AU6018696A

AU6018696A - Fabric

Info

Publication number: AU6018696A
Application number: AU60186/96A
Authority: AU
Inventors: Franciscus Lambertus Tjeerd Goene; Jan Peter Meijnen
Original assignee: Blydenstein Willink NV
Current assignee: Blydenstein Willink NV
Priority date: 1995-06-19
Filing date: 1996-06-19
Publication date: 1997-01-15
Also published as: KR19990023005A; JP2001507759A; NO975934L; EP0833967A1; NL1000591C2; CA2224252A1; WO1997000341A1; NO975934D0

Description

FABRIC

The present invention relates to a new fabric and its applications.

Fabrics are used in a great number of fields. In the cable industry fabrics are used for instance as sheathing material for mutual insulation of cable components such as the conductive core and the polyethylene (PE) layer lying therearound. The PE layer is melted round the conductive core. In order to prevent the PE penetrating into the conductor during this extrusion, a conventional and very dense fabric is used as insulating tape which excludes the melted extrudate.

Known fabrics of this type generally have a high weft density and consist of a comparatively thin yarn. Standard values are for instance a weft density of 25-40 wefts/cm at a titre of 50-100 dtex. The drawback of the known fabrics are the relatively high production costs.

The present invention has for its object to provide a fabric which is improved in relation to the known fabric. This is achieved by the invention with a fabric whereof the warp or the weft consists at least partly of partially oriented yarn (POY) . This type of yarn is per se known and has a very high stretch and a strongly amorphous character. A part of the polymer molecules already lie in the same direction, while the rest is still amorphous, hence the name "partially oriented". By heating and simultaneously exposing the yarn to pressure, for instance by calendering, the yarn melts whereby the fabric becomes dense. The material moreover transposes from an amorphous to a (partially) crystalline state. The stretch hereby decreases but the material acquires a higher melting point.

In untreated state the melting point of partially oriented polyethylene terephthalate polyester (PETP) is for instance roughly 130°C. After calendering at 180°C and pressure of 40 tons the melting point reaches that of normal PETP, i.e. 250°C. Depending on the application, other POYs can also be used in addition to PETP. The applied temperatures and pressures depend of course on the POY being used. In the fabric according to the invention use can be made, as compared with the known fabric, of thicker yarn of for instance 200-300 dtex and a lower weft density of for instance 15-20 wefts/cm. The advantage hereof is a higher production speed and resulting lower production costs.

Depending on the chosen weft density the fabric will be completely closed or almost completely closed. The skilled person in this field will be able to adapt the weft density to the desired application. Almost completely closed fabrics are particularly suitable for foil-like materials with a high stability.

A completely closed fabric is very advantageous for instance in use as sailcloth. A completely closed fabric is also often a prerequisite in the case of use as con- ductor separation tape with water-blocking properties in cables.

For such applications in cables a layer or pattern of super-absorbent material can be applied to the fabric, for instance as described in the non-prepublished Nether- lands patent application number 1.000.572. Because the moisture possibly penetrating through the fabric is immediately absorbed when a super-absorbent material is used, an almost completely closed fabric can also be used in this combination. In an alternative embodiment of the invention a conducting material can be arranged on or in the fabric. Particularly for applications in electrical and data communication cables such a conducting fabric is very advantageous. Known fabrics are used in this application as sheathing material to prevent melted PE penetrating into the conductor during extruding of PE round the conductor. However, concentrations in the electric field around the conductor must preferably be discharged quick¬ ly to prevent disturbances. A non-conducting material would serve no function in dispersing such concentra- tions. The fabric according to the invention, if made conductive, can however do this.

Making the fabric conductive can be performed in different ways. A conducting thread can thus be co-woven. The fabric can after manufacture also be coated or im¬ pregnated with a conducting material such as soot.

The conducting fabrics according to the invention can also be combined with a layer or pattern of super¬ absorbent material. The invention therefore provides fabrics with dif¬ fering combinations of properties. Fabrics can be com¬ pletely or almost completely closed, conductive or non¬ conductive and may or may not be provided with a super¬ absorbent material. In a particularly advantageous embodiment of the invention the fabric consists of warp threads of for instance polyester with a density of 20-40 threads/cm and a titre of 33-150 dtex and weft threads of partially oriented polyethylene terephthalate polyester (PETP) with a titre of 200-300 dtex in a quantity of 15-20 wefts/cm, wherein the final fabric is obtained by calendering at a temperature of 180°C and pressure of 40 tons. The thick¬ ness of the fabric after calendering amounts to approxi¬ mately 0.1 mm. The invention further relates to a method for manu¬ facturing a fabric according to the invention, comprising of weaving a suitable warp yarn with a weft yarn of a partially oriented polymer material to obtain a fabric and subsequently exposing the fabric to increased temper- ature and pressure to make said fabric dense, and option¬ ally making the fabric conductive. The fabric can be made conductive by co-weaving a conducting thread during weaving and/or by coating or impregnating the fabric with a conducting material such as soot after the pressure and temperature treatment.

The invention provides a thin and strong fabric which can optionally be made conductive and/or moisture absorbent and which is particularly suitable for use as sailcloth, as sheathing material in cables and the like.

*****

Claims

1. Fabric whereof the warp or the weft consists at least partly of partially oriented yarn (POY) .

2. Fabric as claimed in claim 1, characterized in that the fabric has been exposed to pressure and tempera- ture.

3. Fabric as claimed in claim 2, characterized in that the exposure to pressure and temperature is per¬ formed by means of calendering.

4. Fabric as claimed in any of the claims 1-3, characterized in that the partially oriented yarn is a polyethylene terephthalate polyester (PETP) .

5. Fabric as claimed in claim 4, characterized in that the calendering is performed at a pressure of 10-60 tons, preferably about 40 tons, and a temperature between 130°C and 250°C, preferably about 180°C.

6. Fabric as claimed in any of the claims 1-5, characterized in that the number of wefts per centimetre ("picks") of the fabric amounts to 10-25, preferably 15- 20.

7. Fabric as claimed in any of the claims 1-6, characterized in that the titre of the yarn amounts to 100-500, preferably 200-300 dtex (g/10, 000 m) .

8. Fabric as claimed in any of the claims 1-7, characterized in that soot is arranged on or in the fabric.

9. Fabric as claimed in any of the claims 1-7, characterized in that a conductive thread is co-woven into the fabric.

10. Fabric as claimed in any of the claims 1-9, further characterized by a layer or pattern of super¬ absorbent material.

11. Fabric as claimed in any of the claims 1-10, consisting of 20-40 warp threads/cm with a titre of 33- 150 dtex and weft threads of partially oriented polyeth- ylene terephthalate polyester with a titre of 200-300 dtex in a quantity of 15-20 wefts/cm, which fabric is obtained by calendering at a temperature of 180°C and a pressure of 40 tons.

12. Fabric as claimed in claim 11, further charac¬ terized by a conductive soot layer.

13. Fabric as claimed in any of the claims 1-7 and 11, for use as sailcloth.

14. Fabric as claimed in any of the claims 1-12, for use as sheathing material in cables.

15. Fabric as claimed in claim 9 or 11, for use as conductor separation tape in cables.

16. Sailcloth consisting at least partially of a fabric as claimed in any of the claims 1-7 and 11.

17. Sheathing material for the cable industry con¬ sisting at least partially of a fabric as claimed in any of the claims 1-12.

18. Method for manufacturing a fabric as claimed in any of the claims 1-12, comprising of weaving a suitable warp yarn with a weft yarn of a partially oriented poly¬ mer material to obtain a fabric and subsequently exposing the fabric to increased temperature and pressure to make said fabric dense, and optionally making the fabric conductive.

19. Method as claimed in claim 18, characterized in that the fabric is made conductive by co-weaving a con- ducting thread during weaving and/or by coating or im¬ pregnating the fabric with a conducting material such as soot after the pressure and temperature treatmen .