JP2003147702A - Synthetic tie - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a synthetic tie with reduced volumes of both glass fiber and thermosetting resin while maintaining mechanical strength suitable for fixed tie application such as compressive strength, nail holding property and bending elastic modulus. SOLUTION: The synthetic tie comprises a core layer and a surface layer covering a core layer surface. The core layer comprises angular particles with an average grain size of 0.5-2 mm, spherical particles with an average grain size of <=0.6 of the angular particles, and a thermosetting resin. The gross of the angular particles and the spherical particles is >=70 vol.% in core layer volume. The surface layer comprises the thermosetting resin reinforced by continuous glass fiber parallel with a longitudinal direction of the surface layer.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a synthetic sleeper comprising a core layer and a surface layer covering the surface of the core layer.

[0002]

2. Description of the Related Art Conventionally, synthetic sleepers provided for track sleepers use a large amount of glass fiber, which is difficult to dispose, and thermosetting resin, which is feared to have an adverse effect on the human body.
Volume reduction and recycling of raw materials are required. For example, Japanese Unexamined Patent Publication No. 5-138797 proposes a synthetic sleeper having a core material layer made of a thermosetting resin and a laminated sleeper having a fiber reinforcement as a surface layer. In contrast to the conventional synthetic sleepers that contain about 15% by volume of glass fiber, the synthetic sleepers can be reduced to less than 10% by volume according to the above-mentioned embodiment of the publication.

However, although the synthetic sleepers described in the above publications have a statement that a filler is added to the thermosetting resin of the core layer, they are lightweight powders such as calcium carbonate and sawdust and have a compressive strength suitable for sleepers, There were still insufficient points in terms of nail retention. Further, since a large amount of thermosetting resin is required to fill the core layer space, the problem has not been solved in terms of volume reduction of the thermosetting resin.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to maintain mechanical strength such as compressive strength, nail retention, bending elastic modulus, etc. suitable for sleeper applications. However, it is to propose a synthetic sleeper with volume reduction of both glass fiber and thermosetting resin.

[0005]

The present invention is a synthetic sleeper comprising a core layer and a surface layer covering the surface of the core layer, wherein the core layer is angular particles having an average particle size of 0.5 to 2 mm, Spherical particles having an average particle size of 0.6 times or less that of the horny particles, and a thermosetting resin, and the total amount of the horny particles and the spheres is 70% by volume or more of the core layer volume, and the surface layer. Is a synthetic sleeper made of a thermosetting resin reinforced by long glass fibers parallel to the longitudinal direction of the surface layer.

The filler particles used in the core layer of the synthetic sleeper of the present invention are composed of angular particles and spherical particles. The above-mentioned angular particles are particles having a relatively coarse particle size and the closest packing ratio is less than 70% by volume when naturally arranged by a method such as putting them in a box and vibrating them. The angular particles are substantially polyhedral, low in symmetry, acicular, scaly, star-shaped, etc.
In addition to angular shape, it includes elongated fibrous shape.

The above-mentioned angular particles have an average particle size of 0.5 to 2 mm. When the average particle size of the angular particles is less than 0.5 mm, it is necessary to make the spherical particles used together with the angular particles finer, and the total amount of these particles is 70% by volume or more based on the volume of the core layer. If it is attempted to do so, it will be difficult to uniformly attach the thermosetting resin to the surfaces of all the particles, and it will be difficult to obtain a core layer that retains sufficient mechanical strength. On the other hand, if the average particle size exceeds 2 mm, the workability may be impaired, for example, the tool may be severely damaged during processing.

Examples of the angular particles include natural ores,
Examples include crushed materials of wood and cement concrete, crushed materials of discarded vinyl chloride resin, crushed materials of discarded FRP, sawdust produced as a by-product in a wood processing plant, and wood chips.

The above-mentioned spherical particles have a relatively small particle size and are particles having a close packing ratio of 70% by volume or more when naturally arranged by a method such as placing them in a box and vibrating them. It has a spherical shape and a polyhedral shape with high symmetry.

The spherical particles used in the core layer of the present invention have an average particle size of 0.6 times or less that of the angular particles, preferably 0.3 times or less. If the average particle size is larger than 0.6 times that of the horny particles, it is difficult to obtain the effect that fine spherical particles enter the gaps between the bulky horny particles to increase the filling rate, and the total amount of the horny particles and the spherical particles is the core. This is because it is difficult to contain 70% by volume or more of the layer volume. Further, the lower limit is not particularly limited.

Examples of the spherical particles include inorganic powder produced as a by-product in the process of refining volcanic ash and iron ore.

The volume ratio of the angular particles to the spherical particles is preferably 9/1 to 4/6. When the above volume ratio exceeds 9/1, it is difficult to obtain the effect of increasing the packing rate because spherical particles having a fine particle size enter into the spaces between the bulky angular particles, and the total amount of the angular particles and the spherical particles is the core layer. This is because it is difficult to contain 70% by volume or more of the volume. On the other hand, when the volume ratio is smaller than 4/6, the sea-island structure of the angular particles and the spherical particles in the core layer space is reversed, and the surface area of the fine spherical particles is larger than that of the angular particles, and the thermosetting This is because it is difficult to uniformly attach the thermosetting resin to the surfaces of all particles in the step of mixing the resin and the particles, and it becomes difficult to obtain a core layer having sufficient mechanical strength.

The particle size of the above particles is JIS Z 8801.
It is obtained by sieving with a standard sieve of. A typical combination of the standard size of the sieve openings used for sieving is 4.00 mm, 2.80 m.
m, 2.00 mm, 1.40 mm, 1.00 mm, 0.
850mm, 0.500mm, 0.300mm, 0.2
The size is 12 mm, 0.106 mm, 0.075 mm, etc., but other sieves with openings may be added as appropriate. The particle size is indicated by the standard size of the remaining sieve openings.
The average particle size in the present invention is a value obtained by summing the product of the volume ratio of particles remaining in each screen and the particle size over all the screens.

In the core layer of the present invention, the total volume of the above-mentioned angular particles and spherical particles, in other words, the filling rate range of the angular particles and spherical particles as the filler is 70% by volume or more,
It is preferably 85% by volume or less. The filling of less than 70% by volume is a range that can be achieved by the closest packing ratio when only the angular particles are naturally arranged. It is difficult to fill 70% by volume or more with only angular particles, and the average particle size is 0.6% of that of angular particles.
When used together with spherical particles having a size equal to or less than double, filling within the above range becomes possible. Further, when the amount of filling exceeds 85% by volume, it becomes difficult to uniformly attach the thermosetting resin to all particle surfaces in the mixing step with the thermosetting resin, and the adhesion between particles becomes insufficient. Therefore, it may be difficult to obtain a core layer having sufficient mechanical strength.

Examples of the thermosetting resin used for the surface layer and the core layer include polyurethane, phenol resin, unsaturated polyester, diallyl phthalate resin, vinyl ester resin, epoxy resin, urea resin, melamine resin, polyimide resin, Polyamideimide resin, acrylic resin, natural rubber, synthetic rubber and the like are mentioned, and these may be used alone or in combination.

Further, a foamed thermosetting resin can be used as the thermosetting resin used for the surface layer and the core layer. As the foaming agent used for the foaming thermosetting resin, a thermal decomposition type foaming agent such as an azo compound or sodium hydrogencarbonate; a soluble foaming agent such as CFCs, carbon dioxide gas, pentane; And a foamed thermosetting resin liquid containing Further, examples of the foaming thermosetting resin using the foaming agent include foamed polyurethane such as rigid or semi-rigid polyurethane foam; phenol foam resin; low-magnification polyester foam.

Among the above-mentioned thermosetting resins, polyurethane foam is preferable because it has relatively high mechanical strength, easily forms closed cells during foaming and is excellent in non-water absorption. Examples of the foamed polyurethane include those generally used, which are obtained by reacting a polyol with a polyisocyanate.

The above-mentioned polyol has two or more hydroxyl groups at the molecular ends, and examples thereof include polyether polyols such as polypropylene oxide, polyethylene oxide and polytetramethylene glycol, and copolymers thereof.
A polycondensate of an aliphatic dicarboxylic acid such as adipic acid and a glycol having a carbon number of 12 or less such as ethylene glycol, propylene glycol, butylene glycol, hexamethylene glycol, or a polycondensate of a hydroxycarboxylic acid such as poly ε-caprolactone. Examples thereof include certain polyester polyols and copolymers thereof, and polymer polyols which are graft copolymers of these polyols and polymers of monomers having a vinyl group. These may be used alone or in combination of two or more.

The above polyisocyanate has two or more isocyanate groups and is, for example, 4,4'-methylenediphenyl diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate. Hydrogenated products of 4,4'-methylenediphenyldiisocyanate and polynuclear compounds of these and their isomers are used. These may be used alone or in combination of two or more, but in consideration of safety, reactivity, handleability, etc., a mixture of 4,4′-methylenediphenylisocyanate and a polynuclear body of its isomer (hereinafter, “Polymeric MDI”).
Is described) is preferable.

Examples of the foaming agent used in the above reaction include a thermal decomposition type foaming agent, a physical foaming agent such as CFC; water and the like, and a decomposition gas generated by the thermosetting resin during the reaction. However, carbon dioxide generated by the reaction between isocyanate and water is preferably used because CFCs may destroy the ozone layer of the global environment. The foaming agent is preferably mixed with the thermosetting resin in advance.

If necessary, the foamed thermosetting resin may contain a catalyst, a foam stabilizer, a foaming aid, a filler, a reinforcing short fiber,
Colorants, UV absorbers, antioxidants, crosslinkers, stabilizers,
A plasticizer, a flame retardant, etc. may be added.

Examples of the above-mentioned catalyst include organic tin catalysts such as dibutyltin dilaurate, amine catalysts and temperature-sensitive catalysts.

In the synthetic sleeper of the present invention, the surface layer is made of a thermosetting resin reinforced by long glass fibers parallel to the longitudinal direction of the surface layer. The long glass fiber used for the surface layer is not limited as long as it has the function as a reinforcing fiber, and examples thereof include monofilament, fibrillated fiber, woven yarn, carbon fiber, synthetic fiber, and the like other than glass fiber. Reinforcing fibers may be used together. Among the above-mentioned long glass fibers, in the case of the continuous production method described later, E glass fiber roving, which is a monofilament bundle, is preferable.

The volume ratio of the long glass fibers used in the surface layer is not particularly limited, but is preferably 5 to 40 volume%. This is because if it is less than 5% by volume, the mechanical strength of the surface layer is lowered, and if it exceeds 40% by volume, workability is deteriorated, for example, cracking is likely to occur in a direction parallel to the fiber during nailing.

When the thermosetting resin used for the surface layer is a foam, the resin specific gravity is preferably 0.2 or more. If it is less than 0.2, the mechanical strength of the surface layer will decrease. The upper limit is not particularly limited.

The flexural modulus of the surface layer is 6000 MPa.
The above is preferable, more preferably 7,000 MPa or more, further preferably 8,000 MPa or more.
When the bending elastic modulus is less than 6000 MPa, the bending elastic modulus of the entire synthetic sleeper is lowered, and the deflection during use in the sleeper becomes large, so that the orbit is likely to be distorted. Further, the bending strength of the surface layer is preferably 100 MPa or more, more preferably 120 MPa or more. Bending strength is 100M
When it is less than Pa, the long-term bending durability tends to be lowered when it is used as a sleeper.

The bending elastic modulus and the bending strength are J
It is measured according to IS Z 2101, and the bending load is applied in the direction perpendicular to the longitudinal direction of the test body with the long fiber direction as the longitudinal direction.

The method for producing the synthetic sleepers of the present invention is not particularly limited, and examples thereof include batch type and continuous type. As the above batch type, for example, JP-A-5-1387
As disclosed in Japanese Patent Publication No. 97, after preforming a preform for a core layer or a preform for a surface layer and setting the preform in a mold, before the preform is cured. Then, the long glass fiber and the thermosetting resin to be the surface layer or the core layer, or a mixture or molding of angular particles, spherical particles, and thermosetting resin is filled in a mold, and the thermosetting resin is thermoset. There is a method of making it.

On the other hand, in the continuous type, a large number of long glass fibers serving as reinforcing fibers are made to proceed in one direction while aligning them at a predetermined interval, and the foaming heat is applied from above the aligned long glass fiber groups. After sprinkling the curable resin liquid, between the fibers and the fibers constituting each glass long fiber, impregnated the sprinkled foam thermosetting resin liquid, this foam thermosetting resin liquid to each glass long fiber An extrusion mold is exposed to the center of the impregnated long glass fiber group, and angular particles and spherical particles that form the core layer and thermosetting are surrounded by the long glass fiber group from this extrusion molding mold. After continuously extruding a mixture of resins while shaping it, introducing it into a tubular molding passage, thermosetting the thermosetting resin in the molding passage, and molding the core layer and the surface layer at the same time. Is mentioned.

Further, in the gap between the long glass fiber groups impregnated with the long glass fibers divided into upper and lower parts by the foamed thermosetting resin liquid, angular particles and spherical particles to be the core layer, and the thermosetting resin. The mixture is fed and pressed by an endless belt etc. to a predetermined cross-sectional shape surrounded by a long glass fiber group, uncured or heat-foam-cured, and then continuously fed, and introduced into a tubular molding passage. Then, the thermosetting resin is foamed and thermoset in the molding passage to form the core layer and the surface layer simultaneously or sequentially.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows an embodiment of a synthetic sleeper according to the present invention. The synthetic sleeper a includes a core layer 2a and a surface layer 1a, and the synthetic sleeper b includes a core layer 2b and surface layers 1b and 3b. The surface layer is formed by integrally laminating the core layers on the core layers 2a and 2b from the periphery or from above and below, respectively. Since the surface layers of the above-mentioned synthetic sleepers a and b are formed in a state in which long glass fibers are arranged in parallel in the longitudinal direction of the surface layer in the thermosetting resin, they are excellent in mechanical strength in the longitudinal direction, particularly in bending elastic modulus. .

Further, as shown in FIG. 2, the core layer is composed of angular particles 4 having a large particle size, spherical particles 5 having a small particle size, and a thermosetting resin. Since the content is 70% by volume or more, the angular particles are in contact with each other and are bonded by the thermosetting resin in a state where the remaining space is filled with spherical particles. Therefore, the deformation of the core layer is small with respect to compression, and the surface layer depends on it, so that it does not fall below the compression proportional limit of the surface layer, it has excellent compressive strength and the nail-holding property is improved by the angular particles of the core layer. To do. That is, since the angular particles are dense, the extraction resistance is increased by the angular particles and the thermosetting resin, and the extraction strength is increased.

(Example) 1 by the compounding composition shown in Table 1
A core layer having a cross section of 90 mm x 100 mm was produced.
Then, the core layer was laminated by the above-mentioned continuous manufacturing method along the four surfaces in the longitudinal direction from the glass fiber and the foamed thermosetting resin liquid shown in Table 1 to form a surface layer of 200 mm × 140.
Synthetic sleepers with a cross section of mm were produced.

[0034]

[Table 1]

[Table 2]

In Table 1, polyether polyol (trade name "Sumiphen 1703", manufactured by Sumitomo Chemical Bayer Urethane Co .; hydroxyl value 380, polyol equivalent 147), silicone oil foam stabilizer (trade name "SRX-295", Toray Dow) Made by Silicon). Table 2 shows the mechanical strength, the glass fiber, and the blending amount of the thermosetting resin thus obtained.
For comparison, the conventional synthetic sleepers glass fiber and thermosetting resin are used in amounts of 10 to 20% by volume and 80% by volume, respectively.
It was ˜90% by volume (including bubbles). As described above, it can be seen that the synthetic sleepers of the present invention have mechanical strength exceeding that of beech wood, and the amount of glass fiber and thermosetting resin used is kept low.

[0036]

EFFECTS OF THE INVENTION The synthetic sleepers of the present invention have improved mechanical strength such as compressive strength, nail retention, and bending elastic modulus, and the amount of glass fiber or thermosetting resin used in comparison with conventional synthetic sleepers. It can be reduced significantly. Further, by adjusting the bulk specific gravity of the angular particles or spherical particles of the core layer and the expansion ratio of the thermosetting resin, the specific gravity of the synthetic sleepers can be easily adjusted, so that the weight is required from the weight required. It can be used widely.

[0037]

[Brief description of drawings]

FIG. 1 is a schematic vertical cross-sectional view of a synthetic sleeper according to the present invention.

FIG. 2 is an enlarged schematic view of a core layer cross section of a synthetic sleeper according to the present invention.

[Explanation of symbols]

a Specific example of the synthetic sleeper of the present invention b Another specific example of the synthetic sleeper of the present invention 1a, 1b 3b surface 2a 2b core layer 4 angular particles 5 spherical particles

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08J 5/04 CEZ C08J 5/04 CEZ C08K 7/00 C08K 7/00 C08L 101/00 C08L 101/00 F term (reference) 4F072 AA04 AA07 AB09 AB22 AD02 AD08 AD09 AD14 AD20 AD21 AD23 AD38 AD43 AD45 AE06 AE23 AE26 AF06 AG02 AG04 AH04 AH13 AH19 AH20 AH24 AJ04 AK02 AK14 AK16 AL09 AL17 4F100 AG00B AK01A AK01B AK51A AK51B BA02 DD31 DE01A DG01B DH02B DJ01A DJ02B GB31 JB13A JB13B 4J002 AA021 AC011 AC031 BF021 BF051 BG041 BG051 CC031 CC161 CC181 CD001 CF211 CK021 CM041 DJ006 FA016 FA096 GF00 GL00 4J034 HC03 HC06 HA06 HC52HC06 HA06HA06 HA06Q12 HA06QDHA07DQDHA07DQDQDQDQDQDQDQDQDQDQDQDQDQDQDQDQDQDQDQDQDQDQDQDQDQDQDQDQDQDQQDQDQDQDQDQDQDQDQDQDQDQDQDQDQDQDQDQDQDHAEDQDED HC71 HC73 KC17 KD02 KD12 KE02 MA04 NA03 QC01 QC03 RA05 RA10

Claims (2)

[Claims] 1. A synthetic sleeper comprising a core layer and a surface layer covering the surface of the core layer, wherein the core layer has an average particle size of 0.5 to 0.5.
2 mm angular particles, spherical particles having an average particle size of 0.6 times or less that of the angular particles, and a thermosetting resin, and the total amount of the angular particles and the spherical particles is 70 volume of the core layer volume. %
It is above, The said surface layer is a synthetic sleeper which consists of thermosetting resin reinforced with the glass long fiber parallel to the longitudinal direction of a surface layer. 2. The synthetic sleeper according to claim 1, wherein the thermosetting resin is polyurethane foam.