High performance and high quality labor sole
Polyurethane elastomer applications in high-performance footwear for nearly 40 years. During this period, because of its diversity in the sole application of formula, low weight selection and exceptional durability and other characteristics, such material is increasingly being accepted. In the mid-1990s, the use of new applications such as thermoplastic polyurethane polyurethane range of options leaving a marked increase. In the past we reported that Huntsman's pioneering action - the introduction of new, more flexible polyurethane products and new production methods, such as dual-density PU / TPU sole solution, we also briefly describe the time of the new low-density, injection-type Thermoplastic polyurethane and other products.
Since then, research and development to the growing ranks of new products, including soft, without plasticizer, and optionally with a variety of features and an improved processing of thermoplastic polyurethane foam material. Most importantly, Huntsman Corporation for the footwear industry with a stable, single component of the complex, by simplifying the handling, storage and logistics, to thermoplastic polyurethane products in a number of high-quality, high performance soles and related applications in more acceptance and recognition. The purpose of this field of thermoplastic polyurethane foam for the review of the most important achievements, describe and demonstrate its features and advantages of the unique quality of these products, to illustrate the Huntsman Corporation for the footwear industry change and development efforts.
Product Description
In detail, let us first take a look at these new materials. Huntsman's thermoplastic polyurethane foam product line has been used SmartLite (r) brand. Table 1 shows the SmartLite (r) family of products typical features. From the table we can see, the first time since its inception in the late 1990s, its density and hardness range have a significantly expanded. Moreover, the range of processing these materials, there are many larger, they can now be injection molding, thermoforming and extruded into a film or other forms of machining operations. In sheet extrusion applications, its density can be as low as 0.4 g / cc. The chemical composition of different grades of products are also extended to the polyether and polyester products. All polyurethane materials typically is that: they can be very good with other building materials compatible with, and without pre-or post-processing operations can have adhesion.
In addition to the superior characteristics of these materials make it a popular sole material, its beautiful appearance but also make them increasingly recognized footwear applications, the soft, velvety texture, light weight and design freedom. Because of these reasons, choose SmartLite (r) foam material made of thermoplastic polyurethane soles, in a variety of applications to produce high-quality shoes.
Unique product performance
◆ durability
The durability of the sole material usually through wear (ie DIN53516) measured. Can be seen from Table 1, these materials show a typical polyurethane wear low. Friction value depends on the processing of specific types of materials, but it is acceptable is: For the sole material, the wear value of not more than 200mm3 is very good. By contrast, the typical value of 100mm3 polyurethane wear or less, and in similar test conditions, thermoplastic rubber (TPR) and other materials, soles show wear many times greater than 300mm3.
We also conducted a special product for the sole test of durability, can be seen from Figure 1: thermoplastic polyurethane sole product is superior than most. It has been observed: SmartLite (r) is a microporous thermoplastic polyurethane and EVA-like features, we also observed, foam PVC compound with characteristics similar to the durability of the product, and tend to lose foam wear resistance of thermoplastic rubber, The wear value depends on the concentration to be cast.
Table 2, the surface of the concrete, 12,000 rpm for wear simulation tests the quality of weight loss soles. We work together with the British SATRA companies to obtain these results. As can be seen from the table to SmartLite (r) made of thermoplastic polyurethane soles with conventional polyurethane composition of the two kinds of wear characteristics similar products.
◆ non-slip
Non-slip soles for all types of materials in a key area of assessment. Design and materials and other factors can affect the performance of non-slip soles. In the past we have discussed in detail the impact of non-slip polyurethane sole product of factors. To compare different products, has conducted SATRA PM144 test, it shows: thermoplastic polyurethane foam with two components similar to conventional polyurethane foam properties, the porous material in the worn skid resistance improvement. In this paper, we have further examined the phenomenon and found that, in fact, after a period of wear after a wet floor conditions, porous thermoplastic polyurethane foam resistance improved.
We are convinced that: hard soles with other materials such as vulcanized rubber ratio, SmartLite (r) products, non-slip thermoplastic polyurethane is reserved to increase its surface roughness conditions in the wet state can better capture of the surface cause. Figure 2 have been explained. Vulcanized rubber
Surface (specific gravity 1.15)
After 3 months of wear, the surface relatively flat, low surface roughness
(Ca.3mm), and porous SmartLite (r) thermoplastic polyurethane surface is more rough (ca.18mm). Skid tests confirm that these samples in the soil on the dry friction coefficient of tiles similar to the state in a wet floor conditions, thermoplastic polyurethane foam products, friction coefficient decreased by 12%, while the vulcanized rubber dropped by 47%. From dry to wet in the process, the new two materials show similar changes in soles (ca. both cases, the friction coefficient decreased by 25%).
We have a variety of different sole materials for these tests. Figure 3 and Figure 4 summarizes the results. In addition to comparing wet and dry conditions, but also tested on frozen soil tiles slip resistance (friction coefficient). As expected, all the frozen state under the conditions of very low friction coefficient, but SmartLite (r) thermoplastic polyurethane products, the highest value and the minimum friction coefficient of variation. In these test conditions, the worst performance of PVC, and in environmental conditions from dry to ice in a very soft thermoplastic rubber greatest change.
◆ bonding characteristics
Reliable bonding is a key factor in quality shoes. Standard polyurethane adhesive system compatibility has always been very good, without some preparation of the operation, such as priming or corona treatment. These new thermoplastic polyurethane foam products are no exception. SmartLite (r) thermoplastic polyurethane soles made of leather upper-independent adhesion tests conducted (SATRA Test Method TM401 and TM402), in a variety of preparation conditions in the standard solvent-and water-based polyurethane adhesives for. Testing found that: In addition to including solvent wipe adhesive system or / bold surface preparation conditions and other traditional techniques beyond all cases (> 10N/mm), sole access to a high bonding strength. Not previously been prepared to test products and samples pre-treated with similar results. Figure 5 shows the results of water-based polyurethane adhesives
The general characteristics of polyether-based products
Huntsman's application development for a variety of different products, their hardness, the target molded density is different, more recently, based on different soft block the main chain. Table 3 for a number of polyether SmartLite (r) summarizes the characteristics of thermoplastic polyurethane products. If it is anticipated that these new materials have excellent resistance to hydrolysis and microbial resistance, and can improve the UV stability of expression. The finished product is soft, the performance is very high reproducibility.
◆ deflection performance
By the SmartLite (r) made of thermoplastic polyurethane sole has a very excellent anti-bending ruptured. So far, nearly 10 million pairs of shoes has not been returned due to rupture of the sole, and sole rupture is a common problem with other types of shoe materials. Shown in Table 4, with Bennewart soles in winding tester flexural test under -25 ℃, the soles of the central cut a 2mm incision, SmartLite (r) thermoplastic polyurethane no openings change, and other products are cut or more or less to grow.
◆ Processing
The new variety of low-density thermoplastic polyurethane material, a variety of methods available for processing, including: injection molding, extrusion and hot molding. Table 5 for the polyether-based products (SmartLite (r) 680) the typical extrusion or injection molding processing conditions. Ideal for the conventional injection molding machine should be back-pressure device with a reciprocating screw injection machine, heating capacity of at least 180 ℃, precise temperature control, one-way valve to prevent the expansion of the bubble in the drum, close the nozzle to prevent air leakage and a precise 15 ℃ to 50 ℃, mold temperature control to minimize the surface micro-bubble expansion or deformation. In fact, it was observed that under certain conditions, these materials can be processed in other equipment.
◆ machining simulation
These new thermoplastic polyurethane foam products are based on a proprietary technology with (European Patent Application No. 116,567) and the system, this technology enables the product light weight, high quality. And regular full-density parts of the injection molding of thermoplastic polyurethane products different is that this case involves the injection mold tank partially filled, then there is a groove completely filled mold foaming process. Depending on part geometry, the location of the injection point, casting structure and other factors, the density distribution of materials and components may be quite different. Therefore, if there is no alternative technologies, new processing fee adjustment may be a physical, time-consuming and takes a lot of money in the process.
Traditional mold filling simulation does not consider the melt flow and bubble expansion and cooling of this part of the complex situation. Recognizing these limitations, our German Aachem Institute of Plastics Processing (IKV) and Simcon - a professional plastic injection simulation software developers to collaborate in Germany to develop a set of packages, this package takes into account bubble-filled mold physical properties, material properties change and to predict the density distribution of the cooling components, and the mold flow simulation to predict the location of entrance, adjustment and other foam mold design details. The high accuracy of this optimization tool has been in many cases are real, and found a high accuracy of predictions made. In fact, the full details of this simulation package is beyond the present scope of work. Figure 6 shows the density distribution of a sole design typical outputs.
Conclusion
In this paper, we introduce and thermoplastic polyurethane foam show several key features of the product. These products for the footwear and other applications developed and used SmartLite (r) brand. These new products expand the awareness of high quality, high performance applications the choice and composition soles. We can cite some of these important features of new materials:
1, in similar applications, lighter weight than the alternatives;
2, in the simulation test has superior wear durability;
3, compared with alternative products, with excellent slip resistance in wet or freezing conditions, the slip resistance can be well maintained;
4, very high quality parts finishing, soft texture and design details can be reproduced;
5, conventional equipment can be simple in operation, in particular, there is a new auxiliary process simulation technology;
6, combined with resin and a component of the system through a proprietary bonding technology.
This polyurethane technology conference in the United States in 2006 and was published in the paper awards will be shoe category
Thermoplastic polyurethanes, TPU, have increasingly gained acceptance in soling applications since the mid 1990s when low hardness TPU products were first introduced by Huntsman, primarily as outsole materials in dual density soling systems. Continued demand for high quality, design freedom and performance led later to breakthrough innovation in blowing technology that allowed the production of high quality, injection molding TPU compounds that delivered, in addition to the well known excellent finish and excellent properties of TPU materials, light weight single and dual density soles. Marketed under the smartLite? brand, a family of products is now being used in numerous brands across the globe.
Figure 1 shoe more durable materials
Figure 2, the old rubber and SmartLite (r) thermoplastic polyurethane soles of the surface roughness of the contrast
a: old vulcanized rubber surface, 35 times magnification, 1.15g/cc when high-quality VR, nearly three-month period of use, the surface roughness (Ra) ± 3m.
b: Old SmartLite (r) thermoplastic polyurethane surface, 35 times magnification, 0.75g/cc when SmartLite (r) thermoplastic polyurethane, nearly three-month period of use, the surface roughness (Ra) ± 18mm.
Figure 3, a new comparison of non-slip soles
Figure 4, the old and new soles non-slip soles comparison
Figure 5, SmartLite (r) thermoplastic polyurethane soles and leather uppers polyurethane adhesive bond strength
Figure 6, typical SmartLite (r) thermoplastic polyurethane molding product of the density distribution
Table 1, SmartLite (r) the typical characteristics of polyurethane plastic
Unit measured characteristics method
Density DIN 53479 grams / cubic centimeter of 0.5 to 0.9
Hardness DIN 53505 Shore A 40-85
DIN 53516 mm3 volume wear loss <180
Hydrolysis of the internal (7d/70 ℃)% retained> 90
Flexural properties of SATRA TM 161 thousand times> 50
Adhesion strength (for leather) SATRA TM 401 N / mm> 8
Table 2, in the concrete on the turn after a 20,000 loss in weight after stepping simulation
Sole material weight loss (g)
Compact thermoplastic polyurethane (Shore A 65) 0.26
SmartLite (r) thermoplastic polyurethane 0.37
Polyurethane (two components) 0.39
Thermoplastic rubber (Shore A 60) 0.51
0.77 vulcanized rubber
PVC 1.00
Thermoplastic rubber (Shore A 50) 1.10
Table 3, different polyether SmartLite (r) comparing the characteristics of thermoplastic polyurethane products
Characteristic method SmartLite (r) 660 SmartLite (r) 680
Density ISO 2781 0.65 0.65
Hardness DIN 53505 60 80
Tensile strength DIN 53504 6 14
Rupture elongation DIN 53504 450 400
100% modulus DIN 53504 2.2 3.1
Tear resistance of DIN 53515 20 28
Wear DIN 53516 70 130
Table 4, at -25 ℃, the flexural properties of the sole material
Material cut growth (mm)
SmartLite (r) thermoplastic polyurethane 0.0
Hard thermoplastic polyurethane (shore A 65) 0.7
Thermoplastic Rubber (shore A 55) 0.7
Thermoplastic Rubber (shore A 60) 9.0
PVC 9.3
Polyurethane (two kinds of components) 10.5
Vulcanized rubber 13.5
Table 5, SmartLite (r) foam processing conditions typical of thermoplastic polyurethane
Extrusion temperature (℃)
Into the area to 25-40 ℃
Barrel 150-170 ℃
Over 150-170 ℃
Die 150-170 ℃
Nozzles 150-170 ℃
Injection temperature (℃)
Into the area to 25-40 ℃
Barrel 160-180 ℃
Over 160-180 ℃
Die 160-180 ℃
Nozzles 160-180 ℃| Updated:2011.11.11 Source: Clicks:1843
