See U.S. 4,908,253. This is a divisional, from O-B Rs original patent application re. the 2nd generation. Still alive in the USA till 2007, but not alive in other countries. It concerns the structure obtained by the process described in "historical survey", but with the addition that the laminate includes a barrier film.
See U.S. 4,793,885. Like the above case this is a divisional in the USA, not alive in other countries. It concerns the use of grooved rollers for combined transverse stretching and lamination.
See U.S. 4,629,525. Like the above two cases it is still alive in the USA,
due to the old U.S. rules for lifetime of a patent, and it is also alive
in Argentine, Australia, Spain and Switzerland but no more in other countries.
It covers 2 mutually independent inventions:
the preferable way of heat-stabilizing the XF, and
the use of a blend of HMWHDPE and LLDPE in the "2nd Generation XF", which is explained in the section "historical survey".
See U.S. 4,767,877. Two or more XFs go through the grooved rollers and other stretching rollers together, one on top of the other, and are separated from each other at the end of the stretching line. Increases the production capacity and produces very smooth surfaces where the XFs were separated from each other.
See U.S. 5,028,289. A very important improvement in the transverse stretching of the XF. The grooves are made in high accuracy and have conical sections which match exactly when they intermesh (in practise an accuracy of about +/-5 micron). The transverse stretching takes place under a high roller pressure, in practise about 150-400 kg per cm, so that this stretching becomes a combination of pulling and squeezing. To enable the exact fitting-together of the intermeshing rollers even over a long distance (e.g. several metres) and with unavoidable temperature differences, the roller system consists of a long central roller and two arrays of very short "satellit rollers". The latter are individually biased towards the central roller, in practise by hydraulic means.
Advantages: increased production capacity, improved surface regularity and improved strength properties.
See U.S. 5,248,366. Efficient and practical methods of carrying out helical cutting of tubular film, as used in the manufacture of crosslaminates.
Shock Absorber Band (S-A-B)
See U.S. 5,205,650. The heat seals in industrial bags, garbage bags or similar, is protected against the impact when the filled bag falls, by an adjacent row of embossments, which is adapted to act shock-absorbing and/or to control the distribution of forces. In many cases the height from which a filled bag can be dropped without failing, can hereby be increased by a factor of about 2.
Parachute with S-A-B
See e.g. U.S. 5,330,133. By means of rows of embossments similar to those in the above mentioned "Shock Absorber Band" patents, a parachute made from plastic film, in particular from XF, is given shock absorbing properties. The prospected use is for parachuting of goods.
See e.g. U.S. 5,626,944. A crosslaminate which has a fine regular pattern of parallel ribs each with cross-section in form of a very shallow "U". These ribs are thicker than the rest of the laminate. Between each pair of the U-formed ribs the laminate is stretched out so that it is less curved here. This structure provides a stiffness in one direction which is very important for most kinds of bagmaking and bagfilling. In practise the method of making the "U-Rib" XF is a further development of the above mentioned invention "Lateral Calendering".
See e.g. the same U.S. Patent as under "U-ribs".
This is an improvement of the "Lateral Calendering" invention. There are two steps of "Lateral Calendering" with longitudinal stretching between these steps. The different stretching rolllers are adabted to make the crests of "U"-tracks from the 1st "Lateral Calendering" fit with the crests on the rollers of the 2nd step of "Lateral Calendering", in other words the two "Lateral Calendering" steps are "in register".
Advantages: Increased eveness and productivity, possibilities to make thicker XF.
Note that according to Certificate of Correction to the US patent, in claim 22, line 19 (col. 24, line 15), before "stretching" insert "longitudinal".
See e.g. U.S. 6,344,258. A heatseal method especially for forming top and bottom seals in industrial bags, and especially suited for oriented films. The advantage conerns the shock-peel strength, which is deciding for the drop performance of filled bags. Problems in heatsealing bags from oriented films are caused by loss of orientation in the molten but unbonded zones adjacent to the bonded zone of the heatseal. The invention involves a pivoting of one of the sealing bars and allows a particular high shrinkage of the film, not only in the bonded zone of the heatseal but also in the immediately adjacent, unbonded zones of the film, at the side of the seal which is predetermined to come in contact with the contents of the bag. By this high shrinkage the film grows thick in the said zones, and this compensates for the loss of orientation in these zones.