Method producing a color coded, cellular thermoplastic resin coated wire and the materials necessary for the coating
AssigneePhillips Cables Limited
InventorShirley Beach
Life of this patent
Estimating the term…
Abstract
A particulate concentrate, for example pellets, is provided comprising predetermined amounts of a pigment and a blowing or foaming agent in a polymer matrix. The concentrate can be added to an extruder together with a polymer insulating material for the formation of color-coded cellular insulation on a conductor wire of a cable, for example a communication cable. The composition of the concentrate is so determined that different color-coded, cellular, insulating coatings can be produced which are dielectrically matched, as required.
Claims25
A method of producing a cable conductor wire insulated with a colour-coded, cellular thermoplastic electrically insulating polymer material in extruded form, which comprises:
- providing a thermoplastic electrically insulating polymer material and a weighed amount of a particulate concentrate comprising weighed amounts of a particulate pigment composition and of a particulate, solid chemical blowing agent material in a polymer matrix compatible with said insulating polymer material,
- introducing said polymer material and said particulate concentrate into a screw extruder barrel, containing a screw mounted for rotation therein, to form a mixture,
- passing the mixture through said barrel,
- heating and shearing the mixture in said barrel to melt said polymer material and form an intimate mixture of said pigment composition and said blowing agent material in said polymer material,
- allowing said blowing agent to thermally decompose to a gaseous product,
- forcing the resulting molten mixture through an extrusion head and about a moving conductor wire to form an extruded coating thereon,
- allowing the extruded coating to expand a predetermined amount, and
- collecting the conductor wire insulated with colour-coded, cellular thermoplastic electrically insulating polymer material.
A process for preparing a particulate concentrate comprising a pigment and a solid blowing agent in a polymeric matrix for use in admixture with a thermoplastic, electrically insulating polymer in the manufacture of colour-coded insulating materials which comprises
- mixing a weighed amount of a pigment composition and a weighed amount of a blowing agent composition with a weighed amount of a solid, thermoplastic electrically insulating polymeric matrix material to form an intimate blend of said matrix material and said compositions, said blend comprising 40 to 65% by weight of said matrix material, and
- recovering the blend as a particulate concentrate,
- said weighed amount of pigment composition being selected to provide a colour-coded insulating material having a visibly discernible colour for identification purposes, and said weighed amount of blowing agent composition being selected to provide an amount of 0.5 to 1.2 parts of blowing agent, by weight, per 100 parts, by weight, of total insulating polymer when said concentrate is admixed with the insulating polymer.
A process for preparing a pelletized concentrate comprising a pigment and a solid blowing agent in a polymeric matrix for use in admixture with a solid, thermoplastic electrically insulating polymer, in the manufacture of dielectrically matched colour-coded insulating materials which comprises:
- (i) mixing a weighed amount of a particulate, pigment composition and a weighed amount of a particulate solid, chemical blowing agent composition with a flowable, organic vehicle, which is electrically and physically compatible with said electrically insulating polymer to form a powdery mass,
- (ii) comminuting and intimately blending the powdery mass to produce a friable mass in which particles of the pigment and blowing agent compositions are coated with the organic vehicle,
- (iii) mixing a weighed amount of the friable mass with a weighed amount of a solid, thermoplastic, electrically insulating polymeric matrix material, which is electrically and physically compatible with said insulating polymer to form an intimate blend, said blend comprising 40 to 65%, by weight of said polymeric matrix material, and having an organic vehicle to polymeric matrix material ratio of from 10:90 to 30:70, and
- pelletizing the intimate blend;
- said weighed amount of blowing agent composition being selected to provide an amount of 0.5 to 1.2 parts of blowing agent, by weight, per 100 parts, by weight, to total insulating polymer when said pellets are admixed with the insulating polymer, and said weighed amount of pigment composition being selected to provide a dielectric matching amount in colour-coded insulating material in which the dielectric mismatch is no greater than 2%.
A set of colour-coded pellets for use in admixture with a thermoplastic, electrically insulating polymer in the manufacture of dielectrically matched colour-coded insulating materials comprising a plurality of separately packaged colour pellets, each package containing pellets of a single colour, each pellet comprising a particulate pigment composition and a particulate organic, solid blowing agent composition in predetermined amounts in a matrix of a thermoplastic polymer, said pellets comprising 40 to 65%, by weight of said matrix, and said predetermined amount of blowing agent being effective to provide an amount of 0.5 to 1.2 parts of blowing agent, by weight, per 100 parts, by weight, of total insulating polymer when said pellets are mixed with said insulating polymer, the pellets contained in each individual package being substantially uniform in composition, and the pellets in each package being dielectrically matchable with the pellets in the other packages of said plurality to provide a dielectric matching amount in colour-coded insulating material formed by extruding pellets of a single colour and a thermoplastic electrically insulating polymer material, in which the dielectric mismatch is no greater than 2%.
Dependencies are inferred from the claim text.