NDI type polyurethane elastomer under-rail backing plate and preparation method thereof

Abstract

The invention provides an NDI type polyurethane elastomer under-rail backing plate and a preparation method thereof, the NDI type polyurethane elastomer under-rail backing plate is prepared by reaction of a component A and a component B, and the component A is prepared by reaction of polymer polyol A and 1, 5-naphthalene diisocyanate. The component B comprises polymer polyol B, a chain extender and a catalyst, and the weight ratio of the component A to the component B is 100: (20-60). 1, 5-naphthalene diisocyanate with a special molecular structure is selected from the component A to obtain a polyurethane elastomer with a compact hard segment and good microphase separation, and the lower rail backing plate prepared from the polyurethane elastomer has the advantages of high tear strength, low abrasion, low compression set, low dynamic and static stiffness ratio and good fatigue resistance; and the service life of the under-rail backing plate can be prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane materials, and in particular relates to a polyurethane elastomer rail underlay plate and a preparation method thereof. Background Art

[0002] In the railway track structure, elastic pads are usually added between the rails and sleepers to provide reasonable elasticity for the track and play a role in vibration reduction and noise reduction. Polyurethane elastomers have excellent mechanical properties, wear resistance, and oil resistance. They still maintain good elasticity in the range of higher hardness (Shore 70A-70D) and have been widely used in the fields of rail transportation, automobiles, bridges, and building vibration reduction.

[0003] Polyurethane elastomers are prepared by the reaction of polyols, isocyanates and chain extenders. They are block copolymers composed of alternating soft segments and hard segments. They have the advantages of easy structural design and adjustable mechanical properties. By selecting different raw materials, the properties of the elastomer can be adjusted over a wide range.

[0004] The polyurethane rail pads currently used in railway tracks are mainly polyurethane elastomers of toluene diisocyanate (TDI type) and 4,4-diphenylmethane diisocyanate (MDI type) systems. These two elastomers have the disadvantages of large compression permanent deformation and poor dynamic performance. Under the action of alternating stress, the internal heat generation is more serious, which accelerates the aging of the material and affects the service life of the pads. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a 1,5-naphthalene diisocyanate (NDI) type polyurethane elastomer rail underlay and a preparation method thereof. The prepared elastic underlay has the characteristics of high tear strength, low wear, low compression permanent deformation, low dynamic-static stiffness ratio, and excellent fatigue resistance.

[0006] To achieve this object, the present invention provides an NDI type polyurethane elastomer rail pad, which is prepared by reacting component A and component B.

[0007] The raw materials for preparing the A component are polymer polyol A and 1,5-naphthalene diisocyanate, and the A component is prepared by reacting the polymer polyol A and 1,5-naphthalene diisocyanate;

[0008] The B component includes polymer polyol B, a chain extender and a catalyst;

[0009] The weight ratio of component A to component B is 100:(20-60), for example, 100:20, 100:30, 100:40, 100:50 or 100:60.

[0010] Preferably, the component A is an isocyanate component, and the raw materials for preparation include the following components in parts by weight:

[0011] Polymer polyol A 75-80 parts, for example 75, 76, 77, 78, 79 or 80 parts;

[0012] 20-25 parts, for example, 20, 21, 22, 23, 24 or 25 parts, of 1,5-naphthalene diisocyanate.

[0013] Preferably, the polymer polyol A in the component A is selected from one or more of polytetramethylene glycol, polycaprolactone glycol, polybutylene adipate diol, polyethylene adipate diol, polyhexanediol adipate diol or polycarbonate diol.

[0014] Preferably, the functionality of the polymer polyol A is 2, and the number average molecular weight is 1000-3000, more preferably 1500-2000, for example 1000, 1500, 2000, 2500 or 3000.

[0015] Preferably, the NCO% content of the A component is 3-7%, more preferably 4-6%, for example 3%, 4%, 5%, 6% or 7%.

[0016] The component B is a polyol component, which includes the following components in parts by weight:

[0017] 100 parts of polymer polyol B;

[0018] 8.2 to 13.8 parts of a chain extender, for example 8.2, 8.5, 9.0, 9.5, 10.1, 10.6, 11.2, 11.5, 12.1, 12.5, 12.9, 13.4, or 13.8 parts;

[0019] The catalyst is 0.06 to 0.2 parts, for example 0.06, 0.10, 0.12, 0.15, 0.18 or 0.2 parts.

[0020] Preferably, the polymer polyol B in the B component is selected from one or more of polytetramethylene glycol, polycaprolactone glycol, polybutylene adipate diol, polyethylene adipate diol, polyhexanediol adipate diol or polycarbonate diol.

[0021] Preferably, the functionality of the polymer polyol is 2, and the number average molecular weight is 1000-3000, more preferably 1500-2000, for example 1000, 1500, 2000, 2500 or 3000.

[0022] The chain extender is one or more of ethylene glycol, propylene glycol, 1,4-butanediol, diethylene glycol, 1,6-hexanediol or neopentyl glycol; preferably, the chain extender is 1,4-butanediol or ethylene glycol with a symmetrical structure.

[0023] Preferably, the B component further comprises 0.05 to 2.75 parts of a crosslinking agent, for example 0.05, 0.1, 0.3, 0.5, 0.8, 1.2, 1.5, 1.8, 2.1, 2.5, or 2.75 parts.

[0024] Preferably, the cross-linking agent comprises a small molecule polyol with a functionality of 3.

[0025] Preferably, the small molecule polyol with a functionality of 3 includes any one of trimethylolpropane, glycerol or triethanolamine, or a combination of at least two thereof.

[0026] Preferably, the content of the crosslinking agent does not exceed 25% of the content of the chain extender by weight, for example, the crosslinking agent does not exceed 5%, 10%, 15% or 20% of the content of the chain extender.

[0027] Preferably, the catalyst is an organometallic catalyst, including an organotin catalyst, an organobismuth catalyst and / or an organozinc catalyst.

[0028] In the present invention, there is no particular limitation on the type of the organic metal catalyst, including but not limited to any one or a combination of at least two of stannous octoate, dibutyltin dilaurate, bismuth isooctanoate, bismuth neodecanoate or zinc isooctanoate catalysts.

[0029] The preparation method of the NDI type polyurethane elastomer rail bottom pad of the present invention comprises the following preparation steps:

[0030] (1) Preparation of component A: According to the weight requirement of component A, polymer polyol A is added to a reaction kettle, the temperature is raised to 115-125° C. (e.g., 115° C., 120° C. or 125° C.), and after vacuum dehydration treatment, 1,5-naphthalene diisocyanate is added, and the reaction is carried out for 30-60 min (e.g., 30 min, 40 min, 50 min or 60 min), and the temperature is lowered to obtain component A; specifically, the vacuum dehydration time is 1-3 h.

[0031] (2) Preparation of component B: According to the weight requirements of component B, polymer polyol B, chain extender and catalyst are added into a reaction kettle respectively, the temperature is raised to 100-120° C., vacuum dehydration treatment is performed, and the temperature is lowered to obtain component B. Specifically, the vacuum dehydration time is 1-3 hours.

[0032] (3) Component A and component B are respectively added to the A and B tanks of a low-pressure casting machine for preheating, component A is preheated to 70-90° C. (e.g., 70° C., 80° C., or 90° C.), and component B is preheated to 50-70° C. (e.g., 50° C., 60° C., or 70° C.). Components A and B are mixed at high speed in proportion, injected into a mold at 100-120° C., aged for 30-60 min (e.g., 30 min, 40 min, 50 min, or 60 min), and left at room temperature for more than 7 days after demolding to obtain the NDI type polyurethane elastomer rail underlay plate.

[0033] In the above step (3), the weight ratio of component A to component B is 100:(20-60), for example, 100:20, 100:30, 100:40, 100:50 or 100:60, preferably 100:31.6-43.7.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) The NDI type polyurethane elastomer rail pad provided by the present invention uses 1,5-naphthalene diisocyanate with a special molecular structure, which has a highly symmetrical molecular structure, is easy to form a compact hard segment and good microphase separation, and gives the polyurethane elastomer excellent thermal stability, dynamic properties and comprehensive mechanical properties.

[0036] (2) The NDI type polyurethane elastomer rail pad provided by the present invention has the advantages of high tear strength, low wear, low compression permanent deformation, low dynamic-static stiffness ratio, and good fatigue resistance, which can improve the service life of the rail pad.

[0037] (3) The static stiffness of the NDI type polyurethane elastomer rail pad provided by the present invention is 75 to 140 kN / mm, which can meet the use occasions with different static stiffness requirements. DETAILED DESCRIPTION

[0038] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0039] Unless otherwise specified, the raw materials involved in the following specific embodiments can be purchased from the market or prepared according to existing methods; among them, the information of some raw materials used is as follows:

[0040] PTMG2000: polytetramethylene glycol; number average molecular weight is 2000;

[0041] PTMG1500: polytetramethylene glycol; number average molecular weight is 1500;

[0042] PCL2000: polycaprolactone diol; number average molecular weight is 2000;

[0043] PEA2000: Polyethylene adipate diol; number average molecular weight is 2000;

[0044] PEA1500: polyethylene glycol adipate diol; number average molecular weight is 1500.

[0045] Example 1

[0046] A method for preparing an NDI type polyurethane elastomer rail pad comprises the following steps:

[0047] (1) Preparation of component A: 79.19 parts of PTMG2000 were added to a reaction kettle, and the temperature was raised to 120°C. After vacuum dehydration for 2 hours, 20.81 parts of 1,5-naphthalene diisocyanate were added. After the 1,5-naphthalene diisocyanate was completely dissolved, the reaction was continued for 50 minutes. The material was sealed and stored. The NCO% of the prepolymer was 5.06%.

[0048] (2) Preparation of component B: 100 parts of PTMG2000, 13.8 parts of BDO and 0.1 parts of bismuth isooctanoate were added into a reaction kettle, the temperature was raised to 100° C., vacuum dehydration treatment was performed for 3 h, the temperature was lowered, the material was discharged, and the mixture was sealed for storage.

[0049] (3) Add component A and component B to the A and B tanks of the low-pressure casting machine for preheating, component A to 70°C and component B to 50°C. Mix components A and B at a ratio of 100 / 31.6 at high speed, inject into a mold at 120°C, mature for 30 minutes, and place at room temperature for more than 7 days after demolding to obtain a polyurethane elastomer rail underlay. Its performance data is shown in Table 1.

[0050] Example 2

[0051] A method for preparing an NDI type polyurethane elastomer rail pad comprises the following steps:

[0052] (1) Preparation of component A: 79.19 parts of PTMG2000 were added to a reaction kettle, and the temperature was raised to 120°C. After vacuum dehydration for 2 hours, 20.81 parts of 1,5-naphthalene diisocyanate were added. After the 1,5-naphthalene diisocyanate was completely dissolved, the reaction was continued for 50 minutes. The material was sealed and stored. The NCO% of the prepolymer was 5.06%.

[0053] (2) Preparation of component B: 100 parts of PTMG2000, 11.02 parts of BDO, 2.75 parts of trimethylolpropane and 0.1 parts of bismuth isooctanoate were added into a reaction kettle, the temperature was raised to 100° C., vacuum dehydration treatment was performed for 3 h, the temperature was lowered, the material was discharged, and the mixture was sealed for storage.

[0054] (3) Add component A and component B to the A and B tanks of the low-pressure casting machine for preheating, component A is preheated to 70°C, and component B is preheated to 50°C. Component A and component B are mixed at a high speed in a ratio of 100 / 31.6, injected into a mold at 90°C, aged for 60 minutes, and placed at room temperature for more than 7 days after demolding to obtain a polyurethane elastomer rail underlay. Its performance data is shown in Table 1.

[0055] Example 3

[0056] A method for preparing an NDI type polyurethane elastomer rail pad comprises the following steps:

[0057] (1) Preparation of component A: Add 79.19 parts of PCL2000 to a reaction kettle, heat to 125°C, and vacuum dehydrate for 2 hours. Then, add 20.81 parts of 1,5-naphthalene diisocyanate. After the 1,5-naphthalene diisocyanate is completely dissolved, react for 30 minutes, and seal the material for storage. The NCO% of the prepolymer is 5.02%.

[0058] (2) Preparation of component B: 100 parts of PCL2000, 10 parts of BDO and 0.06 parts of bismuth neodecanoate were added into a reaction kettle, the temperature was raised to 120° C., vacuum dehydration treatment was performed for 1 hour, the temperature was lowered, the material was discharged, and the product was sealed for storage.

[0059] (3) Add component A and component B to the A and B tanks of the low-pressure casting machine for preheating, component A is preheated to 90°C, and component B is preheated to 60°C. Component A and component B are mixed at a high speed in a ratio of 100 / 38.82, injected into a mold at 110°C, aged for 60 minutes, and placed at room temperature for more than 7 days after demolding to obtain a polyurethane elastomer rail underlay. Its performance data is shown in Table 1.

[0060] Example 4

[0061] A method for preparing an NDI type polyurethane elastomer rail pad comprises the following steps:

[0062] (1) Preparation of component A: 75 parts of PEA1500 were added to a reaction kettle, the temperature was raised to 115°C, and after vacuum dehydration for 2 hours, 25 parts of 1,5-naphthalene diisocyanate were added. After the 1,5-naphthalene diisocyanate was completely dissolved, the reaction was continued for 40 minutes, and the material was sealed and stored. The NCO% of the prepolymer was 6.12%.

[0063] (2) Preparation of component B: Add 100 parts of PEA2000, 9.36 parts of EG (ethylene glycol), 1.98 parts of glycerol (propylene glycol) and 0.12 parts of zinc isooctanoate into a reaction kettle, heat to 120°C, vacuum dehydrate for 1 hour, cool down, discharge, and seal for storage.

[0064] (3) Add component A and component B to the A and B tanks of the low-pressure casting machine for preheating, component A is preheated to 80°C, and component B is preheated to 70°C. Component A and component B are mixed at a high speed in a ratio of 100 / 43.7, injected into a mold at 110°C, aged for 50 minutes, and placed at room temperature for more than 7 days after demolding to obtain a polyurethane elastomer rail underlay. Its performance data is shown in Table 1.

[0065] Example 5

[0066] A method for preparing an NDI type polyurethane elastomer rail pad comprises the following steps:

[0067] (1) Preparation of component A: 79 parts of PTMG1500 were added to a reaction kettle, and the temperature was raised to 115°C. After vacuum dehydration for 2 hours, 21 parts of 1,5-naphthalene diisocyanate were added. After the 1,5-naphthalene diisocyanate was completely dissolved, the reaction was continued for 40 minutes. The material was sealed and stored. The NCO% of the prepolymer was 4.0%.

[0068] (2) Preparation of component B: Add 100 parts of PTMG2000, 8.2 parts of BDO and 0.2 parts of stannous octoate into a reaction kettle, heat to 120°C, vacuum dehydrate for 1 hour, cool down, discharge, and seal for storage.

[0069] (3) Add component A and component B to the A and B tanks of the low-pressure casting machine for preheating, component A is preheated to 80°C, and component B is preheated to 70°C. Component A and component B are mixed at a high speed in a ratio of 100 / 34.92, injected into a mold at 120°C, aged for 50 minutes, and placed at room temperature for more than 7 days after demolding to obtain a polyurethane elastomer rail underlay. Its performance data is shown in Table 1.

[0070] Comparative Example 1

[0071] A method for preparing an MDI type polyurethane elastomer rail underlay plate, comprising the following steps:

[0072] (1) Preparation of component A: 75.64 parts of PTMG2000 were added to a reaction kettle, the temperature was raised to 120°C, vacuum dehydration was carried out for 2 hours, the temperature was lowered to 60°C, 24.36 parts of molten MDI were added, the reaction was continued for half an hour, the temperature was gradually raised to 80°C, the reaction was continued for another 90 minutes, the material was discharged and sealed for storage, and the NCO% of the prepolymer was 5.04%.

[0073] (2) Preparation of component B: 100 parts of PTMG2000, 13.78 parts of BDO and 0.2 parts of bismuth isooctanoate were added into a reaction kettle, the temperature was raised to 100° C., vacuum dehydration treatment was performed for 3 h, the temperature was lowered, the material was discharged, and the mixture was sealed for storage.

[0074] (3) Add component A and component B to the A and B tanks of the low-pressure casting machine for preheating, component A to 70°C and component B to 50°C. Mix components A and B at a ratio of 100 / 31.6 at high speed, inject into a mold at 120°C, mature for 30 minutes, and place at room temperature for more than 7 days after demolding to obtain a polyurethane elastomer rail underlay. Its performance data is shown in Table 1.

[0075] Comparative Example 2

[0076] A method for preparing an MDI type polyurethane elastomer rail underlay plate, comprising the following steps:

[0077] (1) Preparation of component A: 59.78 parts of PTMG2000 were added to a reaction kettle, the temperature was raised to 120°C, vacuum dehydration was carried out for 2 hours, the temperature was lowered to 60°C, 40.22 parts of molten MDI were added, the reaction was continued for half an hour, the temperature was gradually raised to 80°C, the reaction was continued for another 90 minutes, the material was discharged and sealed for storage, and the NCO% of the prepolymer was 11.02%.

[0078] (2) Preparation of component B: 100 parts of PTMG2000, 12.67 parts of BDO and 0.1 parts of bismuth isooctanoate were added into a reaction kettle, the temperature was raised to 100° C., vacuum dehydration treatment was performed for 3 h, the temperature was lowered, the material was discharged, and the mixture was sealed for storage.

[0079] (3) Add component A and component B to the A and B tanks of the low-pressure casting machine for preheating, component A is preheated to 70°C, and component B is preheated to 50°C. Component A and component B are mixed at a high speed in a ratio of 100 / 73.46, injected into a mold at 120°C, aged for 30 minutes, and placed at room temperature for more than 7 days after demolding to obtain a polyurethane elastomer rail underlay. Its performance data is shown in Table 1.

[0080] Table 1 Performance of materials in examples and comparative examples

[0081]

[0082] Comparing Example 1 and Comparative Example 2, under the condition of similar hardness and static stiffness, the polyurethane elastomer rail pad of the present invention has lower compression permanent deformation, Akron wear, dynamic-static stiffness ratio and higher tear strength, and the static stiffness change rate after 3 million fatigue cycles is lower.

[0083] As shown in Table 1, compared with the comparative example, the compression permanent deformation of the polyurethane elastomer rail pad of the present invention is less than 6%, and has better recovery performance; the Akron wear is less than 0.4 cm 3 , better wear resistance; the dynamic-static ratio is lower than 1.3, and the vibration reduction effect is better; the static stiffness change rate after 3 million fatigue tests is less than 4%, the fatigue resistance is better, and it has a longer service life.

Claims

1. An NDI type polyurethane elastomer rail pad, characterized in that: The NDI type polyurethane elastomer rail pad is made by reacting component A and component B; The A component is prepared by reacting polymer polyol A and 1,5-naphthalene diisocyanate; The B component includes polymer polyol B, a chain extender and a catalyst; The weight ratio of the component A to the component B is 100:(20-60).

2. The NDI type polyurethane elastomer rail pad according to claim 1, characterized in that: The raw materials for preparing the A component include the following components in parts by weight: 75-80 parts of polymer polyol A; 20-25 parts of 1,5-naphthalene diisocyanate 3. The NDI type polyurethane elastomer rail pad according to claim 1 or 2, characterized in that: The functionality of the polymer polyol A and the polymer polyol B is 2; The number average molecular weight of the polymer polyol A and the polymer polyol B are both 1000 to 3000, and more preferably 1500 to 2000.

4. The NDI type polyurethane elastomer rail pad according to claim 1 or 2, characterized in that: The polymer polyol A and the polymer polyol B are independently selected from at least one of polytetramethylene glycol, polycaprolactone glycol, polybutylene adipate glycol, polyethylene adipate glycol, polyhexane adipate glycol or polycarbonate glycol.

5. The NDI type polyurethane elastomer rail pad according to claim 1 or 2, characterized in that: The B component comprises the following components in parts by weight: 100 parts of polymer polyol B; Chain extender 8.2-13.8 parts; Catalyst 0.06-0.2 parts.

6. The NDI type polyurethane elastomer rail pad according to claim 1 or 2, characterized in that: The chain extender is selected from at least one of ethylene glycol, propylene glycol, 1,4-butanediol, diethylene glycol, 1,6-hexanediol or neopentyl glycol.

7. The NDI type polyurethane elastomer rail pad according to claim 1 or 2, characterized in that: The B component also includes 0.05 to 2.75 parts of a cross-linking agent, and the content of the cross-linking agent does not exceed 25% of the content of the chain extender; And / or, the catalyst is an organic metal catalyst, and the catalyst is further selected from at least one of an organic tin catalyst, an organic bismuth catalyst or an organic zinc catalyst.

8. The NDI type polyurethane elastomer rail pad according to claim 7, characterized in that: The cross-linking agent includes a small molecule polyol with a functionality of 3.

9. The NDI type polyurethane elastomer rail pad according to claim 8, characterized in that: The cross-linking agent includes any one of trimethylolpropane, glycerol or triethanolamine, or a combination of at least two thereof.

10. A method for preparing the NDI type polyurethane elastomer rail pad according to any one of claims 1 to 9, characterized in that: The preparation method comprises the following steps: (1) Preparation of component A: Add polymer polyol A to a reaction kettle according to the weight requirements of component A, heat to 115-125° C., perform vacuum dehydration, add 1,5-naphthalene diisocyanate, react for 30-60 min, cool and discharge to obtain component A; (2) Preparation of component B: Add polymer polyol B, chain extender and catalyst into a reaction kettle according to the weight requirements of component B, heat to 100-120° C., perform vacuum dehydration treatment, and then cool and discharge to obtain component B; (3) Preheating component A and component B separately, preheating component A to 70-90° C. and preheating component B to 50-70° C., mixing components A and B according to the required weight ratio, and injecting them into a mold at 100-120° C., aging for 30-60 minutes, and leaving them at room temperature after demolding to obtain the NDI type polyurethane elastomer rail bottom pad.

Images