Page 1
Page 2
Page 3
Page 4
Page 5
Page 6
Page 7
Page 8
Page 9
Page 10
Page 11
Page 12
Page 13
Page 14
Page 15
Page 16
Page 17
Page 18
Page 19
Page 20
Page 21
Page 22
Page 23
Page 24
Page 25
Page 26
Page 27
Page 28
Page 29
Page 30
Page 31
Page 32
Page 33
Page 34
Page 35
Page 36
Page 37
Page 38
Page 39
Page 40
Page 41
Page 42
Page 43
Page 44
Page 45
Page 46
Page 47
Page 48
Page 49
Page 50
Page 51
Page 52
Page 53
Page 54
Page 55
Page 56
Page 57
Page 58
Page 59
Page 60
Page 61
Page 62
Page 63
Page 64
Page 65
Page 66
Page 67
Page 68
Page 69
Page 70
Page 71
Page 72
Page 73
Page 74
Page 75
Page 76
Page 77
Page 78
Page 79
Page 80
Page 81
Page 82
Page 83
Page 84
Page 85
Page 86
Page 87
Page 88
Page 89
Page 90
Page 91
Page 92
Page 93
Page 94
Page 95
Page 96
Page 97
Page 98
Page 99
Page 100
world pulppaper 21 It became increasingly clear that a fibre length of less than 20mm is necessary to produce flushable wipes according to EDANA III c Entanglement of fibres q Degree of entanglement can be controlled by the intensity of hydroentanglement water jet pressure q Influence of fibre length bending resistance surface conditions on degree of entanglement d Breaking fibres q Dependent on tenacity elongation and bending resistance of the fibres. Breaking fibres do not play a relevant role for dispersion and therefore for flushability of a wipe. e Fibre-Fibre-Bonding q Surface conditions bending resistance f Hydrogen bonds between fibres q Surface conditions smooth crenellated fibre cross-section On the process side the conventional spunlacing carding process with subsequent hydroentanglement can provide wipes with high tensile strength and softness. However the necessary minimum fibre length of 20mm creates entanglements of the fibres as shown in c that are very difficult to open-up again. Even in case of an initial break-up of the wipe the single web pieces entangle again or build up fibre ropes which prevent a sufficient dispersion into single fibres. It became increasingly clear that a fibre length of less than 20mm is necessary to produce flushable wipes according to EDANA III. The challenge the carding process does not work with such short fibres. This was the point where the combination of wetlaid and hydroentanglement jumped in. In a wetlaid process a blend of pulp and cellulosic long fibres is dispersed in water and then drained on an inclined wire. The homogenously formed wet fibre web is then bonded in a next step of hydroentanglement. Within this process the key to success is the perfect combination of all relevant parameters namely the raw materials the right fibre blend and specific process settings during wetlaid and hydroentanglement. The questions regarding process technology were addressed by machine suppliers such as Voith Trtzschler or Andritz in recent years both of which supply full turnkey lines to the market. INFluENcINg FlusHABIlIty AlrEADy oN tHE FIBrE scAlE In the past Kelheim Fibres GmbH investigated the influences of fibre properties such as length dimensions cross-section and surface on the flushability of nonwoven products to offer tailor made solutions for these applications already on the fibre scale. At the same time Kelheim Fibres GmbH has been supplying Danufil KS a viscose short cut fibre in different lengths from 3 to 12mm for wetlaid processes for many years. Product such as tea bags coffee pads plug-wrap papers or other speciality papers are produced with Danufil KS benefiting from high porosity and either increased absorption or fine dispersion properties. For the new wetlaid-hydroentanglement process the question arose how such a short-cut fibre could be modified to achieve both sufficient bonding to the pulp component of the fabric and the dispersion of the wipe in the wastewater system. Such a fibre would help to fulfil the requirements of initial web strength during production and use and break-up and dispersion after use. Multiple steps of development and trial runs with different fibre types as well as various blends showed that Viloft short cut fibre is particularly suited for this application for various reasons Cellulosic nature Viscose fibres have the potential of building hydrogen bonds to each other as well as to pulp fibres as shown in f this would deliver tensile strength to the wipe. Moreover viscose fibres are widely spread in hygiene products due to their softness and next-to-skin comfort. Fibre length The short fibre length of Viloft short cut prevents entanglements as shown in c. Fibre surface The crenellated surface of the Viloft fibre creates predetermined breaking points within the wipe and increases the fibre-water friction as shown in a and e. In addition the water can pass along the fibres into the wipe construction during flushing to open up the web. Especially in combination with pulp fibres free spaces are generated within the wipe. Here the water can tackle it very effectively. Fibre cross-section The flat cross- section stands out due to its specific stiffness properties. When water impacts vertically on the slim lateral face the fibre opposes high stiffness. However when water impacts vertically to the wide face the fibre shows low stiffness. With this combination the Viloft fibre shows