Shoe press belt with chemically bonded inner oil layer

Details Shoe press belt with chemically bonded inner oil layer Shoe press belt with chemically bonded inner oil layer

2000-10-24

2001-12-04

Hastings, Karen M. (Department: 1731)

Paper making and fiber liberation

Apparatus

Running or indefinite length product forming and/or treating...

C162S901000, C156S172000

Reexamination Certificate

active

06325897

ABSTRACT:

SUMMARY OF THE INVENTION
This invention relates to a belt for a shoe press used in papermaking, and more particularly with the improvement of the durability of the shoe-contacting side of the belt, and to improvements in belt manufacturing methods.
A shoe press is an apparatus used to squeeze water out of a web of pulp in the pressing stage of a papermaking machine. There are two types of shoe presses: open and closed. The open type shoe press takes up a large amount of space and has the drawback that it diffuses oil. Therefore, the current trend is toward the use of the closed shoe press.
In a closed-type shoe press, a shoe press belt passes between a press roll and a shoe. A pulp web containing water is sandwiched between upper and lower felts, which pass between the shoe press belt and the press roll. Water contained in the web is squeezed out by the pressure between the press roll and the shoe.
A conventional shoe press belt is typically composed of an endless layer of a high molecular weight elastic substance, reinforced by a fabric. Since the belt is endless, its diameter is relatively small, and consequently its working conditions are unavoidably severe. Therefore, a lubricating oil is generally supplied from the periphery of the shoe to the contact area between the shoe and the belt in order to reduce friction.
However, as time passes, the lubricating oil infiltrates into the high molecular weight elastic member of the shoe press belt, and causes a gradual decrease in the durability of the belt. The lubricant causes a flaking off phenomenon, cracks and eventual breakage of the high molecular weight elastic member.
The general object of this invention is to solve the above-mentioned problem. More particularly, objects of the invention include the effective inhibition of the infiltration of lubricating oil into the interior of the high molecular weight elastic member of the belt, the improvement of the durability of the shoe-contacting surface of the belt and the prevention of the flaking off phenomenon, cracks and breakage of the high molecular elastic member.
To achieve the above-mentioned objects, an endless shoe press belt in accordance with the invention has its inner portion, which is adapted to contact a shoe of a papermaking machine, composed of a high molecular weight elastic material having a shoe-contacting surface containing a protective oil from the group consisting of an oil the viscosity of which is higher than that of the lubricating oil used to lubricate the contact area between a shoe press belt and a shoe, and an oil having a paste-like consistency. The inner portion of the belt is capable of effectively obstructing the infiltration of lubricating oil into the belt.
Moreover, according to the invention, a manufacturing method is provided wherein a protective oil is applied to the shoe-contacting surface of the belt, the protective oil being from the group consisting of an oil the viscosity of which is higher than that of the lubricating oil used to lubricate the contact area between a shoe press belt and a shoe, and an oil having a paste-like consistency. A chemically bonded structure capable of obstructing the infiltration of lubricating oil into the interior of the belt can be formed easily. Preferably, the belt is formed on a mandrel, and the application of protective oil to the shoe-contacting surface of the belt is carried out by coating the surface of the mandrel with the protective oil, and thereafter forming the belt on the oil-coated mandrel by a series of steps including the step of forming the inner layer of the belt by applying a high molecular weight elastic material to the coated mandrel.
Other objects, details and advantages of the invention will be apparent from the following detailed description when read in conjunction with the drawings.


REFERENCES:
patent: 5968318 (1999-10-01), Hasegawa et al.
patent: 2068800 (1992-05-01), None

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