A thermoplastic polyurethane elastomer for film and preparation method thereof

Abstract

The present invention relates to the technical field of C08L polymer materials, and more specifically, the present invention provides a thermoplastic polyurethane elastomer for film and a preparation method thereof. The present invention provides a thermoplastic polyurethane elastomer for film, and the preparation raw materials include polyester polyol, polyol compound, isocyanate, antioxidant, carbodiimide, ultraviolet absorber, etc. Compared with the prior art, the thermoplastic polyurethane elastomer for film prepared by the present invention has excellent mechanical properties, and also has a medium to low crystallization speed and reduced water vapor permeability. The prepared thermoplastic polyurethane elastomer can be processed not only by film blowing but also by casting in the process of being used in the film field, which provides a new strategy for the preparation of low moisture permeability polyurethane elastomer and expands the application range of thermoplastic polyurethane elastomer.

Description

Technical Field

[0001] The present invention relates to the technical field of C08L polymer materials, and more specifically, to a thermoplastic polyurethane elastomer for a film and a preparation method thereof. Background Art

[0002] With the rapid development of industrial science and technology, higher requirements are put forward for the performance of polymer materials. As an important type of polymer material, thermoplastic polyurethane elastomer is widely used in defense, clothing, packaging and other fields. In the existing technology, the moisture permeability and mechanical properties of thermoplastic polyurethane elastomer still have many defects. Therefore, one of the focuses of scientific researchers in recent years is to develop a thermoplastic polyurethane elastomer material with excellent mechanical properties and low moisture permeability, so as to expand the practical application range of thermoplastic polyurethane elastomer.

[0003] A Chinese invention patent with patent publication number CN106565979A discloses a method for preparing a thermoplastic polyurethane elastomer film. In this patent disclosure, by adding amide compounds such as light stabilizers and matte agents, the problem of poor quality of TPU film products in the prior art is solved. However, the moisture permeability of the film prepared by its solution is not prominently reflected, which limits the application scope of the thermoplastic polyurethane elastomer film.

[0004] The Chinese invention patent with patent publication number CN110922559A discloses a thermoplastic polyurethane elastomer material for degradable medical-grade film and a preparation method thereof. In this patent disclosure, the degradation performance of the elastomer is significantly improved by introducing polymer diols into the polyurethane elastomer molecules, but the tensile strength and elongation at break of the prepared polyurethane elastomer are not prominently reflected.

[0005] Therefore, developing a thermoplastic polyurethane elastomer with excellent low moisture permeability and mechanical properties for film has potential market application value. Summary of the invention

[0006] In order to solve the above problems, the first aspect of the present invention provides a thermoplastic polyurethane elastomer for film. The raw materials for preparation include the following components, by weight: 55-65 parts of polyester polyol, 10-15 parts of polyol compound, 40-50 parts of isocyanate, 0.4-2 parts of primary antioxidant, 0.2-1 parts of auxiliary antioxidant, 0.5-1 parts of carbodiimide, 0.2-0.7 parts of ultraviolet absorber, and 1-3 parts of amide compound.

[0007] As a preferred technical solution of the present invention, the polyester polyol includes at least one of polybutylene adipate, polysuccinic acid polyester polyol, and acrylic polyester polyol.

[0008] As a preferred technical solution of the present invention, the weight average molecular weight of the polybutylene adipate is 600-1200.

[0009] As a preferred technical solution of the present invention, the polyol compound is selected from at least one of 1,4-butanediol, 1,6-hexanediol, glycerol and trimethylolpropane.

[0010] As a preferred technical solution of the present invention, the isocyanate is selected from at least one of 4,4-dicyclohexylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate and hexamethylene diisocyanate.

[0011] The applicant has found that thermoplastic polyurethane elastomers are widely used in various fields of industrial science and technology due to their excellent strength and elasticity, but they have high moisture permeability and too fast crystallization speed, which further limits the application scope of thermoplastic polyurethane elastomers and increases the difficulty of their preparation process. In order to solve the above problems, the applicant unexpectedly discovered through a large number of creative experiments that when polybutylene adipate, 1,4-butanediol, and 4,4-dicyclohexylmethane diisocyanate are used, especially when the weight-average molecular weight of polybutylene adipate is 1000, the moisture permeability of thermoplastic polyurethane elastomer can be effectively reduced and the crystallization speed of elastomer can be improved. The applicant speculates that the possible reason is that by strictly controlling the model of polybutylene adipate, the polarity of the system and the degree of microphase separation between the hard segment in the system can be improved, and the crystallization speed of the system is slowed down while ensuring that the system has an excellent degree of crystallization; at the same time, the structure of the molecular chain is more neat, the rotation of the molecular chain in the system is reduced, the intermolecular force and density are increased, and the moisture permeability of the thermoplastic polyurethane elastomer is reduced.

[0012] As a preferred technical solution of the present invention, the primary antioxidant is selected from at least one of 2,6-di-tert-butyl-p-cresol, β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, and 4,4'-di-tert-octyl diphenylamine.

[0013] As a preferred technical solution of the present invention, the auxiliary antioxidant is selected from at least one of triphenyl phosphite, diphenyl isooctyl phosphite, triisooctyl phosphite, and tritridecyl phosphite.

[0014] As a preferred technical solution of the present invention, the mass ratio of the primary antioxidant to the auxiliary antioxidant is (1-4):1.

[0015] As a more preferred technical solution of the present invention, the mass ratio of the primary antioxidant to the auxiliary antioxidant is 2:1.

[0016] As a preferred technical solution of the present invention, the ultraviolet absorber is selected from at least one of salicylate compounds, benzophenone compounds, benzotriazole compounds, and triazine compounds.

[0017] As a more preferred technical solution of the present invention, the ultraviolet absorber is a benzophenone compound and a benzotriazole compound, and the mass ratio of the benzophenone compound to the benzotriazole compound is (1.2-1.8): (0.2-0.6).

[0018] As a most preferred technical solution of the present invention, the mass ratio of the salicylic acid compound to the benzotriazole compound is 1.6:0.4.

[0019] As a preferred technical solution of the present invention, the salicylate compound is selected from at least one of 1,4-dihydroxybenzophenone, 2,4-methoxybenzophenone, and 2-hydroxy-4-octyloxybenzophenone.

[0020] As a preferred technical solution of the present invention, at least one of the 2,2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2-hydroxy-3,5-di-tert-pentylphenyl)benzotriazole and 2-(2'-hydroxy-4'-benzoylphenyl)-5-chloro-2H-benzotriazole is used.

[0021] The applicant unexpectedly discovered that when 2-hydroxy-4-methoxybenzophenone and 2,2 (2'-hydroxy-5'-methylphenyl) benzotriazole are added to the system in a mass ratio of 1.6:0.4, the anti-aging performance of the thermoplastic polyurethane elastomer can be improved while the moisture permeability of the thermoplastic polyurethane elastomer can be effectively reduced. The applicant speculates that the possible reason is that 2-hydroxy-4-methoxybenzophenone and 2,2 (2'-hydroxy-5'-methylphenyl) benzotriazole are adsorbed around the polyurethane molecules due to the electronic effect, resulting in a decrease in the density of the exposed hydrophilic groups, which reduces the adsorption process of water molecules in the environment on the surface of the thermoplastic polyurethane elastomer, thereby reducing the permeability of water molecules in the thermoplastic polyurethane elastomer.

[0022] As a preferred technical solution of the present invention, the amide compound is selected from at least one of oleic acid amide and formic acid amide.

[0023] A second aspect of the present invention provides a method for preparing a thermoplastic polyurethane elastomer for a film, comprising the following steps:

[0024] (1) Weighing polyester polyol, primary antioxidant, auxiliary antioxidant, carbodiimide, and ultraviolet absorber in proportion and stirring at 90-110° C. for 30-60 minutes to obtain a mixed solution A;

[0025] (2) The mixture A described in step (1) is accurately fed into a twin-screw extruder through a casting head for reaction with isocyanate and polyol compounds, and the thermoplastic polyurethane elastomer for film is obtained through extrusion, pelletizing, dehydration, drying and packaging.

[0026] Wherein, the rotation speed of the twin-screw reaction extruder in step (2) is 370-400r / min, and the temperature is 180-200°C.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The thermoplastic polyurethane elastomer for film prepared by the present invention can improve the polarity of the system and the degree of microphase separation between the system and the hard segment by using polybutylene adipate, 4,4-dicyclohexylmethane diisocyanate and 1,4-butanediol as polyol compounds, especially when the weight average molecular weight of polybutylene adipate is 1000, and slow down the crystallization speed of the system and reduce the moisture permeability of the thermoplastic polyurethane elastomer while ensuring the excellent crystallinity of the system;

[0029] 2. The thermoplastic polyurethane elastomer for film prepared by the present invention can interact with other components in the system by adding 2,6-di-tert-butyl-p-cresol and triphenyl phosphite in a mass ratio of 2:1 into the system, thereby improving the mechanical properties of the thermoplastic polyurethane elastomer and the moisture permeability of the product, thereby expanding the application range of the thermoplastic polyurethane elastomer;

[0030] 3. The thermoplastic polyurethane elastomer for film prepared by the present invention, by adding 2-hydroxy-4-methoxybenzophenone and 2,2 (2'-hydroxy-5'-methylphenyl) benzotriazole in a mass ratio of 1.6:0.4 into the system, not only enhances the mechanical properties of the thermoplastic polyurethane elastomer and prolongs the service life of the elastomer, but also improves the density of the hydrophilic groups exposed to the outside of the thermoplastic polyurethane elastomer, reduces the interaction force between water molecules and the surface of the thermoplastic polyurethane elastomer, and improves the permeability of water molecules in the thermoplastic polyurethane elastomer;

[0031] 4. The thermoplastic polyurethane elastomer for film prepared by the present invention can improve the viscosity of the system and control the crystallization speed of the system without affecting the degree of crystallization of the system by adding talcum powder as an anti-caking agent to the system, so that the prepared thermoplastic polyurethane elastomer can be processed not only by film blowing but also by casting in the process of being used in the field of film;

[0032] 5. The thermoplastic polyurethane elastomer for film prepared by the present invention has simple and easily available raw materials for preparation, and has a reduced water vapor permeability while having excellent mechanical properties. It is widely used in the field of films, especially in the field of waterproof films, and has potential application prospects. It provides a new strategy for the preparation of low moisture permeability polyurethane elastomers and expands the application range of thermoplastic polyurethane elastomers. DETAILED DESCRIPTION

[0033] Example 1

[0034] Example 1 provides a thermoplastic polyurethane elastomer for film. The raw materials for preparation include the following components, by weight: 55 parts of polyester polyol, 10 parts of polyol compound, 40 parts of isocyanate, 0.4 parts of primary antioxidant, 0.6 parts of auxiliary antioxidant, 0.5 parts of carbodiimide, 0.2 parts of ultraviolet absorber, and 1 part of amide compound.

[0035] The polyester polyol is polybutylene adipate, purchased from Wuhan Kemik Biopharmaceutical Technology Co., Ltd., model KMK-1022, with a weight average molecular weight of 1000;

[0036] The polyol compound is 1,4-butanediol, and the CAS number of 1,4-butanediol is 110-63-4;

[0037] The isocyanate is 4,4-dicyclohexylmethane diisocyanate, and the CAS number of 4,4-dicyclohexylmethane diisocyanate is 5124-30-1;

[0038] The main antioxidant is 2,6-di-tert-butyl-p-cresol, and the CAS number of 2,6-di-tert-butyl-p-cresol is 128-37-0;

[0039] The auxiliary antioxidant is triphenyl phosphite, and the CAS number of triphenyl phosphite is 101-02-0;

[0040] The CAS number of the carbodiimide is 151-51-9;

[0041] The ultraviolet absorber is 2-hydroxy-4-methoxybenzophenone and 2,2 (2'-hydroxy-5'-methylphenyl) benzotriazole, and the mass ratio of 2-hydroxy-4-methoxybenzophenone and 2,2 (2'-hydroxy-5'-methylphenyl) benzotriazole is 1.6:0.4; the CAS number of the 2-hydroxy-4-methoxybenzophenone is 131-57-7; 2,2 (2'-hydroxy-5'-methylphenyl) benzotriazole is purchased from Tianjin Anlong New Materials Co., Ltd.;

[0042] The amide compound is oleamide, and the CAS number of oleamide is 301-02-0.

[0043] The method for preparing a thermoplastic polyurethane elastomer for a film comprises the following steps:

[0044] (1) Weighing polyester polyol, primary antioxidant, auxiliary antioxidant, carbodiimide, and ultraviolet absorber in proportion and stirring at 100° C. for 45 minutes to obtain a mixed solution A;

[0045] (2) The mixture A described in step (1) is accurately fed into a twin-screw extruder through a casting head for reaction with isocyanate and polyol compounds, and the thermoplastic polyurethane elastomer for film is obtained through extrusion, pelletizing, dehydration, drying and packaging.

[0046] Wherein, the rotation speed of the twin-screw reaction extruder in step (2) is 380r / min and the temperature is 190°C.

[0047] Example 2

[0048] Example 2 provides a thermoplastic polyurethane elastomer for film. The raw materials for preparation include the following components, by weight: 65 parts of polyester polyol, 15 parts of polyol compounds, 50 parts of isocyanate, 2 parts of primary antioxidant, 1 part of auxiliary antioxidant, 1 part of carbodiimide, 0.7 parts of ultraviolet absorber, and 3 parts of amide compounds.

[0049] The polyester polyol is polybutylene adipate, purchased from Wuhan Kemik Biopharmaceutical Technology Co., Ltd., model KMK-1022, with a weight average molecular weight of 1000;

[0050] The polyol compound is 1,4-butanediol, and the CAS number of 1,4-butanediol is 110-63-4;

[0051] The isocyanate is 4,4-dicyclohexylmethane diisocyanate, and the CAS number of 4,4-dicyclohexylmethane diisocyanate is 5124-30-1;

[0052] The main antioxidant is 2,6-di-tert-butyl-p-cresol, and the CAS number of 2,6-di-tert-butyl-p-cresol is 128-37-0;

[0053] The auxiliary antioxidant is triphenyl phosphite, and the CAS number of triphenyl phosphite is 101-02-0;

[0054] The CAS number of the carbodiimide is 151-51-9;

[0055] The ultraviolet absorber is 2-hydroxy-4-methoxybenzophenone and 2,2 (2'-hydroxy-5'-methylphenyl) benzotriazole, and the mass ratio of 2-hydroxy-4-methoxybenzophenone and 2,2 (2'-hydroxy-5'-methylphenyl) benzotriazole is 1.6:0.4; the CAS number of the 2-hydroxy-4-methoxybenzophenone is 131-57-7; 2,2 (2'-hydroxy-5'-methylphenyl) benzotriazole is purchased from Tianjin Anlong New Materials Co., Ltd.;

[0056] The amide compound is oleamide, and the CAS number of oleamide is 301-02-0.

[0057] The preparation method of the thermoplastic polyurethane elastomer for film is the same as that in Example 1.

[0058] Example 3

[0059] Example 3 provides a thermoplastic polyurethane elastomer for film. The raw materials for preparation include the following components, by weight: 60 parts of polyester polyol, 13 parts of polyol compounds, 45 parts of isocyanate, 1 part of primary antioxidant, 0.5 parts of auxiliary antioxidant, 0.7 parts of carbodiimide, 0.5 parts of ultraviolet absorber, and 2 parts of amide compounds.

[0060] The polyester polyol is polybutylene adipate, purchased from Wuhan Kemik Biopharmaceutical Technology Co., Ltd., model KMK-1022, with a weight average molecular weight of 1000;

[0061] The polyol compound is 1,4-butanediol, and the CAS number of 1,4-butanediol is 110-63-4;

[0062] The isocyanate is 4,4-dicyclohexylmethane diisocyanate, and the CAS number of 4,4-dicyclohexylmethane diisocyanate is 5124-30-1;

[0063] The main antioxidant is 2,6-di-tert-butyl-p-cresol, and the CAS number of 2,6-di-tert-butyl-p-cresol is 128-37-0;

[0064] The auxiliary antioxidant is triphenyl phosphite, and the CAS number of triphenyl phosphite is 101-02-0;

[0065] The CAS number of the carbodiimide is 151-51-9;

[0066] The ultraviolet absorber is 2-hydroxy-4-methoxybenzophenone and 2,2 (2'-hydroxy-5'-methylphenyl) benzotriazole, and the mass ratio of 2-hydroxy-4-methoxybenzophenone and 2,2 (2'-hydroxy-5'-methylphenyl) benzotriazole is 1.6:0.4; the CAS number of the 2-hydroxy-4-methoxybenzophenone is 131-57-7; 2,2 (2'-hydroxy-5'-methylphenyl) benzotriazole is purchased from Tianjin Anlong New Materials Co., Ltd.;

[0067] The amide compound is oleamide, and the CAS number of oleamide is 301-02-0.

[0068] The preparation method of the thermoplastic polyurethane elastomer for film is the same as that in Example 1.

[0069] Comparative Example 1

[0070] The specific implementation method of Comparative Example 1 is the same as that of Example 3, except that the weight average molecular weight of the polybutylene adipate is 3000.

[0071] Comparative Example 2

[0072] The specific implementation method of Comparative Example 2 is the same as that of Example 3, except that the polyol compound is ethylenediamine.

[0073] Comparative Example 3

[0074] The specific implementation method of Comparative Example 3 is the same as that of Example 3, except that the isocyanate is isophorone diisocyanate.

[0075] Comparative Example 4

[0076] The specific implementation of Comparative Example 4 is the same as that of Example 3, except that no ultraviolet absorber is added.

[0077] Performance Evaluation

[0078] The performance of the thermoplastic polyurethane elastomers prepared in Examples 1-3 and Comparative Examples 1-4 was tested.

[0079] (1) Tensile performance test:

[0080] The thermoplastic polyurethane elastomers prepared in Examples 1-3 and Comparative Examples 1-4 were extruded on an extruder with a size of 150 mm×10 mm×2 mm. According to GB / T1040.2-2006 "Test for tensile properties of plastics", the tensile speed was 25 mm / min. The greater the tensile strength, the better the tensile properties of the thermoplastic polyurethane elastomer. The measured data are shown in Table 1.

[0081] (2) Transmittance performance test:

[0082] The thermoplastic polyurethane elastomers prepared in Examples 1-3 and Comparative Examples 1-4 were made into a film with a thickness of 0.02 mm, and the permeability performance was tested according to the inverted cup method in ASTM E96. The smaller the water vapor permeability, the smaller the permeability of the elastomer. The measured data are shown in Table 1.

[0083] Table 1

[0084] Tensile strength(MPa) <![CDATA[Water vapor transmission rate (g / m 2 / 24h)]]> Example 1 46 1613 Example 2 45 1687 Example 3 46 1552 Comparative Example 1 32 3024 Comparative Example 2 31 3187 Comparative Example 3 29 3129 Comparative Example 4 30 3094

Claims

1. A thermoplastic polyurethane elastomer for film, characterized in that: The raw materials for preparation are the following components by weight: 60 parts of polyester polyol, 13 parts of polyol compound, 45 parts of isocyanate, 1 part of primary antioxidant, 0.5 parts of auxiliary antioxidant, 0.7 parts of carbodiimide, 0.5 parts of ultraviolet absorber, and 2 parts of amide compound; The polyester polyol is polybutylene adipate, purchased from Wuhan Kemik Biopharmaceutical Technology Co., Ltd., model KMK-1022, with a weight-average molecular weight of 1000; the polyol compound is 1,4-butanediol; the isocyanate is 4,4-dicyclohexylmethane diisocyanate; the main antioxidant is 2,6-di-tert-butyl-p-cresol; the auxiliary antioxidant is triphenyl phosphite; the ultraviolet absorber is 2-hydroxy-4-methoxybenzophenone and 2,2 (2'-hydroxy-5'-methylphenyl) benzotriazole, and the mass ratio of 2-hydroxy-4-methoxybenzophenone and 2,2 (2'-hydroxy-5'-methylphenyl) benzotriazole is 1.6:0.4; the amide compound is oleic acid amide; The method for preparing a thermoplastic polyurethane elastomer for a film comprises the following steps: (1) Weighing polyester polyol, primary antioxidant, auxiliary antioxidant, carbodiimide, and ultraviolet absorber in proportion and stirring at 100° C. for 45 minutes to obtain a mixed solution A; (2) accurately feeding the mixture A described in step (1) with isocyanate and polyol compounds into a twin-screw extruder through a pouring head for reaction, and then extruding, pelletizing, dehydrating, drying and packaging to obtain the thermoplastic polyurethane elastomer for film; Wherein, the rotation speed of the twin-screw reaction extruder in step (2) is 380r / min and the temperature is 190°C.