Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1998-05-21
2001-04-03
Yao, Sam Chuan (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S148000, C015S229110, C015S244400, C066S191000
Reexamination Certificate
active
06210506
ABSTRACT:
DESCRIPTION
TECHNICAL FIELD
The invention relates to abrading material for use, for example, in the manufacture of scouring pads.
BACKGROUND ART
GB-B-2157329 discloses a method of making an abrading sheet material which comprises knitting a ground structure from a mixture of a polyester yarn of a heat shrinkable PVC yarn with laid-in floated threads of a second material of polyester which is harder than and either non-shrinkable or less shrinkable than the ground structure materials and shrinking the ground structure so that loops of the second material are raised from a surface thereof.
GB-B-2157329 also discloses an abrading sheet material comprising a knitted ground structure including yarns polyester and of a heat shrinkable PVC material having laid in floated threads of a second material of polyester which is harder than and either non-shrinkable or less shrinkable than the ground structure materials, the ground structure being shrunk causing loops of the second material to extend from a surface thereof.
Material made in accordance with GB-B-2157329 provides good abrading properties but possesses certain disadvantages. Thus, for example, heat shrinkable PVC yarns are expensive. Also it is not readily possible to heat weld or bond such known abrading materials since the melt temperatures of the yarns which make up the ground structure of the known abrading material are widely separated. Thus, at present it is necessary to secure such materials to a backing or the like by stitching and/or an adhesive in order to form an abrasive pad.
It is an object of the invention to provide an abrading material which is relatively inexpensive to manufacture.
It is a further object of the invention to provide an abrading material which may readily be heat welded or bonded to other materials, e.g. plastics foam materials.
DISCLOSURE OF INVENTION
From one aspect the present invention provides a method of making an abrading sheet material comprising knitting a ground structure comprising a shrinkable polyolefin yarn with laid-in looped threads of a material which is preferably harder than that or those of the ground structure, such that the loop threads are raised from a surface of the ground structure, and shrinking the shrinkable yarn of the ground structure to grip the looped threads to lock the loops in place in the ground structure.
Preferably the polyolefin yarn is heat shrinkable, and preferably the method of making an abrading material comprises the step of heat treating the ground structure so that the polyolefin yarn in the ground structure contracts to grip the looped threads to lock the loops in place. The heat shrinking properties of the polyolefin yarn are preferably controlled by subjecting the yarn to a pre-treatment process, known per se, which consists of nipping the yarn at intervals along its length under pressure and at a temperature above its heat shrinking temperature.
Preferably the ground structure also comprises a yarn which is substantially non heat shrinkable or which is less heat shrinkable than the polyolefin yarn, e.g. polyester yarn.
Preferably the looped threads are of polyester. The looped threads may be of a yarn or tape made by cutting a synthetic polyester film such as that sold under the Registered Trade Mark “Mylar”. It will be appreciated however that other abrasive tapes or yarns may be utilised.
From a preferred aspect the present invention provides a method of making an abrading sheet material which comprises knitting a ground structure from a polyester yarn and from a heat shrinkable polyolefin yarn with laid-in looped threads of a material, which is preferably harder than the ground structure yarns, such that loops are raised from a surface of the ground structure, and heat treating the ground structure while restraining the ground structure against shrinkage so that the polyolefin yarn in the ground structure contracts to lock the loops in place.
During the knitting process the loop forming material will preferably be positively fed through the knitting machine to form the loops, rather than being held under tension during knitting.
From another aspect the invention is a method of making a scouring pad comprising the step of heat bonding or welding abrading sheet material as described above to a backing of a suitable resilient thermoplastic material e.g. a resilient material such as polyethylene or polyether foam.
From yet another aspect, the present invention provides an abrading sheet material comprising a knitted ground structure comprising a shrinkable polyolefin yarn having laid in looped threads of a material which is preferably harder than that or those of the ground structure, such that loops extend from a surface of the ground structure, and in which the ground structure has been treated to shrink the shrinkable yarn to cause it to grip the looped threads to lock the loops in position.
When the abrading sheet of the present invention is used to provide the working surface of a scouring pad, backed by a resilient pad e.g. of a plastics foam, which may be impregnated with a detergent, the said surface of the sheet from which the loops extend forms the external surface of the pad so that in use of the pad substantially only the loops make contact with the work be scoured, the ground structure serving mainly as an anchor for the loops and as a ground for attachment to the backing.
Thus from a further aspect the invention provides an abrading device comprising a sheet of abrading material as described above attached by heat bonding or welding to a backing pad of foamed plastics such as polyethylene, or polyether. A preferred method of welding is impulse heat welding but it is conceivable that ultrasonic welding may be employed.
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patent: 3984328 (1976-10-01), Brun
patent: 4628709 (1986-12-01), Aeschbach
patent: 4704757 (1987-11-01), Young
patent: 5455060 (1995-10-01), Neamy
patent: 5476506 (1995-12-01), Lunn
patent: 295 03 874 U (1995-07-01), None
patent: 0 336 507 A1 (1989-10-01), None
patent: 2 157 329 (1985-10-01), None
patent: 1292139 (1989-11-01), None
Impak Marketing Limited
Sheridan & Ross P.C.
Yao Sam Chuan
LandOfFree
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