Bleaching and dyeing; fluid treatment and chemical modification – Fluid treatment – Special forms and forming
Reexamination Certificate
1999-09-09
2001-08-07
Coe, Philip R. (Department: 1746)
Bleaching and dyeing; fluid treatment and chemical modification
Fluid treatment
Special forms and forming
C068S18100D
Reexamination Certificate
active
06270532
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention pertains to an element for washing or treating a yarn or similar structure with a fluid, the element comprising a cavity for guiding the yarn and at least one fluid jet for directing the fluid into the yarn.
Such a washing element is known from WO 93/06266, which describes how the exchange of mass and heat between a yarn and a washing fluid can be improved by jetting the fluid into the yarn. As a result of the enhanced exchange, the time needed for washing the yarn is reduced and the machinery involved can be smaller.
However, due to the use of the jet or jets and/or the high speeds of the yarn utilized in modern equipment, the washing fluid is disturbed to such an extent that the formation of a spray or aerosol of the washing fluid, which normally contains the substances that have been washed out of the yarn, is unavoidable. The aerosol seriously contaminates the working environment and the equipment itself. Especially when aggressive materials are involved, which is often the case, for instance in the production of aramid yarn (sulphuric acid) or cellulose yarn (phosphoric acid), the contamination poses a considerable threat to both personnel and equipment and makes it necessary to implement several expensive and impractical safety measures.
Another problem encountered during the washing or treating of yarns is the consumption of washing or treating fluid. A washing fluid containing, e.g., sulphuric acid removed from an aramid yarn usually needs further processing before it can be re-used or discharged, which always incurs additional costs. Therefore, the amount of fluid used in the washing or treating process should be as low as possible and the mass transfer to the fluid should be as effective as possible.
SUMMARY OF THE INVENTION
It is an object of the present invention to reduce or even avoid the formation of aerosol and to reduce the consumption of washing or treating fluid and increase the effectiveness of the mass-transfer to the fluid. This object and additional advantages that will be explained herein below are achieved by an element as described in the first paragraph above where the said, cavity is (substantially) tube-shaped and communicates with the outside of the element via a slot.
Surprisingly, it was found that the formation of aerosol thus can be virtually obviated due to the water from the jets which builds a water column or bath being confined in the slot, which prevents the formation of droplets and aerosol in the vicinity of the jets. Further, it appeared that the fluid consumption could be reduced by approximately half without decreasing the effectiveness of the washing or treatment of the yarn.
It is preferred that the slot runs the length of the cavity. Thus there are no obstacles which prevent the filament from entering the cavity through the slot, and spinning in becomes easy and can be carried out quickly and automatically. The spinning in (also referred to as threading in or lacing up) of the filament in the element can be further enhanced by using a slot that diverges near the outside of the element. That way, the opening for the filament to enter the element is more accessible.
It is also preferred that the element according to the invention comprises two jets making a sharp angle (smaller than 90 degrees) with one another, thus allowing a compact design of the element.
In order to allow the water column or bath inside the slot to have sufficient height, the slot should be relatively narrow. For most fluids it is preferred that the slot has a width in the range from 0.3 to 4 mm. However, the optimal width is dependent on the surface tension of the fluid used and, therefore, in some instances the optimal width may be larger than the said 4 mm. Further, the length of the slot and/or the cavity preferably exceeds 8 mm, the range from 20 mm to 100 mm being most preferred, while the height of the slot preferably exceeds 10 mm, the range from 15 mm to 40 mm being most preferred.
In an advantageous embodiment, the tubular cavity effectively has a cross-section that is V-shaped with the vertex of the V pointing away from the jets, which, as stated above, preferably make a sharp angle with one another. Thus, the water exiting the jets pushes the filament towards the vertex and guarantees that it remains in the same position.
The tubular cavity itself can be V-shaped, but it is preferred that a member which fits into the cavity and has a V-shaped cross-section is inserted in the tubular cavity. Thus, the material of the member can be selected independent from the material of the element for washing or treating a yarn, can be manufactured separately, and can be easily replaced during maintenance after all, the cavity through which the yarn travels will be subject to wear.
In a production environment several yarns run parallel, for instance just after extrusion and coagulation. Accordingly, the element of the present invention preferably comprises at least two parallel cavities. Of course, it is also possible to mount several elements each comprising only one cavity next to each other.
REFERENCES:
patent: 2844019 (1958-07-01), Schurmann et al.
patent: 3474615 (1969-10-01), Irwin et al.
patent: 3581486 (1971-06-01), Dibble
patent: 3771306 (1973-11-01), Ostrowski et al.
patent: 4298565 (1981-11-01), Yang
patent: 4453298 (1984-06-01), Nabulon et al.
patent: 4724588 (1988-02-01), Runkel
patent: 560937 (1932-10-01), None
patent: 82534 (1971-06-01), None
patent: 1155062 (1969-06-01), None
Bauer Heinz-Dieter
Holz Winfried
Kiaubs Hans-Dieter
Akzo Nobel N.V.
Coe Philip R.
Oliff & Berridg,e PLC
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