ベルクロ

US4984339
"1. An improved hook for hook and loop fasteners（面ファスナー）having（＊hook having）a profile defined by an inner generally concave face（２１）and an outer generally convex face（４４）, said hook comprising a planar base member（２４）intimately engaging a tapered base portion and extending therefrom to join, in a transition region, a tapered hook portion（２２）able to engage a loop applying a force to the hook portion substantially normal to the planar base member and terminating in a free end, the taper on the hook portion being much less than the taper on the base portion wherein the hook tapers continuously downwardly in width from the tapered base portion to the free end such that a loop engaging the hook in tension, with the said force being substantially normal to the planar base member, will cause a hinging or buckling of the hook at a location adjacent the outer face in the transition region as the hook deforms under the applied force and such that a loop engaging the hook in shear, with said force substantially parallel to the planar base member, will transmit bending force through the tapered base portion between the location of buckling and the planar base member, the hook being of substantially constant thickness and having a substantially rectangular transverse cross-section, said taper being from about 0.6 in 1 to about 0.2 in 1 in the transition region at about the buckling location."

US6635212
"1. A method of continuously forming a smooth hook strip for a hook-and-loop type mechanical fastener consisting essentially of:

a) providing a web backing having an array of upstanding（起立）substantially uniformly spaced thermoplastic projections which web backing and projections are formed of the same thermoplastic material, the thermoplastic material having a flow temperature, each projection having a stem portion and a top portion, said projection having a given first cross-sectional dimension, and height, said web backing and projections combined having a given second height;

b) providing a gap formed by a first surface and a second surface, the gap being less than the second height, a first surface being heated to a temperature above the flow temperature of the thermoplastic material forming the projections; and

c) moving the web backing into and through the gap such that the thermoplastic material forming the top portion of the projections are deformed, such that the projections have a second cross-sectional dimension and height which height is less than the first height and which second cross-sectional dimension is larger than the first cross-sectional dimension, by the heated surface under pressure, providing hooks with upstanding stem portions and hook heads having a smooth upper surface."

"TESTING

Birefringence（副屈折）

Birefringence can be measured by any of several different optical techniques, such as by using standard fluids with different indices of refraction, the Becke line technique, dispersion staining, or a compensator. The compensator technique is used to obtain the birefringence measurements reported below.

Using an "Ortholux 2 Pol" polarized light microscope with a Berek compensator from E. Leitz Company, Covington, Kentucky, a hook strip is placed under crossed polarized light with its z-axis oriented north-south. The microscope stage is rotated 45 degrees. A compensator is rotated in each direction until a black fringe appears; at this point retardations（レターデーション、位相差；残留歪みの指標）are equal and opposite. Compensator readings are recorded and the birefringence of the sample is calculated according to the equation:

where R=retardation, C=compensator constant, and t=sample thickness. The retardation R, is defined as the phase difference between the two components in numbers of waves."