Józef Świątek,

Janusz Jarzębowski,
Investigation of Fibre Diameter
Jan Cichoń Distribution in Non-Woven Textiles
Polmatex - Cenaro Research for Medical Applications in Melt-Blown
Polyester Technology
and Development Centre of Textile Machinery
ul. Wólczańska 55/59, 90-608 Łódź, Poland,
E-mail: biuro@cenaro.lodz.pl

Abstract
Manufacturing non-wovens from fibre-grade polyesters by the melt-blown method from
a polymer melt causes great technological problems. The structure of non-woven, its
properties and characteristics are influenced by such parameters as the moisture of the
polymer, the temperature of manufacturing at the separate zones of installation, the output
and temperature of the air blowing out the melt, the take-up velocity of the non woven, the
distance of the condenser from the spinning nozzle, and the thickness of the fibres received.
As the non-wovens discussed are devoted to medical applications and filtration materials
an appropriate spatial structure is an important parameter, and the smallest possible fibre
thickness is required. The purpose of investigation was the optimisation of the process
parameters and the obtaining of the thinnest possible fibres with optimum distribution of
thickness, and optimum spatial structure. The manufacturing process allowed to obtain non-
wovens which were characterised by the possibilities of shaping their structure in a wide
range of parameters and with fibres of diameter from 2 µm to 14 µm. For the production
of non-wovens of surface mass 110 g/m2, the air flows that allow to receive optimum fibre
thickness in the determined conditions were assessed.

Key words: melt-blown technology, non-woven, fibres, polyesters, diameter of fibres, air
blow.

n Introduction ven textiles using the melt blown meth- eters for manufacturing poly(ethylene
od has been carried out at the Polmatex terephtalane) (PET) non-woven by the
Non-woven, which is manufactured from R&D Centre of Textile Machinery for melt-blown method, optimisation of its
polymer by the melt-blown method, is many years. Positive results obtained by spatial structure and obtaining the thin-
characterised by comparatively small manufacturing polypropylene non-woven nest possible fibres.
thickness of fibres, a particular spatial textiles inspired a team of researchers to
structure [1], and a lack of an irritating ac- further investigate manufacturing non-
tion, which allows its application for med- woven textiles made from fibre-grade
n Research apparatus
ical and filtration purposes. Nonwoven polyesters. Such works were carried out The investigations were carried out
manufacturing technology from fibre- as part of a a research project entitled with the use of the test rig introduced in
grade polypropylenes is well known, “Polyester non-woven textiles manufac- Figure 1, which was designed for manu-
fully controlled, and used also at our tured by melt-blown polymer method” facturing non-woven textiles by the melt-
institute. All over the world intensive re- (see “Acknowledgment”). blown method.
search works have been carried out on the
technology involved in nonwoven manu- The purpose of our investigations was the The test rig was designed on the basis
facturing using the melt-blown method. selection of technological process param- of experiments carried out with poly-
An example of such an investigation is
the research program of the Reifenhauser
Company [4 - 6]. Manufacturing non-
wovens from polyester polymers by this
method creates great technological prob-
lems which result from the properties of
polyesters, such as the absorptiveness of
moisture, the narrow range of processing
temperatures and the level of drawing the
manufactured fibres. On the other hand,
polyester non-woven can be applied as
an implant and medicine-carrier in medi-
cal applications, as filtration material at
high temperatures and as an important
component of composites.

n Aim of the research Figure 1. Test rig for manufacturing PET non-woven by the melt-blown method; 1 – dryer
tanks, 2 – extruder, 3 – polymer filter, 4 – dosage pump, 5 – spinning beam; 6 – air heater,
Research work on the development of 7 – air supply installation, 8 – net band conveyer, 9 – nonwoven quiling assembly, 10 – control
manufacturing technology for non-wo- compartment, 11 – air-conducting installation.

14 FIBRES & TEXTILES in Eastern Europe July / September 2008, Vol. 16, No. 3 (68)
propylene non-wovens [1] as well as ing out of the spinning nozzles. The in- woven and its grade of consolidation.
the requirements related to drying fibres tensity of the polymer stream depends on Non-woven textile produced at small
formed from polyesters in which the the output of the dosage pump and is pro- distances is compact, flat, the fibres are
content of the moisture in the granulated portional to its rotational speed. For each more stuck together, the strength of non-
product used for production cannot ex- value of rotation speed of the pump, ap- woven is greater and the penetrability of
ceed 0.01%. As a result of these require- propriate temperatures are applied in the air is smaller. An increase in the distance
ments, further development of the test rig heating zones to maintain the assumed between the condenser net and spinneret
was necessary [2, 3]. temperature of the melt at the inflow to gives more spacious (loose) non-woven
the spinning nozzles, which is required textiles. As the air penetrability increas-
The test rig consists of the following parts: for the forming process of fibres. es, the strength decreases as a result of
1. A dryer tank with an additional filling weaker thermal bonding of the fibres
up hopper. The following parameters have an im- building the non-woven.
2. An extruder equipped with a screw pact on the textile structure of nonwoven
for processing polymers, as well as produced by this technology with an es- The chosen method of obtaining non-wo-
three heating zones with continuous tablished volume of flowing oil stream of ven enables non-woven of various area
temperature control, and the possibil- polymer: masses and different grade of consolida-
ity of air- cooling. n output and temperature of blown air, tion to be made. The range of the param-
3. An adjustable polymer filter which n velocity of non-woven received (lin- eter variations is very wide. The installa-
can be changed during the operation ear velocity of the condenser net), tion discussed here is within the range of
of the test rig. n distance of condenser from the spin- 20 to 500 g/m2. The wide choice in shap-
4. A dosage pump with continuous con- ning nozzles, [7]. ing the arrangement of fibre structure as
trol of the rotary speed. well as its surface mass gives great pos-
5. A spinning beam of special design The variation of each parameter affects sibilities of creating a wide assortment of
with nine heating zones of a continu- the structure of non-wovens in a definite non-woven textiles of different proper-
ous temperature control system. It is way. The quantity of air blowing up the ties. For technical purposes non-woven
equipped with a grate, a multi-hole polymer melt determines the drawing, textiles with a strong band and compact
spinneret (nozzle) special polymer which affects the diameter of fibres and
structure to be applied to the loaded foun-
pressure and temperature sensors of their length. An increase in air quantity up
dation, as well as non-woven of loosely
small response time coupled with a to a certain level causes the thinning of fi-
bound fibres made of thin fibres for fil-
continuos control system for the ro- bres, which can be observed in Figure 2.
ter inserts, are required. Similarly, thin
tational speed of the extruder electric Further increase in air quantity does not
non-wovens for dressing materials, or
motor. cause a decrease in its diameter. The air
thick ones for absorption pads, can be
6. An air heater with continuous tem- temperature for this spinning nozzle de-
perature control. used in medical applications. As the in-
sign should be practically equal or higher
7. An air supply installation with a vestigation carried out at the Industrial
than the cooling of the spinning noz-
blower of special design. Medicine Institute showed, the polyester
zle [7]. Too cold air causes disturbances
8. A net band conveyor with the pos- non-woven in question, produced by this
in the process of polymer flow from the
sibility of continuous control of the spinning nozzle or even makes the flow technology and on this installation, does
position in relation to the spinning impossible. An increase in air tempera- not show irritating or toxic properties,
beam. ture results in a decrease in the diameter and it has obtained permission for medi-
9. A non-woven guiding assembly for of fibres produced. However, the effect cal applications.
cutting the edges and making strips of temperature change on fibre diameter
of required length. is weaker than that of the volume of air The forming of fibres, and
10. Two control compartments. quantity. optimisation of thickness distribution
11. An installation to remove air from A very important parameter that charac-
above the spinning beam and from Any change in the distance of the con- terises non-woven produced by the melt-
below the condenser net conveyor. denser net from the spinning nozzles blown method is the thickness of fibres
affects the spatial structure of non- and its statistic distributions. These prop-
The of 1000 mm length polymer melt
is extruded by a single-row spinneret,
in which 1000 bores of 1 mm were ar-
ranged. The streams of polymer melt are
W2
stretched and torn by two co-running
Number of fibres

streams of hot air flowing from the gaps

placed along the line of the polymer spin- W1
ning nozzle. The air stream puts the fibres W3
generated this way onto the moving net
W4
of the condenser, on which continuous,
consolidated non-woven of 1 m width is
obtained. The thickness of the non-wo- Figure 2. Distribu-
ven and its surface masses depend on the tion of fibre thick-
ness; The sample
linear velocity of the net conveyor and denotations: W1, Thickness of fibres, mm
the intensity of the polymer stream flow- W2, W3, and W4.

FIBRES & TEXTILES in Eastern Europe July / September 2008, Vol. 16, No. 3 (68) 15
erties are influenced by the air parameter It can be concluded from the analysis tion of polyester non-woven textiles with
used for polymer blow, particularly the of the results that with an increase in air regard to specific properties and quali-
output. Investigation into the effect of the quantity from 0.049 m3/s to 0.061 m3/s, ties will widen with the improvement of
air quantity required for the blow of poly- the mean diameter of fibres decreases technology and manufacturing installa-
mer melt was made during the process of on average by 6.52 µm to 5.19 µm. The tions. Research works in this domain are
non-woven formation from polytereftelan number of fibres in the range of diameters in progress.
ethylene of the commercial brand name from 2 µm to 8 µm also increases. The fi-
‘PET mat’ manufactured by the ELANA bres in this range reperesents about 96%
Plant in Toruń, Poland. of all fibres of sample W2, and the fibres n Conclusions
of diameter 4 ÷ 6 µm represent about 68% The results of investigations carried-out
During the investigation into the form- of all fibres in the sample. The minimum led to the following conclusions:
ing process of non-woven as a constant diameter of the fibres was obtained with 1. The technology of manufacturing
parameter, the following were estab- such a quantity of air. Further increase non-woven textiles by the melt-blown
lished: the temperature of melt and air, a in the air quantity used to blow polymer method from polymer melt allows to
surface mass of 110 g/m2 (based on the melt (from 0.061 m3/s to 0.066  m3/s) obtain PET fibres of diameter in the
requirements of the Institute of Industrial causes an increase in the mean diameter range of 2 µm – 14 µm.
Medicine), the polymer output, the poly- of fibres in the sample. In sample W3 2. There are optimum conditions of air
mer and air temperature, the linear veloc- the mean diameter of fibres increased to flow and polymer that allow to attain
ity of the condenser net, as well as the 7 µm, and the number of fibres ranging 74% of fibres of thickness within the
position of the condenser versus the spin- from 2 µm to 8 µm in diameter fell to range of 2 µm - 8 µm and 65% of fi-
ning nozzles. 70%. With a further increase in the air bres of thickness within the range of
blowing the polymer, the number of thin 4 µm – 6 µm.
These values are reserved by the “know- fibres decreases within the range of 2 µm 3. The conditions for manufacturing the
how” of the technology developed and to 8 µm, which represents about 66% of fibres given in p. 2 are:
are in the disposition of Polmatex- all fibres of sample W4. n an air stream output blown towards
Cenaro. Only one parameter, i.e. the air the stream of polymer melt of
From the analysis of investigation results 6×10-4 m3/s (2.16 m3/h) for a beam
flow volume of the blow of the polymer
pertaining to the thickness of fibres under of 1 cm width
melt, varied. The range of variations was
different conditions of non-woven forma- n a ratio of air stream mass to poly-
from 0.049 m3/s to 0.075 m3/s, which
tion, it is clear that there is an optimum mer stream mass of approximate-
guaranteed the obtaining of fibres of ad-
air quantity for blowing polymer melt to ly 50.
equate thickness (diameter). Non-woven
achieve the largest number of non-woven
manufactured at an air stream volume
thin fibres of diameter 6 µm. Below and
output of 0.049 m3/s is characterised by
above this optimum the number of thin Acknowledgment
a loose structure and larger quantity of fi-
fibres of non-woven decreases. The dis- The research works presented in this paper
bres sticking-out on the surface. Thanks
tribution of fibre thickness in the non- were carried out as part of research project
to this, the non-woven textile feels softer.
wovens under investigation is presented GRANT No. 4 T08E 038 24 entitled ”Polyester
Opposite to this type of material are the in Figure 2 for samples W1, W2, W3, non-woven textiles manufactured by the melt-
non-wovens that were obtained at an air and W4. blown polymer method”, financially supported
stream volume output of 0.066 m3/s and by the Committee of Scientific Researches
0.075 m3/s. These non-wovens have a (Komitet Badań Naukowych).
To facilitate the transformation of inves-
compact structure which resembles paper tigation results to be applied to a spinning
in its feel, but without fibres sticking-out beam of another design, another hole di- References
on the surface. ameter in the spinneret and a different 1. Research project: “Non woven polyester
pitch of their distribution as well as the textiles manufactured by melt-blown
The samples of non-woven for the inves- quantity of air stream volume for a 1 cm method. No.4 T08E 038 24.
tigation of fibre thickness were denoted length of the beam in normal conditions 2. Bresee R. R., Ko W. Ch.; International
as follows: were analytically recalculated, and the Journal of Non-woven. pp. 21-28. (Sum-
W1 – non-woven obtained at the follow- ratio of air mass to the mass of polymer mer 2003).
ing intensities of air stream blowing the 3. Holloway A. K., Pathavkar M.; Interna-
was determined. It can be concluded from
tional Journal of Non-woven. pp. 27-32
polymer melt: 0.049 m3/s, this analysis that for the non-woven with (Spring 2004).
W2 – 0.061 m3/s, the largest amount of thin fibres of 6 µm 4. Jarecki L.; Computer modelling of melt
W3 – 0.066 m3/s, diameter, the air stream output blown spinning from a crystallizing polymer. Part
W4 – 0.075 m3/s, (see Figure 1). towards the stream of polymer melt is I. Mathematical model, Polimery, vol. 46,
6×10-4 m3/s (2.16 m3/h) for a beam of 1 cm No. 5, pp. 335-343 (2001).
Investigation into fibre thickness was width, and the ratio of air stream mass to 5. Jarecki L.; Computer modelling of melt
carried out at the Laboratory of Raw spinning from a crystallizing polymer.
polymer stream mass is about 50. These
Part II. Applications of the mathemati-
Materials and Textile Products of the values were confirmed experimentally. cal model, Polimery, vol. 46, No. 6, pp.
Textile Research Institute in Łódź accord- 420-427 (2001).
ing to the standard PN-86/P-04761.08 The technology discussed makes it possi- 6. Medical-Textiles. May 7 (1998).
“Methods of Investigation of Raw Textile ble to manufacture polyester non-woven 7. Medical-Textiles. May 3 (1997).
Materials. Chemical Fibres. Diameter of large structural diversity and with a
Determination”. wide range of surface mass. The applica- Received 28.11.2005 Reviewed 15.01.2006

16 FIBRES & TEXTILES in Eastern Europe July / September 2008, Vol. 16, No. 3 (68)