor surface of
At 6 dB.

Example 2 A urethane elastomer all-rubber adhesive having the same composition as in Example 1, having a bulk density of 0.6097 and a thickness of 251III was attached to the bottom and sides of a 1000 x 500 x 50 sam concrete plate substrate. This coating n,
The entire base was fitted into a 75 mm deep recess made in the concrete floor. A 20 horsepower air compressor was completely installed on the top of the base, embedded in the base concrete, and fastened with nine bolts. The 71[t] of the air compressor is approximately 1 ton, and the urethane elastomer used has a unit surface precision Zine constant of 8 kf/cd between 4 chills and 10% strain. Approximately 3mm11. The vibration acceleration of the floor surface was measured at the location of 65 dB. For comparison, the above air compressor was installed directly on the concrete floor surface and the vibration acceleration was similarly measured, and the result was I/'183d.
The value of B is shown.

[BRIEF DESCRIPTION OF THE DRAWINGS] 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-proofing material according to the present invention, and Fig. 3 is 1 is a graph showing the vibration isolation characteristics of a vibration isolation material made of the present BAK and a conventional product. 1: Rail 2: Ballast 3: Concrete 4: Sleeper 6: Anti-vibration material 7:
Coarse (sparse>Dense layer 8: Dense layer Applicant Nisshin Boseki Co., Ltd. Japan National Railways Procedural Amendment a) 75" (+2:,:Y2 lower 21;Japanese-"-4.Morwork) 3 α - ： '5
; ÷, 1 display No. 1983-203364 2, Tei-zuki G) Masterpiece anti-vibration material film and method of its preparation, 3. Relationship with Uramasa Person 1'Relationship with Patent Applicant Address: Tokyo City 5 Chuo-ku Japanese Overseas ■ Yamacho 3-10 Name Date: 1,7 Representative of Spinning Co., Ltd.
Middle, Hideo Q (1 person on f mountain) 4th floor (embedded 〒105 Notes: 9F Marufuji Building, 3-1-10 Inoue, Minato-ku, Tokyo) ', ii, 'l': , ', 7 pairs ° ゛2 request J
! 7. Request for permission to keep one content on the ground G) Right shoulder: Insert the words ``This is a patent application pursuant to the present provisions of Article 38, however, 8 of the Patent Act.''

Claims (2)

[Claims] (1) A vibration-damping material made of a low-foam polyurethane elastomer that has a three-layer structure in which the density changes continuously or intermittently from the middle layer to the surface layer, with a dense layer near the surface layer. (2) (a) Organic polyisocyanate, (b) average number of functional groups is 2.5 to 3.5 and number average molecular weight is 4,500
~8,500 polyether polyol and (c) a chain extender are reacted in a ratio such that the NCO index is 90 to 110 in the presence of Freon gas having a boiling point of 40 to 70°C as a blowing agent. A method for manufacturing vibration-proofing materials.