Ultraviolet-resistant stable TPU color master batch and preparation method thereof

Abstract

The invention relates to an ultraviolet-resistant stable TPU (thermoplastic polyurethane) color master batch and a preparation method thereof, and the ultraviolet-resistant stable TPU color master batch comprises the following components in percentage by weight: 40-50% of TPU resin, 2-2.5% of a lubricant and 7-8% of a light stabilizer, 0.3%-0.5% of antioxidant, 0%-45% of coloring agent, 2%-3% of filler and 0.5%-1.5% of dispersing agent; the light stabilizer comprises an ultraviolet light absorber (UVA) and a hindered amine light stabilizer (HALS), and the weight ratio of the ultraviolet light absorber (UVA) to the hindered amine light stabilizer (HALS) is (2.5: 1)-(3: 1); the TPU resin is a weather-resistant aliphatic TPU resin; the coloring agent comprises any one or combination of titanium dioxide, quinacridone organic pigment and DPP organic pigment, and the surface of the titanium dioxide is coated with silicon dioxide or aluminum oxide. The TPU color master batch is stable in ultraviolet resistance, controllable in quality in the preparation process and excellent in comprehensive use effect.

Description

Technical Field

[0001] The invention relates to the technical field of masterbatch production, in particular to an ultraviolet-resistant and stable TPU masterbatch and a preparation method thereof. Background Art

[0002] Thermoplastic polyurethane (TPU) masterbatches, a key material for coloring plastic products, are widely used in applications such as automotive exteriors, outdoor cables, and building components that are exposed to long-term UV radiation. However, traditional TPU masterbatches are susceptible to molecular chain breakage, pigment degradation, and color migration under UV radiation, leading to fading, embrittlement, and performance degradation in finished products, severely limiting their lifespan in harsh outdoor environments.

[0003] Existing TPU masterbatches have significant defects in formulation and process: First, insufficient weather resistance. Traditional TPU masterbatches tend to fade and crack quickly under ultraviolet light conditions and cannot meet the needs of long-term outdoor use. For example, masterbatches using aromatic TPU and a single light stabilizer have large color differences and low gloss retention after ultraviolet light exposure; second, poor performance controllability. Due to unreasonable process parameters in the preparation process, problems such as uneven pigment dispersion and light stabilizer inactivation are prone to occur, resulting in fluctuations in masterbatch quality; third, the overall use effect is poor, and it is difficult to achieve a balance between high-temperature processing stability, mechanical properties and weather resistance protection, which limits its promotion in high-end application scenarios. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a UV-resistant and stable TPU masterbatch and a preparation method thereof, which achieves the effects of TPU masterbatch being UV-resistant and stable, quality controllable during the preparation process, and excellent comprehensive use effect.

[0005] The above-mentioned object of the present invention is achieved through the following technical solutions: A UV-resistant and stable TPU masterbatch, comprising the following components in weight percentage: 40% to 50% TPU resin, 2% to 2.5% lubricant, 7% to 8% light stabilizer, 0.3% to 0.5% antioxidant, 0% to 45% colorant, 2% to 3% filler, and 0.5% to 1.5% dispersant; The light stabilizer includes an ultraviolet absorber (UVA) and a hindered amine light stabilizer (HALS), and the weight ratio of the ultraviolet absorber (UVA) to the hindered amine light stabilizer (HALS) is (2.5:1) to (3:1); The TPU resin is a weather-resistant aliphatic TPU resin; the colorant includes any one or a combination of titanium dioxide, quinacridone organic pigments, and DPP organic pigments, the surface of which is coated with silicon dioxide or aluminum oxide.

[0006] Through the above technical solution, the UV-resistant and stable TPU masterbatch adopts 40% to 50% of weather-resistant aliphatic TPU resin, and utilizes its molecular chain characteristics without aromatic structure to avoid the risk of degradation caused by ultraviolet rays. It is matched with 7% to 8% of the light stabilization system composed of ultraviolet absorber (UVA) and hindered amine light stabilizer (HALS) in a ratio of (2.5:1) to (3:1) to form a synergistic protection mechanism of "ultraviolet light absorption-excited state quenching". At the same time, colorants with a weather resistance grade of ≥7 are selected (including titanium dioxide with a surface coated with silica or alumina to inhibit photocatalytic oxidation, and quinacrine with intramolecular hydrogen bonds or π-π conjugated structures). The addition of lubricants, antioxidants, fillers, and dispersants ensures processing fluidity and mechanical properties without affecting the efficiency of the light stabilization system, ultimately giving the masterbatch excellent light stability, strong color retention, and minimal color difference after long-term UV exposure. It also has outstanding thermal stability and is not prone to color change in high-temperature processing and use environments, meeting the needs of long-term use in harsh outdoor climates, as well as demanding applications such as wire and cable insulation coloring, which require strict weather and heat resistance.

[0007] As a further technical solution of the present invention: the ultraviolet absorber (UVA) is a benzotriazole compound, and the hindered amine light stabilizer (HALS) is an N-alkoxy hindered amine.

[0008] Through the above technical solution, UVA is limited to a compound of benzotriazole compounds and N-alkoxy HALS. The alkoxy substituents enhance the compatibility with TPU and inhibit photooxidative degradation by capturing free radicals and decomposing hydroperoxides. The combination of the two improves the dispersion uniformity of the light stabilizer in the TPU matrix, solves the phase separation problem of the light stabilizer, and has a relatively improved light aging resistance compared to ordinary HALS systems, ensuring that the masterbatch remains stable even under long-term use in strong light environments.

[0009] As a further technical solution of the present invention: the filler is precipitated barium sulfate with a particle size of 0.1-5 μm, and the surface is treated with a silane coupling agent.

[0010] Through the above technical solution, by using precipitated barium sulfate with a particle size of 0.1-5μm and surface treatment with a silane coupling agent, a strong interface bond can be formed between the barium sulfate and the TPU matrix, eliminating interfacial voids and improving the uniformity of filler dispersion, thereby avoiding cracking caused by interfacial stress concentration under ultraviolet irradiation; at the same time, this filler system can also effectively enhance the tensile strength of the masterbatch without affecting the ultraviolet absorption efficiency of the light stabilizer, thereby achieving synergistic optimization of weather resistance and mechanical properties.

[0011] On the other hand, the present invention also discloses a method for preparing a UV-resistant and stable TPU masterbatch, comprising the following steps: Step 1: Premix TPU resin, colorant, filler, dispersant and lubricant in an inert atmosphere with an oxygen content of ≤30ppm; Step 2: Feed the premix into the main feed port of the twin-screw extruder, and add the light stabilizer and antioxidant into the melting section through the side feed port; Step 3: melt extrusion granulation under vacuum exhaust, the vacuum exhaust is provided with a first-stage vacuum and a second-stage vacuum, the first-stage vacuum degree is -0.095 MPa, used for removing moisture and low-boiling substances; the second-stage vacuum degree is -0.1 MPa, used for removing thermal degradation products with a molecular weight of ≤200; Step 4: The extruded material strips are quenched with cooling water ≤ 25°C and pelletized, and the obtained pellets are nitrogen-filled and sealed.

[0012] Through the above technical solutions, the inert atmosphere premixing process strictly controls the oxygen content, effectively isolating the oxygen from oxidizing the raw materials and blocking the occurrence of photocatalytic oxidation reactions of pigments from the source; the side feeding technology in the melting section accurately controls the timing of adding light stabilizers and antioxidants, avoiding thermal decomposition of additives due to high temperature during the premixing stage, ensuring that they remain highly active in the system; the two-stage vacuum exhaust process directionally removes moisture, low-boiling substances and small-molecule thermal degradation products in the system, eliminates impurities that affect weather resistance, and improves the purity of the masterbatch matrix; low-temperature rapid cooling pelletizing combined with nitrogen-filled sealed packaging stabilizes the microscopic dispersion structure of the light stabilizer in the TPU matrix through rapid curing and inert environment sealing, preventing performance degradation during use and storage, and ensuring the stability and consistency of the masterbatch light resistance level in multiple dimensions.

[0013] As a further technical solution of the present invention: the inert gas in step 1 is nitrogen.

[0014] Through this technical solution, nitrogen is selected as the inert gas in step one. Leveraging its excellent chemical inertness and cost-effectiveness, it effectively isolates oxygen during the premixing stage, significantly slowing the oxidation reaction between the TPU resin and additives. This effectively prolongs the TPU's oxidation induction time, fundamentally suppressing molecular chain degradation and additive failure caused by oxidation during the premixing process. This ensures the chemical stability of the raw material system in the high-temperature premixing environment, laying a solid foundation for achieving the subsequent weatherability of the masterbatch.

[0015] As a further technical solution of the present invention: the temperature of the melting section in step 2 is 200±5°C, and the screw shear rate is ≥500s -1 .

[0016] Through the above technical solution, in step 2, the melting section temperature is controlled within a reasonable range above the melting point of TPU (HMDI-PBA system), ensuring that the TPU resin forms a uniform phase system with the pigment and light stabilizer after complete melting. The high-shear screw design effectively destroys pigment agglomerates, significantly improving dispersion uniformity and avoiding localized weather resistance defects caused by uneven pigment dispersion. The resulting masterbatch exhibits excellent performance consistency under ultraviolet irradiation and does not suffer from problems such as localized fading or cracking.

[0017] In summary, the present invention includes at least one of the following beneficial technical effects: 1. The present invention discloses a UV-resistant, stabilized TPU masterbatch. This UV-resistant, stabilized TPU masterbatch utilizes a collaborative design of a weather-resistant TPU resin matrix, a light-stabilizing compounding system, and a highly weather-resistant colorant to create a three-in-one weathering protection mechanism: a weather-resistant aliphatic TPU resin is used to mitigate the risk of UV degradation through its aromatic-free molecular chain; a UV absorber and a hindered amine light stabilizer are compounded in a specific ratio to create a synergistic "UV absorption-excited state quenching" network; and surface-coated titanium dioxide and weather-resistant organic pigments are used to inhibit photocatalytic oxidation and pigment migration. This solution effectively addresses the issues of traditional TPU masterbatches, which are prone to fading and poor weather resistance under UV conditions, while ensuring processing fluidity and mechanical properties. It is suitable for applications with stringent weather resistance requirements, such as outdoor cables and automotive parts.

[0018] 2. The present invention discloses a method for preparing UV-resistant and stable TPU masterbatch, which achieves synergistic optimization of weather resistance and processing stability through four process innovations: inert atmosphere premixing blocks the source of oxidative degradation, precise temperature control and high shear force in the melting stage ensure uniform dispersion of pigments and additives, two-stage vacuum exhaust directionally removes impurities that affect weather resistance, and rapid cooling and pelletizing and nitrogen-filled packaging freeze the nano-scale dispersion state, thereby solving problems such as local weather resistance defects caused by thermal decomposition of light stabilizers and pigment agglomeration, ensuring that the prepared masterbatch has uniform and stable performance under ultraviolet irradiation, and avoiding fading, cracking, and other phenomena that are prone to occur in traditional processes. DETAILED DESCRIPTION

[0019] The technical solutions of the embodiments of the present application will be described clearly and completely below; obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0020] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "provided with," "mounted / connected," and "connected" should be understood in a broad sense. For example, "connected" can mean a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0021] Example 1: This embodiment provides a UV-resistant and stable TPU masterbatch, comprising the following components in weight percentage: 50% weather-resistant aliphatic TPU resin (soft segment PBA, hard segment HMDI); 5% benzotriazole UVA (UV-328), 2% N-alkoxy HALS (Tinuvin770) (UVA:HALS=2.5:1); 36% silica-coated titanium dioxide (weather resistance grade 7); 2% zinc stearate; 0.5% hindered phenol (1010); 3% silane-treated barium sulfate (0.1-5μm); and 1.5% EVA-g-MAH.

[0022] Example 2: Different from Example 1, in this example, the soft segment of the TPU resin is replaced by PCDL from PBA, and the TPU resin content is reduced to 45%; the UVA content in the light stabilizer is increased to 6% (total 8%), and the compounding ratio is adjusted to 3:1; the colorant is replaced by quinacridone organic pigment from inorganic titanium dioxide, with a content of 41.7%.

[0023] Specific components (weight percentage): weather-resistant aliphatic TPU resin (soft segment PCDL, hard segment HMDI) 45%; benzotriazole UVA (UV-326) 6%, N-alkoxy HALS (Chimassorb944) 2% (UVA:HALS=3:1); quinacridone red (weather resistance grade 8) 41.7%; ethylene bisstearamide (EBS) 1.5%; phosphites (168) 0.3%; silane-treated barium sulfate 2%; oleamide 1%; EVA-g-MAH 0.5%.

[0024] Example 3: Different from Example 1, in this example, the TPU resin content is reduced to 40% and the colorant content is increased to 45%; the colorant is replaced with a DPP organic pigment to verify the high-concentration boundary performance.

[0025] Specific components (weight percentage): weather-resistant aliphatic TPU resin 40%; benzotriazole UVA 6%, N-alkoxy HALS 2% (UVA:HALS=3:1); DPP organic pigment (weather resistance grade 8) 45%. Other components are the same as in Example 1.

[0026] Example 4: This embodiment provides a method for preparing a UV-resistant and stable TPU masterbatch, comprising the following steps: Step 1: Mix the components of Example 1 in nitrogen (oxygen content ≤ 20 ppm) at 1000 rpm for 8 minutes; Step 2: Twin-screw extruder melting section temperature 200±5℃, screw shear rate 550s -1 , light stabilizer and antioxidant are added by side feed; Step 3: Vacuum exhaust, first stage -0.095MPa (dehydration), second stage -0.1MPa (removal of small molecules); Step 4: Pelletize, quench with 20℃ cooling water, and seal with nitrogen.

[0027] Comparative Example 1: Different from Example 1, this comparative example replaces the aliphatic TPU resin with an aromatic TPU; the light stabilizer is changed from a blended system to a single UVA; and the colorant is replaced with uncoated titanium dioxide (Weatherproof Grade 6). Specific components (weight percentage): aromatic TPU (containing a benzene ring structure) 50%; single benzotriazole UVA (no HALS blend) 7%; uncoated titanium dioxide (Weatherproof Grade 6) 36%; other components are the same as in Example 1.

[0028] Comparative Example 2: Unlike Example 1, this comparative example changes the UVA:HALS ratio in the light stabilizer from 2.5:1 to 1:1. Specific components (weight percentage): light stabilizer (3.5% benzotriazole UVA, 3.5% N-alkoxy HALS). Other components are the same as in Example 1.

[0029] Comparative Example 3 In this comparative example, the inert atmosphere premixing and vacuum exhaust process steps are omitted, and the other steps are the same as those in Example 4.

[0030] Application examples: Application Example 1: Masterbatch 1 was prepared using the UV-resistant and stable TPU masterbatch components described in Example 1 by the preparation method described in Example 4. Application Example 2: Masterbatch 2 was prepared using the UV-resistant and stable TPU masterbatch components described in Example 2 by the preparation method described in Example 4. Application Example 3: Using the components of the UV-resistant and stable TPU masterbatch described in Example 3, masterbatch 3 was prepared by the preparation method described in Example 4; Application Example 4: Using the components of the UV-resistant and stable TPU masterbatch described in Comparative Example 1, masterbatch 4 was prepared by the preparation method described in Comparative Example 3; Application Example 5: Using the components of the UV-resistant and stable TPU masterbatch described in Comparative Example 2, masterbatch 5 was prepared by the preparation method described in Example 4; Application Example 6: Masterbatch 6 was prepared using the composition of the UV-resistant and stable TPU masterbatch described in Example 1 by the preparation method described in Example 3.

[0031] Weathering performance test is carried out according to GB / T16422.2-1999 "Determination of light resistance of plastic masterbatch" 1. Test conditions: UVA lamp irradiance of 0.6W / m²; duration of 500 hours; evaluation indicators: light resistance level (0-8), color difference ΔE, and gloss retention.

[0032] 2. Sample preparation: Take 10g of each of the masterbatches 1-6, add 100ml of deionized water and stir, take 10ml and place it in a test tube, the liquid column height is 2.8cm.

[0033] 3. Test results This experiment focuses on the formulation design and preparation process of UV-resistant and stable TPU masterbatch. Through performance tests of multiple sets of examples and comparative examples, the advantages of the technical solution of the present invention are systematically verified. The core conclusions are as follows: 1. The decisive role of ingredient design on weather resistance (Masterbatch 1 vs. Masterbatch 4 / 5) Comparison objects: Masterbatch 1 (Example 1, aliphatic TPU resin + coated titanium dioxide + UVA:HALS = 2.5:1); Masterbatch 4 (Comparative Example 1, aromatic TPU + uncoated titanium dioxide), Masterbatch 5 (Comparative Example 2, UVA:HALS = 1:1) Test performance: Masterbatch 1 has a light resistance level of 7-8 (ΔE<0.8), masterbatch 4 has a light resistance level of 5-6 (ΔE>2.0), and masterbatch 5 has a light resistance level of 5-6 (ΔE=1.5), with significant performance differences.

[0034] Conclusion: The compounding ratio of aliphatic TPU resin structure, coated pigment (such as coated titanium dioxide) and light stabilizer (UVA:HALS) (2.5:1) is the core factor in achieving a weather resistance grade ≥7, which directly determines key properties such as light resistance and color difference.

[0035] 2. The criticality of process control to performance (Masterbatch 1 vs. Masterbatch 6) Comparison objects: Masterbatch 1 (Example 4, inert gas premixing + two-stage vacuum + high shear process); Masterbatch 6 (Comparative Example 3, omitting the inert gas and vacuum processes) Test performance: Masterbatch 1 has a light resistance level of 7-8 (ΔE<0.8), while masterbatch 6 has a light resistance level of 6 (ΔE=1.2), and the gloss retention rate is <75%.

[0036] Conclusion: High-shear process innovations such as inert gas premixing and two-stage vacuum can block the deactivation path of light stabilizers and ensure the realization of weather resistance performance; process defects will directly lead to a decrease in light resistance level and gloss retention, highlighting the criticality of process control to performance realization.

[0037] 3. Boundary ratio and feasibility of high-performance materials (Masterbatch 2 and Masterbatch 3) Comparison objects: Masterbatch 2 (Example 2, PCDL soft segment + quinacridone pigment, TPU resin / colorant ratio within the specified range of this invention); Masterbatch 3 (Example 3, 40% DPP pigment, extreme ratio formula) Test performance: Masterbatch 2 has a light resistance of 7-8 (ΔE<0.7), and masterbatch 3 has a light resistance of 7 (ΔE=0.9), both meeting the weather resistance requirement of ≥7.

[0038] Conclusion: The component ratio range of the present invention (TPU resin 40%-50%, colorant 0%-45%) is completely feasible. Even with extreme ratio formulas (such as masterbatch 3), weather resistance can still be guaranteed, verifying the rationality of the formula ratio boundary and the adaptability of high-performance materials.

[0039] 4. Warning of synergistic failure mechanism (Masterbatch 4) Comparison object: Masterbatch 4 (simultaneous destruction of components: aromatic TPU; process: no vacuum) Test performance: Light resistance level 5-6, ΔE>2.0, gloss <60% and cracking, with complete performance collapse.

[0040] Conclusion: The technical solution needs to be supported by a double closed loop of "ingredient design + process control". The lack of any link (such as unreasonable ingredients + mismatched processes) will lead to a significant decrease in weather resistance, highlighting the necessity of a systematic technical solution.

[0041] In summary, this invention forms an inseparable technical system through component design (aliphatic TPU + coated titanium dioxide / quinacridone / DPP + UVA:HALS = 2.5:1-3:1) and process control (inert gas premixing + side feeding in the melt stage + two-stage vacuum + high shear). The components are the foundation of weather resistance and determine the upper limit of performance; the process ensures the realization of performance and blocks the deactivation pathway. The two work together to support each other; the lack of any one link will result in a 1-2 level drop in weather resistance. Application Examples 1-3 (light resistance ≥ Level 7, ΔE < 1.0) consistently meet the standards, verifying the effectiveness of the technical system and providing a reliable path for the industrialization of TPU masterbatch.

[0042] The embodiments of this specific implementation method are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the scope of protection of the present invention.

[0043] Vacuum + high shear) form an inseparable technical system. The ingredients are the foundation of weather resistance and determine the upper limit of performance; the process ensures the realization of performance and blocks the deactivation pathway. The two work together to support each other. Missing any one link will result in a 1-2 level drop in weather resistance. The consistent compliance of Application Examples 1-3 (light resistance ≥ Level 7, ΔE < 1.0) verifies the effectiveness of the technical system and provides a reliable path for the industrialization of TPU masterbatch.

[0044] The embodiments of this specific implementation method are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A UV-resistant and stable TPU masterbatch, characterized in that: The invention comprises the following components in weight percentage: TPU resin 40% to 50%, lubricant 2% to 2.5%, light stabilizer 7% to 8%, antioxidant 0.3% to 0.5%, colorant 0% to 45%, filler 2% to 3%, dispersant 0.5% to 1.5%; The light stabilizer includes an ultraviolet absorber and a hindered amine light stabilizer, and the weight ratio of the ultraviolet absorber to the hindered amine light stabilizer is (2.5:1) to (3:1); The TPU resin is a weather-resistant aliphatic TPU resin; the colorant has a weather resistance grade of ≥7, and the colorant includes any one or a combination of titanium dioxide, quinacridone organic pigments, and DPP organic pigments whose surfaces are coated with silica or alumina.

2. The UV-resistant and stable TPU masterbatch according to claim 1, characterized in that: The ultraviolet absorber is a benzotriazole compound, and the hindered amine light stabilizer is an N-alkoxy hindered amine.

3. The UV-resistant and stable TPU masterbatch according to claim 1, characterized in that: The filler is precipitated barium sulfate with a particle size of 0.1-5 μm, and the surface of the filler is treated with a silane coupling agent.

4. A method for preparing the UV-resistant and stabilized TPU masterbatch according to claim 1, characterized in that: The following steps are involved: Step 1: Premix TPU resin, colorant, filler, dispersant and lubricant in an inert gas with an oxygen content of ≤30ppm; Step 2: Feed the premix into the main feed port of the twin-screw extruder, and add the light stabilizer and antioxidant into the melting section through the side feed port; Step 3: melt extrusion granulation under vacuum exhaust, the vacuum exhaust is provided with a first-stage vacuum and a second-stage vacuum, the first-stage vacuum degree is -0.095 MPa, used for removing moisture and low-boiling substances; the second-stage vacuum degree is -0.1 MPa, used for removing thermal degradation products with a molecular weight of ≤200; Step 4: The extruded material strips are quenched with cooling water ≤ 25°C and pelletized, and the obtained pellets are nitrogen-filled and sealed.

5. The method for preparing a UV-resistant and stable TPU masterbatch according to claim 4, characterized in that: The inert gas in step 1 is nitrogen.

6. The method for preparing a UV-resistant and stable TPU masterbatch according to claim 4, characterized in that: The temperature of the melting section in step 2 is 200±5°C, and the shear rate of the twin screw is ≥500s -1 .