JPS6160202B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to elastic sleepers, and more specifically, by coating concrete sleepers with low foam urethane elastomer, it simultaneously saves labor in track maintenance and reduces vibration and noise when the vehicle is running. This article concerns an elastic sleeper that has been made possible.

Regarding railway track structures, mainly due to the demand for labor saving, direct-coupled track systems such as slab tracks, which are easy to maintain, are being adopted in place of conventional ballast (gravel) tracks. However, in this direct-coupled track system, concrete slabs are directly constructed on a solid roadbed surface without using ballast, which may cause disadvantages in terms of vibration and noise.

Therefore, there was a need to develop a system that requires less maintenance and is also advantageous in terms of vibration and noise.In order to meet this demand, we used large concrete sleepers (i.e., small track slabs), and the bottom surface of the sleepers So-called elastic sleepers, whose sides are covered with elastic materials, have been proposed, and these sleepers can be used as fillers (e.g., synthetic resin, concrete, etc.).
A so-called direct-coupled elastic sleeper system was studied, which reduces the transmission of vibration and suppresses noise generation by installing the sleeper on the roadbed concrete via the sleeper.

Conventionally, the elastic material used in the above-mentioned elastic sleepers is a mixture of rubber powder obtained from used automobile tires and a polyurethane adhesive, filled into a mold, pressurized with a compressor, and then heated and cured. The method obtained by
(See Publication No. 146722). However, this elastic material is not only time-consuming to mold (one mold per day) but also requires large equipment, and the adhesion between the concrete sleepers and the elastic covering material tends to be incomplete. Peeling may occur. Moreover, when installing this conventionally proposed elastic sleeper on a concrete roadbed, when the sleeper is buried and fixed in the concrete, the elastic material covered with the sleeper is firmly restrained by the concrete and free. Since deformation is hindered, the spring constant increases, the vibration isolation effect decreases, and the benefits of using the elastic covering are reduced.

The present inventors conducted various studies on elastic covering materials for elastic sleepers that do not have such drawbacks, and found that a certain low-foaming urethane elastomer maintains a low spring constant even under the above-mentioned restraint conditions. It has been found that it has a large vibration isolation effect, can be molded to cover concrete sleepers very easily and strongly, and is very suitable as an elastic covering material for elastic sleepers.

Thus, according to the present invention, at least the lower portion of the bottom and side surfaces of the concrete sleeper comprises (a) a polyhydric alcohol having an average functional group number of 2.5 to 3.5 and a number average molecular weight of about 4500 to about 8500; (b) consisting essentially of an organic polyisocyanate, (c) a difunctional chain extender, (d) a urethanization catalyst, and (e) a blowing agent, and wherein the difunctional chain extender is added per unit weight of the urethane elastomer. 0.2× ^10-3
A bulk density of 0.3 formed from a urethane elastomer foam stock solution containing a concentration of 1.0 × 10 ^-3 mol/g
An elastic sleeper is provided, characterized in that it is coated with a low foaming urethane elastomer of ~0.9 g/cm ³ .

The present invention demonstrates that urethane elastomer is extremely suitable as a covering material for elastic sleepers, which can exert a damping effect between concrete sleepers and roadbeds and filled concrete due to energy loss effects based on viscoelastic properties. According to the present invention, by selecting a specific softened urethane elastomer, the spring constant of the elastic sleeper can be changed to the spring constant of the ballast track on a rigid roadbed such as a viaduct. By using a low-foamed urethane elastomer, the elastic coating material Even when the elastomer is restrained by filled concrete, it deforms freely inside the elastomer, achieving various remarkable effects such as preventing the vibration isolation effect from being significantly reduced due to an increase in the spring constant. be able to.

The polyhydric alcohol used in forming the elastic sleepers of the present invention has excellent anti-vibration properties and low spring constant, as well as excellent fatigue resistance, creep resistance, adhesion, hydrolysis resistance, and anti-aging properties. From the viewpoint of providing a urethane elastomer with properties, the average number of functional groups is 2.5 to 3.5, preferably 2.8 to
3.3 and the number average molecular weight is approximately 4500 ~
A value in the range of about 8500, preferably about 4500 to about 6500, has been found to be particularly suitable. Therefore, examples of polyhydric alcohols that can be suitably used in the present invention include low molecular weight polyhydric alcohols such as glycerin, trimethylolpropane, pentaerythritol, and quadrol; or low molecular weight active hydrogen compounds such as ethylenediamine and diethylenetriamine, and ethylene oxide; Included are so-called polyether polyols and polyester polyols obtained by addition polymerization with alkylene oxides such as propylene oxide, and high molecular weight polyhydric alcohols such as hydroxy-terminated liquid polybutadiene.

As the organic polyisocyanate, any of those commonly used in the production of urethane elastomers can be used, such as 4,4'-diphenylmethane diisocyanate (MDI), naphthylene diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, etc. I can do it. These organic polyisocyanates can be used alone or in a mixture of two or more.
Further, the organic polyisocyanate can also be used as a precursor precondensed with the polyhydric alcohol, ie, a prepolymer or a semi-prepolymer.

In any case, the amount of the organic polyisocyanate to be used is determined by the chemical amount and total active hydrogen-containing components (polyhydric alcohol, chain extender, etc.) that should react with the isocyanate residue (-NCO) present in the urethane elastomer stock solution. It is possible to vary the amount within a theoretically equal amount or within a range of ±10% thereof.

The chain extender used for forming the urethane elastomer coating in the present invention reacts with the organic polyisocyanate to form a hard segment mainly composed of hydrogen bonds through urethane bonds, urea bonds, etc. It is an important factor governing the elastic properties of urethane elastomers, and in the present invention, a substantially difunctional active hydrogen compound having a relatively low molecular weight is advantageously used as the chain extender. Examples of such chain extenders include ethylene glycol, propylene glycol, propanediol, butanediol, hydroquinone, hydroxyethylquinone ether, etc.
C ₂ - C ₁₀ diols; amines such as methylenebis-(o-dichloroaniline), quadrol, ethylenediamine, and triethanolamine are included, and these can be used alone or in combination of two or more types. can.

According to the research conducted by the present inventors, when the above-mentioned chain extender is used in combination with the above-mentioned polyhydric alcohol,
The amount of the bifunctional chain extender is expressed as a molar concentration based on the unit weight of the urethane elastomer obtained, and is from 0.2×10 ^-3 mole/g to 1.0×10 ^-3 mole/g.
A range of g has been found to be particularly suitable. If the concentration is lower than this, the chain lengthening effect will not be sufficient, so the strength of the resulting low-foamed urethane elastomer will tend to be ^low .
At a concentration higher than gr, the number of hydrogen bonds increases more than necessary, so the strength of the resulting urethane elastomer improves, but it tends to be an extremely hard elastomer, so it cannot be used as an elastic sleeper subject to compression set and repeated compressive stress. It is not very desirable as an elastic covering for use.

In addition, as the urethanization catalyst, catalysts commonly used in urethanization reactions, such as tertiary amine compounds and organometallic compounds, can be used, such as triethylenediamine, diazabicycloundecene, N-methylmorpholine, etc. ,
N,N-dimethylethanolamine; tin octylate, dibutyltin laurate, and the like. The amount of catalyst used is not critical and can vary over a wide range depending on the desired reaction rate, but depends on the amount of foaming the urethane elastomer, the atmospheric conditions (temperature,
It is necessary to adjust the amount used appropriately depending on the humidity (humidity, etc.). However, adjusting the amount of catalyst used is a common practice in the industry, and it is easy to select the appropriate amount.

Furthermore, in the present invention, a low-foaming urethane elastomer is molded, and the blowing agent used for producing this low-foaming product is a conventional blowing agent, such as water or halogenated hydrocarbon (e.g., trichlorofluoromethane). , methylene chloride), etc. The foaming degree of the urethane elastomer desired in the present invention is not strictly limited, but it is important that the foaming is low, and generally expressed in bulk density is 0.3 to 0.9 g/cm ³ , preferably 0.65 It is advantageous to be within the range of ~0.85 g/cm ³ , and the amount of the blowing agent used and/or the amount of foaming can be adjusted so that the bulk density of the resulting urethane elastomer falls within the above range. .

In addition to the above-mentioned components, the urethane elastomer foaming stock solution according to the present invention may contain a foam stabilizer (e.g., silicone surfactant, etc.), a pigment (e.g., carbon black, etc.), etc., if necessary, as usual. It can also be added.

The components of the urethane elastomer foam stock solution described above are intimately mixed immediately before manufacturing the elastic sleeper of the present invention, and used for forming the elastic sleeper.

In the elastic sleeper of the present invention, after fixing the concrete sleeper in a mold so that at least the lower part of the bottom and side surfaces of the concrete sleeper is almost completely surrounded by the mold with a gap,
A urethane elastomer foaming stock solution having the composition shown above is injected into the space, and the stock solution is foamed and cured, thereby producing an elastic sleeper adhesively coated with a low foaming urethane elastomer. I can do it.

By using this one-piece molding method, it is possible to easily manufacture elastic sleepers using a simple mold of normal pressure injection, and the mold can be demolded in about 2 hours after injection for about 1 minute. The elastic sleepers of the present invention manufactured by the integral molding method have strong adhesion between the concrete and the urethane elastomer covering material, making it possible to significantly increase production efficiency. It has the advantage that it is unnecessary and does not easily peel off.

According to the above method, the components of the urethane elastomer foam stock solution described above are intimately mixed immediately before injection according to a conventional method, and then poured into a mold for integral molding of the elastic sleeper. In order to enable integral molding of the elastic sleeper, the mold allows at least the lower part of the bottom and side surfaces of the concrete sleeper (the part closer to the bottom) to be almost completely surrounded by the mold with a gap. As such, it is fixed to concrete sleepers. A specific example of how to fix it is shown in the attached FIGS. 1 and 2.
That is, in the figure, 1 is a concrete sleeper, and its size varies depending on the railway line to be used, but for example, the length is 50 to 500 cm, and the width is 20 to 100 cm.
cm, and the height can be about 10 to 30 cm.
A box-shaped mold 4 is attached so as to almost completely surround a necessary portion such as the lower part of the side surface 3. At this time, gaps s having gaps w and w' are provided between the bottom surface 2 of the sleeper 1 and the inner bottom surface of the mold, and between the side surface 3 of the sleeper 1 and the inner surface of the mold, respectively. The mold 4 must almost completely surround the sleeper 1 to such an extent that there is no substantial leakage of the urethane elastomer stock solution injected into the gap s. The gaps w and w' can be varied widely depending on the size of the sleeper 1, the type of urethane elastomer, etc., but for example, w is 1 to 5 cm,
More preferably, it is 2 to 3 cm, and w' is 1 to 5 cm, more preferably 1.5 to 3 cm.

In addition, the height h at which the mold 4 surrounds the side surface 3 of the sleeper 1 is also not critical and can be varied widely depending on the use of the elastic sleeper, etc., but in general, the height h of the sleeper 1 is not critical. 1/10 to 1/10 of
It can be reduced to about 1/2.

Next, into the mold set as described above, a urethane elastomer foaming stock solution is injected into the gap s through the injection port 5 provided at an appropriate position in the mold 4. According to the research of the present inventors, the injection is carried out by placing the sleeper 1 with the mold 4 set as described above in such a way that the side of the mold with the injection port 5 is facing down in FIG. It has been found that it is very advantageous in terms of operation to install the sleepers in an upright position with the surface of the mold having the holes 6 facing up, and thus the bottom surface 2 of the sleepers being substantially vertical.

FIG. 3 is a flow sheet showing the operation method for injecting the urethane elastomer foam stock solution into such a mold 4, and the concrete sleeper 1 with the mold 4 set has its bottom surface 2 as described above. A urethane elastomer foaming stock solution is injected from an injection port 5 located substantially vertically below the mold, and air in the gap s is expelled from the degassing hole 6 as the injection is performed. This urethane elastomer foaming stock solution is prepared by charging, for example, a solution A consisting of a polyhydric alcohol, a chain extender, a blowing agent, a urethanization catalyst, a foaming stabilizer, etc., and a solution B consisting of an organic polyisocyanate into stock solution tanks 10 and 10'. , thence through metering pumps 11 and 11', respectively, to a two-part agitator 12, where it is prepared by intimate mixing, the mixture then passing through a conduit 13 with an end valve 14 to an inlet. 5.

Typical compositions of liquid A and liquid B preferably used in the present invention are as follows.

Composition of liquid A Polyether polyol (copolymer adduct of glycerin/propylene oxide/ethylene oxide; number average molecular weight = 6500 100.0 parts by weight Ethylene glycol 0.5 to 10 parts by weight Water 0.1 to 0.5 parts by weight Foam stabilizer (e.g. silicone surfactant) )
0.1 to 1 part by weight Triethylenediamine 0.1 to 0.5 parts by weight Liquid B composition Polyisocyanate/polyol prepolymer (e.g. isocyanate-terminated precondensate of 4,4'-diefylmethane diisocyanate and the above polyether polyol; free
NCO content = 16% by weight)
NCO Index 90-110 parts by weight The injection rate of the urethane elastomer foaming stock solution into the mold is usually 1-100 kg/min, more preferably 30-100 kg/min.
It can be carried out at a speed of 60 kg/min, and the injection amount can be from 1/3 to 9/10 of the total volume of the gap in the mold, depending on the desired degree of foaming. The injected urethane elastomer foam stock solution is then foamed and cured. This foam curing can normally be carried out at room temperature, but if necessary, it may be carried out while being heated to a temperature of up to about 70°C. The foam curing is completed within about 1 to 2 hours, and when the foam curing is completed, the mold is removed from the sleepers.

In this way, the elastic sleeper of the present invention coated with the low foaming urethane elastomer can be obtained. Most of the cells in the low-foaming urethane elastomer that is integrally molded onto concrete sleepers are closed cells, and the desired physical properties of the elastomer include the following.

1 Bulk density: 0.3 to 0.9 g/cm ³ , preferably 0.65 to
0.85g/cm ³ 2 Spring constant per unit area: at least 1Kg/
cm ³ or more, preferably 3 to 10 Kg/cm ³ 3 Compression set: 15% or less, preferably 10% or less 4 Amount of fatigue due to fatigue: 1.5 mm or less, preferably 1 mm or less 5 Expansion ratio: 1 to 3 times, preferably As shown in FIG. 4, the elastic sleeper of the present invention is comprised of a concrete sleeper 1 and a low-foaming urethane elastomer covering material 7 integrally applied to the lower part thereof.

According to the research conducted by the present inventors, if a cutout portion that occupies 0.5% or more, preferably 50% or less of the bottom area of the coating material of this low-foaming urethane elastomer coating material is bored, the It is possible to prevent stress from occurring within the sheathing material, and even in a restrained state, the sheathing material can be freely deformed to some extent, making it possible to further reduce the spring constant.In addition, the amount of urethane elastomer used can be reduced. It turns out that it can be reduced.

In order to exhibit such an effect, the shape of the cutout portion 8 may be, for example, a columnar shape as shown in FIG. 5, a prismatic shape (not shown), or a groove-like structure as shown in FIG. 6. be able to.

It is important to install elastic sleepers at predetermined positions on the roadbed to prevent concrete from flowing into this notch when pouring concrete. For example, polyethylene foam, soft polyurethane foam, soft foam rubber, etc. Bulky soft material objects such as soft vinyl chloride foam can be temporarily filled.

According to the present invention described above, it is possible to provide an elastic sleeper that has an excellent vibration damping effect and generates less vibration and noise.

In particular, since the elastic sleepers of the present invention are formed by integrally foam-molding the low-foam urethane elastomer covering material to the concrete sleepers, it is said that the urethane elastomer covering material firmly adheres to the concrete sleepers. It has its advantages. Normally, a vibration isolator is required to be able to reliably transmit vibrations from a vibration source, block the vibrations, and absorb them within the vibration isolator, so the above-mentioned adhesion is an extremely important practical advantage.

However, the elastic sleepers of the present invention can be easily manufactured using a simple device, and the production cost and labor of the elastic sleepers can be reduced.

Next, the present invention will be further explained with reference to Examples.

Example A concrete sleeper with dimensions of 400 mm x 2000 mm x 200 mm was constructed as shown in Figure 1.
It was set in a mold with 6 degassing holes of mmφ, and the coating thicknesses w and w' were set to 25 mm. Although it is not shown in Figure 1, there is a width of 300mm in the center of the bottom as shown in Figure 6.
A partition wall was attached to the corresponding part of the mold so that a covering material having a cutout part 8 having a groove-like structure with a width of 15 mm and a depth of 15 mm could be formed. Next, using the apparatus shown in FIG. 3, liquids A and B having the compositions shown below were mixed in the stirrer 12.
The mixture was mixed at a rotation speed of 6000 rpm, and 30 kg was injected from the injection port 5 at the bottom of the mold at a rate of 45 kg/min. The mold was removed after being left at room temperature for 2 hours. The resulting urethane elastomer coating material for elastic sleepers has a bulk density of 0.76.
g/cm ³ ; Compression set 6.9%; Amount of set due to fatigue
At 0.43mm, the spring constant per sleeper tightening is
40ton/cm, fully satisfying the requirements in terms of appearance and performance.

Composition of liquid A Polyether polyol (copolymer adduct of glycerin/propylene oxide/ethylene oxide; number average molecular weight = 6500) 100.0 parts by weight Ethylene glycol 3.0 parts by weight Water 0.35 parts by weight Foam stabilizer (e.g. silicone surfactant)
0.50 parts by weight Triethylenediamine 0.20 parts by weight Liquid B composition Polyisocyanate/polyol prepolymer (e.g. isocyanate-terminated precondensate of 4,4'-diefylmethane diisocyanate and the above polyether polyol; free
NCO content = 16% by weight) NCO Index 100

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a mold set in a concrete sleeper, Fig. 2 is an enlarged sectional view taken along line A-A in Fig. 1, and Fig. 3 is a flowchart of the apparatus for manufacturing the elastic sleeper of the present invention. The seat, FIGS. 4, 5, and 6 are perspective views of the elastic sleeper of the present invention (however, the elastic sleeper shown in FIG. 5 is a perspective view when it is turned over). In the diagram, 1... Concrete sleepers, 2...
Bottom surface of the concrete sleeper, 3... Side surface of the concrete sleeper, 4... Mold, 5... Inlet, 6... Deaeration hole.

Claims (1)

[Scope of Claims] 1. At least the lower part of the bottom and side surfaces of the concrete sleeper is made of (a) a polyhydric alcohol having an average number of functional groups of 2.5 to 3.5 and a number average molecular weight of about 4,500 to about 8,500; (b) an organic consisting essentially of a polyisocyanate, (c) a difunctional chain extender, (d) a urethanization catalyst, and (e) a blowing agent; ×10 ^-3
A bulk density of 0.3 formed from a urethane elastomer foam stock solution containing a concentration of 1.0 × 10 ^-3 mol/g
An elastic sleeper characterized by being coated with a low foaming urethane elastomer of ~0.9 g/cm ³ .