Plastics material mesh structure
AssigneeP.L.G. Research Limited
InventorFrank B. Mercer
Life of this patent
Estimating the term…
Abstract
In order to form an improved junction which is less liable to tear under shock loads, a diamond pattern of holes (or depressions) is formed in plastics material sheet. The holes are then in two sets of parallel lines each making an angle to the subsequent stretching direction and the holes are also in parallel rows at right angles to the stretching direction. The sheet is stretched so that the zones between adjacent holes in each line form orientated strands and the zones between adjacent holes in each row form junctions which have their lateral zones orientated but have a central zone which is unorientated or less orientated, i.e. which is thicker. The central zone can extend into two opposite crotches or be completely surrounded by highly orientated lateral zones.
Claims14
An integral plastic material diamond mesh structure, formed from a substantially uniplanar plastic starting material comprising mesh openings defined between orientated strands and junctions interconnecting the strands, substantially each junction having all its lateral zones orientated, so providing continuous lines of orientated plastic material running through the structure, each line comprising in succession a strand, the lateral zone of a junction, another strand, the lateral zone of the next junction, and so on, substantially each junction having a central zone of plastic material which is thicker than the lateral zones and is either unorientated or substantially less orientated than the lateral zones, the central zone being completely surrounded, as seen in plan, by the orientated plastic material of the lateral zones, all zones of said mesh structure being symmetrical about a median plane corresponding substantially to the median plane of the uniplanar starting material.
An integral plastic material diamond mesh structure formed from a substantially uniplanar plastic starting material, comprising mesh openings defined betwen orientated strands, and junctions interconnecting the strands, substantially each junction having orientated lateral zones which provide continuous lines of orientated plastic material running through the structure, each line comprising in succession a strand, the lateral zone of a junction, another strand, the lateral zone of the next junction, and so on, each junction having between its lateral zones a single zone of plastic material which is thicker than the lateral zones and is either unorientated or substantially less orientated than the lateral zones, which single zone forms at least part of two opposite crotches between respective adjacent strands interconnected by the junction, all zones of said mesh structure being symmetrical about a median plane corresponding substantially to the median plane of the uniplanar starting material.
A method of producing an integral plastic material diamond mesh structure, comprising:
- providing a starting material comprising a substantially uniplanar plastic having a pattern of holes or depressions whose centres are on two sets of notional parallel lines which are at a substantial angle to each other;
- wherein the holes or depressions before stretching are in rows extending generally at right angles to the first stretching direction, the holes or depressions of alternate rows being generally aligned in the first stretching direction, the first distance between the sides of two adjacent holes or depressions in the same row being at least 1.5 times the second distance between the side of one hole or depression and the side of the generally aligned depression in the alternate rows;
- and
- stretching the starting material in a first direction at a substantial angle to each set of lines and thereby drawing out into orientated strands the zones between immediately adjacent holes or depressions in each line to form mesh openings, which strands are interconnected by junctions formed from the zones between pairs of holes or depressions which are adjacent in the direction of stretching, which junctions provide crotches between respective adjacent strands, respective pairs of opposite crotches being aligned in the direction of stretching and in the direction normal to stretching, which junctions are orientated along their lateral zones which extend parallel to the direction of stretching, to provide continuous lines of orientated plastic material running through the structure generally in the direction of stretching, each line comprising in succession a strand, the lateral zone of a junction, another strand, the lateral zone of the next junction, and so on, each junction having between its lateral zones a single zone which is either unorientated or substantially less orientated than the lateral zones, which single zone extends as far as the two opposite crotches, between respective adjacent strands, which are generally aligned in the direction of stretching.
Dependencies are inferred from the claim text.