Abstract:
Method and apparatus for longitudinal orientation of thermoplastic film material (20) comprises a width-reduction zone upstream of the longitudinal stretching zone (9, 10), through which the width of the film is gradually reduced so as to allow longitudinal stretching without necking. The width-reduction zone comprises at least two sets of pleating rollers (7, 1) comprising intermeshing grooves or discs for pleating the material. The downstream (1) rollers comprise a mini-roller defined by the following measures a) the pitch of the corrugations, measured from middle of tip to middle of each neighbouring tip is 20 mm or less; b) the perimeter from middle of a tip to the middle of each neighbouring tip measured along the corrugated roller surface, divided by the said pitch is in the range between 1,10 and 1,80; and c) the diameter of the mini-roller, measured at the tips of the corrugations, is at the highest 4 times the said pitch. Preferably a pair of mini-roller sets is arranged on opposing sides of the film in reciprocating mounts enabling alternate entwining of the film around one then the other mini-roller. The method allows achievement of high tensile strength, yield point, resistance to tear propagation and puncture resistance, especially for polyethylene and polypropylene films.
Abstract:
The invention relates to a method for producing a highly oriented, high molecular weight polymer tape. The method comprises: a) forming a non-fibrous polymeric sheet; (30) b) rolling and stretching said sheet (30) to form a partially oriented polymer web; (31) c) drawing the partially oriented polymer web (31) to form an oriented non-fibrous polymer tape (33), the method is discontinuous in that the ingoing line speed of at least one method step differs from the outgoing line speed of the preceding method step. The invention also relates to a device for carrying out the method. The invention further relates to a material sheet comprising the polymer tapes. A ballistic resistant article comprising the material sheet exhibits excellent antiballistic properties.
Abstract:
A non-fibrous ultra high molecular weight polyethylene tape having a width of 1-inch or greater and a modulus of 1,400 grams per denier or greater. The non-fibrous UHMWPE tape is obtained by compression molding powder at a temperature below its melting point and then drawing and stretching the resultant compression molded UHMWPE sheet, with no slitting or splitting, at a draw ratio of at least 100:1. The UHMWPE tape can be produced in weights of 6,000 to 90,000 denier or greater. The UHMWPE tape of the present invention minimizes the effect of stress concentrators that are prevalent with fibers and thereby enables the tape to be drawn at much higher draw ratios than is possible with fibrous UHMWPE. When used in ballistics panels, the high modulus high molecular weight polyethylene tape of the present invention improves ballistic performance by providing enhanced dissipation of the impact energy of a projectile.
Abstract:
The invention relates to a method for producing oriented slit film tapes, comprising the following steps: extruding melt polymer through a die (2); simultaneous quenching and melt-drawing of the molten polymer in the cooling device to form a film sheet (3); slitting the initial film sheet into a plurality of relatively narrow slit film tapes (4); stretching (8) at elevated temperature, by passing the slit film tapes through a heating medium (7) at a temperature just below the softening temperature of the slit film tapes; y annealing and cooling the oriented slit film tapes (10, 11); winding the slit film tapes (13); characterized in that before the stretching step, it has a stage of pre-stretching (108) made by passing the slit film tapes through one set of heated holding rollers (107) turning at a given speed and one set of cooled pre-stretch rollers (109) turning faster than the heated holding rollers, wherein at least one of the rollers of the set of holding rollers is heated and at least one of the rollers of the set of pre-stretch rollers is cooled. The invention also relates to an apparatus for performing this method and to the products obtained by said method.
Abstract:
Eine verbesserte Vorrichtung zum Antrieb einer Vorheizwalzenanordnung in der Heiz- oder Vorheizstufe (H 1 ) mit mehreren Walzen zeichnet sich durch folgende Merkmale aus: die Motoranordnung umfasst wenigstens einen Einzelantrieb und vorzugsweise zwei Einzelantriebe, worüber zumindest die Ausgangswalze (9) und vorzugsweise die Eingangs- und die Ausgangswalze (1, 9) angetrieben werden, die Motoranordnung umfasst ferner einen oder mehrere Asynchronmotoren, wobei jeder Asynchronmotor die Oberflächengeschwindigkeit und das Drehmoment einer der intermediären Walzen steuert, und es ist ein gemeinsamer Frequenzumrichter vorgesehen, mit dem ein oder mehr als ein Asynchronmotor, insbesondere alle Asynchronmotoren, betrieben werden.
Abstract:
[PROBLEMS] To provide a biaxially oriented polyamide based resin film which is excellent in transparency and the slidable property under high humidity and is reduced in the curl during boiling operation and in the divergence in the case of the absorption of moisture. [MEANS FOR SOLVING PROBLEMS] A biaxially oriented polyamide based resin film which is formed by a method comprising providing a unoriented sheet comprising a polyamide based resin containing fine particles for forming surface projections, and subjecting the unoriented sheet to a two-step stretching in the longitudinal direction and then to a stretching in the transverse direction, and which exhibits a divergence of 2.0 to 4.0 mm in the case of the absorption of moisture and a strain during boiling operation of 2 to 3 %.
Abstract:
A blend of two partly incompatible polymers is extruded to form a film under conditions such that the alloy in the blend comprises fibrils extending mainly in one direction, the width and thickness of each fibril having a mean lower than 5 µm, the fibrils being formed of the polymer component having a higher melting point, and the fibrils being surrounded by a matrix of the second polymer, which has a lower coefficient of elasticity. The special morphology is achieved by providing grids (301, 302) in a grid chamber upstream of the exit orifice of the extrusion die, and by sequential hot stretching at a temperature at which the higher melting polymer is at least partly crystalline, and cold stretching, at which both polymers are substantially solid. The second, cold stretching step, is carried out under conditions to give an elongation at break at 20°C of at least 25%. The films are of particular value for forming crosslaminates having high shock resistance. Preferably the polymer forming fibrils is polypropylene and the polymer forming the matrix is an ethylene polymer, preferably LLDPE.