A high-hardness polyurethane resistant to stress relaxation, and a preparation method and application thereof

Abstract

The present application relates to a kind of high hardness thermoplastic polyurethane elastomer resistant to stress relaxation and its preparation method and application.The hardness of the polyurethane elastomer is greater than or equal to 82D, stress relaxation is less than or equal to 20%, glass transition temperature Tg is greater than 80 DEG C, and notched impact strength at-40 DEG C is greater than 75 J / m.The high hardness thermoplastic polyurethane elastomer obtained by the present application has stress relaxation less than or equal to 20%, and still has excellent notched impact strength under the condition of being frozen at-40 DEG C for up to 24 hours.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of polyurethane, and particularly relates to a stress relaxation resistant high-hardness polyurethane and a preparation method and application thereof. BACKGROUND

[0002] High-hardness polyurethane elastomers have excellent mechanical properties and can be used in fields with high modulus and high strength application requirements, such as engineering structural parts. However, high-hardness polyurethane elastomers usually need high-temperature processing due to strong intermolecular hydrogen bond interaction, which easily causes high-temperature oxidative degradation of the material, and in addition, high-hardness polyurethane elastomers are prone to cracking due to stress concentration during high-temperature injection molding and extrusion processing because of the strong rigidity of the material.

[0003] The injection-molded parts, especially complex parts with thin thickness, are prone to brittle fracture, and the extruded products are also prone to fracture due to the brittleness of the material.

[0004] When applied to automobile parts such as oil collecting cups, long-term cold resistance is required under outdoor conditions in winter, so low-temperature toughness is required; for applications that need to maintain stress for a long time, such as orthodontic appliances, conventional hardness polyurethane materials with 60A-80D are prone to stress relaxation, and the stress is quickly released with the extension of time, so the appliance no longer has the effect of correction. SUMMARY

[0005] The present application aims to provide a stress relaxation resistant high-hardness thermoplastic polyurethane elastomer and a preparation method thereof, which has low-temperature toughness and can meet the application requirements in the fields of high-hardness medical and automobile engineering parts.

[0006] The technical solutions adopted by the present application are as follows:

[0007] In a first aspect, the present application relates to a stress relaxation resistant high-hardness thermoplastic polyurethane elastomer:

[0008] A stress relaxation resistant high-hardness thermoplastic polyurethane elastomer, which has a hardness of ≥82D, a stress relaxation of ≤20%, a glass transition temperature of >80℃, and a notched impact strength of >75J / m at -40℃.

[0009] The stress relaxation resistant high-hardness thermoplastic polyurethane elastomer is prepared from raw materials including polyisocyanate, macromolecular polyol, chain extender, plasticizer, antioxidant, ultraviolet absorber, light stabilizer, and lubricant.

[0010] In some specific embodiments, based on the total weight of the raw materials, the proportions of the components are as follows:

[0011]

[0012] In the present application, the polyisocyanate is one or more of aromatic polyisocyanate, aliphatic polyisocyanate, alicyclic polyisocyanate; the preferred polyisocyanate is one or more of 4,4'-diphenylmethane diisocyanate, 2,4-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,5-naphthalene diisocyanate, 1,4-phenylene diisocyanate, m-xylylene diisocyanate, diphenylmethane-3,3'-dimethoxy-4,4'-diisocyanate, 1,6-hexamethylene diisocyanate, 1,10-decane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, 2,4-hexahydrotoluene diisocyanate, 2,6-hexahydrotoluene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 2,2'-dicyclohexylmethane diisocyanate, 2,4-dicyclohexylmethane diisocyanate, isophorone diisocyanate, lysine diisocyanate, L-lysine diisocyanate, 1,4-butane diisocyanate, 1,5-pentane diisocyanate, more preferably 4,4'-diphenylmethane diisocyanate.

[0013] In the present application, the molecular weight of the macromolecular polyol is 600-2000 g / mol, and the macromolecular polyol is one or more of polysiloxane polyol, polyether polyol, polyester polyol, polycarbonate polyol.

[0014] In the present application, the chain extender is aliphatic diol and / or alicyclic diol with a molecular weight of 60-200 g / mol, the aliphatic diol is one or more of ethylene glycol, 1,3-propanediol, 1,2-propanediol, diethylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, preferably 1,4-butanediol, 1,6-hexanediol; the alicyclic diol is 1,4-cyclohexanediol and / or 1,4-cyclohexanedimethanol, preferably 1,4-cyclohexanedimethanol.

[0015] In the present application, the plasticizer includes at least one of di-n-octyl adipate, diisooctyl adipate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, etc.

[0016] In the present application, the antioxidant is one or more of hindered phenol, aromatic secondary amine, sulfur ester, phosphite antioxidant.

[0017] In the present application, the ultraviolet absorber is benzotriazole and / or benzophenone ultraviolet absorber.

[0018] In the present application, the light stabilizer is hindered amine light stabilizer.

[0019] In the present application, the lubricant is one or more of ethylene bis-stearamide, oleic acid amide, ethylene bis-oleic acid amide, erucic acid amide, stearic acid amide, E wax.

[0020] In a second aspect, the present application relates to a method for preparing the high hardness thermoplastic polyurethane elastomer resistant to stress relaxation as described above.

[0021] In some specific embodiments, the method for preparing the high hardness thermoplastic polyurethane elastomer is as follows: a polyisocyanate, a macromolecular polyol, a chain extender, a plasticizer, an antioxidant, an ultraviolet absorber, a light stabilizer, and an optional catalyst are added into a reactor, and are fully mixed and reacted to prepare; the catalyst can be a conventional catalyst and an amount used in the art.

[0022] In a third aspect, the present application relates to the use of the high hardness thermoplastic polyurethane elastomer resistant to stress relaxation as described above.

[0023] The polyurethane elastomer can be used in the medical field, such as a retention needle cannula, an injection molded needle, a medical three-way valve, an intravenous infusion consumable, a dental orthodontic appliance, etc.; the engineering injection molded part field, such as an oil collecting cup, an electronic cigarette tube, etc.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] The present application adjusts the amount of raw materials of the polyurethane elastomer, and introduces a special plasticizer, thereby reducing the interaction between molecular chains, improving the processability of the material, and improving the toughness of the material. A high hardness material resistant to cold and stress relaxation is prepared, which still has good toughness under extremely cold conditions at-40℃; the stress relaxation is less than 20% at 23℃ / 50% relative humidity for 24 hours. DETAILED DESCRIPTION

[0026] The present application will be further described in detail below in combination with specific examples, but the scope of the present application is not limited to these examples. Various substitutions or changes made according to ordinary technical knowledge and conventional means in the art without departing from the above method idea of the present application should be included in the scope of the present application.

[0027] Source of raw materials:

[0028] 4,4'-diphenylmethane diisocyanate, polybutylene adipate glycol WHP-104, number average molecular weight 1000 g / mol, Wanhua Chemical Group Co., Ltd., industrial grade.

[0029] Double-OH terminated polydimethylsiloxane diol, number average molecular weight 1000 g / mol, Shin-Etsu Chemical Co., Ltd.

[0030] Polytetrahydrofuran diol 1000, number average molecular weight 1000 g / mol, BASF, technical grade.

[0031] Polycaprolactone diol PCL 210N, number average molecular weight 1000 g / mol, DOWSIL, technical grade.

[0032] Polycarbonate diol UH-CARB 100, number average molecular weight 1000 g / mol, UBE, technical grade.

[0033] Antioxidant CHINOX 1010, antioxidant CHINOX 1076, ultraviolet absorber CHISORB 326, ultraviolet absorber CHISORB 327, ultraviolet absorber CHISORB 328, light stabilizer CHISORB 770, CHINA TAIWAN DOUBLE BOND, technical grade.

[0034] Antioxidant Irgafos 168, antioxidant Irgafos 126, BASF, technical grade.

[0035] Di-n-octyl adipate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, ITOMAN, technical grade.

[0036] Preparation of high hardness polyurethane

[0037] Example 1

[0038] Put 20 g of double-OH terminated polydimethylsiloxane diol with a number average molecular weight of 1000 g / mol, 721 g of 4,4'-diphenylmethane diisocyanate, 259 g of 1,4-butanediol, 2 g of antioxidant CHINOX 1010, 2 g of antioxidant Irgafos 168, 1 g of ultraviolet absorber CHISORB 326, 1 g of light stabilizer CHISORB 770, 2 g of ethylene bis-stearamide, 5 g of di-n-octyl adipate into a reactor, high speed stirring with stirrer 800 rpm for 2 min, after reaction, pour into polytetrafluoroethylene mold quickly, put into oven for 12 h, prepare thermoplastic polyurethane elastomer. Test hardness, stress relaxation, tensile strength, bending strength, notched impact strength, glass transition temperature.

[0039] Example 2

[0040] A reactor was charged with 50 g of a polybutadiene diol having a number average molecular weight of 1000 g / mol, 650 g of 4,4'-diphenylmethane diisocyanate, 300 g of 1,6- hexanediol, 2 g of antioxidant CHINOX 1010, 2 g of antioxidant Irgafos 126, 1 g of antioxidant CHINOX 1076, 2 g of ethylene bis-oleic acid amide, 5 g of di-n-octyl adipate, and stirred at 800 rpm for 2 min. After the reaction, the mixture was quickly poured into a polytetrafluoroethylene mold and placed in an oven for 12 h to cure. A thermoplastic polyurethane elastomer was produced. The hardness, stress relaxation, tensile strength, bending strength, notched impact strength, and glass transition temperature were tested.

[0041] Example 3

[0042] A reactor was charged with 50 g of a polybutadiene diol having a number average molecular weight of 1000 g / mol, 650 g of 4,4'-diphenylmethane diisocyanate, 300 g of 1,6- hexanediol, 2 g of antioxidant CHINOX 1010, 2 g of antioxidant Irgafos 126, 1 g of antioxidant CHINOX 1076, 2 g of ethylene bis-oleic acid amide, 5 g of di-n-octyl adipate, and stirred at 800 rpm for 2 min. After the reaction, the mixture was quickly poured into a polytetrafluoroethylene mold and placed in an oven for 12 h to cure. A thermoplastic polyurethane elastomer was produced. The hardness, stress relaxation, tensile strength, bending strength, notched impact strength, and glass transition temperature were tested.

[0043] Example 4

[0044] A reactor was charged with 50 g of a polybutadiene diol having a number average molecular weight of 1000 g / mol, 650 g of 4,4'-diphenylmethane diisocyanate, 300 g of 1,6- hexanediol, 2 g of antioxidant CHINOX 1010, 2 g of antioxidant Irgafos 126, 1 g of antioxidant CHINOX 1076, 2 g of ethylene bis-oleic acid amide, 5 g of di-n-octyl adipate, and stirred at 800 rpm for 2 min. After the reaction, the mixture was quickly poured into a polytetrafluoroethylene mold and placed in an oven for 12 h to cure. A thermoplastic polyurethane elastomer was produced. The hardness, stress relaxation, tensile strength, bending strength, notched impact strength, and glass transition temperature were tested.

[0045] Example 5

[0046] A reactor was charged with 60 g of polytetramethylene ether glycol having a number average molecular weight of 1000 g / mol, 668 g of 4,4'-diphenylmethane diisocyanate, 272 g of 1,5-pentanediol, 2 g of antioxidant CHINOX 1010, 1 g of antioxidant CHINOX 1076, 2 g of antioxidant Irgafos 168, 1 g of ultraviolet light absorber CHISORB 327, 3 g of light stabilizer CHISORB 770, 4 g of ethylene bisoleic acid amide, 5 g of 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, and the mixture was stirred at 800 rpm for 2 min. The reaction mixture was quickly poured into a polytetrafluoroethylene mold and cured in an oven for 12 h to produce a thermoplastic polyurethane elastomer. The hardness, stress relaxation, tensile strength, bending strength, notched impact strength, and glass transition temperature were measured.

[0047] Example 6

[0048] A reactor was charged with 100 g of bis-OH terminated polydimethylsiloxane diol having a number average molecular weight of 1000 g / mol, 620 g of 4,4'-diphenylmethane diisocyanate, 280 g of 1,6-hexanediol, 2 g of antioxidant CHINOX 1010, 1 g of antioxidant CHINOX 1076, 2 g of antioxidant Irgafos 126, 2 g of ultraviolet light absorber CHISORB 328, 2 g of light stabilizer CHISORB 770, 3 g of ethylene bisstearamide, and 4 g of di-n-octyl adipate, and the mixture was stirred at 800 rpm for 2 min. The reaction mixture was quickly poured into a polytetrafluoroethylene mold and cured in an oven for 12 h to produce a thermoplastic polyurethane elastomer. The hardness, stress relaxation, tensile strength, bending strength, notched impact strength, and glass transition temperature were measured.

[0049] Comparative Example 1

[0050] A reactor was charged with 20 g of bis-OH terminated polydimethylsiloxane diol having a number average molecular weight of 1000 g / mol, 721 g of 4,4'-diphenylmethane diisocyanate, 259 g of 1,4-butanediol, 2 g of antioxidant CHINOX 1010, 2 g of antioxidant Irgafos 168, 1 g of ultraviolet light absorber CHISORB 326, 1 g of light stabilizer CHISORB 770, and 2 g of ethylene bisstearamide, and the mixture was stirred at 800 rpm for 2 min. The reaction mixture was quickly poured into a polytetrafluoroethylene mold and cured in an oven for 12 h to produce a thermoplastic polyurethane elastomer. The hardness, stress relaxation, tensile strength, bending strength, notched impact strength, and glass transition temperature were measured.

[0051] Comparative Example 2

[0052] A reactor was charged with 50 g of polycarbonate diol having a number average molecular weight of 1000 g / mol, 607 g of 4,4'-diphenylmethane diisocyanate, 343 g of 1,4-cyclohexanedimethanol, 2 g of antioxidant CHINOX 1010, 1 g of antioxidant CHINOX 1076, 1 g of antioxidant Irgafos 168, 2 g of ultraviolet absorber CHISORB 327, 2 g of light stabilizer CHISORB 770, 2 g of oleic acid amide, and stirred at 800 rpm for 2 min. After the reaction, it was quickly poured into a polytetrafluoroethylene mold, placed in an oven for 12 h to cure, and a thermoplastic polyurethane elastomer was prepared. Hardness, stress relaxation, tensile strength, bending strength, notched impact strength, and glass transition temperature were measured.

[0053] Comparative Example 3

[0054] A reactor was charged with 200 g of polytetramethylene glycol having a number average molecular weight of 1000 g / mol, 600 g of 4,4'-diphenylmethane diisocyanate, 200 g of 1,4-butanediol, 2 g of antioxidant CHINOX 1010, 1 g of antioxidant CHINOX 1076, 1 g of antioxidant Irgafos 168, 2 g of ultraviolet absorber CHISORB 327, 2 g of light stabilizer CHISORB 770, 2 g of oleic acid amide, 5 g of 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, and stirred at 800 rpm for 2 min. After the reaction, it was quickly poured into a polytetrafluoroethylene mold, placed in an oven for 12 h to cure, and a thermoplastic polyurethane elastomer was prepared. Hardness, stress relaxation, tensile strength, bending strength, notched impact strength, and glass transition temperature were measured.

[0055] Comparative Example 4

[0056] A reactor was charged with 50 g of polycaprolactone diol having a number average molecular weight of 1000 g / mol, 625 g of 4,4'-diphenylmethane diisocyanate, 130 g of 1,6-hexanediol, 195 g of 1,4-cyclohexanedimethanol, 2 g of antioxidant CHINOX 1010, 1 g of antioxidant CHINOX 1076, 1 g of antioxidant Irgafos 126, 1 g of ultraviolet absorber CHISORB 328, 2 g of light stabilizer CHISORB 770, 4 g of erucic acid amide, 5 g of dioctyl phthalate, and stirred at 800 rpm for 2 min. After the reaction, it was quickly poured into a polytetrafluoroethylene mold, placed in an oven for 12 h to cure, and a thermoplastic polyurethane elastomer was prepared. Hardness, stress relaxation, tensile strength, bending strength, notched impact strength, and glass transition temperature were measured.

[0057] The thermoplastic polyurethane elastomers prepared in the above examples and comparative examples were subjected to performance evaluation, and the test methods of various performances were as follows:

[0058] Equipment information and test standards:

[0059] Hardness test equipment, hardness tester, Zwick Roell, test standard ASTM D2240.

[0060] Stress relaxation test equipment, Shimadzu tensile testing machine, test method: ASTM D412 dumbbell-shaped tensile sample was clamped on the extensometer, the tension was zeroed, stretched to 70N at a rate of 1mm / min, the strain was maintained, the tension value F was tested after 24h, and the stress relaxation was (70-F) / 70, the test condition was 23℃, 50% relative humidity.

[0061] Tensile strength test equipment, Shimadzu tensile testing machine, test standard ASTM D638.

[0062] Bending strength test equipment, Shimadzu tensile testing machine, test standard ASTM D790.

[0063] Notched impact strength test equipment, Instron CEAST impact testing machine, test standard ASTM D256.

[0064] Glass transition temperature test equipment, Mettler Toledo differential scanning calorimeter, test method DSC.

[0065] Cold resistance test: ASTM D256 impact sample was cut to a 2.5mm deep notch, frozen in a-40℃ refrigerator for 24h, a 5.5J cantilever beam hammer was used to test the-40℃ hammer impact strength.

[0066] The example and comparative example data of high hardness polyurethane elastomer are shown in Table 1.

[0067] Table 1 Performance of high hardness polyurethane elastomer

[0068]

[0069]

[0070] According to the aspects of the properties in Table 1, the hardness of the thermoplastic polyurethane elastomer is above 83D, the glass transition temperature is higher than 80℃, the notched impact strength at -40℃ is higher than 75 J / mm, and the stress relaxation is lower than 20%. Although the hardness, the glass transition temperature of Comparative Example 1 and Comparative Example 2 are similar to those of Example 1 and Example 2, the materials exhibit the defect of easy brittle fracture, the mechanical properties decrease, the notched impact strength at -40℃ is only 30 J / m and 26 J / m, and the tensile strength is only 70 MPa and 67 MPa. Although the notched impact strength at -40℃ of Comparative Example 3 reaches 60 J / m, the stress relaxation is obvious, reaching 36%. The notched impact strength at -40℃ of the high hardness thermoplastic polyurethane elastomer of Comparative Example 4 is low, and the material is easy to be brittle.

Claims

1. A stress relaxation resistant high hardness thermoplastic polyurethane elastomer, the proportions of each component based on the total weight of raw materials are as follows: The plasticizer comprises at least one of di-n-octyl adipate, diisooctyl adipate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate; 2.The thermoplastic polyurethane elastomer of claim 1, the proportions of each component based on the total weight of raw materials are as follows:

3. The thermoplastic polyurethane elastomer of claim 1, wherein: The aliphatic diol is one or more of ethylene glycol, 1,3-propanediol, 1,2-propanediol, diethylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol;The alicyclic diol is 1,4-cyclohexanediol and / or 1,4-cyclohexanedimethanol.

4. The thermoplastic polyurethane elastomer according to claim 3, wherein: The aliphatic diol is one or more of 1,4-butanediol, 1,6-hexanediol;The alicyclic diol is 1,4-cyclohexanedimethanol.

5. The thermoplastic polyurethane elastomer according to claim 1 or 2, wherein: The polyisocyanate is one or more of aromatic polyisocyanate, aliphatic polyisocyanate, alicyclic polyisocyanate.

6. The thermoplastic polyurethane elastomer according to claim 5, wherein: The polyisocyanate is one or more of 4,4'-diphenylmethane diisocyanate, 2,4-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,5-naphthalene diisocyanate, 1,4-phenylene diisocyanate, m-xylylene diisocyanate, diphenylmethane-3,3'-dimethoxy-4,4'-diisocyanate, 1,6-hexamethylene diisocyanate, 1,10-decane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, 2,4-hexahydro-toluene diisocyanate, 2,6-hexahydro-toluene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 2,2'-dicyclohexylmethane diisocyanate, 2,4-dicyclohexylmethane diisocyanate, isophorone diisocyanate, lysine diisocyanate, L-lysine diisocyanate, 1,4-butane diisocyanate, 1,5-pentane diisocyanate.

7. The thermoplastic polyurethane elastomer of claim 1, wherein: The macromolecular polyol is selected from one or more of polysiloxane polyol, polyether polyol, polyester polyol, polycarbonate polyol.

8. The thermoplastic polyurethane elastomer according to claim 1 or 2, wherein: The antioxidant is one or more of hindered phenol, aromatic secondary amine, sulfur ester, phosphite antioxidant;And / or: The ultraviolet absorber is one or more of benzotriazole and / or benzophenone ultraviolet absorber;And / or: The light stabilizer is one or more of hindered amine light stabilizer;And / or: The lubricant is one or more of ethylene bis-stearamide, oleic acid amide, ethylene bis-oleic acid amide, erucic acid amide, stearic acid amide, E wax. 9.A method for preparing the thermoplastic polyurethane elastomer of any one of claims 1-8, comprising: The raw materials, optionally catalyst, are added to the reactor and mixed well.

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