Polyurethane elastomer composition and polyurethane elastomer product obtained therefrom

Abstract

The present invention provides a polyurethane elastomer composition, which comprises a polyol component A and an isocyanate component B, wherein the polyol component A comprises at least one first polyether polyol having an unsaturation of less than 0.05 mol / kg, a weight average molecular weight Mw of 6000 to 18000 g / mol, and an average functionality of 2 to 6; polytetrahydrofuran diol having a weight average molecular weight Mw of at least 1000 g / mol; a chain extender; a catalyst; a blowing agent; and optionally an additive, and the isocyanate component B comprises at least one NCO-terminated polyurethane prepolymer, wherein the NCO-terminated polyurethane prepolymer comprises a reaction product of the following components: a) at least one polyisocyanate, and b) at least one second polyether polyol having an unsaturation of less than 0.05 mol / kg, a weight average molecular weight Mw of 6000 to 18000 g / mol, and an average functionality of 2 to 3. The present invention also provides a polyurethane elastomer article obtained from the polyurethane elastomer composition, and use of the polyurethane elastomer article as a highly cold-resistant polyurethane shock-absorbing pad.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane materials, and in particular relates to a polyurethane elastomer composition, a polyurethane elastomer product obtained therefrom, and use of the polyurethane elastomer product as a highly cold-resistant polyurethane shock-absorbing pad. Background Art

[0002] At present, my country's high-speed railway industry is developing rapidly. Most of the newly built railways in my country use ballastless tracks, which have the advantages of long service life, low maintenance cost, and high-speed and stable operation of trains. However, they have high rigidity, low elasticity, and poor shock absorption and noise reduction performance. Using microporous polyurethane elastomer as a shock-absorbing pad can provide damping and shock absorption to overcome the shortcomings of ballastless track, such as high rigidity and great impact damage to the roadbed. It has excellent energy absorption and buffering performance, and its molecular structure is highly designable, and is widely used in the field of shock absorption.

[0003] In addition, due to China's vast territory and complex terrain, the winter temperature in the north and some plateau areas is very low. The construction of high-speed railways in these places requires very high cold resistance of shock-absorbing pads. Therefore, low temperature resistance is a very important performance of shock-absorbing pads for high-speed railways. Its specific manifestation is the static stiffness change rate of the shock-absorbing pad at low temperature compared with normal temperature. In high-cold and high-altitude areas, this parameter needs to be below 20% at temperatures below -35°C, especially at -50°C. However, the existing polyurethane shock-absorbing pads on the market cannot meet such requirements. Summary of the invention

[0004] In order to overcome the deficiencies in the prior art, the present invention provides a polyurethane elastomer composition, the polyurethane elastomer product obtained from the composition has excellent low temperature resistance, good mechanical properties and fatigue resistance, and is particularly suitable for use as a shock-absorbing pad for high-speed railways.

[0005] Therefore, in one aspect, the present invention provides a polyurethane elastomer composition comprising a polyol component A and an isocyanate component B,

[0006] The polyol component A comprises:

[0007] at least one first polyether polyol having an unsaturation of less than 0.05 mol / kg, a weight average molecular weight Mw of 6000 to 18000 g / mol, and an average functionality of 2 to 6;

[0008] Polytetrahydrofuran diol having a weight average molecular weight Mw of at least 1000 g / mol, preferably 1000 to 2000 g / mol;

[0009] Chain extenders;

[0010] catalyst;

[0011] Blowing agents; and

[0012] Optional additives,

[0013] The isocyanate component B comprises at least one NCO-terminated polyurethane prepolymer, and the NCO-terminated polyurethane prepolymer comprises the reaction product of the following components:

[0014] a) at least one polyisocyanate,

[0015] b) at least one second polyether polyol having an unsaturation of less than 0.05 mol / kg, a weight average molecular weight Mw of 6000 to 18000 g / mol, and an average functionality of 2 to 3.

[0016] Polyol component A:

[0017] In the polyurethane elastomer composition of the present invention, the polyol component A comprises at least one first polyether polyol. The first polyether polyol may be a polyether polyol commonly used in the art, such as polyoxypropylene polyol, polyoxyethylene polyoxypropylene polyol, polyethylene glycol, or any combination thereof. The polyether polyol has a high weight average molecular weight Mw of 6000 to 18000 g / mol, preferably 8000 to 12000 g / mol. The average functionality of the polyether polyol is 2 to 6, preferably about 3. The polyether polyol has a low unsaturation of less than 0.05 mol / kg, preferably less than 0.03 mol / kg, more preferably less than or equal to 0.01 mol / kg, and the unsaturation is measured according to GB / T 12008.6-2010.

[0018] The first polyether polyol may have a hydroxyl value of 5 to 50 mg KOH / g.

[0019] Commercially available examples of suitable polyether polyols include Preminol S 4008F, Preminol S 4318F, Preminol S 4013F, Preminol 7001K, Prminol S 3011, Preminol 7012, Preminol S 3015, Preminol S6075, etc. from AGC Chemicals Americas; Acclaim 8200, Acclaim 6300, Acclaim 6320N, etc. from Covestro; CHE-2060, CHE-2080, CHE-2120, CHE-2180, etc. from Changhua Chemical.

[0020] Polyol component A also comprises polytetrahydrofuran diol.The polar group on the soft segment of polytetrahydrofuran diol tends to form interior hydrogen bond, improves crystallinity, thereby improved the rigidity of pad, but too high molecular weight can cause the rising of rigidity and make low temperature resistance deteriorate.Therefore, described polytetrahydrofuran diol has at least 1000 g / mol, preferably the weight average molecular weight Mw of 1000 to 2000 g / mol.Such polytetrahydrofuran diol can be purchased from BASF company with PolyTHF 1000, PolyTHF 1400, PolyTHF 1800, PolyTHF 2000 etc.

[0021] The inventor has found that the combination of using polytetrahydrofuran diol and low-unsaturation, high molecular weight polyol polyol in the polyol component A system provides a good balance of mechanical property and low temperature resistance.Low-unsaturation, high molecular weight polyether polyols have good low temperature resistance, but mechanical property is not good enough, can improve mechanical property by adding an amount of polytetrahydrofuran diol, keep good low temperature resistance simultaneously.Simultaneously, preferably the ratio of polytetrahydrofuran diol (PTHF) should be controlled at a certain level, because too high PTHF content can make the polyurethane pad have too high rigidity at low temperatures and damage its low temperature resistance due to soft phase crystallization.

[0022] Especially, in the polyol component system of the present invention, using low-unsaturation, high-molecular-weight polyol polyols as main polyols can achieve better balance in low-temperature resistance and mechanical properties. Therefore, in a preferred embodiment, based on the gross weight of polyol component A, the content of the polyether polyol is 45-80 wt %, more preferably 60-70 wt %, and the content of the polytetrahydrofuran diol is 20-45 wt %, more preferably 20-35 wt %.

[0023] In addition to the first polyether polyol and polytetrahydrofuran diol, the polyol component A also contains a blowing agent commonly used in the art. Examples of suitable blowing agents include at least one of dichlorofluoroethane, cyclopentane, pentafluoropropane, methylene chloride, and water. More preferably, the blowing agent is water.

[0024] The polyol component A also contains a chain extender commonly used in the art. Examples of suitable chain extenders include ethylene glycol (EG), propylene glycol (PG), 1,4-butanediol (1,4-BDO), 1,6-hexanediol (1,6-HDO), diethylene glycol (DEG), 1,3-butanediol (1,3-BDO), dipropylene glycol (DPG), tripropylene glycol (TPG), hydroquinone dihydroxyethyl ether (HQEE), resorcinol dihydroxyethyl ether (HER), and the like.

[0025] The polyol component A may also contain a catalyst to promote the reaction between component A and component B. Commonly used catalysts include strongly basic amines, tertiary amines and alkanolamine compounds. Exemplary strongly basic amines are 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine. Exemplary tertiary amines are triethylamine, tributylamine, dimethylbenzylamine, N-methylmorpholine, N-ethylmorpholine, N-cyclohexylmorpholine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylbutylenediamine, N,N,N',N'-tetramethylhexanediamine, pentamethyldiethylenetriamine, tetramethyldiaminoethyl ether, bis(dimethylaminopropyl)urea, dimethylpiperazine, 1,2-dimethylimidazole, 1-azabicyclo[3.3.0]octane, and 1,4-diazabicyclo[2.2.2]octane. Exemplary alkanolamine compounds are triethanolamine, triisopropanolamine, N-methyldiethanolamine, N-ethyldiethanolamine and dimethylethanolamine. The above-mentioned catalysts of different types can be used alone or in combination.

[0026] The polyol component A may also optionally contain additives commonly used in the art, and the additives are usually selected from foam stabilizers, flame retardants, antioxidants, light stabilizers, foam softeners, cell openers, pigments, antistatic agents, hydrolysis stabilizers, etc. In a preferred embodiment, the polyol component A also contains a foam stabilizer to increase the mutual solubility of each component, play the role of emulsifying foam materials, stabilizing foam and regulating cells. Examples of commonly used foam stabilizers include polysiloxane-oxyolefin block copolymers, etc.

[0027] Isocyanate component B:

[0028] The isocyanate component B of the present invention comprises at least one NCO-terminated polyurethane prepolymer. The polyurethane prepolymer is the reaction product of at least one polyisocyanate a) and at least one second polyether polyol b). The polyurethane prepolymer obtained by reacting the polyisocyanate with the second polyether polyol at an NCO / OH ratio greater than 1 contains free isocyanate groups and is terminated by isocyanate groups. The NCO content of the NCO-terminated polyurethane prepolymer in the present invention is generally 5%-25%.

[0029] At least one second polyether polyol used in the preparation of the polyurethane prepolymer can be selected from polyoxypropylene polyol, polyoxyethylene polyoxypropylene polyol, polyethylene glycol, and any combination thereof. The polyether polyol has a weight average molecular weight Mw of 6000 to 18000 g / mol, preferably 12000 to 16000 g / mol, and an unsaturation of less than 0.05 mol / kg, preferably less than 0.03 mol / kg, more preferably less than or equal to 0.01 mol / kg, and the unsaturation is measured according to GB / T 12008.6-2010. In addition, the average functionality of the polyether polyol is 2-3, preferably about 2. The second polyether polyol used may be the same as or different from the first polyether polyol.

[0030] The polyisocyanate used to prepare the NCO-terminated polyurethane prepolymer can be any polyisocyanate commonly used in the field of polyurethane microcellular elastomers. In one embodiment, the polyisocyanate is a diisocyanate selected from aliphatic diisocyanates, alicyclic diisocyanates or aromatic diisocyanates. In one embodiment, the aromatic diisocyanate is selected from 2,2'-methylene diphenyl diisocyanate (2,2'-MDI), 4,4'-methylene diphenyl diisocyanate (4,4'-MDI), 2,4'-methylene diphenyl diisocyanate (2, 4'-MDI), 2,4-toluene diisocyanate (TDI), 2,6-toluene diisocyanate, 1,3-phenylene diisocyanate (PDI), 1,4-phenylene diisocyanate, 1,4-naphthylene diisocyanate (NDI), 1,5-naphthylene diisocyanate, and combinations thereof. In one embodiment, the aliphatic diisocyanate may be selected from hexamethylene diisocyanate, trimethyl-1,6-hexamethylene diisocyanate. In one embodiment, the alicyclic diisocyanate may be selected from isophorone diisocyanate (IPDI), dicyclohexylmethane-4,4'-diisocyanate, 1,4-cyclohexane diisocyanate, methylcyclohexyl diisocyanate.

[0031] Preferably, the polyisocyanate is selected from 2,2'-methylene diphenyl diisocyanate (2,2'-MDI), 4,4'-methylene diphenyl diisocyanate (4,4'-MDI), 2,4'-methylene diphenyl diisocyanate (2,4'-MDI), 1,4-naphthylene diisocyanate, more preferably 4,4'-methylene diphenyl diisocyanate (4,4'-MDI).

[0032] A small amount of polymerization inhibitor can also be added in the preparation of NCO-terminated polyurethane prepolymer to improve storage stability and reduce viscosity increase and gelation. Commonly used polymerization inhibitors in the art include phosphoric acid, benzoyl chloride, phenylacetyl chloride, p-toluenesulfonic acid, diethylene glycol bischloroformate, etc.

[0033] Based on the total weight of the isocyanate component B, the amount of the polyisocyanate a) is 10-60 wt%, preferably 20-55 wt%; the amount of the polyether polyol is 10-80 wt%, preferably 30-75 wt%; and the amount of the inhibitor can be 0.01-0.03 wt%.

[0034] In a preferred embodiment, the polyurethane elastomer composition of the present invention comprises a polyol component A and an isocyanate component B.

[0035] The polyol component A comprises:

[0036] 50-80 wt %, preferably 60-70 wt % of at least one first polyether polyol;

[0037] 20-45 wt %, preferably 20-35 wt % of polytetrahydrofuran diol;

[0038] 2-8 wt% chain extender;

[0039] 0.2-1.0 wt% catalyst;

[0040] 0.1-0.2 wt % of a blowing agent;

[0041] 0 to 2% by weight of additives,

[0042] The isocyanate component B comprises at least one NCO-terminated polyurethane prepolymer, which consists essentially of the reaction product of:

[0043] 10-60 wt. % of a) at least one polyisocyanate, preferably MDI; and

[0044] 10 to 80 wt % of b) at least one second polyether polyol.

[0045] The polyol component A of the polyurethane elastomer composition of the present invention can be prepared by mixing the components it contains. There is no limitation on the mixing order, mixing method and mixing equipment of the components, and any commonly used mixing method and equipment known in the art can be used for mixing. The polyisocyanate component B of the polyurethane elastomer composition of the present invention can be prepared by a method including the steps of mixing a second polyether polyol with a polyisocyanate component and reacting at a certain temperature to obtain an NCO-terminated polyurethane prepolymer.

[0046] Therefore, on the other hand, the present invention also provides a method for preparing a polyurethane elastomer article, which comprises:

[0047] (1) preparing a polyol component A: uniformly mixing at least one first polyether polyol, polytetramethylene glycol, a chain extender, a catalyst, a blowing agent and any additives;

[0048] (2) preparing a polyisocyanate component B: mixing at least one second polyether polyol with a polyisocyanate and reacting them at 70-85° C. to obtain an NCO-terminated polyurethane prepolymer;

[0049] (3) The polyol component A and the polyisocyanate component B are mixed and reacted in a weight ratio of 100:30 to 100:200, poured into a mold preheated to a temperature of about 70° C., and demolded after about 10 minutes to obtain a polyurethane elastomer product.

[0050] The polyurethane elastomer composition of the present invention can be used to produce automobile parts and rail transit shock-absorbing materials. The polyurethane elastomer products obtained therefrom have excellent low-temperature resistance and a very low static stiffness change rate at a temperature as low as -50°C. At the same time, they have good mechanical properties and fatigue resistance, and are particularly suitable for use as shock-absorbing pads for high-speed railways in cold regions. DETAILED DESCRIPTION

[0051] The following examples are used to further illustrate and understand the present invention, but are not intended to limit the scope of the present invention in any way.

[0052] Example:

[0053] The following materials were used in the examples:

[0054] Preminol S 4013: Mw about 12000 g / mol, Fn about 2, unsaturation 0.01 mmol / g, 25 o Polypropylene polyol with a viscosity of about 7000 mPa.s at 37°C from AGC Chemicals Americas Inc.

[0055] Preminol 7012: Mw about 10000 g / mol, Fn about 3, unsaturation 0.03 mmol / g, 25 o Polyoxyethylene polyoxypropylene polyol with a viscosity of about 3000 mPa.s at C, from AGC Chemicals Americas Inc.

[0056] PolyTHF® 2000: Mw about 2000 g / mol, Fn 2, 25 o Polytetrahydrofuran diol with a viscosity of about 2000 mPa.s at 37°C, from BASF

[0057] Lupranol® 2095: Mw about 4500 g / mol, Fn about 2.5, unsaturation 0.09 mmol / g, 25 oPolyoxyethylene polyoxypropylene polyol with a viscosity of about 850 mPa.s at C, from BASF

[0058] DABCO 33LV: Amine polyurethane gel catalyst from Evonik, Germany

[0059] DABCO BL11: Amine polyurethane foaming catalyst from Evonik, Germany

[0060] Niax L-1500: Foam Stabilizer from Momentive

[0061] 4,4'-MDI: purchased from BASF

[0062] Table 1: Formulation composition of polyurethane elastomer composition

[0063]

[0064] Embodiment 1:

[0065] (1) Preparation of component A:

[0066] 60.5 parts of Preminol 7012, 30 parts of PolyTHF® 2000, 6.0 parts of 1,4-butanediol, 0.15 parts of water, 0.2 parts of DABCO 33LV, 0.15 parts of DABCO BL11, 1.0 parts of Niax L-1500 and 2.0 parts of color paste were uniformly mixed and sealed to obtain a polyol composition.

[0067] (2) Preparation of component B:

[0068] Heat 24.99 parts of 4,4'-MDI to 60°C, add 0.01 parts of benzoyl chloride, and then slowly add 75 parts of Preminol S4013F. Slowly raise the temperature to 75°C and maintain for 2 hours. The NCO content is measured to be the target value of 8.3%. The prepolymer synthesis is completed and sealed for storage.

[0069] (3) Preparation of polyurethane elastomer:

[0070] Component A was preheated to 40° C., and component B was preheated to 45° C. The preheated components A and B were mixed in a weight ratio of A:B=100:105, and then injected into a mold at 70° C. The sample was demoulded 10 minutes after the mold was closed, and then left at room temperature for 7 days to obtain a polyurethane elastomer product.

[0071] Embodiment 2:

[0072] According to the composition in Table 1 above, component A and component B were prepared in the same manner as in Example 1.

[0073] Then component A was preheated to 40° C., and component B was preheated to 45° C. The preheated components A and B were mixed in a weight ratio of A:B=100:105, and then injected into a mold at 70° C. The sample was demoulded 10 minutes after the mold was closed, and then left at room temperature for 7 days to obtain a polyurethane elastomer product.

[0074] Embodiment 3:

[0075] According to the composition in Table 1 above, component A and component B were prepared in the same manner as in Example 1.

[0076] Then component A was preheated to 40° C., and component B was preheated to 45° C. The preheated components A and B were mixed in a weight ratio of A:B=100:102, and then injected into a mold at 70° C. The sample was demoulded 10 minutes after the mold was closed, and then left at room temperature for 7 days to obtain a polyurethane elastomer product.

[0077] Comparative Example 1:

[0078] According to the composition in Table 1 above, component A and component B were prepared in the same manner as in Example 1.

[0079] Then component A was preheated to 40° C., and component B was preheated to 45° C. The preheated components A and B were mixed in a weight ratio of A:B=100:116, and then injected into a mold at 70° C. The sample was demoulded 10 minutes after the mold was closed, and then left at room temperature for 7 days to obtain a polyurethane elastomer product.

[0080] Comparative Example 2:

[0081] According to the composition in Table 1 above, component A and component B were prepared in the same manner as in Example 1.

[0082] Then component A was preheated to 40° C., and component B was preheated to 45° C. The preheated components A and B were mixed in a weight ratio of A:B = 100:100, and then injected into a mold at 70° C. The sample was demoulded 10 minutes after the mold was closed, and then left at room temperature for 7 days to obtain a polyurethane elastomer product.

[0083] Comparative Example 3:

[0084] According to the composition in Table 1 above, component A and component B were prepared in the same manner as in Example 1.

[0085] Then component A was preheated to 40° C., and component B was preheated to 45° C. The preheated components A and B were mixed in a weight ratio of A:B=100:116, and then injected into a mold at 70° C. The sample was demoulded 10 minutes after the mold was closed, and then left at room temperature for 7 days to obtain a polyurethane elastomer product.

[0086] The following performance tests were performed on the polyurethane elastomer products obtained in Examples 1 to 3 and Comparative Examples 1 to 3. The test results are shown in Table 2 below:

[0087] The tensile strength and elongation at break are tested according to the standard GB / T 10654-2001.

[0088] Permanent compression set is tested in accordance with GB / T 10653-2001.

[0089] The low temperature static stiffness change rate is tested in accordance with TB / T 3395-2015.

[0090] Table 2: Performance test results

[0091]

[0092] It can be seen from the test results of Table 2 that the polyurethane elastomers of Examples 1 to 3 of the present invention not only meet the requirements of tensile strength greater than 2.0 MPa, elongation at break greater than 200%, permanent compression set less than 5%, and even as low as about 4%, but also have excellent low temperature resistance, that is, compared with the static stiffness at room temperature, the static stiffness change rate at -50°C is less than 20%, especially the static stiffness change rate of the polyurethane elastomers of Examples 1 and 3 at -50°C is as low as about 10%. In contrast, in Comparative Example 1, too much polytetrahydrofuran diol is used, and the obtained polyurethane elastomer has good mechanical properties and fatigue resistance, but poor low temperature resistance; in Comparative Example 2, polytetrahydrofuran diol is not included at all, and the obtained polyurethane elastomer has a very low -50°C static stiffness change rate, but poor mechanical strength and fatigue resistance; the first polyether polyol used in Comparative Example 3 has a higher degree of unsaturation and a lower molecular weight Mw, and the obtained polyurethane elastomer has poor mechanical properties, fatigue resistance and low temperature resistance. Therefore, the polyurethane elastomer of the present invention has excellent mechanical properties, fatigue resistance and low temperature resistance, and is very suitable for use as a high cold-resistant polyurethane shock-absorbing pad for railway construction in cold areas, or in the field of automobile shock absorption in extremely cold areas.

Claims

1. A polyurethane elastomer composition comprising a polyol component A and an isocyanate component B, The polyol component A comprises: at least one first polyether polyol having an unsaturation of less than 0.05 mol / kg, a weight average molecular weight Mw of 8000 to 12000 g / mol, and an average functionality of 2 to 6; Polytetrahydrofuran diol, whose weight average molecular weight Mw is 1000 to 2000 g / mol; Chain extenders; catalyst; Foaming agent; and Optional additives, Wherein, based on the total weight of the polyol component A, the polyol component A comprises 45-80 wt % of the at least one first polyether polyol and 20-45 wt % of polytetrahydrofuran diol, The isocyanate component B comprises at least one NCO-terminated polyurethane prepolymer, and the NCO-terminated polyurethane prepolymer comprises the reaction product of the following components: a) at least one polyisocyanate, b) at least one second polyether polyol having an unsaturation of less than 0.05 mol / kg, a weight average molecular weight Mw of 6000 to 18000 g / mol, and an average functionality of 2 to 3.

2. The polyurethane elastomer composition according to claim 1, wherein the at least one first polyether polyol has an average functionality of 3.

3. The polyurethane elastomer composition according to claim 1, wherein the at least one second polyether polyol has an average functionality of 2.

4. The polyurethane elastomer composition according to any one of claims 1 to 3, wherein the polyol component A comprises 60-70 wt% of the at least one first polyether polyol, based on the total weight of the polyol component A.

5. The polyurethane elastomer composition according to any one of claims 1 to 3, wherein the polyol component A comprises 20-35 wt% of polytetramethylene glycol based on the total weight of the polyol component A.

6. The polyurethane elastomer composition according to any one of claims 1 to 3, wherein the NCO-terminated polyurethane prepolymer comprises 10-60 wt. % of a) at least one polyisocyanate and 10-80 wt. % of b) at least one second polyether polyol, based on the total weight of the isocyanate component B.

7. The polyurethane elastomer composition according to any one of claims 1 to 3, wherein the polyisocyanate is at least one selected from 2,2'-methylene diphenyl diisocyanate, 4,4'-methylene diphenyl diisocyanate, 2,4'-methylene diphenyl diisocyanate, and 1,4-naphthylene diisocyanate.

8. The polyurethane elastomer composition according to any one of claims 1 to 3, wherein the at least one first polyether polyol and the at least one second polyether polyol are each independently selected from polyoxypropylene polyol, polyoxyethylene polyoxypropylene polyol, polyethylene glycol, and any combination thereof.

9. The polyurethane elastomer composition according to any one of claims 1 to 3, wherein the weight ratio of the polyol component A to the polyisocyanate component B is 100:30 to 100:

200.

10. A polyurethane elastomer product, prepared from the polyurethane elastomer composition according to any one of claims 1 to 9.

11. Use of the polyurethane elastomer product according to claim 10 as a shock-absorbing pad for high-speed railways.

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