A new dielectric material for a communication cable has a dielectric base with strength members embedded therein. By a new process, vacuum voids are formed in the dielectric base and at least partially contain or abut the strength members. The material is particularly well suited for a first dielectric tape, where the cable includes a first insulated conductor, the first dielectric tape and a second insulated conductor, with the first insulated conductor being twisted with the second insulated conductor with the first dielectric tape residing between the first insulated conductor and the second insulated conductor. The material is also suitable for a separator of the cable serving to separate twisted pairs from each other within the cable, as well as other components of the cable, such as an insulation layer of one or more of the insulated conductors of the twisted pairs.

The invention provides a polyolefin-based resin film including a polyolefin-based resin composition that includes at least a propylene-α olefin random copolymer, wherein (1) an olefin-based block copolymer is 0 to 2 parts by weight based on 100 parts by weight of the propylene-α olefin random copolymer; (2) an olefin-based copolymeric elastomer resin is 0 to 2 parts by weight based on 100 parts by weight of the propylene-α olefin random copolymer; (3) a propylene homopolymer is 0 to 40 parts by weight based on 100 parts by weight of the propylene-α olefin random copolymer; (4) the polyolefin-based resin film exhibits a thermal shrinkage rate of 25% or less in a direction in which the thermal shrinkage rate is larger between a longitudinal direction and a lateral direction; and (5) a planar orientation coefficient ΔP calculated from a refractive index of the polyolefin-based resin film is 0.0100-0.0145.

A method for perforating a film of plastic material in which the film is perforated whilst it is slid through a perforating device by a plurality of pressurised hot gas jets having a temperature above the melting temperature of the main film, in which the hot gas jets are correlated with the sliding speed of the main film, and in which reinforcing bands obtained from an auxiliary film of plastic material are connected to the perforated main film, making the reinforcing bands adhere between parallel rows of base holes. During perforating, the main film of plastic material is pressed against a perforating template, making the main film of plastic material instantaneously penetrate openings of the perforating template by said hot gas jets. A hot gas perforating device and a suitable apparatus for perforating and stretching a film of plastic material are also provided.

A method for perforating a film of plastic material in which the film is perforated whilst it is slid through a perforating device by a plurality of pressurised hot gas jets having a temperature above the melting temperature of the main film, in which the hot gas jets are correlated with the sliding speed of the main film, and in which reinforcing bands obtained from an auxiliary film of plastic material are connected to the perforated main film, making the reinforcing bands adhere between parallel rows of base holes. During perforating, the main film of plastic material is pressed against a perforating template, making the main film of plastic material instantaneously penetrate openings of the perforating template by said hot gas jets. A hot gas perforating device and a suitable apparatus for perforating and stretching a film of plastic material are also provided.

The method includes unwinding a thermoplastic film from a roll, stretching the thermoplastic film in the machine direction so that it plastically deforms and decreases in width, slitting the stretched thermoplastic film into the multiple mechanical fastening strips, and winding the multiple mechanical fastening strips into multiple rolls. The thermoplastic film has a first surface and a second surface opposite the first surface, and the first surface of the thermoplastic film bears a plurality of male fastening elements. In the method, the unwinding, stretching, slitting, and winding are completed in-line.

The method includes unwinding a thermoplastic film from a roll, stretching the thermoplastic film in the machine direction so that it plastically deforms and decreases in width, slitting the stretched thermoplastic film into the multiple mechanical fastening strips, and winding the multiple mechanical fastening strips into multiple rolls. The thermoplastic film has a first surface and a second surface opposite the first surface, and the first surface of the thermoplastic film bears a plurality of male fastening elements. In the method, the unwinding, stretching, slitting, and winding are completed in-line.

A polymer thin film includes polyvinylidene fluoride (PVDF) and is characterized by a Young's modulus along an in-plane dimension of at least 4 GPa, an electromechanical coupling factor (k.sub.31) of at least 0.1 at room temperature. A method of manufacturing such a polymer thin film may include forming a polymer composition into a polymer thin film, applying a tensile stress to the polymer thin film along at least one in-plane direction and in an amount effective to induce a stretch ratio of at least approximately 5 in the polymer thin film, and applying an electric field across a thickness dimension of the polymer thin film. Annealing and poling steps may separately or simultaneously accompany and/or follow the act of stretching of the polymer thin film.

The invention provides a polyolefin-based resin film including a polyolefin-based resin composition that comprises a propylene-α olefin random copolymer, an ethylene-butene copolymeric elastomer, and a propylene-butene copolymeric elastomer, wherein (1) the polyolefin-based resin composition contains 2 to 9 parts by weight of the ethylene-butene copolymeric elastomer and 2 to 9 parts by weight of the propylene-butene copolymeric elastomer based on 100 parts by weight of the propylene-α olefin random copolymer; (2) the polyolefin-based resin film exhibits a thermal shrinkage rate after heating at 120° C. for 30 minutes of 25% or less in a direction in which the thermal shrinkage rate after heating at 120° C. for 30 minutes is larger between a longitudinal direction and a lateral direction of the polyolefin-based resin film; and (3) a planar orientation coefficient ΔP calculated from a refractive index of the polyolefin-based resin film is 0.0100-0.0145.

The present invention provides for an elastic film comprising a machine direction (MD) and a cross-machine direction (CD) wherein a first MD orientated zone comprises a first polymer composition which comprises of a first melt strength and a first width dimension. The film also comprises a second MD orientated zone disposed immediately adjacent to the first MD orientated zone in the CD and comprises a second polymer composition which comprises of a second melt strength with a second width dimension. The first polymer composition and first melt strength are different in comparison with the second polymer composition and second melt strength.

A stretch film (1) contains an olefin elastomer and an inorganic filler (3). Stress at 50% elongation is 6.0 N or more and 15.0 N or less, and moisture permeability is 1000 g/(m.sup.2.Math.24 h) or more.