Fabric (woven – knitted – or nonwoven textile or cloth – etc.) – Scrim
Reexamination Certificate
2000-06-22
2003-10-07
Juska, Cheryl A. (Department: 1771)
Fabric (woven, knitted, or nonwoven textile or cloth, etc.)
Scrim
C442S312000, C442S315000, C442S318000, C442S319000, C066S16900R, C066S195000, C066S196000, C428S114000, C428S116000, C428S117000, C428S118000, C428S320200
Reexamination Certificate
active
06630414
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a three-dimensional net made by warp knitting, particularly a three-dimensional net that is superior in structural stability and shape retainability in three-dimensional cords defining three-dimensional mesh spaces, press-load resistance and elasticity and that can be widely suitably used for various applications, and it also relates to a composite structural material using said net.
BACKGROUND ART
Following three-dimensional net is known as a net formed by double-web warp knitting. First and second webs at least one of which is of mesh construction are connected together by connecting yarns, so as to form three-dimensional cord portions which defining three-dimensional mesh spaces (mesh perforations penetrating the three-dimensional net), thus increasing the thickness and void content.
This three-dimensional net made by warp knitting has a direction dependency due to knitting construction including loop-forming configurations of connecting yarns, which is a drawback inherent in double-web knitted fabrics formed by warp knitting, with the result that the net is liable to collapse or fall in one direction (mainly in the knitting direction). Particularly, the larger the thickness of the net, the more distinct is said drawback.
In the case where the cord portions defining three-dimensional mesh spaces formed by double-web knitting constitute substantially vertical walls with respect to the front and back mesh webs due to double knit, the larger the thickness of the net, the greater the length of the connecting yarns (the height of the cord portions defining the three-dimensional mesh spaces), so that the stability against collapsing or falling is lost. To compensate for this drawback, it is necessary, for example, to increase web-wise dimension of the three-dimensional mesh spaces. That is, a three-dimensional net having an increased thickness necessarily has three-dimensional mesh spaces of increased dimension.
If, however, the three-dimensional mesh spaces is increased in size, the press-load-receiving area per unit area of the net becomes smaller and partialized, because the area for supporting external load is limited onto the three-dimensional cords. Thus, no sufficient pressure-resisting strength is achievable. Moreover, even if the surfaces is covered with sheeting, such as knitted or woven fabric, the regions corresponding to the three-dimensional mesh spaces are recessed, so that the surface presents net-peculiar undulations, which are unsightly and feel unpleasant to the touch. In addition, the pressure-resisting strength differs from place to place.
Therefore, it is far from satisfactory for use as a spacer, shoe insole, cushion material, mat material or the like that is desired to have a large thickness, sufficient elasticity and pressure resistance and to have three-dimensional mesh spaces of reduced size.
Further, in the case where high pressure resistance, high elasticity and high structural stability are required, the net thickness or the three-dimensional mesh space diameter (the distance across) cannot be made so large and the use of the net is limited. That is, it is impossible to provide a net whose mesh openings are large as a whole.
Further, in the case of articles of clothing, such as spacers for clothing, cushion materials or the like where substantial pressure resistance, elasticity and structural stability are required and where the three-dimensional mesh spaces are required to be small, the void content of a conventional three-dimensional net is low and grammage or weight (g) per unit area (m
2
) increases, a fact which is disadvantageous from the standpoint of use and cost.
Further, in order to allow a three-dimensional net made by warp knitting to be widely used for various applications in mat materials, cushion materials or the like, the applicant of the present invention has previously proposed a net designed to improve pressure resistance and structural stability (for example, (a) Japanese Registered Patent NO. 2762052, (b) JP-A-10131008(JP-A-1988-131008, Japanese Unexamined Patent Publication Hei 10-131008).
In the above, according to a document (a), yarns on the three-dimensional cords defining three-dimensional mesh spaces are alternately inclined right and left to form a truss structure. Meanwhile, according to a document (b), connecting yarns constituting three-dimensional cords defining three-dimensional mesh spaces are passed or extended in X-form to prevent collapsing or falling.
Heretofore, effort has been made to secure, by said techniques, structural stability for three-dimensional nets made by warp knitting. However, in either case, sufficient structural stability cannot be obtained unless a balance between the size of three-dimensional mesh spaces and the length of connecting yarns is achieved. Moreover, there are cases where the three-dimensional structure itself cannot be secured, and the void content lowers while the grammage (g/m
2
) increases.
For example, in the case of a net of truss construction in the document (a), if the thickness of the net increases, so does the diameter of three-dimensional mesh spaces, so that the strength to support a load in the direction of the thickness of the net is weakened, with the result that the pressure-resisting strength and elastic force in the direction of the thickness of the net are reduced. That is, in order to provide structural stability against collapsing or falling, it is necessary to increase the diameter of three-dimensional mesh spaces the more, the greater the thickness.
Further, in the case of the net of truss construction, the positions of the junctions of braids defining the mesh openings of front and back mesh webs are shifted in the knitting direction, so that a connecting yarn connecting a braid on first mesh web and corresponding braid on second mesh web is inclined rightward and leftward alternately. Thus, in plan view, the braid on the first mesh web crosses the braid on the second mesh web. Therefore, when the net is unfolded to be spread and subjected to a treatment such as heat setting, the distance between stitch forming positions of connecting yarns hung between the braids in the first and second mesh webs differs. The distance between which the connecting yarn are passed and hung become largest when the connecting yarns are passed and hung between junctions of the first and second mesh web, while the distance become smallest at the plan-view-wise crossing point.
On the other hand, since the length of the connecting yarns passed and hung between the front and back braids is basically constant, the connecting yarns are almost linear between said junctions between which the distance is largest, while in said crossing portion where the distance is smallest, the connecting yarns are bent, failing to develop sufficient pressure-resisting strength. Further, since the connecting yarns between said junctions are most greatly inclined, the pressure-resisting strength is lower than when the connecting yarns extend vertically.
Further, in a three-dimensional net of the type in which the front and back braids that are in zigzag form cross each other, there are connecting yarns that are upright with respect to the front and back mesh webs and connecting yarns that are inclined. The effect of these connecting yarns provides two strengths, the pressure-resisting strength and the strength to resist transverse collapsing or falling. If the number of upright connecting yarns is increased in order to increase the pressure-resisting strength, the strength to resist falling decreases. Reversely, if the number of inclined connecting yarns is increased in order to increase the strength to resist collapsing or falling, this results in a decrease in the pressure-resisting strength in the direction normal to the net surface (the direction of the net thickness.) Further, since a complete balance between the pressure-resisting strength in the direction of the net thickness and the strength to resist transverse falling cannot be achieved, stabili
Asahi Doken Kabushiki Kaisha
Jordan and Hamburg LLP
Juska Cheryl A.
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