U.S. patent number 3,912,432 [Application Number 05/496,896] was granted by the patent office on 1975-10-14 for base material for synthetic leather, and apparatus for the production thereof.
This patent grant is currently assigned to Vepa AG. Invention is credited to Heinz Fleissner.
United States Patent |
3,912,432 |
Fleissner |
October 14, 1975 |
Base material for synthetic leather, and apparatus for the
production thereof
Abstract
An apparatus for producing a dense stitched fleece includes a
treatment chamber, one or more sieve drums rotatably disposed in
said treatment chamber for conveying a fleece therethrough, inlet
means for introducing the fleece to the treatment chamber, fan
means associated with the sieve drum means for subjecting the
interior of the sieve drum means to a suction draft and for drawing
a treatment medium therethrough, heating means disposed in a
circulation zone of the treatment chamber for heating the treatment
medium, perforated felt means associated with at least a portion of
the surface of the sieve drum means for compressing the fleece held
on a sieve drum means by said suction draft, and outlet means for
removing the compressed stitched fleece from the treatment chamber,
at least a part of the perforated belt means being positioned in
the proximity of said outlet means.
Inventors: |
Fleissner; Heinz (Egelsbach,
DT) |
Assignee: |
Vepa AG (CH)
|
Family
ID: |
27509922 |
Appl.
No.: |
05/496,896 |
Filed: |
August 12, 1974 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
14808 |
Feb 17, 1970 |
3876745 |
|
|
|
Foreign Application Priority Data
|
|
|
|
|
Feb 17, 1969 [DT] |
|
|
1907860 |
|
Current U.S.
Class: |
425/75; 264/122;
425/373; 19/308; 425/83.1; 425/384 |
Current CPC
Class: |
D04H
1/54 (20130101); D04H 3/14 (20130101) |
Current International
Class: |
D04H
3/14 (20060101); D04H 1/54 (20060101); B29C
015/00 () |
Field of
Search: |
;425/75,80,373,83,73,384
;264/113,122,92 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Spicer, Jr.; Robert L.
Attorney, Agent or Firm: Craig & Antonelli
Parent Case Text
This is a division of application Ser. No. 14,808 filed Feb. 17,
1970, now U.S. Pat. No. 3,876,745.
Claims
What is claimed is:
1. An apparatus for producing a dense stitched fleece which
comprises a treatment chamber, at least one sieve drum means
rotatably disposed in said treatment chamber for conveying the
fleece therethrough, inlet means for introducing the fleece to be
treated to the treatment chamber, fan means associated with the
sieve drum means for subjecting the interior of said sieve drum
means to a suction draft, heating means disposed in the circulation
zone of the treatment chamber, pretensioned sieve means associated
with at least a portion of the surface of the sieve drum means and
in the proximity of the outlet to the treatment chamber for
compressing the fleece therebetween, drive means for driving the
fan means, drive means for rotating the sieve drum means and outlet
means for removing the dense stitched fleece from the treatment
chamber.
2. The apparatus of claim 1, wherein the sieve means is a
perforated belt means.
3. The apparatus of claim 2, wherein the outlet means includes an
aperture provided in the treatment chamber, said perforated belt
means extending out of the treatment chamber through said
aperture.
4. The apparatus of claim 3, wherein a plate means is hinge-mounted
to the treatment chamber at the outlet aperture, said plate means
being adapted to cover and expose that portion of the perforated
belt means extending through said aperture.
5. The apparatus of claim 4, wherein a pair of cooled compression
rolls are provided behind the aperture outlet of the treatment
chamber.
6. The apparatus of claim 1, wherein said outlet means includes an
outlet aperture for discharge of said fleece and a pair of cooled
compressioned rolls are provided adjacent to the outlet aperture of
the treatment chamber.
7. The apparatus of claim 1, wherein said outlet means includes an
outlet aperture provided in said treatment chamber, and further
comprising means in the proximity of said outlet aperture for
allowing fresh air to be drawn into said treatment chamber by said
suction draft whereby said fresh air cools the fleece compressed
between the sieve means and the sieve drum means.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a base material (substrate) for
synthetic leather, and to a process and apparatus for the
production of a densely stitched fleece comprising at least two
types of fibers, one of which is employed as the binding fiber.
This fleece, which is suitable as a base material for synthetic
leather, can be strengthened by means of a thermal treatment.
It is conventional to utilize stitched fleeces as a base material
for synthetic leather. These fleeces generally contain a large
proportion of high-shrinkage fibers, for example about 30-50%, or
more. In case high-shrinkage fibers of polyesters or polyamides are
employed, the shrinking step is most advantageous conducted in a
water bath heated to a temperature of about 90.degree.-95.degree.C.
However, in this connection, considerable difficulties are
encountered in obtaining a uniform shrinkage over a specific width
of the material. A uniform shrinkage is necessary since this
produces the closeness (denseness) in the material. Only when the
density is uniform is it possible to obtain uniform properties in
synthetic leather. When using polypropylene as the shrinkage fiber,
the shrinkage is carried out in heated air. By means of the
shrinking process, a very close, dense and compact fleece is
obtained exhibiting a correspondingly good fluxural elasticity.
Because of the difficulty encountered in obtaining a uniform
shrinkage, it is also known to employ knitted and woven fabrics as
the base. These fabrics are expensive in their manufacture, and the
final products do not possess properties equal to a synthetic
leather utilizing a shrunk fleece as a base material. In order to
avoid the difficult shrinking process, it has also been suggested
to use a stitched fleece as a base (carrier or substrate) material,
said fleece having a certain proportion of binding fibers. These
fleeces are very voluminous and do not exhibit the closeness of a
shrunk fleece and thus do not exhibit the good properties of a
shrunk fleece.
SUMMARY OF THE INVENTION
An object of the present invention is to avoid the prior art
disadvantages in providing a base material for synthetic
leather.
Another object of the present invention is to provide an improved
process and apparatus for producing a base material for synthetic
leather wherein a good bonding of the individual fibers and a
uniform compactness of the fibers is achieved.
A further object of the present invention is to avoid the
difficulties encountered in the treatment of shrunk fleece but, at
the same time, imparting to the base material the similar
advantageous properties of a shrunk fleece.
Other objects and further scope of applicability of the present
invention will become apparent from the detailed description given
hereinafter; it would be understood, however, that the detailed
description and specific examples, while indicating preferred
embodiments of the invention, are given by way of illustration
only, since various changes and modifications with the spirit and
scope of the invention will become apparent to those skilled in the
art from this detailed description.
Pursuant to the present invention, it has been found that the
above-mentioned disadvantages may be eliminated and a much improved
process and apparatus for producing a base material for synthetic
leather may be obtained by heating the stitched fleece to the
melting or softening temperature of the binding fiber, compressing
the fleece, and then cooling the fleece during the compression
step. The compression (pressing) step effects, on the one hand, a
very good bonding of the individual fibers to one another by
welding, and, on the other hand, a considerable compacting of the
fleece. By cooling the fleece during the pressing step, the fleece
is simultaneously solidified in the compressed condition, so that
as a result thereby a very close fleece is produced which,
additionally, is also extremely uniform, particularly in its
closeness (compactness).
It is advantageous to conduct the heating process utilizing air,
steam, or a steam-air mixture as the treatment medium, wherein this
treatment medium is drawn through the fleece. In order to compress
the fleece, at least one pair of cooled rolls can be employed, and
for cooling purposes, air can be utilized.
It is furthermore advantageous to hold the fleece compressed
between two screens, at least during the cooling step, and to guide
it therebetween, with a gaseous or liquid cooling medium, e.g.,
air, steam, or water, being conducted through the fleece during the
cooling process. The feature of starting the compression of the
fleece while it is in the plastic condition of the melt fiber
afford the advantage that a more satisfactory welding is achieved
due to the relative movement of the individual fibers with respect
to one another. A particularly good fleece for a base material for
synthetic leather is obtained according to the present process by
providing that the fleece contains up to about 50% binding fibers,
preferably about 10-15% of said melt fibers or binding fibers, and
is strengthened by a thermal treatment and a pressure treatment as
described above. By increasing the proportion of binding fibers,
the closeness of the fleece can be enhanced.
A fleece consists of a specific fiber having a specific melting
point. If another fiber having a different chemical composition and
a lower melting point is added to this fiber, it serves as a
binding fiber when the temperature of the fleece is increased in
the range of the melting point of said another fiber. Thus, the
fleece as defined by the present invention comprises at least two
of any material of synthetic fibers having a defined melting point,
at least one of said fibers having a melting point lower than that
of the remaining fibers.
The fibers which can be utilized by the present invention include
any of the natural or synthetic fibers. The natural fibers can
include cotton, wool, silk, cellulose, etc., and the synthetic
fibers may comprise synthetic polymers such as polyolefins, e.g.,
polyethylene, polypropoylene, etc., polyamides, e.g., Nylon 6
obtained by condensation of caprolactam, Nylon 66 obtained by the
condensation of hexamethylenediamine with adipic acid, etc.,
polyesters, e.g., polyethylene terephthalate, etc., phenolic
resins, e.g., phenol formaldehyde resins, urea formaldehyde resins,
etc., polyvinyl materials, e.g., polyvinyl chloride, polyvinyl
acetate etc., and acrylate resins, such a polymethylmethacrylate.
Copolymers of these materials with one another or with
ethylenically unsaturated monomers, and similar type polymers are
also encompassed by the present invention. Typical fleece
compositions include, for example, polyester fibers utilizing
polypropylene or polyamides as the binding fiber.
A good, uniform coalescence and thus a fleece which possesses an
extraordinary uniform strength is obtained by combining the two
types of fibers to a bi-component fiber. Such a fleece can also be
advantageously produced as a spun fleece from endless fibers. A
fleece of this type exhibits an especially high fluxural elasticity
and a wrinkle-recovery angle of about 170.degree.-180.degree.C.
Examples of bicomponent fibers include Nylon 66 and Nylon 6, Orlon
21, 23 and 27 a polyester with a polyamide, and HS1 and Nylon.
For the manufacture of such fleeces, it is suggested to employ an
apparatus containing at least one sieve drum subjected to a suction
draft, for heating the binding fibers to the melting temperature.
Also, a perforated belt which is associated with the sieve drum is
provided in the proximity of the outlet of the treatment chamber,
said belt applying an initial pressure against the sieve drum and
the fleece disposed thereon. It is also advantageous to draw in by
suction fresh air for cooling the fleece, at least in a portion of
this zone.
It is also possible, in the case of certain fleeces, to provide
after the sieve drum at least one pair of cooled compression rolls,
in a place of such a performated belt. A cooled pair of compression
rolls can be advantageously employed when treating thin fleeces
wherein the cooling is extensively effected by contact with the
compression rolls. In the case of thick fleeces, an apparatus with
the above-described perforated belt is more desirable.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more fully understood from the
detailed description given hereinbelow and the accompanying
drawings which are given by way of illustration only and thus are
not limitative of the present invention and wherein
FIG. 1 shows a longitudinal section through the apparatus;
FIG. 2 shows a cross-section through the apparatus of FIG. 1 along
line A-A of FIG. 1.
BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, the apparatus of the present
invention comprises a heat-insulated housing 1, containing a sieve
drum 2, subjected to a suction draft. Above and beneath the sieve
drum 2, heating elements 3 are provided for heating the circulated
treatment medium, for example air and/or steam. At the front face
thereof, the sieve drum is provided with a fan 4, which drawn the
treatment medium out of the sieve drum and blows it back to the
outer surface of said sieve drum, by way of additional heating
elements 5. In the sieve drum 2, a cover plate 6 is arranged at
that side of the sieve drum, which is free from the material being
treated. The cover plate prevents the treatment medium from
entering the sieve drum at this side. The fleece 7 to be
strengthened is fed to the sieve drum 2 on a conveyor belt 8, in
the apparatus shown in the drawings, and is suddenly heated, in a
shock-like manner, to the treatment temperature, by drawing the
treatment medium into the first drum through the fleece disposed on
the sieve drum. A perforated belt 9 is associated with a portion of
the periphery of the sieve drum, said belt, which is under tension
or pressure, functioning to compress the fleece. By utilizing this
compressing step, a more satisfactory welding together of the
binding fibers with the other fibers is accomplished. At the same
time, the fleece is prevented from lateral shrinking by means of
the bilateral guidance. This is particularly important when
polypropylene is employed as the binding or shrinking fiber. In the
proximity of the outlet of the apparatus, fresh air is drawn into
the treatment chamber through an opening 10. This fresh air cools
the fleece compressed between the perforated belt 9 and the sieve
drum 2, and thus the fleece structure is solidified in the
compressed state. In place of cooling by means of fresh air, it is
also possible to effect the cooling by a pair of cooled compression
rolls 11 arranged at the outlet of the apparatus. However, this
pair of compression rolls 11 can also be additionally provided. The
fan drive 12 and the drum 13 are attached at the outside of the
housing 1.
The invention being thus described, it will be obvious that the
same may be varied in many ways. Such variations are not to be
regarded as a departure from the spirit and scope of the invention,
and all such modifications as would be apparent to one skilled in
the art are intended to be included.
* * * * *