The hottest thermoplastic polyurethane stabilizer

when thermoplastic polyurethane is processed into ordinary thermoplastic resin, it is elastic. Like most industrial compounds, polyurethane will degrade after heating; Polyurethane extracted from aromatic diphenylmethane diisocyanate is also particularly sensitive to light

polyurethane will be degraded by heat and light in the process of production, processing, storage and final use, which will lead to the reduction of physical and mechanical properties of polyurethane and the fading of polyurethane products. The free radicals produced by the thermal degradation of polyurethane can destroy the structure of the composite by spreading in polyurethane materials. Exposed to air, the formation of by-products such as peroxides further exacerbated the degradation of the complex

thermoplastic polyurethane widely used in the market is mainly made of ethylene glycol chain extension products such as dimethyl [4-isocyanophenyl], diphenylmethane diisocyanate, linear polyether, polyester polyol or 1,4-butanediol

according to the data, the oxidation of the soft segment is the main reason for the aging of polyether polyurethane. Thermal degradation and photooxidation are the reasons for the aging of diphenylmethane diisocyanate. Hydrogen peroxide formed by photooxidation has a unique structure, while photodegradation generates benzophenone derivatives from methylene

the purpose of this paper is to explain how the innovative stabilizer system can improve the performance of thermoplastic polyurethane in synthesis and processing, so as to prolong the service life of terminal products and expand the application range of thermoplastic polyurethane. Thermoplastic polyurethane can have a wide range of properties through different processing methods: from high hardness materials to very soft and non plastic tactile materials with high flexibility and toughness, as well as special materials with anti-seismic, anti-skid and anti-wear properties. Because of this series of properties, thermoplastic polyurethane is widely used in car instrument panels and some internal parts in the automotive industry. In addition, it is also used in conveyor belts, hoses, oil pipes, wires and cables and other fields

thermoplastic polyurethane is playing an increasingly important role in the production of sports shoes and casual shoes. A series of unique properties of thermoplastic polyurethane, such as excellent wear resistance, low density, high elasticity and flexibility, make it the best material for producing thinner and lighter soles

in addition, thermoplastic polyurethane can be well bonded with most shoe production materials, which is the main reason why we use this material: it can make shoes have light resistance, in other words, prevent shoes from yellowing. Because of this, we can design bright and fashionable colors on shoes, such as shoelaces or trademarks

this paper describes how the new light stabilizer tinuvinpur 866 gives thermoplastic polyurethane excellent initial color and color retention performance under light exposure. This is the most fundamental demand in the continuously developing field of sports shoes and casual shoes production

experiment

thermoplastic polyurethane without stabilizer (aromatic polyether type)

◆ sample preparation

after grinding and drying, the thermoplastic polyurethane without stabilizer is compounded into samples by adding additives in a twin-screw extruder at 180 ℃. Samples (2mm plate and dumbbell type) are made by injection molding at 190 ℃

◆ test methods and conditions

under the aging conditions of 135 ℃ and 150 ℃, the processing stability and long-term thermal stability can be tested by circulating air oven

detect the initial color and fading process of the sample through DIN 5033 (ASTM 1925). The light stability of the sample can be tested by exposing it to xenon lamp (ASTM g 155, 65 ℃ black panel temperature, 340 nm, 0.35 w/m2) or vitalux 300 lamp (ASTM D 1148,50 ℃)

the gray value of the sample is tested under AATCC

the elongation of the sample is tested by ISO 527 and DIN 53504

results and discussion

adding antioxidants and reaction stabilizers in the synthesis process or thermoplastic processing process of thermoplastic polyurethane can enhance the mechanical properties and color retention of thermoplastic polyurethane, so as to improve the thermal degradation resistance and color retention performance of thermoplastic polyurethane

in the production and application of thermoplastic polyurethane, such as the production of sports shoes and casual shoes, keeping colorfastness and visual appeal under light are crucial properties. Therefore, we use the same method to add photodegradation stabilizer to thermoplastic polyurethane to enhance the above properties

◆ durability of the composite

★ processing stability

before we discuss the various special properties of thermoplastic polyurethane after adding additives, such as photodegradation stability or antibacterial activity, we should know that the composite needs special protection during synthesis and/or processing to avoid degradation reaction

the thermal stability of thermoplastic polyurethane is significantly enhanced after the use of phenolic antioxidants such as Ciba irganox1076 or Irganox 245. The use of synergist can further improve the thermal stability of the composite. The mixed use of synergists composed of phosphite and thioether and phenolic antioxidants has been reported in the literature. The best mixing ratio of phenolic antioxidants and synergists is determined according to different substrates

as shown in Figure 1, synergists can also be observed in polyurethane, which shows that the sample block has the initial color after processing and injection molding. After processing and injection molding, the stabilizer dosage of 2mm sample block is 0.5%, and the mixing ratio of phosphite and phenol is 2/1

as shown in the bar graph, the antioxidant mixed with phenolic and phosphite has the best initial color effect. Among the phosphite esters currently used in the market, cibairgafos 126 can provide the best initial color effect for thermoplastic polyurethane. Figure 2 shows the 2mm plaque after processing and injection molding. The amount of stabilizer is 0.5%, and the mixing ratio of phosphite and phenol is 2/1

◆ long term thermal stability

test the long-term thermal stability of the sample through the oven aging process, and the test results are shown in Figure 3. The discoloration of the thermoplastic polyurethane sample without stabilizer is obvious (in Figure 3, the thermoplastic polyurethane patch is 2mm, the amount of stabilizer is 0.5%, and the mixing ratio of phosphite and phenols is 2/1)

in the test, we also found that the phenolic antioxidant with phosphite synergist has the best stability effect. As shown in Figure 4, the mixture of Irganox I010 and Irgafos 126 shows the best long-term thermal stability and is conducive to the mechanical properties of aging thermoplastic polyurethane patches (thermoplastic 3 in Figure 4, tensile test motor: the amount of elongation stabilizer is 0.5%, and the mixing ratio of phosphite and phenol is 2/1)

★ light stability

when ordinary thermoplastic polyurethane (aromatic hydrocarbon) is exposed to sunlight, the fading phenomenon is quite serious. The fading phenomenon can be effectively inhibited by adding UV stabilizers, such as benzophenone, benzotriazole and sterically hindered amine. When it is necessary to maintain the stability of bright colors in application, the dosage of UV stabilizer is 1 part. The new aliphatic thermoplastic polyurethane has no fading phenomenon, but its mechanical properties are easy to weaken. The main application field of thermoplastic polyurethane - footwear industry is sports shoes that require high performance. Trademarks, badges, soles, rivets and other components can be made of thermoplastic polyurethane. The inlays made of thermoplastic polyurethane on the bearing parts of sports shoes, airbags, energy recovery systems, badges and trademarks are increasingly welcomed by people to make full use of the advantages of composite materials

compared with other thermoplastic elastomers, thermoplastic polyurethane is a good substitute, especially in the sports shoe industry. However, if there are requirements for the UV resistance of materials, we must use light stabilizer system to modify aromatic thermoplastic polyurethane or directly use alkane thermoplastic polyurethane. And those terminal applications that require materials to remain transparent have the greatest demand for UV stabilizer systems

this high-performance material needs to find a light color light stabilizer system to improve the visual effect of the final product. In view of the above considerations, only by developing a light stabilizer system with a very light initial color and can keep the color unchanged for a long time, can it be applied to transparent thermoplastic polyurethane

we can combine UV absorber (UVA) and sterically hindered amine light stabilizer (HALS) on antioxidants to improve the light stability of thermoplastic polyurethane. The synergistic effect of UVA and HALS has been reported in the literature. This effect is often observed for thermoplastic polyurethane

some UV stabilizers will be slightly yellow. When they are used in polymer materials, especially those with very light and transparent color, it will obviously affect the initial color of the material

tinuvin pur 866 this innovative light stabilizer system is mainly used in thermoplastic polyurethane for sports clothing, aiming to eliminate the shortcomings of possible discoloration, because this stabilizer will not change the initial color of thermoplastic polyurethane, and can improve the color retention of materials at the same time

the good performance of tinuvin pur866 in polyester thermoplastic polyurethane has also been reported recently. A paper published at uretech API (Orlando, Florida) in 2007 compared tinuvin pur 866 with the new tinuvin 328/tinuvin 622 stabilizer system and another well-known organic light stabilizer in the market, and described in detail how tinuvin pur 866 showed superior initial color and color retention when used in aromatic polyester polyurethane system. The filling amount of stabilizer in normal system is generally 1%, but for this new light stabilizer, even if its filling amount is reduced to 0.5%, its performance is still better than other stabilizers

this paper describes the effect of tinuvin pur 866 in aromatic polyether polyurethane when the filling amount is 0.5%. Compared with polyester polyurethane, polyether polyurethane is more sensitive to the degradation of soft segments. In this paper, the new stabilizer system of tinuvin 328/tinuvin 770 with uva/hals synergistic effect and another well-known competitive product in the market (an organic light stabilizer, we call it "competitive LS" here) are used as the control samples, and the performance level of tinuvin pur 866, a new stabilizer system, is evaluated in detail. All the data mentioned below are measured when the light stabilizer filling amount is 0.5% (mass ratio)

the color retention of colored thermoplastic polyurethane modified with tinuvin pur 866 will also be described below

◆ initial color

in Figure 5, after mixing and molding, we measured the initial color of the thermoplastic polyurethane template. The amount of processing stabilizer is 0.5%, the amount of light stabilizer is 0.5%, and the ratio of uva/hals is 1/1

from figure