Types of Fibres

Contur Flock LTD
398024 Russia c. Lipetsk, str. Dovatora 14
+7(4742) 40-18-12, 28-37-75
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1. Applicable Fibre Types

Industrial

DIN marking 60 001

Polyamide (nylon, perlon)

PA

Polyester

PES

Rayon (artificial silk)

CV

Cotton

BW

Of special use:

 

Polyacryle

PAC

Carbon fibre

CF

Aramid

 

New developments:

 

Polypropylene

PP

2. Polyamide

The polyamide flock is made from polyamide 6 (PA 6) and 6.6 (PA 6.6). Polyamide 6 is melted at approximately 215-2200C, melting temperature of polyamide 6.6 is 255-2600C. Polyamide 6 is softer than polyamide 6.6, it is easier to dye, but it is less resistant to UV radiation. Milled and cut flock is made from polyamide. Produced titers vary from 0.9 up to 44 dtex. The most applied lengths range from 0.3 mm up to 2.0 mm. In some specific cases they use flock up to 12 mm in length (for example: imitation of the animal skin). The polyamide flock possesses good wear resistance and creases slightly under mechanical effect. Specific density of PA 6 is 1.125 — 1.15.

Polyamide has a wide sphere of application: from floor coverings and technological use up to continuous flocking on textile and paper substrates; from the one-colour flocking of flat surfaces up to the multi-colour printing on curvilinear substrates.

Polyamide 6 flock coat maintains temperature up to 150 0C, without changing its linear dimensions and texture. Due to this quality, textured effects on the flock-surface are made by means of thermal embossing. The temperature of polyamide 6.6 embossing is approximately 1800C.

Some fluorescent dyes are specially developed for polyamide. The flock coloured by these dyes gives a luminescent effect under UV light. This ability is actively used as one of protection levels of securities and banknotes. Besides, the fluorescent flock is used for interior finishing and advertising purposes. It is necessary to note, that light resistance of fluorescent flock is noticeably worse, than the one of usual flock.

3. Polyester

The polyester flock is similar to the polyamide flock. The basic difference is water repellency of polyester fibres. It complicates electrostatic processing of the polyester flock. Besides, dying of polyester is more expensive.

Polyester possesses better light resistance than polyamide. If long influenced by UV radiation or intensive sunlight polyamide becomes more breakable, than polyester. Due to this polyester is applied in motor industry on visible parts of details: basically for flocking of side glass rubber guide rails of cars. The black-spun flock is used for this purpose. Spun dying of flock is carried out at the stage of tow extrusion for flock manufacturing. In this case quite other kinds of dyes providing greater light resistance are used. Spun dyeing, as a rule, is only used for dying flock in black colour. For these and other spheres of application the polyester flock can be dyed in any colour in a general way.

Nowadays series-produced titers range from 1.3 dtex up to 6.7 dtex. The most applied lengths are 0.5 mm and 1 mm. Specific density accounts for 1.38-1.41.

The processing of polyester flock coated surface wherein fibres are creased by thermomechanical influence is called embossing. Temperature of thermal embossing of polyester amounts approximately to 1500C

Flock

Creasing property

Dyeability

UV-resistance

Embossing temperature

Polyamide

+

0

+

1800C

Polyester

0

-

++

1500C

Evaluation

++ very good, + good, 0 satisfactory, — poor, — very poor

4. Rayon

The rayon flock can be milled and cut. Series-produced lengths of rayon flock vary from 0.3 mm up to 4.0 mm. Rayon poil is noticeably deformed during mechanical loading therefore its application spheres are limited.

It is applied, first of all, for articles' decoration. The rayon flock is used for the manufacturing of packing, toys, wall-papers, wall panels, and also during flocking of some textile and nonwoven materials. Rayon is mainly used for flock-pressing on clothes. For manufacturing of tranfer paper they use the rayon flock of ultraprecise cutting of 0.3 mm in case of a multi-colour press, and as to simple transfer the rayon flock of 0.5 mm up to 1.0 mm is used.

Thin titers (from 0.55 up to 0.9 dtex) of rayon flock are applied for manufacturing of packing and some cosmetic goods. The most rough titer (28 dtex) is used for manufacturing of artificial grass in toy railroads.

5. Cotton

The flock made of cotton can be only milled. It has very low wear resistance. Its surface is very similar to artificial suede. The advantages of cotton flock are: low price and high wetting ability. It is very efficient, as a coat of rubber gloves inner side. The cotton flock is also applied to manufacture low-cost packing.

The series-produced titers of cotton flock range from 1 up to 4 dtex.

6. Polyacryle

Polyacryle is the most complex fibre, both for flock manufacturing, and for dealing with it. Polyacryle has a number of advantages, but from the point of view of modern application spheres of flock, they are not interesting. The issues of polyacrilyc flock manufacturing were actively developed when there was a threat of rayon fibre deficiency. Nowadays the polyacrilyc flock is not produced.

7. Carbon Fibre

The flock made of carbon fibre is a new development in the field of flocking materials. The carbon fibre is made from polyacrylonitrile (PAN) by means of oxidation. The colour of initial fibre varies from colourless up to black. Black fibres cannot be re-dyed in other colour. Today the carbon fibre flock is produced in titers 1.7 — 5 dtex.

Advantages of Carbon Flock:

1. Does not burn (other fibres demand special processing).
2. It is not deformed under mechanical loading at temperatures up to 4000C.
The industrial use of carbon flock demands special metering devices.
The carbon flock has not found any significant industrial application, but as it is a newly developed product, not all advantages of this kind of fibre are studied.

8. Aramid

Aramid (Kevlar) is a kind of polyamide, enriched by aromatic hydrocarbons with parametric structure. Its natural colour is yellow. It is not dyed. Aramid splits up only at temperature above 5500C. It is considered as flock for specific technical spheres of application.

9. Polypropylene

The polypropylene flock is a material basically applied for some technical purposes (for example: carpet coats, floor mats, concrete reinforcing). It is also applied for outerwear trimming. But polypropylene has lower characteristics than other fibres.

The polypropylene flock represents the greatest interest for the solution to the problem of flock materials recycling. The plastic details coated by the polyamide flock are rather difficult to recycle. It is necessary to divide three kinds of material what is very expensive. A polypropylene item, flocked with the polypropylene flock, contains a trace amount of adhesive which can be neglected when the item is recycled and subsequently remanufactured from second-hand materials.

The Disadvantages of Polypropylene Flock:
1. Polypropylene melts at 1600C and becomes soft at 1200C, therefore during drying of an end product deviations in temperature modes are not supposed.
2. Fibres of polypropylene cannot be dyed in the usual way. Spun-dying is only possible, that only means a mass manufacturing of colour polyethylene flock (from 1 ton and above).
3. The polypropylene flock has lower resistance to mechanical influence than the polyamide flock.
The suggested thickness of filaments in tow ranges from 3.3 dtex up to 70 dtex. Specific density amounts to 0.85-0.92;

Wetting Ability of Fibres

Different kinds of fibres used for flock manufacturing possess various wetting ability. The textile tables give the following parameters at temperature of 21 0C and relative air humidity of 65%:

Polyamide (nylon, perlon)

PA

3,5-4,5%

Polyester

PES

0,2-0,5%

Rayon

CV

11,0-14.0%

Cotton

BW

7,0-11,0%

Polyacryle

PAC

1,0-2,0%

Carbon fibre

CF

abt 8,0%

Aramid

 

3,0-4,0%

Polypropylene

PP

0%

The measurement of relative flock moisture gives, as a rule, slightly higher results. It is caused by the fact that the layer of chemical substances coating flock at processing also absorbs some quantity of liquid. Besides, the value of this parameter can be influenced by the fibre sectional shape. So, for example, trilobal (in section it has a three-beam form) has great ability to absorb liquid. But the test results should not exceed by 15 % the values specified in the table. The relative flock moisture is almost linear in another important flock parameter, such as electrical conductivity. Therefore unfair manufacturers increase liquid quantity in the end flock in order to veil flaws during activation. Besides, superfluous water in flock means superfluous expenses for the purchasing of raw material.

Influence of Fibre Nature on Flocked Surface

Luster

Two parameters influence on the external view of flocked surface: luster and fibre type. Flock can be luster, semi-luster, non-luster and deeply non-luster.

Non-uniformity of visual perception of flock colour and luster depending on a sight or illumination angle to flocked surface is referred to as «chatoyment». The more luster flock is, the stronger chatoyment effect it has. Besides, the occurrence of this effect can be explained by the difference in fibre colours in cross-section and on the linear side.

The chatoyment effect is a rather negative phenomenon for the manufacturer. For example, when flocking great areas (e.g. rolled materials) the luster flock shows even the slightest flaws, while the non-luster flock veils non-uniformity of coat. The non-luster flock is better charged by the chemical agents which poil is processed by to make a non-luster effect.

The luster flock is not recommended for flocking of plastic parts. On plastics the chatoyment effect gives an impression, that the coat of flocked part is non-uniform. To minimize this effect they apply the non-luster flock as well as so-called «curved flock». Each filament, in this kind of flock, has a bend. Due to this, at any sight or illumination angle, the observer sees an identical surface, both by glitter and by luster. Wide use of curved flock is limited by its high price and difficulty in application.

Surface Texture (Subjective Tactile Perception)

The haptic (or tactile perception) of any flocked surface is determined by the following factors:
1. Length and thickness of fibres;
2. Degree of straightness of filaments;
3. Quality of poil filling;
4. Type of flock processing;
The filament length of cut flock or average length of milled flock determine the height of poil and form sensation of softness or rigidity of flock-surface with the set thickness.

Fibre thickness can be set in millimeters or micrometers. But such approach is not that correct, as the cross-section of fibre does not always have an ideal form and can change along its length;
Therefore there are special (statistical) units describing fibre thickness in the textile industry. These measuring units, called titers, are defined as weight of a filament with the fixed length. With a certain density of raw material (polyamide, polypropylene …) these units unequivocally determine the average thickness of filament. Titers are designated:
1. «Denier»: weight of 9 000 meters of filament in grams = denier (den)
2. «tex»: weight of 1000 meters of filament in grams = Tex (tex)
3.10 «tex»: weight of 10 000 meters of filament in grams = Dtex (dtex)
Tex, in comparison with denier, is more conformable to SI-system.
There is a linear dependence between these two units:
1000 meters of PA 6.6 filament weigh 0.33 g and, accordingly, has a titer equal to 0.33 tex.
9 000 m of the same filament weigh approximately 3.0 g — 3 denier, and 10 000 m — 3.3 g-3.3 dtex.
Let's calculate the average diameter of 10 000 m of PA6.6 filament with thickness 3.3 dtex:

A titer is a relative measure unit. For example, diameter of 3.3 dtex polyester fibre is less than diameter of 3.3 dtex polyamide fibre, because specific density of polyester is more than the one of polyamide, it accounts approximately for 1.4 g/cm3.

Using a simple arithmetic formula it is possible to determine filaments quantity in the set weight of flock (3.3 g; PA 6.6; 3.3 dtex):

n = 10 000m/TLc = 10000*3.3/3.3* 0.001 = 10 000 000 pieces.
n (1g) = 3030303 pieces

m — weight of flock in grams
T — thickness in dtex
Lc — length of cutting in m

Dtex is a more applied measure unit of flock. The fibre thickness used for flock manufacturing ranges from 0.55 up to 44 dtex. The correlation between length and thickness of flock determines stability of flocked surface to mechanical loadings.

The density of poil filling also influences on the quality of flocked surface. The scarcer poil filling is, the worse hand properties and wear resistance of surface are.

It is also impossible to overlook the influence of processing on haptic of flocked surface. There are rough and soft kinds of processing.

Contur Flock LTD
398024 Russia c. Lipetsk, str. Dovatora 14
+7(4742) 40-18-12, 28-37-75
e-mail:

Production: manual flocker FP-01, high-voltage power supply VIP-04, electrostatic charging device UEZ-70, Flocking services, sale of adhesives in cooperation with German, Swiss, French and Chinese manufacturers

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