WO2014175576A1

WO2014175576A1 - Composition for synthetic resin sleeper and method for preparing same

Info

Publication number: WO2014175576A1
Application number: PCT/KR2014/002900
Authority: WO
Inventors: 이하우; 이상호; 김용수; 양정규; 권건호; 박성민; 김도엽; 김동환
Original assignee: 케이피엑스케미칼 주식회사; 주식회사 폴리타이
Priority date: 2013-04-24
Filing date: 2014-04-03
Publication date: 2014-10-30
Also published as: KR101424683B1

Abstract

The present invention relates to a composition for a synthetic resin sleeper and a method for preparing the same, and more specifically, to a composition for a synthetic resin sleeper which comprises a polyol mixture, isocyanate, a natural reinforcing agent, a silicon foam stabilizer, a foaming agent, and a catalyst, the polyol mixture containing: 1) 40-80 wt% of polyether polyol having functionality of not less than three but less than four; 2) 15-45 wt% of polyether polyol having functionality of not less than four but less than five; 3) 5-20 wt% of polyether polyol having functionality of not less than five but not more than six; and 4) 2-15 wt% of polyester polyol having functionality of two, the polyol mixture having a viscosity of 500-2000 cps (25℃), the natural reinforcing agent including a fiber type or a fabric type, thereby enhancing mechanical strength in an eco-friendly and semi-permanent manner and facilitating the processability and maintenance, and to a method for preparing the same.

Description

Synthetic resin sleeper composition and preparation method thereof

The present invention relates to a composition for a synthetic resin sleeper containing a natural reinforcing material and a method for producing the same.

Railway sleepers mainly use wood and concrete. Wood sleepers are weak in moisture and have a short life due to decay or erosion (durable life of about 7 to 10 years), which is difficult to repair and requires periodic replacement and problems of supply and demand for wood. Concrete sleepers are made of reinforcing bars with high strength, good durability, and convenience of production.However, they are difficult to transport, and there are problems such as noise generation due to breakage, crack and shock absorption, and deterioration of rail due to severe vibration. There is a problem that the weight is heavy and is restricted by the construction site.

Therefore, in recent years, development of sleepers to replace them has been variously progressed, and research on synthetic sleepers using double synthetic resins or foamed resins is being conducted. Synthetic resin sleepers have a high shrinkage and expansion rate, resulting in a change in form, resulting in the escape of accessory materials, and thus, foamed sleepers have high production costs and environmental pollution.

Korean Patent Registration No. 187,903 discloses a recyclable and smooth train rail sleeper manufactured by extrusion, injection molding by mixing polyethylene, coal ash and rice hull powder. However, chaff powder is weak in fiber and its function is poor in compensating the strength of synthetic resin, and coal ash has a problem in practical use because it serves to control humidity but lowers the strength to easily cause cracks.

In addition, Korean Patent Laid-Open No. 1997-58869 discloses a synthetic sleeper prepared by mixing waste paper and sand with waste synthetic resin such as low density polyethylene, high density polyethylene, polypropylene or polyamide. However, the sleeper is difficult to maintain dimensional stability due to the high expansion and contraction, such as expansion and contraction at a high temperature of more than 60 ℃ below the summer rail and wear resistance is also not suitable.

In addition, Japanese Patent No. 3,444,724 is formed of a base layer made of hard urethane and glass fiber, which is a foamed resin, and a wear-resistant material layer made of elastic urethane and glass fiber, and sleepers for tracks placed in a traffic passage of a vehicle or a railroad crossing. Is suggested. However, the glass fiber is harmful to the human body and when disposed of the sleeper, the glass fiber does not decompose in nature has a problem that is difficult to process.

The present invention uses a natural reinforcing material that can be decomposed in nature, environmentally friendly and can maintain the mechanical properties more than the same as when using inorganic fibers, such as conventional glass fibers, provides a composition for synthetic resin sleepers excellent in processability and economical efficiency and a method for producing the same. Its purpose is to.

In order to achieve the above object, the present invention comprises a polyol mixture, isocyanate, natural reinforcing material, silicone foam stabilizer, foaming agent and catalyst, the polyol mixture is 1) 40 to 80% by weight of polyether polyol having a functional group of 3 to less than 4; 2) 15 to 45 weight percent of a polyether polyol having at least 4 and less than 5 functional groups; 3) 5 to 20% by weight of a polyether polyol having at least 5 to 6 functional groups; And 4) 2 to 15% by weight of a polyester polyol having functional group 2 are mixed, and the polyol mixture has a viscosity of 500 to 2000 cps (25 ° C.), and the natural reinforcing material provides a composition for synthetic resin sleeper which is fibrous or woven.

The natural reinforcing material may have a diameter of 0.1 to 10 mm, a tensile strength of 3.0 g / d or more, and a moisture content of 15% or less.

The natural reinforcing material may be at least one member selected from the group consisting of manila hemp, germ (sheep, ramie), flax (linen), jute (jute), sisal hemp, hemp (hemp, hemp), cotton and kapok.

100 to 130 parts by weight of isocyanate based on 100 parts by weight of the polyol mixture; 0.5 to 5 parts by weight of the silicone foam stabilizer; 0.05 to 5 parts by weight of blowing agent; And 0.1 to 2 parts by weight of catalyst, and 10 to 50 parts by weight of a natural reinforcing material, based on 100 parts by weight of the total content of the polyol mixture and isocyanate.

The synthetic resin sleeper composition may have a viscosity (25 ° C.) of 500 to 2000 cps.

The blowing agent may be water.

In addition, the present invention provides a synthetic resin sleeper prepared by foam-curing the composition for the synthetic resin sleeper.

The synthetic sleeper has a density of 300 kg / ㎥ or more, horizontal bending strength of 600 kgf / ㎠ or more, horizontal compressive strength of 90 kgf / ㎠ or more, vertical compressive strength of 100 kgf / ㎠ or more, screw spike The pullout strength may be 30 kN or more.

The present invention is also carried out by impregnating a fibrous or woven natural reinforcing material with a composition containing a polyol mixture, an isocyanate, a silicone foam stabilizer, a blowing agent, and a catalyst, followed by foaming, wherein the polyol mixture comprises: 1) a functional group 40 to 80% by weight of a polyether polyol that is at least 3 but less than 4; 2) 15 to 45 weight percent of a polyether polyol having at least 4 and less than 5 functional groups; 3) 5 to 20% by weight of a polyether polyol having at least 5 to 6 functional groups; And 4) 2 to 15% by weight of a polyester polyol having functional group 2 are mixed, and the polyol mixture has a viscosity of 500 to 2000 cps (25 ° C.), and the step is a method of preparing a synthetic sleeper which is performed continuously or discontinuously. There is another feature.

The fibrous natural reinforcing material may be continuously performed after the impregnation and foaming.

The fabric-like natural reinforcing material may be performed in a discontinuous manner after the impregnation and foaming.

With the isocyanate; The gel time of the composition containing the polyol mixture, silicone foam stabilizer, blowing agent and catalyst can be from 2 minutes to 20 minutes.

The surface of the foamed foam may further include applying at least one resin selected from the group consisting of polyurethane, acrylic, polyurethane-acrylic, polyurethane-epoxy and acrylic-epoxy.

Synthetic resin sleepers according to the present invention can improve the mechanical strength by using a reinforcement, in particular, it can be used semi-permanently, including eco-friendly natural reinforcing material excellent in light weight, weather resistance, wear resistance, durability, water resistance and chemical resistance.

In addition, the synthetic sleeper according to the present invention is excellent in workability, easy to manufacture, low maintenance costs, there is an economically advantageous advantage over the conventional wood or concrete sleepers or some glass fiber-type synthetic resin sleepers.

Therefore, the above-mentioned synthetic resin sleepers are more effective when used for light rail, subway, etc., where the noise is generated as well as for railroads that can absorb the noise and vibration of the railroad. In addition to sleepers, it can be used for purposes such as synthetic wood, telephone poles.

Hereinafter, the present invention will be described in detail.

The synthetic resin sleeper composition of the present invention contains a polyol mixture, an isocyanate, a natural reinforcing material, a silicone foam stabilizer, a blowing agent, and a catalyst.

The polyol mixture is 1) 40 to 80% by weight of a polyether polyol having a functional group of at least 3 to less than 4; 2) 15 to 45 weight percent of a polyether polyol having at least 4 and less than 5 functional groups; 3) 5 to 20% by weight of a polyether polyol having at least 5 to 6 functional groups; And 4) 2 to 15% by weight of polyester polyol having functional group 2 are mixed.

The present invention uses a mixture of three kinds of polyether polyols and polyester polyols having different functional groups in order to improve the deterioration of physical properties such as compressive strength, flexural strength, impregnation, etc. due to the use of natural reinforcing materials, and their content is optimized have.

When the content of the polyether polyol having a functional group of 3 to less than 4 is less than 40% by weight, the viscosity of the sleeper composition may increase, the flexural strength may be lowered, and when the content exceeds 80% by weight, the compressive strength may decrease.

When the content of the polyether polyol having a functional group of 4 to less than 5 is less than 15% by weight, the flexural strength and the compressive strength may be lowered, and when the content exceeds 45% by weight, the viscosity of the sleeper composition may increase.

When the content of the polyether polyol having a functional group of 5 to 6 or less is less than 5% by weight, the compressive strength is lowered, and when the content is more than 20% by weight, the viscosity of the sleeper composition may increase, and the flexural strength may decrease.

In addition, when the content of the polyester polyol having the functional group 2 is less than 2% by weight, the flexural strength is lowered, and when the content exceeds 15% by weight, a problem may occur in that the compressive strength is lowered.

The polyether polyols and polyester polyols are generally used in the art and are not particularly limited.

Specifically, a polyether polyol means a polyol in which alkylene oxide is added to a polyfunctional alcohol or a polyfunctional amine.

Examples of the polyfunctional alcohol include ethylene glycol, diethylene glycol, glycerin, trimethanol propane, pentaerythritol, dipentaerythritol, α-methylglucoside, xylitol, sorbitol, and sugar, and these may be used alone or in combination. Can be.

Examples of the polyfunctional amine include ethylenediamine, diethylenetriamine, triethanolamine, ortho-toluenediamine, diphenylmethanediamine, diethanolamine, and the like, and these may be used alone or in combination.

The alkylene oxide compound is a compound having at least one alkylene oxide group, for example, ethylene oxide, propylene oxide (1,2-epoxypropane), butylene oxide (1,4-epoxybutane), 1,2- Epoxybutane, 2,3-epoxybutane, 1,2-epoxypentane, 1,2-epoxyhexane, 1,2-epoxyheptane, 1,2-epoxycyclopentane, 1,2-epoxycyclohexane, amylene oxide And styrene oxide. These can be used individually or in mixture. In view of commercialization, ethylene oxide, propylene oxide and butylene oxide are preferred, and ethylene oxide and propylene oxide are more preferred.

In addition, polyester polyol means a compound consisting of a polyfunctional alcohol and a polyfunctional acid. Examples of the polyfunctional alcohol include ethylene glycol, diethylene glycol, glycerin, 1,6-hexanediol, and the like. The polyfunctional acid may include adipic acid, phthalic anhydride, terephthalic acid, isophthalic acid, and the like.

The polyol mixture preferably has a viscosity of 500 to 2000 cps (25 ° C.), preferably 600 to 1600 cps. If the viscosity is less than 500 cps, the compressive strength is lowered, and if the viscosity exceeds 2000 cps, the impregnation with the natural reinforcing material is reduced. May occur.

Isocyanates include compounds in which an aromatic, cycloaliphatic and or aliphatic group is linked to an isocyanate group. For example, ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,12-dodecane diisocyanate, cyclobutane-1,3-diisocyanate, cyclohexane-1,3 And cyclohexane-1,4-diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (isophorone diisocyanate), 2,4- and 2 , 6-hexahydrotoluene diisocyanate, dicyclohexylmethane-4,4'-diisocyanate (hydrogenated MDI, or HMDI), 1,3- and 1,4-phenylene diisocyanate, 2,4- and 2, 6-toluene diisocyanate (TDI), diphenylmethane-2,4'- and -4,4'-diisocyanate (MDI), naphthylene-1,5-diisocyanate, triphenyl-methane-4,4 ' , 4 "-triisocyanate, polyphenyl-polymethylene-polyisocyanate (crude MDI), norbornane diisocyanate, m- and p-isocyanatophenyl sulfo Isocyanates, perchlorated aryl polyisocyanates, carbodiimide-modified polyisocyanates, urethane-modified polyisocyanates, allophanate-modified polyisocyanates, isocyanurate-modified polyisocyanates, urea-modified polyisocyanates, biuret-containing polyisocyanates Isocyanate-terminated prepolymers or mixtures thereof.

The isocyanate may control the content of the NCO group according to the required properties of the polyurethane to be produced finally, preferably 25 to 35%.

Such isocyanate may contain 100 to 130 parts by weight of isocyanate based on 100 parts by weight of a polyol mixture, and if the content is less than 100 parts by weight, the compressive strength and the flexural strength may be lowered, and if the content exceeds 130 parts by weight, the flexural strength may be lowered. .

Natural reinforcing material is to reinforce the strength, specifically compressive strength, flexural strength and shear strength of the polyurethane foamed cured composition, for example, manila hemp, yam, ramie, linen, jute (jute) ), Sisal, hemp (hemp, hemp), cotton and kapok may be one or more selected from the group consisting of. Considering compressive strength, flexural strength, drawing strength, and impregnation, manila ginseng, yam, and sisal hemp are preferred.

The natural reinforcing material is 0.1 to 10mm in diameter, tensile strength is more than 3.0g / d, it is preferable that the water content is 15% or less. If the diameter is less than 0.1mm, the volume of the natural reinforcing material increases, so that impregnation and production is difficult. If the diameter exceeds 10mm, the flexural strength and the pullout strength may be lowered. If the tensile strength is less than 3.0g / d, the bending strength And the pullout strength is lowered, if the moisture content exceeds 15% may be difficult to dry.

The natural reinforcing material may be used in the form of a fabric that can be impregnated in the composition for the synthetic resin sleeper, or in a fiber shape that can be impregnated in the synthetic resin sleeper composition in a straight line arranged in the longitudinal direction without tangling.

The natural reinforcing material contains 10 to 50 parts by weight of the natural reinforcing material with respect to 100 parts by weight of the total content of the polyol mixture and the isocyanate. If the content is less than 10 parts by weight, the flexural strength and the pullout strength are lowered and the compressive strength is greater than 50 parts by weight. And a problem that the impregnation is lowered.

A silicone foam stabilizer can be suitably selected and used in consideration of the structure of the polyurethane which foam-hardened the said composition, especially the cell structure in a polyurethane foam. For example, Evonik's B-8404 or B-8462 products can be used.

Such silicone foam stabilizer contains 0.5 to 5 parts by weight with respect to 100 parts by weight of the polyol mixture. When the content is less than 0.5 parts by weight, the cell of the urethane foam is non-uniform, and when the amount exceeds 5 parts by weight, the price of the sleeper composition increases and the bending strength. The problem of mechanical properties such as compressive strength may occur.

The blowing agent serves to generate bubbles during the urethane reaction, and can be classified into water, which is a physical blowing agent and a chemical blowing agent. The two types may be used alone or in combination. It is preferable to use water, which is a chemical blowing agent, in an environmentally friendly manner.

The physical blowing agent vaporizes (sublimates) the heat of the reaction, and the resulting gas may accumulate by the enclosed cells of the foam so that the foam produced may exhibit low thermal conductivity. At this time, hydrocarbon-based C-pentane, hydrochlorofluorocarbon based HCFC-141b (1,1-dichloro-1-fluoroethane), hydrofluorocarbon (HFC) based HFC-245fa (1,1,1,3,3 -Pentafluoropropane), HFC-365mfc, mixed HFC-365mfc / 227ea, mixtures thereof and the like may be preferably used as blowing agent. Although it does not exclude the use of CFC-based blowing agents that have been used in the past, it may be preferable to exclude the use as possible because it may cause environmental problems. Preferably, more environmentally friendly components such as C-Pentane, HFC-based, and the like may be used. In particular, HFC-245fa can be used as the HFC-based blowing agent used in the manufacture of closed cell insulation foam.

In addition, water, a chemical blowing agent, reacts with isocyanates to produce carbon dioxide gas.

Such chemical blowing agents contain 0.05 to 5 parts by weight with respect to 100 parts by weight of the polyol mixture, and if the content is less than 0.05 parts by weight, the density increases to 950 kg / m 3 or more, and when it exceeds 5 parts by weight, the density is 300 kg / m 3 or less. The problem may be lowered.

Catalysts are commonly used in the art and include metals such as secondary or tertiary amine compounds (e.g. DMEA, TEDA, DMCHA, TMCHA, etc.), amine based catalysts, organic metals (e.g. organotin) A catalyst or the like can be used.

These catalysts contain 0.1 to 2 parts by weight with respect to 100 parts by weight of the polyol mixture, and the gelation time is slowed to 20 minutes or more when the content is less than 0.1 parts by weight, and gel time is increased to 2 minutes or less when the content is more than 2 parts by weight. Problems may arise.

In addition, the synthetic resin sleeper production method according to the present invention comprises impregnating a composition containing a polyol mixture, an isocyanate, a silicone foam stabilizer, a blowing agent and a catalyst in a natural reinforcing material, and then foaming. The step can be carried out continuously or discontinuously.

Preferably, the fibrous natural reinforcing material is impregnated and then foaming is performed continuously, and the fabric-like natural reinforcing material is preferably impregnated with foaming after being impregnated.

In addition, the fibrous natural reinforcing material is preferably used after drying for 24 hours or more in a dryer of 100 to 150 ℃ for water removal after cutting to a certain size.

The synthetic resin sleeper composition is to maintain a temperature of 18 to 35 ℃, it is preferred to foam under a pressure of 90 to 180 bar after injecting it into a mold of room temperature to 50 ℃. At this time, the fibrous natural reinforcing material may be divided or chopped during the injection of the foaming machine to improve the impregnation.

With the isocyanate; The gel time of the composition containing the polyol mixture, silicone foam stabilizer, blowing agent and catalyst is maintained for 2 to 20 minutes.

Thereafter, the surface of the foamed foam may further include applying at least one resin selected from the group consisting of polyurethane, acrylic, polyurethane-acrylic, polyurethane-epoxy and acrylic-epoxy. In addition, flame retardants (for example, phosphorus-based flame retardants such as TCPP, TCEP, Phosphorus ester, etc.), colorants, fillers, internal mold release agents, antistatic agents and antibacterial agents commonly used in the art may be additionally used in the application.

The synthetic resin sleepers prepared above have a density of 300 kg / ㎥ or more, horizontal bending strength of 600 kgf / cm 2 or more, horizontal compressive strength of 90 kgf / cm 2 or more, and vertical compressive strength of 100 kgf / cm 2 or more. The thread spike pullout strength may be 30 kN or more.

Hereinafter, preferred examples are provided to aid the understanding of the present invention, but the following examples are merely for exemplifying the present invention, and it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the present invention. It is natural that such variations and modifications fall within the scope of the appended claims.

제조예 1-4 및 비교 제조예 1-4 : 폴리올 혼합물 제조Preparation Example 1-4 and Comparative Preparation Example 1-4: Preparation of a polyol mixture

To prepare a polyol mixture by mixing as in the composition of Table 1 below.

TABLE 1

실시예 1-7 및 비교예 1-4Example 1-7 and Comparative Example 1-4

As shown in Table 2, a synthetic resin sleeper composition was prepared using the polyol, isocyanate, natural reinforcing material, silicone foam stabilizer, foaming agent, and catalyst of Table 1.

The natural reinforcing material of the fabric was cut into 240 × 150 × 2500 (W × H × L, mm) and dried in a dryer at 120 ° C. for at least 24 hours, and then cooled to room temperature. Thereafter, the mold was uniformly arranged longitudinally in a mold having a size of 240 × 150 × 2500 (W × H × L, mm). (At this time, the natural reinforcing material was divided into two to six times arranged.) The mixture of the polyol, the silicon foam stabilizer, the blowing agent and the catalyst synthetic resin and isocyanate was injected at 130 bar pressure into a mold at 40 ° C. At this time, the gel time of the mixture and the isocyanate was performed under the conditions shown in Table 2.

Thereafter, about 120 minutes after the lid of the foamer, the rigid polyurethane foam was taken out, and the surface of the foam was coated with a polyurethane-acrylic resin to prepare a synthetic sleeper.

TABLE 2

실시예 8-16Example 8-16

In the same manner as in Example 1, the synthetic resin sleepers were prepared by varying the type, natural diameter and content of the natural reinforcing material as shown in Table 3.

TABLE 3

시험예Test Example

The physical properties of the prepared rigid polyurethane foam and synthetic resin sleepers were measured in the following manner, and the results are shown in Table 4 below.

1) Apparent shrinkage: After foaming, leave at room temperature and check for shrinkage.

2) Density: Deformed in a foaming machine, left for 24 hours, and measured according to the KSF 2198 test method.

3) Compressive strength: measured horizontally and vertically using universal test machine (UTM) according to KS 2206 test method.

4) Flexural Strength: Measured using universal testing machine (UTM) according to KS 2208 test method.

5) Thread Spike Pullout Strength: Measured with the maximum value when the thread spike for rail (L = 144mm) is driven to 25mm and pulled out at a speed of 5mm per minute.

TABLE 4

As shown in Table 4, the synthetic resin sleepers of Examples 1 to 16 containing specific polyol mixtures, isocyanates, natural reinforcing materials, silicone foam stabilizers, foaming agents, and catalysts according to the present invention are apparent shrinkage, density compared to Comparative Examples 1 to 4 , Compressive strength, flexural strength, threaded spike pullout strength, etc., were excellent, and at the same time, it was confirmed that it had a value suitable for synthetic sleepers.

In particular, it was confirmed that the flexural strength of the example is much superior to the comparative example.

Claims

Containing polyol mixtures, isocyanates, natural reinforcements, silicone foam stabilizers, blowing agents and catalysts,

The polyol mixture is 1) 40 to 80% by weight of a polyether polyol having a functional group of at least 3 to less than 4;

2) 15 to 45 weight percent of a polyether polyol having at least 4 and less than 5 functional groups;

3) 5 to 20% by weight of a polyether polyol having at least 5 to 6 functional groups; And

4) 2 to 15% by weight of the polyester polyol having functional group 2 are mixed,

The polyol mixture has a viscosity of 500 to 2000 cps (25 ° C),

The natural reinforcing material is a synthetic resin sleeper composition, characterized in that the fiber or fabric.
The composition of claim 1, wherein the natural reinforcing material has a diameter of 0.1 to 10 mm, a tensile strength of 3.0 g / d or more, and a water content of 15% or less.
The method of claim 2, wherein the natural reinforcing material is at least one selected from the group consisting of manila hemp, yam (sheath, ramie), flax (linen), jute (jute), sisal, hemp (hemp, hemp), cotton and kapok. Synthetic resin sleeper composition, characterized in that.
The method according to claim 1, 100 to 130 parts by weight based on 100 parts by weight of the polyol mixture; 0.5 to 5 parts by weight of the silicone foam stabilizer; 0.05 to 5 parts by weight of blowing agent; And 0.1 to 2 parts by weight of catalyst,

To about 100 parts by weight of the total content of the polyol mixture and isocyanate, synthetic resin sleeper composition comprising 10 to 50 parts by weight of natural reinforcing material.
The composition of claim 1, wherein the synthetic resin sleeper composition has a viscosity (25 ° C) of 500 to 2000 cps.
The composition according to claim 4, wherein the blowing agent is water.
Synthetic resin sleepers prepared by foam-curing the composition of any one of claims 1 to 6.
The method according to claim 7, wherein the synthetic sleeper has a density of 300kg / ㎥ or more, the horizontal bending strength is 600kgf / ㎠ or more, the horizontal compressive strength is 90kgf / ㎠ or more, the vertical compressive strength 100kgf / ㎠ Above, the screw spike pullout strength is 30kN or more synthetic resin sleepers.
Impregnating a fibrous or woven natural reinforcement with a polyol mixture, an isocyanate, a silicone foam stabilizer, a blowing agent and a composition containing a catalyst, followed by foaming (preferably to limit the conditions),

The polyol mixture is 1) 40 to 80% by weight of a polyether polyol having a functional group of at least 3 to less than 4;

2) 15 to 45 weight percent of a polyether polyol having at least 4 and less than 5 functional groups;

3) 5 to 20% by weight of a polyether polyol having at least 5 to 6 functional groups; And

4) 2 to 15% by weight of the polyester polyol having functional group 2 are mixed,

The polyol mixture has a viscosity of 500 to 2000 cps (25 ° C),

The step of producing a synthetic sleeper, characterized in that carried out in a continuous or discontinuous manner.
The method of claim 9, wherein the fibrous natural reinforcing material is impregnated and then the foaming step of producing a synthetic resin sleeper, characterized in that is carried out continuously.
10. The method of claim 9, wherein the fabric-like natural reinforcing material is impregnated and then foaming is performed in a discontinuous manner.
The method of claim 9, wherein the isocyanate; The gel time of the composition containing a polyol mixture, a silicone foam stabilizer, a blowing agent and a catalyst is 2 minutes to 20 minutes.
The method of claim 9, further comprising the step of applying a surface of the foamed foam at least one resin selected from the group consisting of polyurethane, acrylic, polyurethane-acrylic, polyurethane-epoxy and acrylic-epoxy clock Method of producing a synthetic sleeper characterized in that.