Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1998-02-18
2001-05-08
Michl, Paul R. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
Reexamination Certificate
active
06228906
ABSTRACT:
This invention relates to blending rubber or plastics materials.
Pelleted and agglomerated particulates which have internal voids as a result of being agglomerated or pelleted are often used as fillers in rubber and plastics materials. Their large internal void volume—typically two thirds of the total volume for fillers used in the rubber industry—enables them to absorb up to twice their solid volume of oils or plasticisers, after the fashion of activated carbon.
The oils or plasticisers are conventionally added to the particulates in a mixing chamber to which other components of the rubber or plastics system either have already been added or will be added before mixing.
To achieve a homogeneous product, thorough mixing is required, which takes more or less time according to the nature of the materials involved. Some particulates are prone to causing problems in transportation, particularly where attrition gives rise to a fine dust content. These problems are dealt with to some extent by choice of transport system, but some problems remain, particularly from dust as a working environment problem, also, however, as a product quality problem, where it can give rise to inhomogeneities which can critically affect the performance, for example, of automobile tires.
The present invention provides a method for blending rubber or plastics materials that can reduce or even eliminate these problems.
The invention comprises a method for blending rubber or plastics in a system with particulate filler material and liquid such as oils and plasticisers, characterised in that the particulate filler material is impregnated with the liquid by a liquid spray arrangement while the filler material is being conveyed, in a manner in which the particles are generally accessible, to a mixing chamber to which other components of the rubber or plastics system have already been added or will be added before mixing.
The material may be conveyed pneumatically, gravitationally or by using for example a vibratory, screw, belt or bucket conveyor, it merely being necessary to access the particulates so that they are at least to a significant extent able to absorb the liquid.
Clearly, a pneumatic conveyor in which the particles are carried in an airstream is particularly suited to the method but with any of the conveying methods mentioned the particulate material is accessible as a continuous stream or at least divided up into small batches.
The liquid may be metered to the particulate material and may be fed in an amount which is not substantially greater than the amount which can be absorbed by the material.
The impregnation may be effected, in a pneumatic conveying arrangement, by spraying against the flow of the particles using a wide-dispersion nozzle or an array of nozzles.
It is found, rather surprisingly, that the liquid which initially coats the particles is swiftly absorbed and actually improves the mixability of the particles as well as acting as a dust suppressant. Mixing times in the mixing chamber can be significantly reduced with greatly improved homogeneity.
The impregnation may be effected close to an outlet end of a conveyor arrangement in which the particulate material is conveyed.
In a particularly effective arrangement, the particulate material is fed gravitationally to an inclined fluidised air slide delivering to the mixing chamber. The liquid spray arrangement may be located at the lower end of the slide and may comprise a spray bar located above the inclined floor of the slide spraying downwardly. The particulate material may be admitted to the slide from a gravity feed chute and may be controlled by a regulator device, which may be adjustable.
The invention also comprises apparatus for blending rubber or plastics in a system with particulate filler material and liquid such as oils and plasticisers, characterised by a conveyor arrangement delivering the particulate material to a mixing chamber, the conveyor arrangement being arranged to convey the particulate material in a manner in which the particles are generally accessible and the conveyor arrangement having an associated liquid spraying arrangement adapted to spray the particulate material with the liquid to impregnate it while it is being conveyed, and the conveyor arrangement delivering the impregnated particulate material to a mixing chamber to be mixed with other components of the rubber or plastics system.
The invention also comprises a rubber or plastics system blended with liquid impregnated particulate filler material by a method or by apparatus as described.
REFERENCES:
patent: 3668177 (1972-06-01), Van Herpt
patent: 4004782 (1977-01-01), Jeppsen
patent: 4532271 (1985-07-01), Kai
patent: 4599370 (1986-07-01), Grossman
patent: 4961887 (1990-10-01), Crumpler
patent: 5024531 (1991-06-01), Will
patent: 5073032 (1991-12-01), Berion
patent: 5232306 (1993-08-01), Sterner
patent: 5447388 (1995-09-01), Rouse
Bradley James E.
Felsman, Bradly, Vaden, Gunter & Dillon, LLP
Loughborough University Innovations Limited
Michl Paul R.
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