A MACHINE UTILIZED FOR PRODUCING AND

MANUFACTURING A RESILIENT FILM SOFT AT TOUCH,

SUITABLE TO DRAINING USE.

DESCRIPTION

RELATED ART

There exists in the related art, disposable hygienic articles for women, such as absorbent pads, panty liners and internal tampons. It is known that many

such articles have a side in contact with the consumer formed by a

perforated film with three dimensional apertures. These apertures quickly

collect body fluids while remaining dry and clean after the passage of the

body fluids.

The disadvantage of such perforated films is the visual and tactile plastic

sensation ,which is unpleasant to consumers.

It is therefore desirable to have available a three dimensional apertured

film that is soft to the touch and has a similar appearance to a textile

material, whilst maintaining the handling characteristics of the body fluids as per the above mentioned perforated films

Currently there exists the production of film with micro perforations . There also exists production of films with a type of micro aperture in 3

dimensions which make the material soft to the touch .

These micro cones can be formed with pressurized water technology or by

pneumatic vacuum forming. Both mentioned process are known art.

An improvement of the process and result has been obtained by applying a

series of three dimensional apertured macro cones to the film containing

micro perforations, which results in improved draining capabilities of the

product.

The construction of the macro cones must be such so as not to destroy the

micro cones produced beforehand.

Such a result can be obtained in different ways.

In patent n. US 4.839.216, as in patent US 4.609.518, is taught the

construction of non shaped macro holes on a film where micro apertures are already present, using a pressurised water technology.

Such a method does not thermoform the macro cones, so limiting the

draining properties of the film.

In patent US 6.780.372, is taught a method for creating thermoformed

macro holes whereby the film is locally treated in the thermoforming zone

without heating the surrounding area of micro holes.

Whilst the technique of perforating with hot needles is known art, the

disadvantage of the macro cones thermoforming process is the tendency to

stiffen the film,

Also the film tends to stick to the needles creating difficulties in

detachment . hi the application of Patent US 2.004.161.586, the problem of fused material rims made around the thermo fused cone is solved by interposing

a layer of high melting material so as to avoid direct contact between the

film and the hot needles.

The high melting material being mechanically more resistant compared to

the film to be processed, greatly helps the detachment of the film from the

hot needles.

The disadvantages of this last process is that the insertion of the mentioned

high melting material means an increase in the cost of the film and an

unwanted increase in thickness.

SUMMARY OF INVENTION

The purpose of this invention is the manufacture of a film apertured three

dimensionally, soft to the touch, resilient, and with a matt finish , suitable

for the efficient correct handling of body fluids, that eliminates the above

mentioned disadvantages of the film and the processes to obtain it.

Such a film shows, at least on one side, an almost continuous pattern of

three dimensional micro cones, arranged according to an axis close to

perpendicular to the surface from where the micro apertures have their

origin.

On the opposite side, there is a continuous pattern composed of three

dimensional macro cones arranged according to an axis close to

perpendicular to the surface from where the macro cones have their origin,

where the orientation of the mentioned micro cones and the macro cones are opposite.

The term "micro cones" refers to cones not discernible by human eye at a

distance equal to or grater than 450mm while the term "macro cones" refers to cones clearly visible by human eye at a distance greater than

450mm.

Because the macro cones are thermoformed on thermoplastic film that

already contains the micro cones ,the process can cause over-destruction of

the micro cones . The technical problem to be solved is to thermoform the

macro cones without damaging the micro cones previously made and at the

same time maintain the softness of the obtained film.

Technical solutions available today allow a process to thermoform cones

using hot needle technology, forcing the film to pass through a calander

where, on one reel there are needles while on the other there are holes,

each needles fits in the corresponding slot on the other reel, perforating and

forcing the contact between needles and film so that thermoforming can

occur.

Nevertheless, the time of contact between needles and film is very limited

in order to avoid that the whole film reaches temperatures near the softening point, a condition which would prevent the detachment of the

film from the needle reel.

Short contact times between needles and film require a higher needle

temperature which will melt the thermoplastic film locally also after

cooling, the thermoplastic film will harden creating an unpleasant effect

to the touch.

Lower film gsm imposed by the market make the actual hot needle

technologies not viable for the above mentioned reason.

DESCRIPTION OF DRAWINGS

Fig.l shows schematically the travel of the micro perforated film between

the hot needle calander and perforated reel for the thermoforming of the

macro cones and between the hot needle calander and the vacuum reel for

the detachment from the needles.

Fig.2 shows schematically the travel of the product through a series of

grooved reels so as to obtain localised stretching

Fig.3 shows schematically the film with micro holes and macro holes

formed in opposite directions

TECHNICAL DESCRIPTION OF INVENTION

This document explains how to obtain thermoformed macro holes on a

thermoplastic matrix where there already exists micro apertures, and to

maintain the performance of collection and retention of the discharge of

the body fluids and also achieving desirable tactile and visual properties,

soft to the touch ,even distribution of holes and of a matt finish.

In order to avoid the localized over melting of the thermoplastic film it is

necessary to work with temperatures lower than the melting point .To achieve correct formation of the holes it is necessary to work with

temperatures above the softening point but substantially below the melting

point thus it is necessary to have a much longer contact time between the

needles and the film.

The formation of the cone happens by forcing the travel of the film between the needles of the first reel and the corresponding slots in the

second reel. Once the cones are created, the film is left in contact with the

needles for sufficient time to effect the correct thermo formation. This involves that the whole film reaches a temperature near to the softening point making the detachment of the film from the needles unfeasible with

a simple pull because the cohesion force between the needles and the film

is such as to ruin the material. This unwanted effect is even more enhanced

by use of lower film gsm. To solve this problem a third perforated reel is

used. This reel is composed of an external sleeve with holes distributed in

such a way that during the rotation each slot engages with a corresponding

needle.

The external sleeve rotates an a hollow fixed shaft. The hollow fixed shaft

has opening along its length wide enough to cover the contact area between

the needles and the third perforated reel. A vacuum is formed inside the

hallow fixed shaft which generates a pulling force at the base of the

thermoformed cone such as to detach the film from the needles without

incurring damage to the film.

Even though the thermoforming process has been slowed minimising the

annealing of the film, it is impossible to completely eliminate some

hardened or stiffened areas caused by the heating process.

To further minimise this hardening a further step has been developed

whereby the film is passed through one or more grooved reels .

The film is appropriately stretched locally so as to break and soften the

areas hardened in the thermoforming process especially around the macro

cones.

Another method that the invention can employ to detach the thermoplastic film from the needles is by using electrostatic electricity, by which, instead

of creating a depressurised area, can charge the film on the third perforated reel with electrostatic charge of opposite polarity, in such a way that an electrostatic force is generated at the base of the thermoformed cones this

force detaches the film from the needles, in a way similar to the method

described in the previous point.

The localised stretching system can have grooves in both axial or radial

directions, therefore creating localised stretching in machine direction or

in cross direction.

As can be seen in Fig.l, thermoplastic film n.l (normally ldpe and lldpe

base) is extruded with cast technology.

The film still in a plastic condition is laid on a matrix 7 that has a variety of

micro apertures with a density between 140 holes per sq.cm to 1024 holes

per sq.cm and is immediately put under vacuum making the film implode

and thus creating the three dimensional micro cones.

The film is left in contact with the matrix for enough time to elapse so that the temperature of the film changes to a temperature that allows the

detachment of the film from the matrix.

Such formed film n.2 is now ready for the macro perforation.

Subsequently a reel 3 with needles, appropriately thermo regulated at a

temperature near to the thermo forming temperature of the thermoplastic

film is set to rotate and is synchronised with the pair of perforated reels 4

and 5 with a density of holes equal to the density of needles.

Both perforated reels can be thermo regulated.

The perforated reel 4 has the function of creating the three dimensional cone and can be substituted by a brush reel with high density of bristles.

Perforated reel 5 has the function of detaching the perorated film from the

needles.

The micro perforated film is passed through the pair of reels 3, 4 creating

the three dimensional macro apertures.

The film is then left in contact with the needles for the necessary time to

achieve a correct thermoforming. Such a method allows much lower

operating temperatures compared to known methods. In fact such a long

contact time between film and needle allows operating temperatures of

needles near to thermoforming ones or in any case lower than the fusion

temperature of the film, limiting the phenomenon of annealing which

makes the film rough and wrinkled.

Increasing the contact time between the film and the needles limits the

annealing effect on the film but unfortunately the whole film reaches a

higher temperature making it difficult to detach the film from the needles.

The film in contact with the needles should maintain a temperatures

preferably between approximately 50 and 60 degrees C;

It is known that low gsm films (15-30 gsm) at such high temperatures

drastically loose their mechanical characteristics, so that the adhesion force

between the needles and just formed macro holes can be such that it makes

it unfeasible to detach the film using a force acting directly on the film as

this would damage the film.

To achieve successful detachment without damaging the product it is

desirable to apply the detaching force to the bottom of the macro holes.

The perforated reel 5 has a pneumatic vacuum chamber so to exert a light force on the base of the macro cones, during rotation, the force exerted by

the pneumatic vacuum detaches the firm from the needles without

modifying the characteristics of the product.

Also the volume of air that crosses the de pressurised sector cools the

macro cones just formed.

The film has been detached from the needles by vacuum and travels away

from the vacuum aperture and thus free of any rollers.

The film 6, 206 has micro cones 207 produced by micro perforation and

macro cones 208 produced by macro perforation.

The product is now passed through one or more pairs of reels 101, 102

grooved as indicated in Fig.2.

Film 103 is suitably stretched so to break eventual hardened areas by the

thermo forming process especially around the macro cones.

Film 104 is ready to be cooled and winded.