COMPOSITION AND PROCEDURE FOR OBTAINING A FILM OF MICRO POROUS THERMOPLASTIC POLYMER THAT IS ESPECIALLY SUITED TO THE PRODUCTION OF PERSONAL HYGIENE ARTICLES SUCH AS DIAPERS AND SANITARY TOWELS

Abstract

The present invention consists in a method and a composition for obtaining films of a thermoplastic polymer, preferably polyethylene, that are non-breathable and heavily charged with treated mineral particles in order to leave hollow spaces in the structure thereof, resulting in a significant reduction in density.

Owing to the fact that said films exhibit improved stability to the stresses they undergo during processing in diaper-production machines, and because, furthermore, they offer an important saving in terms of costs owing to the high mineral-filler content thereof and the low density thereof, they are especially suited to use as an outer covering for disposable diapers and sanitary towels.

Claims

1. A method to obtain a non-breathable film having a micro-porous structure comprising a base polymer loaded with mineral particles covered by a fatty acid partially adhered to the base polymer by means of a co-polymer adhesive, the method comprising: a stage of dispersion of the particles of mineral load with the polymer; and a film forming stage.

2. The method according to claim 1, wherein the stage of dispersion of the polymer with the mineral load is carried out apart from the extrusion line of the film by mixers with arms, turbo-mixers for powder or single or multiple screw extruders-mixers, preferably double screw co-rotating extruders with gas removal assisted by a vacuum pump.

3. The method according to claim 1, wherein the stage of dispersion of the polymer with the mineral load is carried out directly in the film extrusion line, through a simple or double screw extruder-mixer, preferably a double screw co-rotating extruder with gas removal assisted by a vacuum pump.

4. The method according to claim 11, wherein, in the film forming stage, the film is only subject to hot stretching between the extrusion nozzle and the solidification of the film between 20/1 and 60/1 and no subsequent stretching.

Description

DESCRIPTION OF THE DRAWINGS

[0035] FIG. 1.

[0036] Tension-elongation graph obtained according to embodiment no. 1 and from a 21-micron commercial film.

[0037] X: Elongation in %

[0038] Y: Tension in megapascals

[0039] A: Curve of the embodiment no. 1 film

[0040] B: Curve of a 21-micron commercial film

[0041] FIG. 2:

[0042] Microphotograph of a cross section through the film corresponding to embodiment number 1.

[0043] 1: micro-pores

[0044] 2: particles of calcium carbonate