16 December 2015

Problems with selection and use of synthetic heat insulators in clothing

It appears that everyone knows, what do synthetic heat insulators (mainly non-woven materials, in popular belief – “sintepons”) mean in clothing. The time has come, when replacement of fly and feather, woolen or quilted heat insulators in items designed for extreme sub-zero temperatures (down to - 60 С!) raises no doubts. High-quality synthetics доказала has proved is efficiency having shown its worth in winterized clothes even for extreme weather conditions, workwear for oil and gas workers, departmental uniform, children’s and fashion clothes. However, the wider the opportunities of synthetic heat insulators implementation in clothes, the more are the complications. More and more problems arise related to selection of non-woven materials. Often even experienced experts (production engineers, designers, specialists involved in procurement of materials for clothes manufacturing, managers of garment manufacturers) make fundamental mistakes, poorly familiarized with the key peculiarities of synthetic materials “operation” in final items, and sometimes the difference between the technical fact and advertised information, technological data and unsubstantiated commercial declaration escapes their attention... Recommendations presented here will help you with selection of synthetic heat insulating materials for clothing.

Synthetic heat insulator always “works” in a so-called package and never “on its own”. The package is a combination of various materials applied for clothes manufacturing. E.g., 1) top cloth, 2) wind-protective membrane 3) heat insulator, 4) backing material (see the picture).

Therefore, all assertions that the heat insulator “warms” at a temperature of minus 10, -20, -30, etc. are incompetent and unprofessional. Heat insulator can just aid in “heat retaining”, more precisely have thermal resistance, on the one hand, and thermal conductivity, on the other hand.

We remind you that the higher the thermal resistance indicator, the more efficient the heat insulator is, the higher the thermal conductivity indicator, the less useful it is. During development of modern synthetic heat insulators, the emphasis is made on retaining of static air mass within the unit volume, and on selection of materials with low thermal conductivity.

One of the significant factors of the “winterized package” efficiency is air permeability of the top cloth combined with the convective ability of the backing. Unfortunately, during selection of heat insulators it is not taken into account at all. However, it directly influences the efficiency of the finished winterized item and requires particular attention.

All this makes up the equation of aggregate thermal resistance of the “package”, which should be considered in complex, rather than attributed to the synthetic layer only.

Currently, most widespread are the heat insulators manufactured using different types of polyester fibersHowever, their structure and properties vary. E.g., cheap sintepons are manufactured of polyester (and polypropylene) produced mainly by means of reprocessing. Plastic bags, bottles, plastic crockery – all these are production rejects, wastes from dumps go to the so-called reprocessing, of which, in its turn, cheap heat insulator is manufactured, however, having low usability, heat-protecting properties, doubtful eco-friendliness, etc. Such heat insulators are called “single-use”, as the strength of synthetic fibers connection and their shape retention are extremely low. Items (usually of economy class) with such heat insulators soon go out of service, sintepon drops down the sleeves leaving the parts of the clothes, where most mechanical impact during wearing and use is observed (shoulders, sleeves, waist), almost unprotected.

Reprocessed” heat insulators can be easily visually identified: they have grayish or bottle (green, brown, etc.) color, easily shred at insignificant mechanical impact, do not resume volume when compressed, often have chemical odor, crumble, peel off, etc. (see the picture)


Picture shows sintepon

of beer and kvass PET-bottles

Picture shows sintepon of sparkling water PET-bottles. 

Detailed information you can find on websites www.cintepona.net и www.sintepona.net.

On the other hand, synthetic heat insulators made of primary polyester fiber (almost impeccable white, strong, retaining shape, pleasant to touch), usually of a hollow structure are much more effective. Such materials involve thermal fibers connection: wavy tough fibers are welded at certain areas at high temperatures (up to 200 С). Correspondingly, such heat insulators afterwards withstand even boiling (in case of disinfection required, indelicate cleaning, etc.). Currently, with application of such heat insulators, the RF produces clothes even for very low temperatures – down to minus 60 С (!), and it’s they that drove expensive foreign brands out of the market.

Of course, not all synthetic heat insulators are similar, even when the identical raw is used. Different technologies, production approaches, the level of personnel competence, quality control and many other indicators – all this make the heat insulators differ in: 1) properties, 2) qualities and 3) performance characteristics. Let’s say, grain can be used to produce thousands of dishes using various recipes, but it cannot serve as a ground to state that all they are identical in properties only because they are made based on the same raw material... Either unite all vehicles because they all have wheels, body, motor, etc. It is absurd, but such analogies at the market of synthetic heat insulators are not rare, and the material selection experts should be attentive and competent.

One and the same heat insulator, when used in combination with different top cloths and backings, will work differently.

One and the same aggregate density of a heat insulator or heat insulators, e.g. 300 g/sq.m in one sheet layer or in three layers 100 g/sq.m each will give different thermal protection performance of the final item (the number of layers will increase thermal protection, especially, if they are calendered).

Synthetic heat insulators have an advantage of calendering. It is an additional thermomechanical cloth treatment giving two denser layers. First, in the RF calendered cloths Holofiber-Soft were introduced in 2006 at the Moscow plant of non-woven materials Termopol (www.hollowfiber.ru), and are still a unique feature in this manufacturer product line. Calendering of heat insulators gives a number of advantages during winterized clothes manufacturing: 1) no necessity in additional quilting; 2) convenient making-up and fabrication; 3) faster restoration after vacuuming of packaged heat insulator.

While selecting the heat insulator, it is necessary to take into account, that calendered and non-calendered heat insulators “work” differently making up different layers in the clothes “pie” (package). Calendering (additional thermal treatment of heat insulators surface giving it an elastic “crust”) of heat insulators provides for: 1) increase of aggregate thermal resistance; 2) improvement of strength characteristics, 3) absence of fibers migration, 4) additional resistance to multiple compression, 5) uniform restorability across the entire cloth surface, 6) uniform distribution of heat insulator in the finished item and longer preservation of declared properties and qualities.

To obtain the maximally impartial and professional information, it is recommended to address to manufacturers, rather than sellers or retail sellers of synthetic heat insulators. There are known cases of experts’ delusion with the primitive names contextually implying some northern countries or well-known mountains, to which the sintepons produced in the vicinities of Moscow have no relation at all. Specialists should elementary request at least one official (not advertising!) substantiation of technology of this or that heat insulator production.

One more recommendation is to study available test, research and experimental results (TsNII (Central Research Institute of clothing industry, NII (Research Institute) of occupational medicine, Gazprombezopasnost and accredited centers), etc., and select heat insulators based on these data, rather than based on advertising publications of dealers. If possible, perform additional ones, before series production of collection and large-scale manufacturing, subject to the specifics of design.

Up-to-date technologies of synthetic heat insulators production do not imply inclusion of additives of natural and artificial fibers to improve properties and qualities. Moreover, non-woven synthetic materials exceeded natural, artificial and composite (i.e. with additives) materials in performance and usability. Fiber additives, like “merino wool”, “camel wool”, “sheep wool” are just advertising tricks aimed at an unqualified specialist confident that “it is better, because it is better”. However, it is not so: performance of high-quality synthetics produced as an alternative to natural materials with their inherent drawbacks is impaired. Moreover, inclusion of the above additives reduced the overall effect of winterization.

Besides, it is not widely known that synthetic heat insulators presented as “natural synthetics” or “more natural synthetics” (which is strange, in fact) contain about 2% wt. “wool wastes” (fibers rejected during the process of high-quality woolen items production), providing for calling this synthetic heat insulator almost “natural pure woolen”. It is apparent for any textile expert: for any natural additive to somehow manifest itself at a level of properties and qualities in the heat insulator, its weight content should make up at least 20-25% and over, rather than about 2% (it is a useless inclusion, besides, impairing the properties of high-quality synthetics).

So, having encountered the problem of selection and use of synthetic heat insulators in clothes:

  1. Study technical, rather than information from commercials

  2. Send an inquiry to the heat insulator manufacturer, better – visit the production facilities, study the conditions of materials release, storage, shipment, consult real technical experts, rather than virtual sales assistants usually having no basic textile education

  3. Compare the data of different kind of heat insulators (maybe, of one and the same manufacturer)

  4. Review the application experience of other companies (maybe, your competitors, market leaders)

  5. Be sure to personally select the highest quality heat insulators

  6. Perform testing and/or wear test of items to make sure your choice is correct, and only then warrant the properties, qualities and performance characteristics of the entire item

  7. Aim at well-known and reputable brands of heat insulators.



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