Low-temperature-resistant high-strength polyurethane elastomer and preparation method thereof

Abstract

The invention discloses a low-temperature-resistant high-strength polyurethane elastomer and a preparation method thereof.The polyurethane elastomer is composed of a prepolymer component A and a curing agent component B. The prepolymer component A is prepared from, by weight, 26.7-72.5 parts of polyol 1, 9.1-53.4 parts of polyol 2 and 18.4-23.8 parts of toluene diisocynate; and the curing agent B component comprises the following components in parts by weight: 50-70 parts of copolyether, 30-50 parts of a chain extender and 0.1-0.2 part of a defoaming agent. The tensile strength of the polyurethane elastomer is greater than 35 MPa, the elongation is greater than 450%, the tear strength is greater than 70 kN / m, and the glass transition temperature is less than-60 DEG C.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a low-temperature-resistant high-strength polyurethane elastomer and a preparation method thereof. Background Art

[0002] Polyurethane elastomer is a block copolymer composed of diisocyanate, small molecule chain extender, etc. as hard segment structure and flexible high molecular weight polyol as soft segment. The hard segment has a high glass transition temperature and melting temperature, which provides high hardness and strength of PU; while the soft segment has a low glass transition temperature, which gives PU flexibility and elasticity.

[0003] The hydroxy-terminated polybutadiene polyurethane elastomer has a low glass transition temperature, but since the hydrogen bonds usually present in polyether and polyester PU are not generated between the hard and soft segments, the intermolecular force is small, the compatibility of the soft and hard segments is poor, and the elastomer strength is very low. There are few reports on high-strength polyurethane materials with low glass transition temperatures in the prior art.

[0004] CN 103483528 A discloses a polyetherester polyurethane elastomer and a preparation method thereof, which has excellent tensile strength, hardness, elongation and tear strength, but because the system contains polyester, the material has poor low temperature resistance. The low temperature resistant polyurethane elastomer prepared by CN105482055A is polyester type, and the glass transition temperature is ≥-50°C. The low temperature resistant polyurethane for sealing prepared by CN110396162A using polytetrahydrofuran ether polyol and polycaprolactone polyol as soft segments has high tensile strength, but the use temperature range is above -45°C.

[0005] CN 107602817 A discloses a cold-resistant polyurethane. The composite material is prepared by compounding caprolactone-modified polyether polyol, polyether polyol, terminal hydroxyl polybutadiene and terminal primary hydroxyl siloxane. Although the low-temperature resistance of the material can be improved, the mechanical properties of the material are greatly reduced.

[0006] Fang Zhou et al. (Fang Zhou, Han Hongqing, Yin Xianze, Jia Lincai. Preparation and performance study of new PTMG-PO copolyether polyurethane elastomer. Polyurethane Industry [J]. 2009: 24: 21-23.) used PTMG-PO copolyether as the soft segment to prepare a polyurethane elastomer with a glass transition temperature of <-70°C, but the mechanical properties of the material were <20MPa.

[0007] However, in the special working conditions of actual applications, polyurethane elastomer materials are required to have high strength and not lose their elasticity and toughness in low temperature environments. Summary of the invention

[0008] In order to solve the above technical problems existing in the prior art, the present invention provides a low-temperature resistant and high-strength polyurethane elastomer and a preparation method thereof. The polyurethane elastomer has a tensile strength greater than 35 MPa, an elongation greater than 450%, a tear strength greater than 70 kN / m, and a glass transition temperature less than -60°C.

[0009] The first aspect of the present invention provides a low-temperature resistant and high-strength polyurethane elastomer, wherein the polyurethane elastomer is composed of a prepolymer component A and a curing agent component B. The prepolymer A component comprises, by weight: Polyol 1 26.7~72.5 Polyol 2 9.1~53.4 Toluene diisocyanate 18.4~23.8; The curing agent component B includes, by weight: Copolyether 50~70 Chain extender 30~50 Defoaming agent 0.1~0.2.

[0010] The polyol 1 is a polytetramethylene ether polyol having a number average molecular weight of 1000-2000 g / mol, Polyol 2 is a polyoxypropylene ether polyol having a number average molecular weight of 400 to 2000 g / mol.

[0011] The copolyether is one or two of polytetrahydrofuran-ethylene oxide copolyether (PET) with a hydroxyl value of 23.8-63.9 mgKOH / g.

[0012] The chain extender is one or a mixture of two of di-o-chloroaniline methane (MOCA), dimethylthiotoluene diamine (E300), 2,4-diamino-3,5-dimethylthiochlorobenzene (TX-2), and 2,4-diamino-5-mercaptotoluene (TX-1).

[0013] The defoamer is a commercially available general-purpose polyurethane defoamer.

[0014] A second aspect of the present invention provides a method for preparing a low-temperature resistant polyurethane elastomer, comprising the following steps: (1) Preparation of component A: Add toluene diisocyanate, add polyol 1 and polyol 2 under stirring, react for a certain time, test NCO%, and when it reaches the designed value, seal and store the discharged material to obtain prepolymer component A; (2) Preparation of component B: Add copolyether, chain extender and defoamer, and mix evenly to obtain a curing agent component; (3) Preparation of low temperature resistant polyurethane elastomer: Component A and component B are mixed, poured into a mold, and cured to obtain the low-temperature resistant polyurethane elastomer.

[0015] Preferably, polyol 1, polyol 2, and copolyether are dehydrated before use, preferably: polyol 1, polyol 2, or copolyether are dehydrated at 100-110° C. for 2-3 hours, and the moisture content is not more than 300 ppm, and the materials are discharged for use.

[0016] Preferably, in step (1), the reaction temperature is 80-85°C.

[0017] Preferably, in step (2), copolyether and chain extender A are added and stirred at 110-120°C until the chain extender is completely melted, and then the temperature is lowered to 60-80°C, chain extender B and defoamer are added and stirred and mixed to obtain a curing agent component. The chain extender A is di-o-chloroaniline methane (MOCA), and the chain extender B is one or a mixture of 2,4-diamino-3,5-dimethylthiochlorobenzene (TX-2) and 2,4-diamino-5-mercaptotoluene (TX-1); chain extender A and chain extender B can be used simultaneously or separately.

[0018] Preferably, the weight ratio of component A to component B is 100 / 24-42, and the aging temperature is 100-110°C.

[0019] The beneficial effect of the present invention is that when designing the curing agent B component, a copolyether polyol that is liquid at room temperature is added as a soft segment, the copolyether contains more ether bonds, can rotate freely, and has good flexibility of the molecular chain. The prepared material has a lower glass transition temperature, while not reducing the hydrogen bond force in the prepared polyurethane material, and can ensure the balance between the mechanical strength and low-temperature performance of the material, meeting the requirements of application fields with high requirements for the mechanical properties and low-temperature resistance of the material. In addition, the B component is liquid at room temperature and can be used at room temperature or after preheating as needed, and the material has good operability and processability.

[0020] When designing the elastomer structure, using polypropylene oxide ether polyol and polytetramethylene oxide polyol as soft segments in the prepolymer and introducing polytetramethylene oxide copolyether as a soft segment in the curing agent component can reduce the glass transition temperature of the elastomer. The prepared material has excellent mechanical properties and low temperature resistance, and the material has good operability and processability. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with embodiments, but is not limited to the present invention.

[0022] Example 1

[0023] Preparation of component A: ① Preparation of component A: Add 238.1g toluene diisocyanate into a dry three-necked flask, start stirring, add 571.4g dehydrated polytetrahydrofuran ether polyol (molecular weight 2000, trade name PTMG2000) and 190.5g dehydrated polypropylene oxide ether polyol (molecular weight 400, trade name PPG400), react at 80-85℃ for 3h, test NCO%, and discharge the material after NCO% is qualified, seal and store for later use; ② Preparation of component B: Add 667g PET (hydroxyl value 26.2mgKOH / g) into a three-necked flask and dehydrate at 100-110℃ for 2h, then add 333g MOCA and stir at 110-120℃ until MOCA is completely melted, cool to 80℃, add 1g BYK535 defoamer, stir and mix at 80℃ for 30min to obtain curing agent component B; ③ Preparation of polyurethane elastomer: The above-mentioned component A and component B were mixed in a weight ratio of 100 / 41, poured into a mold at 100°C, and aged at 100-110°C for 16 hours to obtain a polyurethane elastomer, whose performance test is shown in Table 1 below.

[0024] Example 2

[0025] ① Preparation of component A: Add 198.5g toluene diisocyanate into a dry three-necked flask, start stirring, add 657.8g dehydrated polytetramethylene ether polyol (molecular weight 2000, trade name PTMG2000) and 143.8g dehydrated polypropylene oxide ether polyol (molecular weight 700, trade name PPG700), react at 80-85℃ for 3h, test NCO%, and discharge the material after NCO% is qualified, seal and store for later use.

[0026] ② Preparation of component B: Add 437.5g PET-1 (hydroxyl value 26.2mgKOH / g) and 125g PET-2 (hydroxyl value 63.9 mgKOH / g) into a three-necked flask, dehydrate at 100-110℃ for 2h, add 218.75g MOCA and stir at 110-120℃ until MOCA is completely melted, cool to 80℃, add 218.75g TX-2 and 1.2g BYK535 defoamer, stir and mix at 80℃ for 30min to obtain curing agent component B.

[0027] ③ Preparation of polyurethane elastomer: The above-mentioned component A and component B were mixed in a weight ratio of 100 / 30, poured into a mold at 100°C, and aged at 100-110°C for 16 hours to obtain an elastomer, and its performance test is shown in Table 1 below.

[0028] Example 3

[0029] ① Preparation of component A: Add 184.3g toluene diisocyanate into a dry three-necked flask, start stirring, add 725g dehydrated polytetramethylene ether polyol (molecular weight 2000, trade name PTMG2000) and 90.6g dehydrated polypropylene oxide ether polyol (molecular weight 1000, trade name PPG1000), react at 80-85℃ for 3h, test NCO%, and discharge the material after NCO% is qualified, seal and store for later use.

[0030] ② Preparation of component B: Add 500g PET (hydroxyl value 23.8mgKOH / g) into a three-necked flask and dehydrate at 100-110℃ for 2h, then cool to 80℃, add 500g E300 and 1.5g BYK535 defoamer, and stir and mix at 80℃ for 30min to obtain curing agent component B.

[0031] ③ Preparation of polyurethane elastomer: The above-mentioned component A and component B were mixed in a weight ratio of 100 / 24, poured into a mold at 100°C, and aged at 100-110°C for 16 hours to obtain an elastomer, and its performance test is shown in Table 1 below.

[0032] Example 4

[0033] ① Preparation of component A: Add 198.8g toluene diisocyanate into a dry three-necked flask, start stirring, add 266.8g dehydrated polytetramethylene ether polyol (molecular weight 1000, trade name PTMG1000) and 534g dehydrated polypropylene oxide ether polyol (molecular weight 2000, trade name PPG2000), react at 80-85℃ for 3h, test NCO%, discharge the material after NCO% is qualified, seal and store for later use.

[0034] ② Preparation of component B: Add 700g PET (hydroxyl value 23.8mgKOH / g) into a three-necked flask and dehydrate at 100-110℃ for 2h, then add 200g MOCA and stir at 110-120℃ until MOCA is completely melted, cool to 80℃, add 100g E300 and 2g BYK535 defoamer, and stir and mix at 80℃ for 30min to obtain curing agent component B.

[0035] ③ Preparation of polyurethane elastomer: The above-mentioned component A and component B were mixed in a weight ratio of 100 / 42, poured into a mold at 100°C, and aged at 100-110°C for 16 hours to obtain an elastomer, and its performance test is shown in Table 1 below.

[0036] Comparative Example 1

[0037] ① Preparation of component A: Add 238.1g toluene diisocyanate into a dry three-necked flask, start stirring, add 190.5g dehydrated polypropylene oxide ether polyol (molecular weight 400, trade name PPG400) and 571.4g dehydrated polytetrahydrofuran ether polyol (molecular weight 2000, trade name PTMG2000), react at 80-85℃ for 3h, test NCO%, discharge the material after NCO% is qualified, seal and store for later use.

[0038] ② Preparation of component B: Add 667g of polyoxypropylene ether polyol (molecular weight 2000, trade name PPG2000) into a three-necked flask and dehydrate at 100-110℃ for 2h, then add 333g of MOCA and stir at 110-120℃ until MOCA is completely melted, cool to 80℃, add 1g of BYK535 defoamer, and stir and mix at 80℃ for 30min to obtain curing agent component B.

[0039] ③ Preparation of polyurethane elastomer: The above-mentioned component A and component B were mixed in a weight ratio of 100 / 37, poured into a mold at 100°C, and aged at 100-110°C for 16 hours to obtain a polyurethane elastomer. Its performance test is shown in Table 1 below.

[0040] Comparative Example 2

[0041] ① Preparation of component A: Add 184.3g toluene diisocyanate into a dry three-necked flask, start stirring, add 90.6g dehydrated polytetramethylene ether polyol (molecular weight 1000, trade name PTMG1000) and 725g polytetramethylene ether polyol (molecular weight 2000, trade name PTMG2000), react at 80-85℃ for 3h, test NCO%, and discharge the material after NCO% is qualified, seal and store for later use.

[0042] ② Preparation of component B: Add 500g PET (hydroxyl value 23.8mgKOH / g) into a three-necked flask and dehydrate at 100-110℃ for 2h, then cool to 80℃, add 500g E300 and 1.5g BYK535 defoamer, and stir and mix at 80℃ for 30min to obtain curing agent component B.

[0043] ③ Preparation of polyurethane elastomer: The above-mentioned component A and component B were mixed in a ratio of 100 / 24, poured into a mold at 100°C, and aged at 100-110°C for 16 hours to obtain an elastomer, and its performance test is shown in Table 1 below.

[0044] Comparative Example 3

[0045] ① Preparation of component A: Add 198.8g toluene diisocyanate into a dry three-necked flask, start stirring, add 266.8g dehydrated polypropylene oxide ether polyol (molecular weight 1000, trade name PPG1000) and 534g dehydrated polypropylene oxide ether polyol (molecular weight 2000, trade name PPG2000), react at 80-85℃ for 3h, test NCO%, discharge the material after NCO% is qualified, seal and store for later use.

[0046] ② Preparation of component B: Add 700g PET (hydroxyl value 23.8mgKOH / g) into a three-necked flask and dehydrate at 100-110℃ for 2h, then add 200g MOCA and stir at 110-120℃ until MOCA is completely melted, cool to 80℃, add 100g E300 and 2g BYK535 defoamer, and stir and mix at 80℃ for 30min to obtain curing agent component B.

[0047] ③ Preparation of polyurethane elastomer: The above-mentioned component A and component B were mixed in a ratio of 100 / 42, poured into a mold at 100°C, and aged at 100-110°C for 16 hours to obtain an elastomer, and its performance test is shown in Table 1 below.

[0048] Comparative Example 4

[0049] ① Preparation of component A: Add 154.6g toluene diisocyanate into a dry three-necked flask, start stirring, add 845g dehydrated PET (hydroxyl value 37.5mgKOH / g), react at 80-85℃ for 3h, test NCO%, and discharge the material after NCO% is qualified, seal and store for later use.

[0050] ② Preparation of component B: Add 700g of polyoxypropylene ether polyol (molecular weight 2000, trade name PPG2000) into a three-necked flask and dehydrate at 100-110℃ for 2h, then add 200g of MOCA and stir at 110-120℃ until MOCA is completely melted, cool to 80℃, add 100g of E300 and 2g of BYK535 defoamer, and stir and mix at 80℃ for 30min to obtain curing agent component B.

[0051] ③ Preparation of polyurethane elastomer: The above-mentioned component A and component B were mixed in a ratio of 100 / 36.8, poured into a mold at 100°C, and aged at 100-110°C for 16 hours to obtain an elastomer, and its performance test is shown in Table 1 below.

[0052] Table 1 Performance test results

[0053] By analyzing the test results of tensile strength and glass transition temperature of the polyurethane elastomers of the embodiments and comparative examples, we found that when designing the elastomer structure, using polypropylene oxide ether polyol and polytetramethylene oxide ether polyol as soft segments in the prepolymer and introducing polytetramethylene oxide copolyether as a soft segment in the curing agent component can reduce the glass transition temperature of the elastomer. The prepared material has excellent mechanical properties and low temperature resistance, and the material has good operability and processability.

Claims

1. A low temperature resistant and high strength polyurethane elastomer, the polyurethane elastomer is composed of a prepolymer component A and a curing agent component B, The prepolymer A component comprises, by weight: Polyol 1 26.7~72.5 Polyol 2 9.1~53.4 Toluene diisocyanate 18.4~23.8; The curing agent component B includes, by weight: Copolyether 50~70 Chain extender 30~50 Defoaming agent 0.1~0.

2.

2. The low temperature resistant and high strength polyurethane elastomer according to claim 1, characterized in that: The polyol 1 is a polytetramethylene ether polyol with a number average molecular weight of 1000-2000 g / mol.

3. The low temperature resistant and high strength polyurethane elastomer according to claim 1, characterized in that: Polyol 2 is a polyoxypropylene ether polyol having a number average molecular weight of 400 to 2000 g / mol.

4. The low temperature resistant and high strength polyurethane elastomer according to claim 1, characterized in that: The copolyether is one or two of polytetrahydrofuran-ethylene oxide copolyether (PET) with a hydroxyl value of 23.8-63.9 mgKOH / g.

5. The low temperature resistant and high strength polyurethane elastomer according to claim 1, characterized in that: The chain extender is one or a mixture of two of di-o-chloroaniline methane (MOCA), dimethylthiotoluene diamine (E300), 2,4-diamino-3,5-dimethylthiochlorobenzene (TX-2), and 2,4-diamino-5-mercaptotoluene (TX-1).

6. The low temperature resistant and high strength polyurethane elastomer according to claim 1, characterized in that: The defoamer is a commercially available general-purpose polyurethane defoamer.

7. A method for preparing the low-temperature resistant polyurethane elastomer according to any one of claims 1 to 6, comprising the following steps: (1) Preparation of component A: Add toluene diisocyanate, add polyol 1 and polyol 2 under stirring, react for a certain time, test NCO%, and when it reaches the designed value, seal and store the discharged material to obtain prepolymer component A; (2) Preparation of component B: Add copolyether, chain extender and defoamer, and mix evenly to obtain a curing agent component; (3) Preparation of low temperature resistant polyurethane elastomer: Component A and component B are mixed, poured into a mold, and cured to obtain the low-temperature resistant polyurethane elastomer.

8. The preparation method according to claim 7, characterized in that: Polyol 1, polyol 2 and copolyether were dehydrated before use.

9. The preparation method according to claim 7, characterized in that: In step (1), the reaction temperature is 80-85°C.

10. The preparation method according to claim 7, characterized in that: The weight ratio of component A to component B is 100 / 24~42.

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