Fiber-reinforced rigid polyurethane foam composite railway sleeper with high fiber content and manufacturing method thereof

Abstract

A fiber-reinforced rigid polyurethane foam composite railway sleeper with high fiber content and a manufacturing method thereof. The railway sleeper is formed by bonding a plurality of fiber-reinforced rigid polyurethane foam composite boards with high fiber content by a binder, and the outer surface of the railway sleeper is provided with an anticorrosive paint film. The fiber-reinforced rigid polyurethane foam composite boards with high fiber content include a polyurethane resin as a matrix material and a fiber as a reinforcing material. The problem of insufficient impregnation of the polyurethane and the fiber is solved by using a plurality of technical means such as using a mixed polyether polyol having a low hydroxyl value and a low functionality, using a coupling agent, etc., thus a fiber-reinforced rigid polyurethane foam composite product having a density higher than 840 kg/m.sup.3 and a fiber content greater than 60% is manufactured.

Claims

1. A fiber-reinforced rigid polyurethane foam composite railway sleeper, wherein the fiber-reinforced rigid polyurethane foam composite railway sleeper is formed by bonding a plurality of fiber-reinforced rigid polyurethane foam composite boards together with a binder; an outer surface of the fiber-reinforced rigid polyurethane foam composite railway sleeper is provided with an anticorrosive paint film; the fiber-reinforced rigid polyurethane foam composite boards comprise a polyurethane resin as a matrix material and a fiber as a reinforcing material; and the fiber-reinforced rigid polyurethane foam composite boards are prepared from a formulation comprising: TABLE-US-00010 a polyether polyol A having 90-95 parts by mass a hydroxyl value of 400-480 and a functionality of 2-3 a polyether polyol B having 5-10 parts by mass a hydroxyl value of 60-160 and a functionality of 2 flame retardant 5-15 parts by mass hard foam stabilizer 2.5-5 parts by mass coupling agent 5-15 parts by mass catalyst 0.1-1 parts by mass foaming agent 0.1-1 parts by mass antioxidant 0.25-1 parts by mass ultraviolet screening agent 0.25-1 parts by mass isocyanate 100-135 parts by mass reinforcing fiber 420-2000 parts by mass.

2. The fiber-reinforced rigid polyurethane foam composite railway sleeper of claim 1, wherein, the reinforcing fiber is one or more selected from the group consisting of glass fiber, basalt fiber, carbon fiber, aramid fiber, and steel fiber.

3. The fiber-reinforced rigid polyurethane foam composite railway sleeper of claim 1, wherein the fiber-reinforced rigid polyurethane foam composite boards have a thickness of 10 mm-120 mm, a width of 100 mm-600 mm, and a density of 200 kg/m.sup.3-2000 kg/m.sup.3.

4. The fiber-reinforced rigid polyurethane foam composite railway sleeper of claim 1, wherein, said bonding of the plurality of fiber-reinforced rigid polyurethane foam composite boards is selected from the group consisting of vertical bonding, lateral bonding, and cross bonding.

5. The fiber-reinforced rigid polyurethane foam composite railway sleeper of claim 4, wherein, at least two fiber-reinforced rigid polyurethane foam composite boards are provided, vertically arranged side by side, and vertically bonded by the binder.

6. The fiber-reinforced rigid polyurethane foam composite railway sleeper of claim 4, wherein, at least two fiber-reinforced rigid polyurethane foam composite boards are provided, and laterally bonded by the binder.

7. The fiber-reinforced rigid polyurethane foam composite railway sleeper of claim 4, wherein, at least four fiber-reinforced rigid polyurethane foam composite boards are provided, and at least two of the at least four fiber-reinforced rigid polyurethane foam composite boards are arranged laterally and at least two additional fiber-reinforced rigid polyurethane foam composite boards are arranged vertically and bonded to each other via the binder.

8. The fiber-reinforced rigid polyurethane foam composite railway sleeper of claim 1, wherein, the binder is selected from the group consisting of a vinyl resin binder, an epoxy resin binder, a polyurethane resin binder, an ortho-phenyl resin binder, a meta-phenyl resin binder and a phenol resin binder.

9. The fiber-reinforced rigid polyurethane foam composite railway sleeper of claim 1, wherein, the anticorrosive paint film is selected from the group consisting of a polyurethane paint film, a fluorocarbon paint film, an acrylic paint film, an epoxy resin paint film, and a vinyl resin paint film.

10. A method for manufacturing the fiber-reinforced rigid polyurethane foam composite railway sleeper of claim 1, comprising the following steps: preparing the fiber-reinforced rigid polyurethane foam composite boards grinding a surface of the fiber-reinforced rigid polyurethane foam composite boards, bonding with a binder the fiber-reinforced rigid polyurethane foam composite boards, mold pressing and curing the fiber-reinforced rigid polyurethane foam composite boards, grinding after curing the surface of the fiber-reinforced rigid polyurethane foam composite boards, cutting the fiber-reinforced rigid polyurethane foam composite boards, and coating the fiber-reinforced rigid polyurethane foam composite board.

11. The method of claim 10, wherein, the fiber-reinforced rigid polyurethane foam composite railway sleeper has a thickness of 100 mm-400 mm, a width of 200 mm-400 mm, and a density of 200 kg/m.sup.3-2000 kg/m.sup.3.

12. The fiber-reinforced rigid polyurethane foam composite railway sleeper of claim 2, wherein, the binder is selected from the group consisting of a vinyl resin binder, an epoxy resin binder, a polyurethane resin binder, an ortho-phenyl resin binder, a meta-phenyl resin binder and a phenol resin binder.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic diagram showing a production process of a fiber-reinforced rigid polyurethane foam composite board with high fiber content according to the present invention;

(2) FIG. 2 is a structural schematic diagram showing that fiber-reinforced rigid polyurethane foam composite boards with high fiber content are vertically bonded into a railway sleeper according to the present invention;

(3) FIG. 3 is a structural schematic diagram showing that fiber-reinforced rigid polyurethane foam composite boards with high fiber content are laterally bonded into a railway sleeper according to the present invention; and

(4) FIG. 4 is a structural schematic diagram showing that fiber-reinforced rigid polyurethane foam composite boards with high fiber content are formed into a railway sleeper through a cross bonding according to the present invention.

(5) In the drawings, components represented by each reference number are listed below:

(6) 1. creel, 2. high pressure foaming machine, 3. moving casting device, 4. crawler type laminating host machine, 5. cutting machine, 6. long fiber, 7. short-cut fiber, 8. polyurethane resin, 9. fiber felt, 10. fiber-reinforced rigid polyurethane foam composite board with high fiber content, 11. binder, 12. anticorrosive paint film.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(7) The principles and features of the present invention are described in the following with reference to the accompanying drawings. The embodiments listed are only used to illustrate the present invention, and not to limit the scope of the present invention.

(8) The present invention relates to a fiber-reinforced rigid polyurethane foam composite railway sleeper with high fiber content. The railway sleeper is formed by binding a plurality of fiber-reinforced rigid polyurethane foam composite boards with high fiber content 10 by an binder 11, and the outer surface of the railway sleeper is provided with an anticorrosive paint film 12, the fiber-reinforced rigid polyurethane foam composite boards with high fiber content 10 includes a polyurethane resin 8 as a matrix material and a fiber as a reinforcing material. With parts by mass, a formulation of the polyurethane resin 8 and the mass ratio of the polyurethane resin 8 to the reinforcing fiber are as follows:

(9) TABLE-US-00002 Polyether polyol A having a hydroxyl value of 90-95 parts 400-480 and a functionality of 1-3 Polyether polyol B having a hydroxyl value of 60-160 5-10 parts and a functionality of 1-2 Flame retardant 5-15 parts Hard foam stabilizer 2.5-5 parts Coupling agent 5-15 parts Catalyst 0.1-1 part Foaming agent 0.1-1 part Antioxidant 0.25-1 part Ultraviolet screening agent 0.25-1 part Isocyanate 100-135 parts Reinforcing fiber 420-2000 parts

(10) The reinforcing fiber is one or a mixture selected from the group consisting of glass fiber, basalt fiber, carbon fiber, aramid fiber, and steel fiber.

(11) The reinforcing fiber is mainly composed of a long fiber 6, and further includes a short-cut fiber 7 and a fiber felt.

(12) The coupling agent is a silane coupling agent.

(13) The ultraviolet screening agent is a UV-type ultraviolet screening agent.

(14) The fiber-reinforced rigid polyurethane foam composite boards with high fiber content 10 are prepared by a continuous molding process. The continuous molding process includes seven processes of unwinding the long fiber 6 and the fiber felt, injecting the polyurethane resin 8, adding the short-cut fiber 7, uniformly impregnating, curing in a crawler type laminating host machine 4, cooling and fixed length cutting.

(15) The uniformly impregnating specifically refers to uniformly impregnating the polyurethane resin 8 on the surface of the reinforcing fiber and inside the reinforcing fiber by a high-pressure foaming machine 2, a moving casting device 3 and corresponding tool equipment.

(16) The crawler type laminating host machine 4 is composed of a crawler type laminating machine and a side stopper, the side stopper is fixed on the crawler type laminating machine, and a height and a width of a mode cavity are adjusted according to a size of the side stopper.

(17) The fixed length cutting is performed by the cutting machine 5, after the fixed length cutting, the fiber-reinforced rigid polyurethane foam composite board with high fiber content 10 has a thickness of 10 mm-120 mm, a width of 100 mm-600 mm, and a density of 200 kg/m.sup.3-2000 kg/m.sup.3.

(18) As shown in FIGS. 2-4, an interior of the fiber-reinforced rigid polyurethane foam composite board with high fiber content 10 is provided with the long fiber 6 extending along a length direction, and an outer portion of the long fiber 6 is covered with the polyurethane resin 8.

(19) The interior of the fiber-reinforced rigid polyurethane foam composite board with high fiber content 10 is further provided with the short-cut fiber 7 extending along the length direction, and an outer portion of the short-cut fiber 7 is covered with the polyurethane resin 8.

(20) The outer surface of the polyurethane resin 8 covering the long fiber 6 and the short-cut fiber 7 is provided with the fiber felt.

(21) The bonding manner of the plurality of fiber-reinforced rigid polyurethane foam composite boards with high fiber content 10 is vertical bonding, lateral bonding or cross bonding.

(22) As shown in FIG. 2, at least two fiber-reinforced rigid polyurethane foam composite boards with high fiber content 10 are provided, vertically arranged side by side and vertically bonded by the binder 11.

(23) As shown in FIG. 3, at least two fiber-reinforced rigid polyurethane foam composite boards with high fiber content 10 are provided, stacked from top to bottom and laterally bonded by the binder 11.

(24) As shown in FIG. 4, at least four fiber-reinforced rigid polyurethane foam composite boards with high fiber content 10 are provided, two boards are provided laterally at upper and lower ends of the other boards, and the other boards are vertically arranged side by side and vertically bonded by the binder 11. The two boards are laterally bonded to the other boards by the binder 11 (the cross bonding includes both the vertical bonding and the lateral bonding). In addition to the boards laterally provided at both the upper end and lower end, another board may be provided at the upper end or the lower end, that is, at least three boards are provided. One of the three boards is laterally provided at the upper ends or the lower ends of the other boards, the other boards are vertically arranged side by side, and vertically bonded by the binder 11. The one of the three boards are laterally bonded to the other boards by the binder 11.

(25) The binder 11 is any one item of a vinyl resin binder, an epoxy resin binder, a polyurethane resin binder, an ortho-phenyl resin binder, a meta-phenyl resin binder or a phenol resin binder.

(26) The anticorrosive paint film 12 is any one item of a polyurethane paint film, a fluorocarbon paint film, an acrylic paint film, an epoxy resin paint film, or a vinyl resin paint film.

(27) The present invention further relates to a method for manufacturing a fiber-reinforced rigid polyurethane foam composite railway sleeper with high fiber content. A fiber-reinforced rigid polyurethane foam composite board with high fiber content 10 is first prepared and then processed. The process steps include six steps of surface grinding, bonding with a binder 11, mold pressing and curing, surface grinding after curing, fixed length cutting and coating.

(28) The obtained fiber-reinforced rigid polyurethane foam composite railway sleeper with high fiber content has a thickness of 100 mm-400 mm, a width of 200 mm-400 mm, and a density of 200 kg/m.sup.3-2000 kg/m.sup.3. Preferably, the total apparent density is from 800 kg/m.sup.3 to 1800 kg/m.sup.3.

(29) As shown in FIG. 1, the continuous molding process of the fiber-reinforced rigid polyurethane foam composite board with high fiber content 10 of the present invention is performed by the devices shown in the drawing. First, the long fibers and fiber felts are unwound on the creel 1, the polyurethane resin is injected, and the short-cut fibers are added. Then the uniform impregnation is realized by the high-pressure foaming machine 2, the moving casting device 3 and corresponding tool equipment. Then, curing is performed in the crawler type laminating host machine 4, and after being cooled, the cured board is cut by the cutting machine 5.

Embodiment 1

(30) With parts by mass, a formulation of the polyurethane resin and the mass ratio of the polyurethane resin to the reinforcing fiber were as follows: 90 parts of polyether polyol A having a hydroxyl value of 400-480 and a functionality of 1-3, 10 parts of polyether polyol B having a hydroxyl value of 60-160 and a functionality of 1-2, 10 parts of flame retardant, 5 parts of hard foam stabilizer, 15 parts of coupling agent, 0.3 part of catalyst, 0.1 part of foaming agent, 0.3 part of antioxidant, 0.3 part of ultraviolet screening agent, 120 parts of isocyanate, 430 parts of long fiber, 10 parts of short-cut fiber, and 5 parts of fiber felt. The content of the reinforcing fiber was 64%, and the prepared fiber-reinforced rigid polyurethane foam composite boards with a density of 140050 kg/m.sup.3 had a specification of 260 mm50 mm3000 mm. The parameters of the crawler type laminating host machine were set as follows: running speed: 0.4 m/min, and temperature: 90 C./60 C. The surface grinding was performed on the surface of the composite board. Four composite boards were vertically bonded by using a vinyl resin as a binder into a composite railway sleeper with a specification of 260 mm200 mm3000 mm. The performance of the composite railway sleeper manufactured according to the present embodiment was shown in Table 1.

(31) TABLE-US-00003 TABLE 1 Item Unit Test result Total apparent density kg/m.sup.3 1358 Bending strength MPa 358 Bending elastic modulus GPa 17.8 Compressive strength MPa 226 Shear strength MPa 27.8 Flame retardancy HB grade Breakdown voltage kV 50.1 Surface resistivity 8.3 10.sup.14 Water absorption mg/m.sup.2 0.56 Rail spike anti-pulling kN 180 strength Anti-bending load kN 400 Anti-fatigue performance / Under 40 t load, 2 million times without crack Material strength after UV aging (UV-B lamp irradiation for 1000 h) Bending strength MPa 398 Bending elastic modulus GPa 19.8 Compressive strength MPa 256 Shear strength MPa 29.8

Embodiment 2

(32) With parts by mass, a formulation of the polyurethane resin and the mass ratio of the polyurethane resin to the reinforcing fiber were as follows: 95 parts of polyether polyol A having a hydroxyl value of 400-480 and a functionality of 1-3, 5 parts of polyether polyol B having a hydroxyl value of 60-160 and a functionality of 1-2, 10 parts of flame retardant, 3 parts of hard foam stabilizer, 5 parts of coupling agent, 0.3 part of catalyst, 0.1 part of foaming agent, 0.3 part of antioxidant, 0.3 part of ultraviolet screening agent, 110 parts of isocyanate, 410 parts of long fiber, 10 parts of short-cut fiber, and 0 parts of fiber felt. The content of the reinforcing fiber was 65%, and the prepared fiber-reinforced rigid polyurethane foam composite boards with a density of 120050 kg/m.sup.3 had a specification of 240 mm50 mm3000 mm. The parameters of the crawler type laminating host machine were set as follows: running speed: 0.6 m/min, and temperature: 90 C./60 C. One of the composite boards was grinded to have a thickness of 40 mm. Five composite boards having a thickness of 50 mm and the one composite board having a thickness of 40 mm were bonded by using an epoxy resin as a binder into a composite railway sleeper with a specification of 240 mm290 mm3000 mm through a cross bonding. The performance of the composite railway sleeper manufactured according to the present embodiment was shown in Table 2.

(33) TABLE-US-00004 TABLE 2 Item Unit Test result Total apparent density kg/m.sup.3 1180 Bending strength MPa 286 Bending elastic modulus GPa 15.5 Compressive strength MPa 204 Shear strength MPa 25.8 Flame retardancy HB grade Breakdown voltage kV 50 Surface resistivity 6.3 10.sup.14 Water absorption mg/m.sup.2 0.61 Rail spike anti-pulling kN 138 strength Anti-bending load kN 400 Anti-fatigue performance / Under 40 t load, 2 million times without crack Material strength after UV aging (UV-B lamp irradiation for 1000 h) Bending strength MPa 316 Bending elastic modulus GPa 16.5 Compressive strength MPa 228 Shear strength MPa 27.8

Embodiment 3

(34) With parts by mass, a formulation of the polyurethane resin and the mass ratio of the polyurethane resin to the reinforcing fiber were as follows: 90 parts of polyether polyol A having a hydroxyl value of 400-480 and a functionality of 1-3, 5 parts of polyether polyol B having a hydroxyl value of 60-160 and a functionality of 1-2, 15 parts of flame retardant, 5 parts of hard foam stabilizer, 10 parts of coupling agent, 0.2 part of catalyst, 0.3 part of foaming agent, 0.5 part of antioxidant, 0.5 part of ultraviolet screening agent, 115 parts of isocyanate, 520 parts of long fiber, 5 parts of short-cut fiber, and 1 part of fiber felt. The content of the reinforcing fiber was 68.5%, and the prepared fiber-reinforced rigid polyurethane foam composite boards with a density of 100050 kg/m.sup.3 had a specification of 500 mm30 mm3000 mm. The parameters of the crawler type laminating host machine were set as follows: running speed: 0.5 m/min, and temperature: 90 C./70 C. The composite boards of 500 mm30 mm were first machined into composite boards of 250 mm30 mm. Six of the composite boards were selected to be subjected to the surface grinding, and then laterally bonded by using a vinyl resin as a binder into a composite railway sleeper with a specification of 250 mm180 mm3000 mm. The performance of the composite railway sleeper manufactured according to the present embodiment was shown in Table 3.

(35) TABLE-US-00005 TABLE 3 Item Unit Test result Total apparent density kg/m.sup.3 1014 Bending strength MPa 193 Bending elastic modulus GPa 13.8 Compressive strength MPa 112 Shear strength MPa 13.2 Flame retardancy HB grade Breakdown voltage kV 50.2 Surface resistivity 2.3 10.sup.14 Water absorption mg/m.sup.2 0.63 Rail spike anti-pulling kN 128 strength Anti-bending load kN 400 Anti-fatigue performance / Under 30 t load, 2 million times without crack Material strength after UV aging (UV-B lamp irradiation for 1000 h) Bending strength MPa 218 Bending elastic modulus GPa 12.7 Compressive strength MPa 127 Shear strength MPa 13.5

Embodiment 4

(36) With parts by mass, a formulation of the polyurethane resin and the mass ratio of the polyurethane resin to the reinforcing fiber were as follows: 95 parts of polyether polyol A having a hydroxyl value of 400-480 and a functionality of 1-3, 10 parts of polyether polyol B having a hydroxyl value of 60-160 and a functionality of 1-2, 5 parts of flame retardant, 5 parts of hard foam stabilizer, 10 parts of coupling agent, 0.1 part of catalyst, 0.1 part of foaming agent, 0.25 part of antioxidant, 0.25 part of ultraviolet screening agent, 125 parts of isocyanate, 460 parts of long fiber, 10 parts of short-cut fiber, and 0 parts of fiber felt. The content of the reinforcing fiber was 65%, and the prepared fiber-reinforced rigid polyurethane foam composite boards with a density of 80050 kg/m.sup.3 had a specification of 200 mm60 mm3000 mm. Three composite boards were subjected to the surface grinding, and laterally bonded by using a vinyl resin as a binder into a composite railway sleeper with a specification of 200 mm60 mm3000 mm. The performance of the composite railway sleeper manufactured according to the present embodiment was shown in Table 4.

(37) TABLE-US-00006 TABLE 4 Item Unit Test result Total apparent density kg/m.sup.3 806 Bending strength MPa 138 Bending elastic modulus GPa 10.8 Compressive strength MPa 108 Shear strength MPa 12 Flame retardancy HB grade Breakdown voltage kV 50.2 Surface resistivity 2.2 10.sup.13 Water absorption mg/m.sup.2 0.73 Rail spike anti-pulling kN 92 strength Anti-bending load kN 242 Anti-fatigue performance / Under 20 t load, 2 million times without crack Material strength after UV aging (UV-B lamp irradiation for 1000 h) Bending strength MPa 171 Bending elastic modulus GPa 11.2 Compressive strength MPa 117 Shear strength MPa 12.5

Embodiment 5

(38) With parts by mass, a formulation of the polyurethane resin and the mass ratio of the polyurethane resin to the reinforcing fiber were as follows: 92 parts of polyether polyol A having a hydroxyl value of 400-480 and a functionality of 1-3, 8 parts of polyether polyol B having a hydroxyl value of 60-160 and a functionality of 1-2, 10 parts of flame retardant, 2.5 parts of hard foam stabilizer, 15 parts of coupling agent, 1 part of catalyst, 1 part of foaming agent, 1 part of antioxidant, 1 part of ultraviolet screening agent, 100 parts of isocyanate, 1330 parts of long fiber, 30 parts of short-cut fiber, and 10 parts of fiber felt. The content of the reinforcing fiber was 85%, and the prepared fiber-reinforced rigid polyurethane foam composite boards with a density of 150050 kg/m.sup.3 had a specification of 600 mm10 mm3000 mm. The parameters of the crawler type laminating host machine were set: running speed: 0.4 m/min, and temperature: 90 C./60 C. The composite boards of 600 mm10 mm were first machined into composite boards of 300 mm10 mm. Ten of the composite boards were subjected to the surface grinding, laterally bonded by using an epoxy resin as a binder into a composite railway sleeper with a specification of 300 mm100 mm3000 mm. The performance of the composite railway sleeper manufactured according to the present embodiment was shown in Table 5.

(39) TABLE-US-00007 TABLE 5 Item Unit Test result Total apparent density kg/m.sup.3 1521 Bending strength MPa 377 Bending elastic modulus GPa 19.2 Compressive strength MPa 234 Shear strength MPa 29.8 Flame retardancy HB grade Breakdown voltage kV 50.7 Surface resistivity 8.9 10.sup.14 Water absorption mg/m.sup.2 0.53 Rail spike anti-pulling kN 180 strength Anti-bending load kN 400 Anti-fatigue performance / Under 40 t load, 2 million times without crack Material strength after UV aging (UV-B lamp irradiation for 1000 h) Bending strength MPa 428 Bending elastic modulus GPa 22.8 Compressive strength MPa 276 Shear strength MPa 31.3

Embodiment 6

(40) With parts by mass, a formulation of the polyurethane resin and the mass ratio of the polyurethane resin to the reinforcing fiber were as follows: 93 parts of polyether polyol A having a hydroxyl value of 400-480 and a functionality of 1-3, 7 parts of polyether polyol B having a hydroxyl value of 60-160 and a functionality of 1-2, 10 parts of flame retardant, 2.5 parts of hard foam stabilizer, 15 parts of coupling agent, 0.8 part of catalyst, 0.6 part of foaming agent, 0.7 part of antioxidant, 0.5 part of ultraviolet screening agent, 135 parts of isocyanate, 1940 parts of long fiber, 40 parts of short-cut fiber, and 20 parts of fiber felt. The content of the reinforcing fiber was 88%, and the prepared fiber-reinforced rigid polyurethane foam composite boards with a density of 180050 kg/m.sup.3 had a specification of 100 mm100 mm3000 mm. The parameters of the crawler type laminating host machine were set as follows: running speed: 0.4 m/min, and temperature: 90 C./60 C. Sixteen composite boards were selected, and bonded through a cross bonding by using an epoxy resin as a binder into a composite railway sleeper with a specification of 400 mm400 mm3000 mm. The obtained composite railway sleeper has a four-layer structure with four composite boards in each layer. The performance of the composite railway sleeper manufactured according to the present embodiment was shown in Table 6.

(41) TABLE-US-00008 TABLE 6 Item Unit Test result Total apparent density kg/m.sup.3 1768 Bending strength MPa 413 Bending elastic modulus GPa 23.8 Compressive strength MPa 253 Shear strength MPa 31.5 Flame retardancy HB grade Breakdown voltage kV 51.3 Surface resistivity 9.4 10.sup.14 Water absorption mg/m.sup.2 0.52 Rail spike anti-pulling kN 180 strength Anti-bending load kN 400 Anti-fatigue performance / Under 40 t load, 2 million times without crack Material strength after UV aging (UV-B lamp irradiation for 1000 h) Bending strength MPa 468 Bending elastic modulus GPa 26.8 Compressive strength MPa 287 Shear strength MPa 35.8

(42) Comparative Analysis

(43) In the fiber-reinforced rigid polyurethane foam composite railway sleeper with high fiber content of the present invention, the problem of insufficient impregnation of the polyurethane and the fiber is solved by using a plurality of technical means such as using a mixed polyether polyol having a low hydroxyl value and a low functionality, using a coupling agent, etc., thus the fiber content is increased and a fiber-reinforced rigid polyurethane foam composite product having a density higher than 840 kg/m.sup.3 and a fiber content greater than 60% is capable of being prepared, which fills in the technical gap of fiber-reinforced rigid polyurethane foam composite railway sleepers and makes a diversification of the product specifications and performance to meet various technical requirements.

(44) By increasing the mass ratio of the reinforcing fiber to more than 60%, not only is the production cost reduced, but also the strength of the fiber-reinforced rigid polyurethane foam composite railway sleeper is greatly increased compared to that at the same density. The product is more compact, the water absorption and other indicators are greatly reduced, which improves the water resistance of the product.

(45) By manufacturing the high-fiber-content fiber-reinforced rigid polyurethane foam composite railway board and forming by the method of bonding, the manufacturing method and process of the composite railway sleeper are simplified, and the specifications and models of the composite railway sleeper are increased without increasing the investment of the mold. The problem that the polyurethane is too difficult to impregnate due to excessive fibers in the integrated molding is solved. Meanwhile, composite boards of various densities can be manufactured to diversify the density of the composite railway sleepers, thereby diversifying the strength and meeting the requirements of composite railway sleepers for trains at different axle loads in railway transportation.

(46) At present, no reports and material objects of the fiber-reinforced rigid polyurethane foam composite railway sleeper with a fiber density higher than 840 kg/m.sup.3 and a fiber content higher than 60% have been seen. The composite railway sleeper with a density of 80050 kg/m.sup.3 is prepared by the manufacturing method of the present invention, which is tested and compared with the material objects of fiber-reinforced rigid polyurethane foam composite railway sleepers produced by well-known domestic and foreign manufacturers. The results are shown in Table 7.

(47) TABLE-US-00009 Average value Average value Average value of test results of test results of test results of foreign of domestic of the present Test items manufacturer manufacturer invention Mechanical Bending strength, 86.8 85.2 138 properties MPa of materials Bending elastic 6.35 7.69 10.8 at room modulus, GPa temperature Longitudinal 48.9 73.1 108 compressive strength, MPa Shear strength, MPa 10.9 8.77 12 Mechanical Bending strength, 87.3 106 171 properties MPa of materials Bending elastic 5.65 9.4 11.2 after UV modulus, GPa aging Longitudinal 51.3 74.3 117 compressive strength, MPa Shear strength, MPa 7.6 9.1 12.5 Mechanical Thread rail spike 49.1 48 92 properties anti-pulling of finished strength, kN product Anti-bending load, 198 186 243 kN Anti-fatigue 10.sup.5 no 10.sup.5 no 2 10.sup.6 no property abnormality abnormality abnormality Electrical Insulation 1.3 10.sup.13 1.68 10.sup.10 2.2 10.sup.13 properties resistance, Breakdown 38.7 32.0 50.2 voltage, kV Other Water absorption, 61 7.77 0.73 properties mg/m.sup.2 Horizontal burning HB HB HB level Fiber content, % 45.5 50.5 62.5 Total apparent 788 792 806 density, kg/m.sup.3

(48) Conclusion of Comparative Analysis

(49) It can be seen that the fiber-reinforced rigid polyurethane foam composite railway sleeper with high fiber content of the present invention has a fiber content of more than 60%. In the case where the density is almost the same, the manufactured products are far superior to the composite railway sleeper products of well-known domestic and foreign manufacturers in terms of mechanical properties, anti-UV aging properties, electrical properties, water resistance, etc., especially anti-bending properties, thread rail spike anti-pulling strength and anti-fatigue properties of the composite railway sleepers.

(50) The above descriptions are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention should be included within the scope of the present invention.