A polyurethane composition and its preparation method and application

Abstract

The invention discloses a polyurethane composition and its preparation method and application. The polyurethane composition comprises, by weight, 80 to 90 parts of thermoplastic polyurethane resin, 1.5 to 3.5 parts of complex azo dye, 0.3 to 1.5 parts of carbon black, and 0.3 to 1 part of antioxidant; the mass ratio of complex azo dye to carbon black is 1:0.2 to 0.5; the specific surface area of ​​carbon black is 150 to 250 m 2 / g; the complex metal in the complex azo dye is iron; the parent dye of the complex azo dye is formed by coupling a coupling azo dye and a diazo azo dye; wherein the coupling azo dye is a derivative of phenol and naphthol; the diazo azo dye is selected from one or more of phenol containing nitro, naphthalene derivative containing sulfonic acid group or naphthalene derivative containing nitro. The polyurethane composition prepared by the present invention not only has a high blackness, but also has significantly improved laser marking clarity, migration resistance and tensile modulus ratio.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermoplastic polyurethane compositions, and more specifically, relates to a polyurethane composition and a preparation method and application thereof. Background Art

[0002] Thermoplastic polyurethane (TPU) is one of the most commonly used plastics in the world. It combines the processing performance of plastics with the physical and mechanical properties of rubber. It has mechanical properties such as high elasticity, high strength, high wear resistance, radiation resistance, oil resistance, resistance to low-temperature brittleness, and hardness that can be adjusted over a wide range. It is widely used in many fields of the national economy.

[0003] Azo dyes (azo dyes, a class of organic compounds with aromatic groups connected at both ends of the azo group) are the most widely used type of synthetic dyes in the printing and dyeing process of textiles and clothing. According to the number of azo groups contained, they can be divided into monoazo dyes, disazo dyes and polyazo dyes. ① Monoazo dyes, such as acid scarlet G. ② Disazo dyes. For example, direct scarlet 4B. ③ Polyazo dyes, such as direct black BN. The more azo groups, the darker the color. According to the application properties, azo dyes can be divided into acid dyes, direct dyes, mordant dyes, ice dyes, disperse dyes, reactive dyes, solvent dyes, azo pigments, etc. According to solubility, they can be divided into soluble azo dyes and insoluble azo dyes. Azo dyes are used for dyeing and printing of various types of fibers, and for dyeing leather, paper, soap, candles, wood, straw, feathers, etc., as well as paint, ink, plastic, rubber, food, etc. The method for manufacturing azo dyes mainly includes two steps: diazotization and coupling.

[0004] The blackness of thermoplastic polyurethane materials is usually relatively low, and when used in parts with higher blackness requirements, it often cannot meet the use requirements. The most direct way to increase the blackness of thermoplastic polyurethane materials is to increase the amount of carbon black powder, but when the amount of carbon black powder added is large, due to the attraction between carbon black particles (dipole, hydrogen bond and electrostatic force), carbon black particles are easy to agglomerate during injection molding, affecting the performance of the product; in addition, when carbon black is added to a certain amount, it will also form a saturated state, and the blackness cannot be further improved. After a period of time, the material with excessive carbon black will precipitate on the surface of the part, which greatly affects the appearance of the product, as well as the blackness of the surface of the product and the clarity of laser marking. Summary of the invention

[0005] In view of the above existing technical problems, the object of the present invention is to provide a polyurethane composition which has not only high blackness but also excellent tensile modulus ratio, migration resistance and laser marking clarity after laser marking.

[0006] The second object of the present invention is to provide a method for preparing the polyurethane composition.

[0007] The third object of the present invention is to provide an application of the polyurethane composition in the field of electronic appliances.

[0008] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0009] A polyurethane composition, comprising, by weight, 80-90 parts of a thermoplastic polyurethane resin, 1.5-3.5 parts of a complex azo dye, 0.3-1.5 parts of carbon black, and 0.3-1 parts of an antioxidant; the mass ratio of the complex azo dye to the carbon black is 1:0.2-0.5; the specific surface area of ​​the carbon black is 150-250 m 2 / g; the complex metal in the complex azo dye is iron; the parent dye of the complex azo dye is formed by coupling a coupling azo dye and a diazo azo dye; wherein the coupling azo dye is a derivative of phenol and naphthol; and the diazo azo dye is selected from one or more of phenol containing a nitro group, naphthalene derivatives containing a sulfonic acid group or naphthalene derivatives containing a nitro group.

[0010] The inventors found that when the mass ratio of the complex azo dye and carbon black is controlled within a specific range and used in combination, the agglomeration and precipitation problems caused by carbon black in the polyurethane composition can be improved, and the blackness, tensile modulus, migration resistance and laser marking clarity of the prepared polyurethane composition are significantly improved. The inventors speculate that this may be due to the small particle size of the complex azo dye and the carbon black itself, the arrangement mode itself is similar to graphite, and the compatibility with the thermoplastic polyurethane composition is good, which helps to improve the dispersibility of the dye inside the matrix, and can maintain the performance of the material matrix itself as much as possible. Further, the inventors found that the complex azo dye composed of specific coupling azo dyes and diazo azo dyes has a good effect of improving the blackness, migration resistance and laser marking clarity of the composition. In addition, the inventors found that carbon black within a specific specific surface area range not only has high blackness and tinting power, but also has low viscosity and good fluidity in the polyurethane system, and thus has a good dispersion effect, which weakens the occurrence of carbon black agglomeration and precipitation to a certain extent, and can improve the various properties of the polyurethane composition. In summary, the inventors controlled the mass ratio of the complex azo dye to carbon black and the total added parts of the complex azo dye and carbon black within a specific range, and preferred hindered phenol antioxidants and specific complex azo dyes, and carbon black with a specific specific surface area range, so that the blackness of the prepared polyurethane resin material is within 25.1, the E-35℃ / E35℃ tensile modulus ratio is ≤5, and the laser marking clarity △L is ≥40.

[0011] Preferably, the total amount of the complex azo dye and carbon black added is 2.5 to 4.5 parts. The inventors further found that when the total amount of carbon black and complex azo dye added is low, the material will have a large transmittance, resulting in poor blackness and laser marking clarity of the material; and when the total amount of carbon black and complex azo dye added is high, since the amount of carbon black and complex azo dye added has reached saturation, the blackness will not increase, and the carbon black will also agglomerate, affecting the performance of the product; and too high an amount of addition will also reduce the clarity of laser marking, resulting in no marking and a significantly higher tensile modulus.

[0012] Preferably, the oil absorption value of the carbon black is in the range of 70 to 150 ml / 100 g; and / or, the mass ratio of the complex azo dye to the carbon black is 1:0.3 to 0.35, and the total added amount of the complex azo dye and the carbon black is 3.5 to 4 parts. Further preferably, the oil absorption value of the carbon black is in the range of 100 to 150 ml / 100 g. More specifically, the oil absorption value of the carbon black can be selected from 70 ml / 100 g, 80 ml / 100 g, 90 ml / 100 g, 100 ml / 100 g, 110 ml / 100 g, 120 ml / 100 g, 130 ml / 100 g, 140 ml / 100 g, 150 ml / 100 g; the oil absorption value range of the carbon black in the present application is not limited thereto.

[0013] Preferably, the specific surface area of ​​the carbon black can be selected from 150 m 2 / g,160m 2 / g,170m 2 / g, 180m 2 / g, 190m 2 / g,200m 2 / g, 210m 2 / g,220m 2 / g, 230m 2 / g,240m 2 / g,250m 2 / g; the specific surface area of ​​carbon black in this application is not limited thereto.

[0014] The test method used for the above carbon black specific surface area is: GB / T 10722-2003-Determination of total surface area of ​​carbon black-Nitrogen adsorption method. The test method used for the above carbon black oil absorption value is: GB / T 3780.2-2007-Carbon black-Part 2: Determination of oil absorption value.

[0015] Further, the coupling azo dyes are 2-naphthol and 2-amino-8-naphthol-6-sulfonic acid; the diazo azo dyes are 6-nitro-1,2-diazooxynaphthalene-4-sulfonic acid and 2-amino-4-nitrophenol. More specifically, this type of complex azo dye is commonly available in the market, such as Black X45.

[0016] Preferably, the antioxidant is a hindered phenol antioxidant. Compared with other antioxidants, hindered phenol antioxidants are more likely to form phenoxy free radicals to make the polymer relatively stable, have high thermal stability, and during laser marking, the marking process mainly forms a thermal oxidation reaction with the polyurethane composition, and better synergistic effect with the polyurethane composition makes the blackness of the composition and the marking effect clearer.

[0017] Further preferably, the hindered phenol antioxidant is selected from one or more of [r-3,5-di-tert-butylphenyl] ester, (β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, bis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl] hydrazine or 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine.

[0018] Further preferably, the hindered phenol antioxidant comprises a primary antioxidant and a secondary antioxidant; the mass ratio of the primary antioxidant to the secondary antioxidant is 1:2-3.

[0019] Further preferably, the primary antioxidant is selected from one or two of [r-3,5-di-tert-butylphenyl] ester and (β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate octadecyl alcohol ester; the secondary antioxidant is selected from one or two of bis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl] hydrazine and 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine.

[0020] Preferably, the thermoplastic polyurethane resin is selected from polyether polyurethane resins.

[0021] Preferably, the Shore hardness of the thermoplastic polyurethane resin is 70 to 85. Further preferably, the Shore hardness of the thermoplastic polyurethane resin is 70 to 80. The test standard of Shore hardness is ASTM D2240.

[0022] Preferably, the elongation at break of the thermoplastic polyurethane resin is 650-750%. Further preferably, the elongation at break of the thermoplastic polyurethane resin is 650-700%. The test standard for elongation at break is ASTM D412.

[0023] In addition, the present invention also provides a method for preparing a polyurethane composition, wherein a thermoplastic polyurethane resin, an antioxidant, carbon black and a complex azo dye are mixed and extruded into granules to obtain the polyurethane composition.

[0024] Furthermore, the raw materials are mixed uniformly at a rotation speed of 2000-3000 rpm.

[0025] Furthermore, a twin-screw extruder is used for extrusion granulation, and the aspect ratio of the twin-screw extruder is 40 to 50:1.

[0026] Furthermore, the temperature of the extrusion granulation is 160-190°C.

[0027] Furthermore, the present invention also claims the use of the polyurethane resin composition in the field of electronic appliances. Specifically, the applicable fields include but are not limited to the encapsulation materials of electric tools, protective covers of electrical appliances, etc.

[0028] Compared with the prior art, the present invention has the following beneficial effects: by controlling the mass ratio of the complex azo dye to the carbon black and the total added portions within a specific range, combining a specific type of complex azo dye and carbon black with a specific specific surface area, and compounding with a hindered phenol antioxidant, the polyurethane composition prepared not only has a higher blackness, but also has significantly improved laser marking clarity, migration resistance, and E-35°C / E35°C tensile modulus ratio. DETAILED DESCRIPTION

[0029] The present invention is further described below in conjunction with the specification and specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0030] Examples and Comparative Examples Raw Materials Description:

[0031] Polyurethane resin 1, polyether type TPU-M75, Shore hardness (ASTM D2240) is 75, elongation at break (ASTMD412) is 680%, Merrill Corporation.

[0032] Polyurethane resin 2, polyether type TPU-M85, Shore hardness (ASTM D2240) is 85, elongation at break (ASTMD412) is 695%, Merrill Corporation.

[0033] Polyurethane resin 3, polyether type TPU-M70D, Shore hardness (ASTM D2240) is 72, elongation at break is 750%, Merrill Corporation.

[0034] Polyamide resin 4, polyester type TPU-E270, Shore hardness (ASTM D2240) is 73, elongation at break (ASTMD412) is 655%, Merrill Corporation.

[0035] Dye 1: The complex metal in the complex azo dye is iron; the parent dye of the complex azo dye is prepared by coupling a coupling azo dye and a diazo azo dye; wherein the coupling azo dye is 2-naphthol and 2-amino-8-naphthol-6-sulfonic acid; the diazo azo dye is 6-nitro-1,2-diazooxynaphthalene-4-sulfonic acid and 2-amino-4-nitrophenol, brand BlackX45, BASF, Germany.

[0036] Dye 2, complex azo dye, solvent black 34, the complex azo dye adopts chrome alum complexation; the mother dye of the complex azo dye is prepared by coupling a coupling azo dye and a diazo azo dye; wherein the coupling azo dye is 2-naphthol; the diazo azo dye is 2-amino-4 (and 5)-nitrophenol, Alilan Company.

[0037] Carbon black 1, M717, DBP oil absorption value 122cc / 100g, specific surface area 200m 2 / g, Cabot.

[0038] Carbon black 2, M800, DBP oil absorption value 75cc / 100g, specific surface area 210m 2 / g, Cabot.

[0039] Carbon black 3, M1000*, DBP oil absorption value 146cc / 100g, specific surface area 310m 2 / g, Cabot.

[0040] Carbon black 4, BP570, DBP oil absorption value 114cc / 100g, specific surface area 110m 2 / g, Cabot.

[0041] Antioxidant 1: [r-3,5-di-tert-butylphenyl] ester, antioxidant 1135, Hubei Xinkang Chemical.

[0042] Antioxidant 2: (β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, antioxidant 1076, Beijing Jiyi Chemical.

[0043] Antioxidant 3: bis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, antioxidant 1024, Beijing Jiyi Chemical Company.

[0044] Antioxidant 4: 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine, antioxidant 1098, BASF.

[0045] Antioxidant 5: tris(2,4-di-tert-butylphenyl) phosphite, antioxidant 168, Henan Longji.

[0046] Unless otherwise specified, the components used in the parallel embodiments and comparative examples are all the same commercially available products.

[0047] Examples 1 to 10

[0048] The weight parts of the raw materials used in the following examples are shown in Table 1.

[0049] The following examples adopt the same preparation method, and the specific steps include:

[0050] Thermoplastic polyurethane resin, antioxidant, carbon black and complex azo dye are put into a high-speed mixer and mixed evenly at a rotation speed of 2000-3000 rpm, and then extruded and granulated at 175° C. through a twin-screw extruder with an aspect ratio of 48:1 to obtain the polyurethane composition.

[0051] Comparative Examples 1 to 7

[0052] The weight parts of the raw materials used in the following comparative examples are shown in Table 2. The specific preparation steps of each comparative example are the same as those of Example 1.

[0053] Table 1 and Table 2 are the formula components of each embodiment and each comparative example respectively.

[0054] Table 1

[0055]

[0056] Table 2

[0057]

[0058]

[0059] Testing: The embodiments and comparative examples were tested according to the following method:

[0060] Color difference test: After drying the above products in a blast oven at 80℃ for 4 hours, use an injection molding machine to mold them into a smooth color plate with a size of 83MM*54MM*2MM and no skin grain on the surface at 200℃. After cooling, use an X-rite7000A colorimeter to measure the data of the color plate under D65 light source. The color difference is expressed by L*. The smaller the L*, the higher the blackness.

[0061] Migration test: According to the method specified in EN 14469.2, the sample is pressed into a sheet to prepare a sample with a size of 50mmX50mln; the white sheet is pressed into a sheet with a size of 75mm×75mmX0.5 rain, and the white sheet contains 5% titanium dioxide. The surface of the aluminum plate or glass plate is flat, and the size is not less than the white sheet, and the load mass is not less than 500g. The oven is equipped with a hot air circulation system, which is stably kept at (80±5)℃ and a pressure roller. Visually observe the degree of contamination of the tested color sheet on the white sheet (EN20105-A03). The visual reference surface is the white edge of the white contact plate that is not in contact with the sample sheet, and the standard gray card is used for judgment. Level 5 means no migration, and level 1 means severe migration.

[0062] Tensile modulus test: The tensile modulus is measured according to the measurement method of GB / T 1040.2-2006 at a tensile rate of 50 mm / min. The main test is the ratio of the tensile modulus at -35°C to the tensile modulus at 35°C. The smaller the value, the better the material performance changes with temperature; the larger the value, the worse the performance.

[0063] Laser marking clarity test: After drying the above products in a blast oven at 80℃ for 4 hours, they were injection molded into smooth color plates with a size of 83MM*54MM*2MM and no leather grain on the surface by an injection molding machine at 200℃. The infrared laser marking equipment DPF-M30 was used for marking. After marking, the color plate data before and after marking was measured by X-rite7000A colorimeter under D65 light source. The color difference was expressed by △L. The higher the △L, the better the marking clarity.

[0064] Table 3 and Table 4 are the performance test results of each embodiment and comparative example respectively.

[0065] Table 3

[0066]

[0067]

[0068] Table 4

[0069] Test items Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 L* 26.4 27.6 25.2 25.1 25.8 25.7 27 Migration resistance level 4 4 3 5 2 3 2 Tensile modulus ratio 6.6 5.5 6.8 6.6 7.5 6.2 7 △L 17 23 36 42 33 35 25

[0070] It can be seen from the above examples that the polyurethane composition prepared by the present invention not only has excellent blackness, but also has significantly improved laser marking clarity, E-35℃ / E35℃ tensile modulus ratio and migration resistance. Its blackness is controlled within 25.1, the migration resistance is 4 to 5 levels, the E-35℃ / E35℃ tensile modulus ratio is within 5.3, and the laser marking clarity △L is above 40.

[0071] It can be seen from Example 1 and Example 2 that Example 1 preferably uses polyether polyurethane resin as the raw material, and the polyurethane composition prepared therefrom has better blackness, tensile modulus ratio and laser marking clarity.

[0072] It can be seen from Examples 3 and 4 that Example 1 uses a polyurethane resin with a Shore hardness and elongation at break within a specific range, and the polyurethane composition prepared in Example 1 has better migration resistance, tensile modulus ratio and laser marking clarity; in addition, the blackness is also slightly improved.

[0073] It can be seen from Examples 1 and 5 that Example 5 uses carbon black with a lower oil absorption value, and the migration resistance grade, tensile modulus ratio and laser marking clarity of the polyurethane composition prepared therefrom are significantly reduced.

[0074] It can be seen from Comparative Example 1, Comparative Example 2 and Example 1 that when the total amount of complex azo dye and carbon black remains unchanged, too little or too much dye will greatly affect the performance of the polyurethane composition. The blackness, tensile modulus ratio and laser marking clarity of the prepared polyurethane composition are far from those of Example 1.

[0075] It can be seen from Comparative Example 3 and Example 1 that the mass ratio of the complex azo dye to carbon black in Comparative Example 3 is the same as that in Example 1. However, the total added amount of the complex azo dye and carbon black in Comparative Example 3 is too much. The blackness, tensile modulus ratio and laser marking clarity of the polyurethane composition prepared in Comparative Example 3 are significantly different from those of the polyurethane composition in Example 1.

[0076] It can be seen from Comparative Example 4 that when other types of antioxidants are selected, the blackness, tensile modulus ratio and laser marking clarity of the prepared polyurethane composition are significantly different from those of the polyurethane composition of Example 1.

[0077] It can be seen from Comparative Examples 5 and 6 that the specific surface area of ​​carbon black has a great influence on the performance of the polyurethane composition. When the specific surface area of ​​carbon black is too large or too small, the performance of the polyurethane composition will be greatly affected, and the corresponding effects of the blackness, migration resistance grade, tensile modulus ratio and laser marking clarity of the polyurethane composition will deteriorate.

[0078] It can be seen from Comparative Example 7 that when a complex azo dye formed by coupling other coupling azo dyes and diazo azo dyes is used, the above-mentioned effects of the present invention cannot be achieved, and the blackness, migration resistance grade, tensile modulus ratio and laser marking clarity of the polyurethane composition prepared in Comparative Example 7 become worse.

[0079] The foregoing embodiments are merely illustrative and are used to explain some features of the method of the present invention. The appended claims are intended to require the widest possible range that can be imagined, and the embodiments presented herein are demonstrated by the applicant's actual test results. Therefore, the applicant's intention is that the appended claims are not limited by the selection of examples that illustrate the features of the present invention. Some numerical ranges used in the claims also include sub-ranges within them, and changes in these ranges should also be interpreted as being covered by the appended claims where possible.

Claims

1. A polyurethane composition, characterized in that Calculated by weight, it includes 80-90 parts of thermoplastic polyurethane resin, 1.5-3.5 parts of complex azo dye, 0.3-1.5 parts of carbon black, and 0.3-1 part of antioxidant; The mass ratio of the complex azo dye to carbon black is 1:0.2-0.5; the specific surface area of ​​the carbon black is 150-250m 2 / g; the complex metal in the complex azo dye is iron; the parent dye of the complex azo dye is formed by coupling a coupling azo dye and a diazo azo dye; wherein the coupling azo dye is a derivative of phenol and naphthol; the diazo azo dye is selected from one or more of phenol containing a nitro group, a naphthalene derivative containing a sulfonic acid group or a naphthalene derivative containing a nitro group; The antioxidant is a hindered phenol antioxidant.

2. The polyurethane composition according to claim 1, characterized in that: The total added amount of the complex azo dye and carbon black is 2.5 to 4.5 parts.

3. The polyurethane composition according to claim 1, characterized in that: The oil absorption value of the carbon black is in the range of 70 to 150 ml / 100 g; and / or, The mass ratio of the complex azo dye to carbon black is 1:0.3-0.35, and the total added amount of the complex azo dye and carbon black is 3.5-4 parts.

4. The polyurethane composition according to claim 1, characterized in that: The coupling azo dyes are 2-naphthol and 2-amino-8-naphthol-6-sulfonic acid; the diazo azo dyes are 6-nitro-1,2-diazooxynaphthalene-4-sulfonic acid and 2-amino-4-nitrophenol.

5. The polyurethane composition according to claim 1, characterized in that: The thermoplastic polyurethane resin is selected from polyether polyurethane resins.

6. The polyurethane composition according to claim 1, characterized in that: The Shore hardness of the thermoplastic polyurethane resin is 70-85.

7. The polyurethane composition according to claim 1, characterized in that: The elongation at break of the thermoplastic polyurethane resin is 650-750%.

8. The method for preparing the polyurethane composition according to any one of claims 1 to 7, characterized in that: Thermoplastic polyurethane resin, antioxidant, carbon black and complex azo dye are mixed and extruded into granules to obtain the polyurethane resin composition.

9. Use of the polyurethane composition according to any one of claims 1 to 7 in the field of electronic appliances.

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