JP5985427B2 - Track pad - Google Patents

Description

  The present invention relates to a track pad which is interposed between a rail and a sleeper or a tie plate fixed on the sleeper and has a required spring constant.

  Conventional rubber pads used natural rubber or SBR rubber (styrene butadiene rubber), but the rubber pads are turned off and removed by long-term use due to the expansion and contraction of the rails due to the cold and warm conditions. Have been frequent. Further, the rubber material has increased in hardness over time and has a function of preventing vibration and noise at the initial stage of laying, but has a drawback that the function deteriorates with time.

  As a track pad that has improved such a drawback, a steel pad bonded to the upper surface of a rubber material has been proposed. Since the steel sheet and the rubber material are inferior in adhesiveness, the steel sheet is easily peeled off from the rubber material, and a number of contrivances have been made so as not to be detached even if it is peeled off (for example, patent documents 1 to 4).

  However, even after many years of use, poor adhesion occurs, and the steel plate separates from the rubber pad due to the breaking force caused by the expansion and contraction of the rail and the vibration caused by the passing of the vehicle. There is a case where a serious failure such as a traffic signal failure occurs, for example.

  And as a track pad which improved these faults, what fixed ebonite instead of adhering a steel plate on the upper surface of a rubber material is proposed (for example, patent documents 5).

Japanese Patent Laid-Open No. 07-238502 JP-A-10-237802 JP-A-11-323801 JP 2004-44113 A JP 2006-265841 A

  However, in the proposed product of Patent Document 5, since the rubber member and ebonite are simultaneously vulcanized and bonded at the time of rubber vulcanization, the bonding surface is reactively bonded and the bonding reliability is high. This proposed product is superior in that ebonite is good and sliding adhesion is quite firm, but in order to adjust the low spring constant, a method is adopted in which the bottom surface of the rubber material is thinned, that is, a recess is provided to adjust the pressing area. As a result, the pressure is borne in a small area by passing through the meat, and when a high load is repeatedly applied for a long time, there is a problem that the rubber part of the small area is cracked and the rubber material is dropped. Further, it has been found that ebonite has extremely poor wear characteristics because it is a rubber material having a very high degree of crosslinking in which a large amount of sulfur is blended with rubber. In addition, the present situation is that the defect that the hardness of the rubber increases with time is not corrected.

In view of the above-described facts, an object of the present invention is to provide a track pad that is easy to control the spring constant, has excellent durability, and is difficult to be detached from the rail.

  The above problem is solved by the following means.

The invention according to claim 1
A track pad interposed between a rail and a sleeper or a tie plate fixed on the sleeper and having a required spring constant,
A crosslinked urethane foam layer having a static friction coefficient of 0.35 or less;
An adhesive layer provided on the whole or part of the surface of the sleeper or tie plate side of the crosslinked urethane foam layer;
Orbital pad with.

The invention according to claim 2
The track pad according to claim 1, wherein the crosslinked urethane foam layer includes a silicone compound having an OH group in a molecule.

The invention according to claim 3
The orbital pad according to claim 1 or 2 in which said adhesion layer contains acrylic resin or urethane resin.

The invention according to claim 4
The track pad according to any one of claims 1 to 3, wherein the crosslinked urethane foam layer is a closed-cell foam layer.

The invention according to claim 5
The track pad according to any one of claims 1 to 4, wherein the crosslinked urethane foam layer is a layer formed using at least a polyether polyol and an isocyanate as a urethane raw material.

The invention according to claim 6
The track pad according to claim 5, wherein the isocyanate is a diphenylmethane diisocyanate (MDI) isocyanate.

  ADVANTAGE OF THE INVENTION According to this invention, the control of a spring constant is easy, and while being excellent in durability, the track pad which cannot be easily detached from a rail can be provided.

FIG. 1 is a schematic configuration diagram illustrating an interposition mode of a track pad according to the present embodiment. FIG. 2 is a schematic perspective view showing the track pad according to the present embodiment. FIG. 3 is a cross-sectional view taken along the line AA of FIG. FIG. 4A is a plan view illustrating an example of an arrangement position of the adhesive layer. FIG. 4B is a plan view illustrating another example of the arrangement position of the adhesive layer. FIG. 4C is a plan view illustrating another example of the arrangement position of the adhesive layer.

  Hereinafter, a track pad according to an embodiment of the present invention will be described with reference to the drawings.

The track pad 10 according to the present embodiment is a pad provided on the track slab.
Specifically, as shown in FIG. 1, the track slab is fixed on, for example, a sleeper 20 arranged on a roadbed (not shown), a tie plate 22 fixed on the sleeper 20, and a tie plate 22. Rail 24.

  The tie plate 22 is fastened and fixed on the sleeper 20 by bolts 22A and nuts 22B, for example. The rail 24 is pressed and fixed on the tie plate 22 by, for example, a leaf spring 26 fastened and fixed by bolts 26A and nuts 26B.

  For example, the rail 24 is fixed to the tie plate 22 with a variable pad 28 (for example, a resin injection type variable pad) and a track pad 10 interposed therebetween. Here, the variable pad 28 is a pad for adjusting the rail height, and is a pad provided arbitrarily.

Thus, the track pad 10 according to the present embodiment is interposed between the rail 24 and the tie plate 22. However, the track slab may not have the tie plate 22, and in this case, the track pad 10 is interposed between the rail 24 and the sleeper 20.
The track slab is not limited to the above configuration, and may be a known configuration.
The sleeper tree is not only a tree but also, for example. Including wood, concrete, glass fiber or resin, or a mixture of these materials.

  As shown in FIG. 2 to FIG. 3, the track pad 10 according to the present embodiment interposed in the above-described aspect is a crosslinked urethane foam layer 12 and a surface of the crosslinked urethane foam layer 12 on the sleeper 20 or tie plate 22 side ( And an adhesive layer 16 provided on the entire surface or a part of the rear surface). The track pad 10 according to the present embodiment is a pad having a required spring constant.

  In addition, the shape of the track pad 10 which concerns on this embodiment can be made into a known shape according to the intervention aspect.

  In the track pad 10 according to the present embodiment, by providing the cross-linked urethane foam layer 12 as the track pad body, the composition of the urethane raw material (isocyanate concentration, etc.) The spring constant of the target track pad 10 can be easily controlled by adjusting the state (such as the ratio of closed cells) and the film thickness, and the resilience and durability are high. Moreover, the slidability with respect to the rail 24 increases by setting the static friction coefficient of the crosslinked urethane foam layer 12 in the above range.

  In addition to this, by having the adhesive layer 16 on the back surface of the crosslinked urethane foam layer 12, when the track pad 10 is interposed, a member that comes into contact with the surface of the sleeper 20 or tie plate 22 (for example, the sleeper 20, type) Adhesion with the rate 22 or the variable pad 28) is enhanced. Even if the force accompanying the expansion and contraction of the rail is applied to the track pad 10 by this adhesion force, the track pad 10 is not easily displaced. As a result, the detachment of the track pad 10 from the rail 24 caused by the expansion and contraction of the rail 24 or the vibration when passing through the vehicle is easily suppressed.

  For this reason, in the track pad 10 according to the present embodiment, the control of the spring constant is easy, the durability is excellent, and it is difficult to separate from the rail 24. As a result, the service life can be extended, and even when the cutting force due to the expansion and contraction of the rail 24 and the vibration due to the passing of the vehicle are loaded, it is difficult to detach from the rail 24 and is blown off when passing the vehicle, causing damage to the vehicle. The traffic signal failure caused by the insulation failure caused by contacting the insulating portion of the rail 24 is suppressed.

  Hereinafter, details of the track pad 10 will be described. In the following description, reference numerals are omitted.

(Crosslinked urethane foam layer)
The crosslinked urethane foam layer corresponds to the spring of the raceway pad, and is a layer that particularly requires restorability. And in order to satisfy | fill a characteristic, the said layer is comprised with the crosslinked urethane foam.

  In addition, the cross-linked urethane foam layer is a layer that is in direct contact with the rail, and is a layer that needs to be a slippery surface so that the track pad does not shift due to expansion and contraction of the rail. For this reason, the static friction coefficient of a crosslinked urethane foam layer is 0.35 or less, Preferably it is 0.3 or less. The lower limit value of the static friction coefficient of the crosslinked urethane foam layer varies depending on the fastening force of the track pad, but is about 0.15, for example.

  The crosslinked urethane foam layer is, for example, 1) a method in which a mixed stock solution containing polyol, isocyanate, and, if necessary, a chain extender is injected into a mold as a urethane raw material, and 2) the mixed stock solution is applied to a release paper. It can be formed by a method of punching into a predetermined shape after heat curing. The mixed stock solution containing the urethane raw material contains a foaming agent and may contain other additives.

-Polyol-
As the polyol, for example, a polyether-based polyol such as polyoxypropylene polyol (PPG), polyoxyethylene polyol (PEG), a copolymer of PPG and PEG, or polyoxytetramethylene polyol (PTMG) is preferably used. Polyether polyols (particularly PPG and PTMG) are excellent in hydrolysis resistance as well as reactivity, so that the durability and resilience of the crosslinked urethane foam layer are easily increased. In addition, polyether polyols have the advantage of low viscosity and high handleability.

  In addition to polyether polyols, polyols include dicarboxylic acids (adipic acid, sebacic acid, phthalic acid, dimer acid, etc.) and glycols (ethylene glycol, propylene glycol, 1.4-butanediol, 1.6-hexanediol, 2 Polyester polyol (PES), polycaprolactone polyol (PCL), polycarbonate polyol (PCA), (hydrogenated) polybutadiene-based polyol, (hydrogenated) polyisoprene condensed with -methylpropanediol, 3-methylpentanediol, etc. A system polyol or the like may also be used.

  In addition, it is preferable that the polyol is reacted with an excess equivalent of an isocyanate in advance and used as a prepolymer of a terminal NCO group because the restoring property and toughness of the crosslinked urethane foam layer are enhanced.

-Isocyanate-
As the isocyanate, for example, toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), or crude MDI (cr-MDI) is preferably used. In particular, it is preferable to use diphenylmethane diisocyanate (MDI) -based isocyanate because it has high reactivity and the durability and resilience of the crosslinked urethane foam layer are easily increased.

-Chain extender-
Examples of the chain extender include aromatic diamines (eg, 4.4′-diamino-3.3′-dichlorodiphenylmethane (MOCA)), glycols having a molecular weight of 500 or less, or polyfunctional alcohols (eg, ethylene glycol, 1.4-butane). Diol, 1.6-hexanediol, trimethylolpropane, glycerin, trimethylolpropane, etc.) and their ethylene oxide adduct or propylene oxide adduct, bisphenol A ethylene oxide adduct or propylene oxide adduct, hydroquinone ethylene oxide It is preferable to use an adduct, an ethylene oxide adduct of resorcin.

  Among these, the chain extender is a low molecular polyol of a primary alcohol having a molecular weight of 200 or less, and ethylene oxide addition of ethylene glycol, 1,4-butanediol, 1,6-hexanediol, trimethylolpropane, hydroquinone, resorcin. A thing etc. are the most preferable.

-Foaming agents and other additives-
As other additives, well-known additives such as a catalyst and a foam stabilizer are used in addition to the foaming agent.
As the blowing agent, for example, water, a low-boiling organic solvent (such as cyclopentane or dichloromethane), a halogenated hydrocarbon, a mixture thereof, or the like is used. In addition, the foaming of urethane can also take the method of enclosing a bubble using polyol or a prepolymer using air or nitrogen.
As the catalyst, for example, an amine-based catalyst or a tin-based metal catalyst is used.
As the foam stabilizer, for example, a silicone compound represented by a copolymer of polydimethylsiloxane and polyoxyalkylene polyol is used.

  Here, a slidability improving material may be used for the crosslinked urethane foam layer in order to realize the static friction resistance.

  As the sliding property improving material, for example, a sliding powder made of silicone resin powder, fluororesin powder, high density polyethylene powder, ultrahigh molecular weight polyethylene powder, polypropylene powder, polyoxymethylene powder, graphite powder, molybdenum disulfide powder is used. . Further, the slidability improving material may be reacted with an isocyanate using a silicone compound having an active hydrogen group in the molecule as a raw material. In addition to the slidability improving material, a liquid silicone oil, a foot coat compound, a metal soap or the like may be used in combination as a slidability improving aid.

  Among these, the slidability improving material is preferably a silicone compound having an active hydrogen group in the molecule. Thereby, the silicone compound as a slidability improving material reacts with isocyanate, and the static friction coefficient of a crosslinked urethane foam layer is reduced. Moreover, the water absorption rate of a crosslinked urethane foam layer can be reduced.

Silicone compounds having an active hydrogen group in the molecule are urethanes of silicone compounds having OH groups, NH groups, NH ₂ groups, mercapto groups, or two or more of these groups at at least one of the terminals and side chains of polydimethylsiloxane. You may add to a raw material and make it react at the time of urethane manufacture.

  Of these silicone compounds having an active hydrogen group in the molecule, silicone compounds having an OH group in the molecule are most preferred. The silicone compound having an OH group in the molecule has an advantage that the urethane hard layer can be easily produced because the reactivity with the urethane raw material is about the same in terms of speed.

  As the silicone compound having an active hydrogen group in the molecule, a polydimethylsiloxane-terminal OH group polyalkylene ether-graft copolymer may be used. When this silicone compound is used for producing a crosslinked urethane foam layer, it functions as a silicone foam stabilizer and can control the static friction coefficient of the crosslinked urethane foam layer.

  Silicone compounds having an active hydrogen group in these molecules melt well in the urethane raw material, but at the same time as the reaction proceeds, they bleed to the surface and are eventually unevenly distributed on the surface of the layer, which is effective in reducing the friction coefficient. In addition, since it is incorporated into the composition, it does not elute, and long-term effects are easily maintained.

-Introducing urethane crosslinking-
In order to introduce crosslinking into urethane, it is necessary to use a bifunctional or higher functional polyol in any of polyol, isocyanate, and chain extender. In particular, when a terminal NCO group polyol prepolymer is used, in order to introduce crosslinking into urethane, the terminal NCO group polyol prepolymer is bifunctional and the chain extender is bifunctional or more. It is preferable to use an isocyanate together or to use these together because the prepolymer can be easily synthesized and the viscosity can be reduced.

-Other aspects-
The crosslinked urethane foam layer may be a closed cell foam layer. If the air bubbles in the crosslinked urethane foam layer are closed cells, the layer is difficult to absorb water and the durability is likely to increase.

Density of crosslinked urethane foam layer, for example, 0.4~0.95g / cm ³ C., preferably 0.6~0.9g / cm ^3.
The closed cell foam layer has a closed cell ratio of, for example, 30 to 100%, preferably 50 to 100%.
The thickness of the crosslinked urethane foam layer is, for example, preferably 1 to 15 mm, and preferably 3 to 13 mm.

(Adhesive layer)
The adhesive layer is a layer that is in close contact with a member (for example, a sleeper, a tie plate, or a variable pad) that is in contact with a sleeper or tie plate side surface of the track pad, and suppresses the release of the track pad from the rail. Then, the separation of the track pad from the rail is preferably suppressed over a long period of time.

  For this reason, the probe tack value of the adhesive layer is preferably 0.5 to 150 kPa, preferably 1.0 to 50 kPa, and more preferably 1.0 to 10 kPa.

  In particular, when the probe tack value of the adhesive layer is 0.5 kPa or more and 50 kPa or less, self-adhesion between track pads or adhesion of dust, sand, or the like is suppressed, and workability is high. On the other hand, when the probe tack value of the adhesive layer is more than 50 kPa and 150 kPa or less, a peelable separator (for example, release paper) or the like is pasted on the surface (exposed surface) of the adhesive layer and the track pad is interposed It is preferable to peel the separator from the adhesive layer because workability is improved.

  As the pressure-sensitive adhesive layer satisfying such probe tack value, it is preferable that the pressure-sensitive adhesive layer is a flexible material. Therefore, as a physical property index for selecting a pressure-sensitive adhesive, a 100% tensile modulus is 0.7 to 7.5 MPa. However, it is preferably 1.7 to 5.0 MPa.

  As a material for the adhesive layer, an acrylic resin, a urethane resin, an epoxy resin, and a nylon resin are preferable from the viewpoint of adhesion to the crosslinked urethane foam layer, and an acrylic resin and a urethane resin are more preferable.

  Examples of adhesive acrylic resins include double-sided adhesive tapes sold by Sekisui Chemical Co., Ltd. and Sumitomo 3M, acrylic adhesive SK Dyne (manufactured by Soken Chemical Co., Ltd.), and water emulsion acrylic-styrene resins. It is preferable to use a product name spray paste (manufactured by Sumitomo 3M Co., Ltd.) or the like with an acronal (manufactured by BASF Japan) or a spray-like adhesive.

  Examples of the urethane resin having adhesiveness include the resin name “Barnock” (manufactured by DIC) as a resin for paint, or the product name “Crisbon” (manufactured by DIC), which is used for synthetic leather, automobile interior materials, adhesives, and the like. The product name “Nippray” (manufactured by Nihon Hojo Co., Ltd.) sold as a foamed urethane-based sheet, a moisture curable urethane hot melt manufactured by Cemedine Co., Ltd. or Hitachi Chemical Polymer Co., Ltd. may be used.

  As an adhesive epoxy resin, for example, a bond (manufactured by Konishi Roku Shoten Co., Ltd.) used as an adhesive or a “liquid gasket” sold by ThreeBond Co., Ltd. may be used.

  As the adhesive nylon resin, for example, dimer acid polyamide-based adhesives and adhesives sold by Harima Kasei Co., Ltd., Henkel Japan Co., Ltd., and Loctite Co., Ltd. are preferably used.

  The adhesive layer may be provided on the entire back surface of the crosslinked urethane foam layer, or may be provided on a part thereof. When providing an adhesion layer in a part of crosslinked urethane foam layer, the mode shown below is mentioned, for example.

Aspect 1): A mode in which a flat square pressure-sensitive adhesive layer is provided in the central portion excluding the edge on the back surface of the crosslinked urethane foam layer (see FIG. 4A).
Aspect 2): A mode in which linear adhesive layers along the longitudinal direction are arranged on the back surface of the crosslinked urethane foam layer with an interval in the lateral direction (a mode in which wiring layers are arranged in stripes: see FIG. 4B) )
Aspect 3): Aspect in which planar square adhesive layers are arranged in a lattice pattern on the back surface of the crosslinked urethane foam layer (see FIG. 4C).

  4A to 4C, 12 indicates a crosslinked urethane foam layer, and 14 indicates an adhesive layer.

Here, the arrangement | positioning aspect of an adhesion layer is not necessarily restricted to the aspect of said 1) -3).
For example, in the aspect of 1), the planar shape of the adhesive layer is not limited to a square shape, and may be a circular shape, a polygonal shape, or other geometric shapes. The pressure-sensitive adhesive layer is not limited to the central portion, and may be provided only on the edge of the back surface of the crosslinked urethane foam layer.

  In the aspect 2), the adhesive layer is not limited to a linear shape, and may be provided in a curved line shape (for example, a wavy shape) or a bent line shape (for example, a broken line shape). The pressure-sensitive adhesive layer may be arranged on the back surface of the crosslinked urethane foam layer with a linear pressure-sensitive adhesive layer along the short direction at intervals in the longitudinal direction.

  In the aspect 3, the planar shape of the adhesive layer is not limited to a square shape, and may be a circular shape, a polygonal shape, or other geometric shapes. The adhesive layer is not limited to the lattice shape, and may be arranged in a staggered manner or irregularly.

  The aspect which provided the adhesion layer of the aspect of 2) or 3) in the center part of the back surface of a bridge | crosslinking urethane foam layer, an edge part, four corners, or a longitudinal direction or a transversal direction both ends may be sufficient.

  In addition, the adhesion layer may be patterned in arbitrary planar shapes and provided on the back surface of the crosslinked urethane foam layer.

  The thickness of the adhesive layer is 0.005 to 1.0 mm, preferably 0.01 to 0.5 mm.

  The method for forming the adhesive layer on the back surface of the cross-linked urethane foam layer is not particularly limited, and a resin-made sheet serving as the adhesive layer is prepared in advance, and a urethane resin conversion reaction is performed when forming the cross-linked urethane foam layer. A method sometimes performed by reactive bonding is mentioned. Specifically, a urethane foam layer is prepared by a coating method or a casting method on or under a resin sheet that becomes an adhesive layer, and the adhesive layer is formed on the back surface of the crosslinked urethane foam layer.

  Other methods for forming the adhesive layer include, for example, 1) as an in-mold coating, after previously applying a coating liquid for forming an adhesive layer on a mold, a urethane raw material is cast to form a crosslinked urethane foam layer. A method of integrally forming a pressure-sensitive adhesive layer on the back surface, 2) A method of forming a pressure-sensitive adhesive layer by preparing a crosslinked urethane foam layer in advance and applying a coating solution for forming a pressure-sensitive adhesive layer to the back surface of the crosslinked urethane foam layer Can be mentioned.

  In particular, when a moisture-curing reactive urethane hot melt type is used as a coating liquid for forming an adhesive layer, for example, a pressure-sensitive adhesive layer that is solvent-free, has good adhesion to the crosslinked urethane foam layer, and has high durability. Can be formed.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. In the following description, unless otherwise specified, “part” and “%” relating to the blending amount (content, addition amount) are based on mass.

Example 1
1,100 butanediol / trimethylolpropane (mass ratio 75/25) 9.6 parts to 100 parts of a prepolymer consisting of 100 parts of PTMG1000 (Mitsubishi Chemical PTMG, molecular weight 1000) and 77.9 parts of Millionate P-MDI, 0.1 parts of water, 0.03 parts of dibutyltin dilaurate catalyst, and 8.0 parts of foam stabilizer SH-193 (OH group-containing silicone compound manufactured by Toray Dow Corning Co., Ltd.) are stirred and molded (dimensions 185 × 145 × 13) .9 mm) and a predetermined amount was injected to close the mold. After 5 minutes, it was left in an oven at 100 degrees for 10 minutes to be cured by heating. Thereafter, the mold was removed and the product was taken out. About 20 μm of Crisbon NY328FTR (manufactured by DIC, urethane-based coating agent) was sprayed on the entire back surface of the obtained crosslinked urethane foam layer and dried at 100 ° C. for 5 minutes to prepare an adhesive layer. The probe tack value of the adhesive layer was 1.0 kPa, and it did not peel off at all with the crosslinked urethane foam layer and was firmly adhered. In addition, since the track pads of Example 1 did not adhere to each other and dust did not adhere to the adhesive layer, release paper for protecting the adhesive layer was unnecessary.

(Example 2)
In place of 8.0 parts of foam stabilizer SH-193 (OH group-containing silicone compound manufactured by Toray Dow Corning) of Example 1, SH-193 (OH group-containing silicone compound manufactured by Toray Dow Corning) 0.5 In the same manner as in Example 1, except that 8 parts of KF-6002 (manufactured by Shin-Etsu Chemical Co., Ltd., both-end carbinol-modified silicone oil, hydroxyl value 35) was added as a silicone-based reactive oil, Was made.

(Example 3)
Instead of the Crisbon NY328FTR (made by DIC, urethane-based coating agent) of Example 1, SK Dyne 1495 (Akaken Chemical Co., Ltd. acrylic pressure-sensitive adhesive solution, solid content 30%) was formed on the entire back surface of the crosslinked urethane foam layer with a thickness of 25 μm. A track pad was prepared in the same manner as in Example 1 except that the coating was applied. The probe tack value of the adhesive layer was 9.4 kPa. In addition, since the track pads of Example 3 did not adhere to each other and dust did not adhere to the adhesive layer, release paper for protecting the adhesive layer was unnecessary.

Example 4
Instead of forming a pressure-sensitive adhesive layer by applying Crisbon NY328FTR (made by DIC, urethane-based coating agent) to the entire back surface of the crosslinked urethane foam layer in Example 1, SK Dyne 1495 (Akaken Chemical Co., Ltd. acrylic pressure-sensitive adhesive solution, Example 1 except that an adhesive layer was formed by applying a solid content of 30%) in a stripe shape (line width: about 1 mm, pitch: 2 mm: see FIG. 4B) along the longitudinal direction of the back surface of the crosslinked urethane foam layer. A track pad was produced in the same manner.

(Comparative Example 1)
A method similar to Example 1 except that the number of parts of the foam stabilizer SH-193 (OH group-containing silicone compound manufactured by Toray Dow Corning Co., Ltd.) of Example 1 was changed to 8.0 parts instead of 8.0 parts. Thus, a track pad was produced.

(Comparative Example 2)
A track pad was produced in the same manner as in Example 1 except that the adhesive layer of Example 1 was not formed.

(Example 5)
Instead of Crisbon NY328FTR (made by DIC, urethane-based coating agent) of Example 1. A track pad was produced in the same manner as in Example 1 except that the adhesive layer was formed using Crisbon ASPU-112 (manufactured by DIC, urethane-based coating agent). The probe tack value of the adhesive layer was 1.6 kPa. In addition, since the track pads of Example 5 did not adhere to each other and dust did not adhere to the adhesive layer, a release paper for protecting the adhesive layer was unnecessary.

(Example 6)
Instead of forming an adhesive layer by applying Crisbon NY328FTR (made by DIC, urethane-based coating agent) to the entire back surface of the crosslinked urethane foam layer in Example 1, Crisbon ASPU-112 (made by DIC, urethane-based coating agent) In the same manner as in Example 1, except that the adhesive layer was formed by applying a striped shape along the longitudinal direction of the back surface of the crosslinked urethane foam layer (line width of about 1 mm and pitch of 2 mm: see FIG. 4B). A track pad was made.

(Example 7)
Instead of using the foam stabilizer SH-193 (OH group-containing silicone compound manufactured by Toray Dow Corning) of Example 1, 0.5 part of SF-2936 (silicone foam stabilizer manufactured by Toray Dow Corning) and a silicone system A track pad was produced in the same manner as in Example 1 except that 8 parts of KF-6002 (manufactured by Shin-Etsu Chemical Co., Ltd., both-end carbinol-modified silicone oil, hydroxyl value 35) was added as a reactive oil.

(Example 8)
Instead of Crisbon NY328FTR (made by DIC, urethane-based coating agent) in Example 1, a hot-melt adhesive HM650-2 (synthetic rubber-based hot-melt adhesive made by Cemedine) was applied with a hot-melt gun to form an adhesive layer. A track pad was produced in the same manner as in Example 1 except that it was formed. The probe tack value of the adhesive layer was 100 kPa. The track pads of Example 8 adhere to each other with the adhesive layer exposed, and dust also adheres to the adhesive layer. Therefore, a release paper for protecting the adhesive layer is attached to the surface of the adhesive layer. Protected.

(Evaluation)
In addition to measuring the physical properties of the track pads obtained in each example, various tests were performed for evaluation. However, the track pad of Example 8 was measured and tested with the release paper peeled from the adhesive layer.

  Hereinafter, various measurement methods and various tests performed in this example will be described. In addition, the various values of this invention are values measured by the measuring method shown below.

(Measuring method)
-Thickness-
The thickness was obtained as an average value by measuring the thickness of a total of nine points in three vertical rows and three horizontal rows of the test piece (140 mm × 180 mm).

-Density-
The density was measured by dividing the weight of the test piece (140 mm x 180 mm x thickness) by the volume.

-Static friction coefficient-
The static friction coefficient is in accordance with JISK7125. A test piece (30 mm × 30 mm × thickness) is placed on a steel plate, and a weight of 200 g is placed on the test piece. One end of the test piece was pulled at a speed of 50 mm / min, and the initial maximum load was divided by the load (200 g).

-Cellular foam rate-
The self-bubble ratio was measured in accordance with ASTM D2856 with a test piece (30 mm × 30 mm × 10 mm) using a Beckman air comparison hydrometer 930 type (manufactured by Tokyo Science).

−Spring constant−
In accordance with JISE1117, the track pad (size is the product size) is first compressed to 40 kN, then returned to 10 kN, then loaded to 50 kN, and the deformation amount from 10 kN to 50 kN is measured. The spring constant was determined by the formula spring constant = ΔP ÷ deformation amount. Here, ΔP is 50 kN−10 kN = 40 kN.

-Probe tack value-
In accordance with ASTM D2979, a stainless steel (SUS304) 10Φ probe is brought into contact with the surface (adhesive surface) of the adhesive layer, a load of 0.1 kg / cm ² is applied for 20 seconds, and then peeled off at a speed of 10 mm / second. The load per hour was read and the value per area was calculated.
And this measurement was performed about arbitrary 10 places of the adhesion layer provided in the back surface of the crosslinked urethane foam layer, and the average value was made into the probe tack value of the adhesion layer. However, when the adhesive layer was provided on a part of the back surface of the crosslinked urethane foam layer, the measurement was performed so that the center of the probe was in contact with the adhesive layer.

-100% tensile modulus (indicated as 100% M)
The 100% tensile modulus was obtained as a value obtained by dividing a test sample obtained by punching out a dry sample of an adhesive layer with dumbbell No. 1 at a pulling speed of 200 mm / min and obtaining a stress of 100% elongation and dividing by a thickness in accordance with JISK7215.

(Various tests)
-Fatigue test-
The fatigue test was performed in accordance with JISE1117, after a test piece (50 mm × 50 mm × thickness) was pre-compressed 9 kN, and after 9 kN load was repeatedly compressed and restored 1 million times at 5 Hz, and the amount of settling 24 hours after unloading was measured. And by observing the appearance such as cracks and cracks of the test piece. And it was set as the pass by the amount of sludge being 6% and having no appearance abnormality such as peeling.

-Fukui resistance-
As for the resistance to advance, the track pad (the size is the product size) was placed on the tie plate, and the approximately 300 mm length of the 60 kg / m rail was placed on the sliding layer side of the track pad and fastened with a torque of 600 kgf · cm. A load was horizontally applied from one end of the rail to the rail, and the load at which the rail slides on the track pad was determined. The value of the Fuku advance resistance was determined to be 4.8 kN or less of the current steel plate track pad (manufactured by Shin-Eslite Kogyo Co., Ltd.).

-Pullout strength and adhesive layer peeling-
The track pad was sandwiched between the tie plate and the rail (60 kg / m) and fastened with a torque of 600 kgf · cm so that the tip of the track pad was 30 mm. The portion where the track pad came out was grasped with a chuck, and the pullout strength was measured. And this tensile strength made 3000N or more pass. In addition, the peeling of the adhesive layer after the track pad was pulled out was observed and evaluated.

-Water absorption rate-
The water absorption was determined by allowing a test piece (50 mm × 50 mm × thickness) to stand for 24 hours at a water depth of 10 cm, and determining the amount of water absorption as a ratio per volume.

Tables 1 and 2 list the physical property measurement results and various test results together with details of each example. Abbreviations in Table 1 and Table 2 are as follows.
-Foam layer: Cross-linked urethane foam layer-Product: Track pad

From the above results, it can be seen that in this example, both the fatigue resistance and the pullout strength are excellent in comparison with the comparative example in addition to the good fatigue test. Further, in this example, it can be seen that the spring constant of the track pad can be easily adjusted by the composition of the crosslinked urethane foam layer.
From this, it can be seen that the track pad of the present invention can easily control the spring constant, has excellent durability, and is difficult to be detached from the rail.

10 Track Pad 12 Crosslinked Urethane Foam Layer 16 Adhesive Layer 20 Pillow 22 Tie Plate 22A Bolt 22B Nut 24 Rail 26 Leaf Spring 26A Bolt 26B Nut 28 Variable Pad

Claims (6)

A track pad interposed between a rail and a sleeper or a tie plate fixed on the sleeper and having a required spring constant,
A crosslinked urethane foam layer having a static friction coefficient of 0.35 or less;
An adhesive layer provided on the whole or part of the surface of the sleeper or tie plate side of the crosslinked urethane foam layer;
Orbital pad with.   The track pad according to claim 1, wherein the crosslinked urethane foam layer includes a silicone compound having an OH group in a molecule.   The orbital pad according to claim 1 or 2 in which said adhesion layer contains acrylic resin or urethane resin.   The track pad according to any one of claims 1 to 3, wherein the crosslinked urethane foam layer is a closed-cell foam layer.   The track pad according to any one of claims 1 to 4, wherein the crosslinked urethane foam layer is a layer formed using at least a polyether polyol and an isocyanate as a urethane raw material.   The track pad according to claim 5, wherein the isocyanate is a diphenylmethane diisocyanate (MDI) isocyanate.

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