A dual-melting-point thermoplastic elastomer and preparation method thereof

Abstract

The present invention provides a method for preparing a dual-melting-point thermoplastic elastomer, comprising the following steps: (1) preparing a dicarboxyl-terminated nylon hard segment A and a dicarboxyl-terminated polyester hard segment B, respectively; wherein the molecular weights of the dicarboxyl-terminated nylon hard segment A and the dicarboxyl-terminated polyester hard segment B are 500-10,000, respectively; (2) heating the dicarboxyl-terminated nylon hard segment A, a catalyst 1, and a polyether polyol C to 180-250° C. to carry out an esterification reaction to obtain a dihydroxy-terminated nylon elastomer oligomer; and (3) further carrying out an esterification reaction on the dicarboxyl-terminated polyester hard segment B, a catalyst 2, and the dihydroxy-terminated nylon elastomer oligomer to finally prepare a dual-melting-point thermoplastic elastomer having a structure similar to an ACB-type triblock. The thermoplastic elastomer prepared by the present invention has dual melting points and has a higher operating temperature at a lower hardness.

Description

Technical Field

[0001] The present invention relates to the technical field of preparing elastomers, and in particular to a dual-melting-point thermoplastic elastomer and a preparation method thereof. Background Art

[0002] Nylon elastomer is a copolymer composed of polyamide as the hard segment and polyether or polyester polyol as the soft segment. It is a thermoplastic elastomer with high resilience, low temperature resistance, and aging resistance. It is widely used in footwear, sports equipment, antistatic agents, medical catheters, industrial components and other fields. Its hard segment can range from 20D to 80D.

[0003] Chinese invention patent CN105612197B uses at least two different nylons as hard segments and polyether as soft segments to prepare nylon elastomers. The purpose is to break the crystallization and obtain nylon with higher transparency. At the same time, the heat resistance of the material is reduced, indicating that the nylon elastomer prepared therefrom has a small block and a large random structure. In order to improve the transparency of the nylon elastomer, the invention uses at least two different nylons as hard segments for random copolymerization, resulting in a lower melting point and poorer heat resistance of the material. Chinese invention patent CN105801846B uses a one-pot method to prepare a cast nylon / polyester elastomer through anionic ring opening. It is a random copolymer that improves impact strength and ductility. This method is only applicable to nylon prepared from lactam, which has limitations, and the addition of polyester is only for toughening modification.

[0004] When preparing products with lower hard segments, existing nylon elastomers require the selection of long carbon chain nylon with a lower melting point as the hard segment. This will result in the prepared nylon elastomer having a lower melting point and poor heat resistance, limiting its application range or even making it unusable. Summary of the Invention

[0005] To overcome the challenges of existing technologies, the present invention provides a method for preparing a dual-melting-point thermoplastic elastomer. Through a special process and melt polycondensation, a triblock ACB-type precision elastomeric polymer is produced. This polymer exhibits dual melting points. While the long-chain nylon hard segment and polyether soft segment provide low hardness, the polyester hard segment provides a higher operating temperature. It is suitable for applications in sportswear, antistatic agents, and other fields.

[0006] In order to achieve the purpose of the present invention, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for preparing a thermoplastic elastomer, comprising the following steps:

[0008] (1) preparing a dicarboxyl-terminated nylon hard segment A and a dicarboxyl-terminated polyester hard segment B respectively; wherein the molecular weights of the dicarboxyl-terminated nylon hard segment A and the dicarboxyl-terminated polyester hard segment B are 500 to 10,000 respectively;

[0009] (2) heating the dicarboxyl-terminated nylon hard segment A, catalyst 1, and polyether polyol C to preferably 180-250° C. to carry out an esterification reaction to prepare a dihydroxy-terminated nylon elastomer oligomer;

[0010] (3) The dicarboxyl-terminated polyester hard segment B, catalyst 2 and dihydroxy-terminated nylon elastomer oligomer are further subjected to esterification reaction to finally prepare a dual-melting-point thermoplastic elastomer.

[0011] In the present invention, the nylon hard segment refers to a nylon oligomer formed by a long carbon chain dibasic acid and a long carbon chain diamine or lactam. The polyester hard segment is a low molecular weight polyester polymerized by terephthalic acid and ethylene glycol or butanediol.

[0012] The dicarboxyl-terminated nylon hard segment in step (1) of the method of the present invention can be prepared by conventional methods in the art, for example, see "Plastics Industry Handbook: Polyamides" published by Chemical Industry Press in 2001, reference page 495. In some specific embodiments, the dicarboxyl-terminated nylon hard segment can be prepared by reacting the nylon hard segment with a dibasic acid in the presence of a solvent; the dibasic acid can be selected from one or more of succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, or hexadecanedioic acid. Similarly, the dicarboxyl-terminated polyester hard segment can be prepared by conventional methods in the art, and the dicarboxyl-terminated polyester is obtained by adjusting the molar ratio of the raw acid to the alcohol, see "Thermoplastic Polyesters and Their Applications" published by Chemical Industry Press in 2011, reference page 224.

[0013] In some specific embodiments, the nylon hard segment of the present invention is selected from one of long carbon chain nylon 1010, nylon 1012, nylon 1014, nylon 1212, nylon 11 or nylon 12; the number average molecular weight of the dicarboxyl terminated nylon hard segment is 500 to 10,000.

[0014] In some specific embodiments, the dicarboxyl-terminated polyester hard segment in step (1) of the present invention is selected from one of PET and PBT; the number average molecular weight of the dicarboxyl-terminated polyester hard segment is 500 to 10,000.

[0015] In a preferred embodiment of the method of the present invention, in step (2), the dicarboxyl-terminated nylon hard segment A, catalyst 1, and polyether polyol C are heated to 180-250° C. for esterification to produce a dihydroxy-terminated nylon elastomer oligomer. In some specific operations, the added catalyst 1 accounts for 0.01 wt% to 0.1 wt% of the total amount of the dicarboxyl-terminated nylon hard segment A and polyether polyol C.

[0016] The catalyst is selected from one of sodium phosphite, magnesium phosphite, zinc phosphite, calcium phosphite, sodium hypophosphite, magnesium hypophosphite, calcium hypophosphite, zinc hypophosphite, potassium phosphate, zinc phosphate, calcium phosphate, magnesium phosphate or any mixture thereof, preferably sodium hypophosphite.

[0017] Step (3) further esterifies the dicarboxyl-terminated polyester hard segment B, catalyst 2, and dihydroxy-terminated nylon elastomer oligomer to obtain a dual-melting-point thermoplastic elastomer, wherein the catalyst 2 is selected from metal alkoxides, specifically, the catalyst can be selected from the general formula M(OR) n Metal alkoxide; wherein M is Sb, Ti, Zr or Ge, and R is C 1～10 The alkyl group, the value of n is adjusted according to the valence of M, and can be 1 to 6, preferably 4; for example, tetrabutyl titanate, zirconium n-propoxide, tetraethyl germanium, ethylene glycol antimony; catalyst 2 accounts for 0.01wt% to 0.1wt% of the total of the polyester hard segment B and the dihydroxy-terminated nylon elastomer oligomer.

[0018] In the preparation method of the thermoplastic elastomer provided by the present invention, in step (2), the esterification temperature is 180-250° C. and the vacuum absolute pressure is ≤2000 PaA for 2-6 hours; in step (3), the esterification temperature is 220-300° C. and the vacuum absolute pressure is ≤100 PaA for 2-10 hours.

[0019] In steps (2) and (3) of the present invention, the molar ratio of the dicarboxyl-terminated nylon hard segment A, the dicarboxyl-terminated polyester hard segment B and the polyether polyol C is (0.67-0.95):(0.05-0.33):1; wherein the polyether polyol can be selected from one of polyethylene glycol, polypropylene glycol or polybutylene glycol; the molecular weight of the polyether polyol is preferably 500-3000.

[0020] In some preferred technical solutions of the present invention, a reaction aid is further added before the esterification polymerization in step (2); the amount of the reaction aid added is 0.05 wt% to 0.3 wt% based on the total mass of the dicarboxyl-terminated nylon hard segment A, the dicarboxyl-terminated polyester hard segment B, and the polyether polyol as 100%. The reaction aid is selected from an antioxidant and / or a UV absorber.

[0021] The thermoplastic elastomer prepared as described above has an (AC)xB type block structure, wherein x is 1 to 20. A represents a repeating unit of a dicarboxyl-terminated nylon hard segment in the polymer, B represents a repeating unit of a dicarboxyl-terminated polyester hard segment in the polymer, and C represents a repeating unit of a polyether polyol in the polymer.

[0022] The above technical solution has the following technical effects:

[0023] The preparation method of the present invention comprises the following steps: firstly forming an AC-type dihydroxyl-terminated nylon elastomer oligomer by reacting a dicarboxyl-terminated nylon hard segment A and a polyether polyol C; then reacting the AC-type dihydroxyl-terminated nylon elastomer oligomer with a dicarboxyl-terminated polyester hard segment to form a ternary block copolymer with a precise structure similar to that of the ACB type; and having a double melting point. On the basis of the lower hardness provided by the block composed of the nylon hard segment and the polyether soft segment, the polyester hard segment can provide a higher operating temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the DSC spectrum of the thermoplastic elastomer resin 1 prepared in Example 1;

[0025] Figure 2 This is the DSC spectrum of the thermoplastic elastomer resin 1-1 obtained in Comparative Example 1. DETAILED DESCRIPTION

[0026] In order to better understand the technical solutions of the present invention, the present invention is further described below with reference to the following embodiments, but the present invention is not limited to the following embodiments.

[0027] The following test methods were used in each example of the present invention:

[0028] (1) Melting point test method: ISO 11357 standard is adopted, and the equipment is a differential scanning calorimeter;

[0029] (2) Hardness test method: ISO868, Shore D.

[0030] The raw materials used in the following examples and comparative examples are all commercial chemicals with industrial grade purity.

[0031] Example 1

[0032] (1) 3.7 kg of laurolactam, 1.1 kg of dodecanedioic acid, and 5 kg of water were added to a polymerization reactor. The reaction conditions were a temperature of 290°C and a pressure of 4.0 MPa for 2 h to obtain a dicarboxyl-terminated nylon 12 hard segment with a number average molecular weight of 1000.

[0033] 3.84 kg of terephthalic acid and 1.16 kg of ethylene glycol were added to a polymerization reactor. The reaction was carried out at a temperature of 270°C and a vacuum pressure of 5000 PaA for 4 hours to obtain a dicarboxyl-terminated polyester hard segment with a number average molecular weight of 1000.

[0034] (2) 2 kg of the dicarboxyl-terminated nylon 12 hard segment prepared in step (1), 3 kg of polybutylene glycol (PTMG-1000), and 5 g of sodium hypophosphite were added to a polymerization reactor. After replacing the reactor with nitrogen three times, the temperature was raised to 180° C., and the absolute pressure was controlled at 2000 PaA for 6 h to prepare a dihydroxy-terminated nylon elastomer oligomer.

[0035] (3) 1 kg of the dicarboxyl-terminated polyester hard segment prepared in step (1), 5 kg of the dihydroxy-terminated nylon elastomer oligomer prepared in step (2), 6 g of ethylene glycol antimony, and 6 g of antioxidant (1098) were put into a polymerization reactor. After nitrogen was replaced in the polymerization reactor three times, stirring was started and the temperature was raised to 270° C. The reactor was evacuated to an absolute pressure of 100 PaA. After reacting for 6 hours, a thermoplastic elastomer resin 1 was obtained through a discharge port. Figure 1 Shown is the DSC spectrum of nylon elastomer resin 1, which has two melting points.

[0036] Example 2

[0037] (1) 3.7 kg of laurolactam, 1.35 kg of adipic acid, and 5 kg of water were added to a polymerization reactor. The reaction conditions were a temperature of 300°C and a pressure of 4.5 MPa for 6 h to obtain a dicarboxyl-terminated nylon 12 hard segment with a number average molecular weight of 500.

[0038] 3.65 kg of terephthalic acid and 1.24 kg of ethylene glycol were added to a polymerization reactor. The reaction was carried out at a temperature of 275°C and a vacuum pressure of 4500 PaA for 3 hours to obtain a dicarboxyl-terminated polyester hard segment with a number average molecular weight of 2000.

[0039] (2) 1.425 kg of the dicarboxyl-terminated nylon 12 hard segment prepared in step (1), 3 kg of polyethylene glycol (PEG-1000), and 4.4 g of magnesium hypophosphite were placed in a polymerization reactor. After replacing the reactor with nitrogen three times, the temperature was raised to 195° C., and the absolute pressure was controlled at 1500 PaA for 4 hours to prepare a dihydroxy-terminated nylon elastomer oligomer.

[0040] (3) 300 g of the dicarboxyl-terminated polyester hard segment prepared in step (1), 4.425 kg of the dihydroxy-terminated nylon elastomer oligomer prepared in step (2), 2.35 g of zirconium n-propoxide, and 12 g of antioxidant (1010) were put into a polymerization reactor. After nitrogen was replaced in the polymerization reactor three times, stirring was started and the temperature was raised to 300° C. The reactor was evacuated to an absolute pressure of 50 PaA. After reacting for 6 hours, a thermoplastic elastomer resin 2 was obtained through a discharge port.

[0041] Example 3

[0042] (1) 2.73 kg of decanediamine, 3.93 kg of dodecanedioic acid, and 5 kg of water were reacted in a polymerization reactor at a temperature of 210°C and a pressure of 1.8 MPa for 4 h to obtain a dicarboxyl-terminated nylon 1012 hard segment with a number average molecular weight of 5000;

[0043] 4.98 kg of terephthalic acid and 2.61 kg of butanediol were added to a polymerization reactor. The reaction was carried out at a temperature of 290°C and a vacuum pressure of 5000 PaA for 2 hours to obtain a dicarboxyl-terminated polyester hard segment with a number average molecular weight of 500.

[0044] (2) 5 kg of the dicarboxyl-terminated nylon 1012 hard segment prepared in step (1), 2.4 kg of polypropylene glycol (PPG-2000), and 4 g of zinc hypophosphite were added to a polymerization reactor. After replacing the reactor with nitrogen three times, the temperature was raised to 180° C., and the absolute pressure and vacuum were controlled at 1000 PaA for 6 hours to prepare a dihydroxy-terminated nylon elastomer oligomer.

[0045] (3) 100 g of the dicarboxyl-terminated polyester hard segment prepared in step (1), 7.4 kg of the dihydroxy-terminated nylon elastomer oligomer prepared in step (2), 3.9 g of tetraethyl germanium, 10 g of antioxidant (1098), and 10 g of antioxidant (168) were put into a polymerization reactor. After nitrogen was replaced in the polymerization reactor three times, stirring was started and the temperature was raised to 220° C. The reactor was evacuated to an absolute pressure of 20 PaA. After reacting for 10 h, a thermoplastic elastomer resin 3 was obtained through a discharge port.

[0046] Example 4

[0047] (1) 2.49 kg of decanediamine, 3.03 kg of sebacic acid, and 6 kg of water were reacted in a polymerization reactor at a temperature of 245°C and a pressure of 2.8 MPa for 2 h to obtain a dicarboxyl-terminated nylon 1010 hard segment with a number average molecular weight of 10,000;

[0048] 4.4 kg of terephthalic acid and 2.34 kg of butanediol were added to a polymerization reactor. The reaction was carried out at a temperature of 280°C and a vacuum pressure of 4500 PaA for 3 hours to obtain a dicarboxyl-terminated polyester hard segment with a number average molecular weight of 10,000.

[0049] (2) 10 kg of the dicarboxyl-terminated nylon 1010 hard segment prepared in step (1), 3.3 kg of polybutylene glycol (PTMG-3000), and 11.3 g of sodium hypophosphite were placed in a polymerization reactor. After replacing the reactor with nitrogen three times, the temperature was raised to 250° C. and the absolute pressure was controlled at 500 PaA for 4 hours to prepare a dihydroxy-terminated nylon elastomer oligomer.

[0050] (3) 0.5 kg of the dicarboxyl-terminated polyester hard segment prepared in step (1), 6.65 kg of the dihydroxy-terminated nylon elastomer oligomer prepared in step (2), 6.4 g of tetrabutyl titanate, 5 g of antioxidant (1098), and 6 g of antioxidant (168) were added to a polymerization reactor. After nitrogen was replaced in the polymerization reactor three times, stirring was started and the temperature was raised to 260° C. The reactor was evacuated to an absolute pressure of 80 PaA. After reacting for 7 hours, a thermoplastic elastomer resin 4 was obtained through a discharge port.

[0051] Example 5

[0052] (1) 3.7 kg of laurolactam, 1.02 kg of sebacic acid, and 5 kg of water were added to a polymerization reactor. The reaction conditions were a temperature of 275°C and a pressure of 3.6 MPa for 3 h to obtain a dicarboxyl-terminated nylon 12 hard segment with a number average molecular weight of 1000.

[0053] 4.4 kg of terephthalic acid and 2.34 kg of butanediol were added to a polymerization reactor. The reaction was carried out at a temperature of 280°C and a vacuum pressure of 4500 PaA for 3 hours to obtain a dicarboxyl-terminated polyester hard segment with a number average molecular weight of 10,000.

[0054] (2) 3 kg of the dicarboxyl-terminated nylon 12 hard segment prepared in step (1), 3.5 kg of polybutylene glycol (PTMG-1000), and 4.5 g of sodium hypophosphite were added to a polymerization reactor. After replacing the reactor with nitrogen three times, the temperature was raised to 190° C. and the absolute pressure was controlled at 800 PaA for 6 h to prepare a dihydroxy-terminated nylon elastomer oligomer.

[0055] (3) 2 kg of the dicarboxyl-terminated polyester hard segment prepared in step (1), 2.6 kg of the dihydroxy-terminated nylon elastomer oligomer prepared in step (2), 3.2 g of tetrabutyl titanate, and 6 g of antioxidant (1098) were added to a polymerization reactor. After nitrogen was replaced in the polymerization reactor three times, stirring was started and the temperature was raised to 265° C. The reactor was evacuated to an absolute pressure of 20 PaA. After reacting for 4 hours, a thermoplastic elastomer resin 5 was obtained through a discharge port.

[0056] Example 6

[0057] (1) 4.3 kg of decanediamine, 6.9 kg of dodecanedioic acid, and 10 kg of water were added to a polymerization reactor. The reaction conditions were a temperature of 255°C and a pressure of 3.2 MPa for 4 h to obtain a dicarboxyl-terminated nylon 1012 hard segment with a number average molecular weight of 2000.

[0058] 3.65 kg of terephthalic acid and 1.24 kg of ethylene glycol were added to a polymerization reactor. The reaction was carried out at a temperature of 275°C and a vacuum pressure of 4500 PaA for 3 hours to obtain a dicarboxyl-terminated polyester hard segment with a number average molecular weight of 2000.

[0059] (2) 3 kg of the dicarboxyl-terminated nylon 1012 hard segment prepared in step (1), 6 kg of polybutylene glycol (PTMG-3000), and 7.5 g of sodium hypophosphite were added to a polymerization reactor. After replacing the reactor with nitrogen three times, the temperature was raised to 210° C., and the absolute pressure was controlled at 1100 PaA for 4 hours to prepare a dihydroxy-terminated nylon elastomer oligomer.

[0060] (3) 1 kg of the dicarboxyl-terminated polyester hard segment prepared in step (1), 9 kg of the dihydroxy-terminated nylon elastomer oligomer prepared in step (2), 4.4 g of tetraethyl germanium, and 6 g of antioxidant (1010) were added to a polymerization reactor. After nitrogen was replaced in the polymerization reactor three times, stirring was started and the temperature was raised to 255° C. The reactor was evacuated to an absolute pressure of 70 PaA. After reacting for 8 hours, a thermoplastic elastomer resin 6 was obtained through a discharge port.

[0061] Example 7

[0062] (1) 3.7 kg of laurolactam, 1.02 kg of sebacic acid, and 5 kg of water were added to a polymerization reactor. The reaction conditions were a temperature of 275°C and a pressure of 3.6 MPa for 3 h to obtain a dicarboxyl-terminated nylon 12 hard segment with a number average molecular weight of 1000.

[0063] 4.98 kg of terephthalic acid and 2.61 kg of butanediol were added to a polymerization reactor. The reaction was carried out at a temperature of 290°C and a vacuum pressure of 5000 PaA for 2 hours to obtain a dicarboxyl-terminated polyester hard segment with a number average molecular weight of 500.

[0064] (2) 4 kg of the dicarboxyl-terminated nylon 12 hard segment prepared in step (1), 2.5 kg of polyethylene glycol (PEG-500), and 4.9 g of calcium phosphite were placed in a polymerization reactor. After replacing the reactor with nitrogen three times, the temperature was raised to 205° C. and the absolute pressure was controlled at 1400 PaA for 4 hours to prepare a dihydroxy-terminated nylon elastomer oligomer.

[0065] (3) 0.5 kg of the dicarboxyl-terminated polyester hard segment prepared in step (1), 6.5 kg of the dihydroxy-terminated nylon elastomer oligomer prepared in step (2), 4.9 g of zirconium n-propoxide, and 15 g of antioxidant (1098) were added to a polymerization reactor. After nitrogen was replaced in the polymerization reactor three times, stirring was started and the temperature was raised to 260° C. The reactor was evacuated to an absolute pressure of 40 PaA. After reacting for 2 h, a thermoplastic elastomer resin 7 was obtained through a discharge port.

[0066] Example 8

[0067] (1) 4.02 kg of aminoundecanoic acid, 1.01 kg of sebacic acid, and 5 kg of water were reacted in a polymerization reactor at 240°C and a pressure of 2.8 MPa for 6 h to obtain a dicarboxyl-terminated nylon 11 hard segment with a number average molecular weight of 1000;

[0068] 3.65 kg of terephthalic acid and 1.24 kg of ethylene glycol were added to a polymerization reactor. The reaction was carried out at a temperature of 275°C and a vacuum pressure of 4500 PaA for 3 hours to obtain a dicarboxyl-terminated polyester hard segment with a number average molecular weight of 2000.

[0069] (2) 2 kg of the dicarboxyl-terminated nylon 11 hard segment prepared in step (1), 3 kg of polybutylene glycol (PTMG-1000), and 3.5 g of potassium phosphate were added to a polymerization reactor. After replacing the reactor with nitrogen three times, the temperature was raised to 225° C., and the absolute pressure was controlled at 1700 PaA for 2 h to prepare a dihydroxy-terminated nylon elastomer oligomer.

[0070] (3) 2 kg of the dicarboxyl-terminated polyester hard segment prepared in step (1), 5 kg of the dihydroxy-terminated nylon elastomer oligomer prepared in step (2), 6.5 g of tetrabutyl titanate, 10 g of an antioxidant (1010), and 7 g of an anti-ultraviolet agent (UV312) were added to a polymerization reactor. After nitrogen was replaced in the polymerization reactor three times, stirring was started and the temperature was raised to 290° C. The reactor was evacuated to an absolute pressure of 90 PaA. After reacting for 10 h, a thermoplastic elastomer resin 8 was obtained through a discharge port.

[0071] The elastomer resins 2-8 prepared in the above examples have a double melting point similar to that of the nylon elastomer resin 1.

[0072] Comparative Example 1

[0073] (1) 3.7 kg of laurolactam, 1.1 kg of dodecanedioic acid, and 5 kg of water were added to a polymerization reactor. The reaction conditions were a temperature of 290°C and a pressure of 4.0 MPa for 2 h to obtain a dicarboxyl-terminated nylon 12 hard segment with a number average molecular weight of 1000.

[0074] (2) 2 kg of the dicarboxyl-terminated nylon 12 hard segment prepared in step (1), 3 kg of polybutylene glycol (PTMG-1000), and 5 g of sodium hypophosphite were added to a polymerization reactor. After replacing the reactor with nitrogen three times, the temperature was raised to 180° C., and the absolute pressure was controlled at 2000 PaA for 6 h to prepare a dihydroxy-terminated nylon elastomer oligomer.

[0075] (3) 1 kg of dicarboxyl-terminated nylon 12 hard segment prepared in step (1), 3 kg of dihydroxy-terminated nylon elastomer oligomer prepared in step (2), 4 g of ethylene glycol antimony, and 4 g of antioxidant (1098) were put into a polymerization reactor. After nitrogen was replaced in the polymerization reactor for 3 times, stirring was started and the temperature was raised to 270° C. The reactor was evacuated to an absolute pressure of 100 PaA. After reacting for 6 hours, nylon elastomer resin 1-1 was obtained through the discharge port. The DSC of the obtained nylon elastomer resin 1-1 is as follows: Figure 2 shown in ; it has only one melting point.

[0076] Comparative Example 2

[0077] (1) 3.7 kg of laurolactam, 1.35 kg of adipic acid, and 5 kg of water were added to a polymerization reactor. The reaction conditions were a temperature of 300°C and a pressure of 4.5 MPa for 6 h to obtain a dicarboxyl-terminated nylon 12 hard segment with a number average molecular weight of 500.

[0078] (2) 1.425 kg of the dicarboxyl-terminated nylon 12 hard segment prepared in step (1), 3 kg of polyethanol (PEG-1000), and 4.4 g of sodium hypophosphite were placed in a polymerization reactor. After replacing the reactor with nitrogen three times, the temperature was raised to 195° C. and the absolute pressure was controlled at 1500 PaA for 4 hours to prepare a dihydroxy-terminated nylon elastomer oligomer.

[0079] (3) 75 g of the dicarboxyl-terminated nylon 12 hard segment prepared in step (1), 4.425 kg of the dihydroxy-terminated nylon elastomer oligomer prepared in step (2), 2.35 g of zirconium n-propoxide, and 12 g of antioxidant (1010) were put into a polymerization reactor. After nitrogen was replaced in the polymerization reactor three times, stirring was started and the temperature was raised to 300° C. The reactor was evacuated to an absolute pressure of 50 PaA. After reacting for 6 hours, nylon elastomer resin 1-2 was obtained through the discharge port.

[0080] The melting point and hardness of the nylon elastomer resin prepared above were tested for performance. The results are shown in Table 1 below.

[0081] Table 1

[0082]

[0083]

[0084] As shown in Table 1, the elastomers prepared using this method exhibit dual melting points. For example, Example Elastomer Resin 1 and Comparative Example Elastomer Resin 1-1 both have a hardness of 38D, but Resin 1 exhibits dual melting points, with the higher melting point reaching 183.06°C, demonstrating improved heat resistance. While the block structure composed of nylon hard segments and polyether soft segments provides lower hardness, the polyester hard segments can provide a higher operating temperature.

Claims

1. A method for preparing a dual-melting-point thermoplastic elastomer, characterized in that: The following steps are included: (1) preparing a dicarboxyl-terminated nylon hard segment A and a dicarboxyl-terminated polyester hard segment B respectively; wherein the molecular weights of the dicarboxyl-terminated nylon hard segment A and the dicarboxyl-terminated polyester hard segment B are 500 to 10,000 respectively; (2) heating the dicarboxyl-terminated nylon hard segment A, catalyst 1, and polyether polyol C to carry out an esterification reaction to prepare a dihydroxyl-terminated nylon elastomer oligomer; (3) further subjecting the dicarboxyl-terminated polyester hard segment B, catalyst 2, and dihydroxy-terminated nylon elastomer oligomer to an esterification reaction to prepare a dual-melting-point thermoplastic elastomer; In steps (2) and (3), the molar ratio of the dicarboxyl-terminated nylon hard segment A, the dicarboxyl-terminated polyester hard segment B and the polyether polyol C is (0.67-0.95): (0.05-0.33):

1.

2. The preparation method according to claim 1, characterized in that In step (2), the temperature is raised to 180-250°C.

3. The preparation method according to claim 1, characterized in that In step (1), a nylon hard segment and a dibasic acid are reacted in the presence of a solvent to obtain the dicarboxyl-terminated nylon hard segment.

4. The preparation method according to claim 3, characterized in that The dibasic acid is selected from one or more of succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid or hexadecanedioic acid.

5. The preparation method according to claim 3, characterized in that In step (1), the nylon hard segment is selected from one or more of long carbon chain nylon 1010, nylon 1012, nylon 1014, nylon 1212, nylon 11 or nylon 12; and / or the dicarboxyl terminated polyester hard segment B is selected from PBT or PET.

6. The preparation method according to claim 1, characterized in that The catalyst 1 added in step (2) accounts for 0.01 wt% to 0.1 wt% of the total of the dicarboxyl-terminated nylon hard segment A and the polyether polyol C; and / or The catalyst is selected from one or more of sodium phosphite, magnesium phosphite, zinc phosphite, calcium phosphite, sodium hypophosphite, magnesium hypophosphite, calcium hypophosphite, zinc hypophosphite, potassium phosphate, zinc phosphate, calcium phosphate, and magnesium phosphate.

7. The preparation method according to claim 6, characterized in that The catalyst is selected from sodium hypophosphite.

8. The preparation method according to claim 1, characterized in that The catalyst 2 added in step (3) accounts for 0.01wt% to 0.1wt% of the total of the dicarboxyl-terminated polyester hard segment B and the dihydroxy-terminated nylon elastomer oligomer.

9. The preparation method according to claim 8, characterized in that The catalyst 2 is selected from the general formula M(OR) n Metal alkoxide; wherein M is Sb, Ti, Zr or Ge, and R is C 1～10 The alkyl group of n is 1 to 6.

10. The preparation method according to any one of claims 1 to 9, characterized in that The polyether polyol is selected from one or more of polyethylene glycol, polypropylene glycol or polybutylene glycol.

11. The preparation method according to claim 10, characterized in that: The molecular weight of the polyether polyol is 500-3000.

12. The preparation method according to any one of claims 1 to 9, characterized in that In step (2), the esterification reaction is carried out at a temperature of 180-250° C. and a vacuum absolute pressure of ≤2000 PaA for 2-6 hours; and / or, in step (3), the esterification reaction is carried out at a temperature of 220-300° C. and a vacuum absolute pressure of ≤100 PaA for 2-10 hours.

13. The preparation method according to any one of claims 1 to 9, characterized in that Step (2) further adds a reaction aid before esterification polymerization; Based on the total mass of the dicarboxyl-terminated nylon hard segment A, the dicarboxyl-terminated polyester hard segment B and the polyether polyol C being 100%, the added amount of the reaction aid is 0.05 wt % to 0.3 wt %.

14. The preparation method according to claim 13, characterized in that The reaction aid is selected from antioxidants and / or ultraviolet absorbers.

15. A dual-melting-point thermoplastic elastomer prepared according to the preparation method according to any one of claims 1 to 14, having (AC) x B-type block structure, wherein X is 1-20; A represents the repeating unit of dicarboxyl-terminated nylon hard segment in the polymer, B represents the repeating unit of dicarboxyl-terminated polyester hard segment in the polymer, and C represents the repeating unit of polyether polyol in the polymer.

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