ITPD960111A1 - PROCEDURE FOR THE PRODUCTION OF NON-WOVEN FABRICS - Google Patents

Description

"PROCEDURE FOR THE PRODUCTION OF NON-WOVEN FABRICS"

DESCRIPTION

The present invention relates to a process for the production of non-woven fabrics.

As is known, a non-woven fabric is made up of a set of synthetic fibers that undergo various processes in succession including: - opening

- mixing

- carding

- folding

- needling

- rolling up.

In particular, needling, following the splicing, that is to say the superimposition of a plurality of layers of fibers, is a mechanical process which allows to consolidate the whole by binding the fibers together to obtain a felt of specific compactness and thickness.

A traditional needle puncher essentially comprises a pair of introduction calenders which convey the layers of fibers or fabrics, which may have already undergone a pre-punching, between one or more pairs of plates in succession.

Each pair of plates comprises a lower plate or depth bench and an upper plate or strippers.

The plates are crossed by numerous holes in which the needles slide alternately (back and forth) which, penetrating into the fabric, intertwine and bind the fibers together.

Downstream of the plates, the treated fabric is made to come out of the needle after passing between a pair of calenders.

The more pairs of in-line needling plates, the better the finishing characteristics at a high production rate.

Depending on the speed of passage of the non-woven fabric inside the needle puncher, naturally the bushel fibers more or less needled.

In some types of non-woven fabric, so-called geotextiles and fibers derived from plastic materials such as polypropylene or polyester, it is very important, among other things, that the product is well sharpened and solid in order to achieve good tensile strength.

Also of particular importance, in order to reduce the transport costs of the product, is the ability to wrap the greatest number of linear meters in a roll.

For this purpose, some manufacturers at the exit from the needle puncher, immediately before rolling, subject the material to hot calendering in order to reduce its thickness with the same mechanical resistance characteristics.

However, this operation is particularly onerous since the investment required for the construction and / or purchase of a hot calendering machine is so high that some manufacturers consider it excessive.

The main aim of the present invention is therefore to develop a process for the production of non-woven fabrics which allows to obtain a product with a thinner thickness than known types, in an economically convenient way even if with mechanical characteristics at least equal to the aforesaid ones. known types.

Within the scope of the aforementioned task, the consequent primary purpose is to obtain considerable economic savings in the storage and transport of the product.

Another important object is to provide a method which allows savings linked to the operating and maintenance costs of the machines.

These and still other purposes, which will appear more clearly below, are achieved by a process for the production of non-woven fabrics which consists, at the end of the carding and lapping phases, in:

- perform hot needling.

Advantageously, said hot needling is carried out by carrying out the needling in a heated thermally insulated environment or by heating the product immediately upstream of the needling machine.

Further characteristics and advantages of the invention will become clearer from the detailed description of the operating steps of two of its embodiments illustrated by way of indication, but not of limitation, in the attached drawings in which:

fig. 1 is a schematic sectional view of a first needle puncher suitable for a first way of carrying out the process; fig. 2 is a schematic sectional view of a second needle puncher suitable for a second way of carrying out the process.

With reference to the aforementioned figures, a process for the production of non-woven fabrics comprises per se known steps not illustrated in the figures generally consisting of consecutive processes of opening, mixing, carding, mowing.

After bending, according to a first embodiment, the non-woven fabric 10 is passed through a needle punching machine indicated as a whole by the reference number 11 and which provides in succession a pair of inlet calenders 12, one or more pairs of plates 13 consisting of from stripping benches and depth benches with needles 14 and a pair of output calenders 15, all contained in an environment 16 thermally insulated and heated with various systems (thermo-ventilated electric resistances, introduction of hot air, diathermic oil circuits , etc. not illustrated).

The heating temperature varies according to the material constituting the fibers of the non-woven fabric, but it is preferably kept at a lower level than the melting point of the material, a level which may vary according to the desired effect, the speed of passage in the machine or other parameters.

However, it is expected that the material must be heated to at least 60-70 degrees centigrade.

Alternatively, fig. 2, a needle puncher is provided, now 111, always made up of a pair of inlet calenders 112, pairs of plates 113 with needles 114, a pair of outlet calenders 115, but now the assembly is not contained in a thermally insulated environment , but upstream it is provided that the non-woven fabric 110 passes between heat sources 116 which also in this case heat it to a suitable temperature.

The hot needling of synthetic fibers takes place with the fibers themselves which are made very ductile.

The process can therefore be much faster than the traditional ones and the fabric can be compacted more so as to considerably reduce its thickness.

The fibers thus thermally conditioned are also less fragile and are more resistant to the aggression of the needles; for the latter, less wear is expected, therefore an economic saving.

It should also be emphasized that the fabric also undergoes a thermostabilization process during hot needling.

In practice it has been found that the intended aim and objects of the present invention have been achieved.

The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept.

Furthermore, all the details can be replaced by other technically equivalent elements

Claims (8)

CLAIMS 1) Process for the production of non-woven fabrics which consists, at the end of the carding and mowing phases, in: - perform hot needling. 2) Process according to claim 1, characterized in that said needling is carried out in a thermally insulated and heated environment. 3) Process as in claim 1, characterized in that said needling is carried out on non-woven fabric which has been heated immediately before. 4) Process as in claim 1, characterized in that said needling is carried out with one or more needling machines in series. 5) Needling machine for carrying out the process as in claim 1, characterized in that it comprises at least one pair of needling benches in a thermally insulated and heated environment. 6) Needling machine for carrying out the process according to claim 1, characterized in that it comprises at least a pair of needling benches and, upstream, heat sources between which the non-woven fabric being processed is made to pass. 7) Needle punching machine as claimed in claim 5 or 6, characterized in that pairs of calenders are placed upstream and downstream of said needling benches, between which the material is passed. 8) Process for the production of non-woven fabrics as per one or more of the preceding claims, which is characterized by what is described and illustrated in the attached drawings.