Method for producing leather fibrous tissues planted on a basic clothing sheet and sheet products produced thereby

This invention is concerned with a novel method for producing leather fibrous tissues in the form of raw material and semi-leather sheets produced by this method wherein odd flocks and other unnecessary fragments of animals' leathers produced subsequent to cutting or shaving operations of the leathers are cut into very short length in dried conditions and then resoluted in water, thereafter being dried up again to form small leather pieces. These pieces are selectively assorted through a filter means and uniformly stuck onto the outer surface area of a suitable basic clothing sheet. The invention further involves the construction of semi-leather sheet products produced by this method, which are far superior in heat-resisting, moisture-absorbent and releasing properties to the conventional semi-leather sheet products now on the market.

BACKGROUND OF THE INVENTION 
The present invention is generally related to a method for producing 
semi-leather fibrous tissue sheets, and more particularly to provision of 
the choice of raw material composed of short-cut animals' leather pieces 
so as to produce semi-leather sheet products such as what is called 
"backskin" sheet, by planting these pieces on a woven or unwoven basic 
clothing sheet in uniformly and inseparably attached relation to the 
outside surface area of the sheet. Thus are finished sheet products 
reproducing animals' leather sheets most similar to the original leather 
of animals' skin. 
With a view to artificially reproducing leather sheets similar to animals' 
leather there have been practically applied such well known method in the 
field of skilled arts for example as of cutting animals' leather into 
short length and resoluting the cut amount thereof. 
However, as in shown in FIG. 1(A) of the accompanying drawings, most of the 
artificially finished leather fabric tissues 1 produced by the 
conventional method are, as the whole, doomed to be curled and frizzled 
unexceptionally to excess because each of tissues 1 or fiber elements 
cannot but be accompanied with a number of bristles and sprays or twigs 
1a. Thus in case of planting these tissues 1 on a basic clothing sheet 2 
by means of a binder 3 with respect to FIG. 1(B), there is no expectation 
to plant uniformly on the basic clothing sheet 2 almost equal number of 
tissues, differently from any natural or animals' fiber elements 1. Also 
it is infeasible to plant a pre-determined number of the conventional 
fibers on the basic clothing sheet 2 per fixed surface area, thus 
resulting in the fibers having some portions densely planted while other 
portions are thinly planted. Moreover, due to the structurally curled and 
frizzled conditions of the existing fibrous tissues, an extremity of each 
fiber element cannot be fully pierced into adhesive layer of the basic 
clothing sheet 2; wherein some fiber elements are left, at the midway 
thereof, stuck to the basic clothing sheet 2, thus giving rise to a 
difficulty that desired planting effeciency cannot be secured. 
As has been mentioned in the foregoing description, even if animals' 
leather fibrous tissues are to be carefully planted or pierced onto the 
basic clothing sheet 2 in accordance with the conventional manufacturing 
methods, the leather fibrous tissues thus produced are still essentially 
short of piercing power. As a result the sensitive tone of slipperiness 
peculiar to animals' leather fibrous tissues themselves cannot be 
reproduced on the basic clothing sheet 2 when baffing operations are 
applied thereto since, during the course of this operation, a number of 
fibrous tissues entangled or twisted with each other are forcibly to come 
off the basic clothing sheet 2 by baffing power which is repeatedly and 
unavoidably added to the entangled or twisted force of the planted fiber 
elements per se. 
Furthermore, referring to the conventional semi-leather fibrous tissue 
sheets, it is technically impossible to plant these tissues or fiber 
element 1 on the basic clothing sheet 2 through the whole surface area 
thereof, consequently bringing about disadvantages that the products thus 
finished are inferior to animals' leather sheet products with respect to 
strength and durability in practical use. In addition thereto, when the 
planted tissues 1 are dyed either from men's sense of beautiful color or 
in obedience to any color of animals' leather per se, no effect can be 
reproduced much less of animals' leather colours because the planted fiber 
elements 1 are inevitably dyed thick on the portions thereof aslant to the 
basic clothing sheet 2 only, so that, compared with other thin planted 
portions, the former portions are subjected to different light refrection 
from the latter portions whereas animals' leathers are reflected uniformly 
to equal reflection of colour through the whole surface thereof from any 
angles. 
The main reason, among many others, why conventional semi-leather fibrous 
tissues 1 are fatally curled and frizzled through the course of treating 
operations is considered to be attributable to neglegence of the most 
important facts that animals' leathers in the form of a raw material must 
be cut into short length and a suitable quantity of water be added to said 
pieces, thereafter being cut or smashed by means of a sharp cutting blade. 
In other word, animals' leathers are widely accepted to be good enough to 
cut them into a short length only without paying attention as to how 
important it is to add a suitable quantity of water to the amount of cut 
pieces and select a smashing means for cutting said pieces to further cut 
the pieces into shorter length. Namely, according to the existing cutting 
method, the raw material is forcibly cut into short length by tearing off 
the material by use of cutting instruments having on obtuse blade edge, 
regardless of the percentage of water contained an the raw material. For a 
fuller understanding, a maximum elemental unit composing animals' leather 
fibrous tissues 1 is a bundle which comprises a group of fibers gathering 
together with each other, in which each of the fibers is composed of 
plurality of fiber elements having diameters between 4 and 8 microns, 
respectively, further each of said fiber elements comprising several 
hundred pieces of fibrils, as are generally well known in the field of 
skilled art. 
In spite of the above-mentioned properties peculiar to animals' leather 
fibrous tissues 1, the realities are that use is made of such a dull 
implement as the obtuse knife as has already been referred to in the 
foregoing description to comminute or smash thereby the animals' leathers 
into short length of pieces without mixing the former with a suitable 
quantity of water just when the smashing operation is being carried out. 
Thus to say nothing of said bundles and said fibers, both the fiber 
elements and the fibrils that compose the former two and are of by far 
diametrally smaller elemental components thereof are also directly 
subjected to the effect of this smashing operation until at last the 
latter two are broken up; consequently, this quantity of dismantled fibers 
and fibrils are branched off in free directions to give rise to bristling 
and branching-off phenomena. 
OBJECTS OF THE INVENTION 
Accordingly, the present invention has been devised to eradicate all the 
above-mentioned drawbacks and disadvantages of the existing semi-leather 
fibrous tissue sheet products, having for one of its main objects the 
provision of a method for producing a high quality semi-leather sheet 
goods wherein, in the first place, a sharp cutting blade edge of cutting 
means is employed to sharply smash an original first raw material so as 
not to permit each tissue of smashed raw material to be curled and 
frizzled; in the second place, second raw material produced by smashing 
said original first raw material is mixed with a suitable quantity of 
water by means of a mixer in priority to setting the latter material to a 
mill until the second raw material can be uniformly agitated within said 
mixer so that an ample quantity of moisture is uniformly bestowed to the 
second raw material. 
In the process of the foregoing smashing and moistening operations, said 
second raw material which is mixed with water within the mixer before 
being resoluted into a fibrous state by means of the mill is kept on being 
further mixed until it reaches water content of 50 to 70%; then after the 
lapse of a fixed length of time it will be found that said percentage of 
moisture has fully permeated into the fiber elements and the fibrils. 
However, the fact with water contained in the fibrous tissues 1 is in 
generally such that the more the fibrous tissues 1 are, the more powerful 
the water is liable to be condensed therein and vice versa. Therefore, on 
the one hand, a quantity of water that has been permeated into both said 
bundles and said fibrils is less dense in structure of the fibrous tissues 
and ready to separate said both two from the basic clothing sheet 2. But 
on the other hand, the other quantity of water that has been permeated 
into both the fibers and the fibrils is more dense than the preceding two, 
the result being that the latter two serve to stick to the outer surface 
area layer of the basic clothing sheet. 
For the very foregoing reasons, it is recommended in the present invention 
that a suitable quantity of water is to be added to the second raw 
material prior to being resoluted into a fibrous state. In this case, the 
second raw material may become separable upto a single fiber unit, but 
said fiber elements and each fibrils still remain inseparable without 
being subjected to said separability since the permeation of water into 
the fiber elements and the fibrils has not advanced as yet. Because of the 
above-mentioned fact, it is considered that there are not caused the 
fibrous tissue bristling and branching-off phenomena which otherwise go 
always as in the case with the conventional semi-leather fibrous tissue 
sheet products. 
Another object of the invention is to provide a semi-leather fibrous tissue 
sheet product wherein, as shown by numeral 4 of FIG. 2(A) of the 
accompanying drawings and referred thereto in the preceding description of 
the invention, although some of said fibrous tissues 4 are never 
excessively curled or frizzled with suitable curvature lengthwise thereof, 
yet most of other fibrous tissues 4 are formed soft in touch and as the 
whole in slow curvature almost similar to a straight lineal shape; in 
addition, each of fibrous tissues 4 being quite free of bristling from the 
adhesive outer surface area layer of the basic clothing sheet 2 thereby to 
reproduce a semi-leather fibrous tissues uniformly planted with an 
animals' leather fibers throughout the whole surface area of the basic 
clothing sheet 2. 
A further object of the invention is to provide a semi-leather fibrous 
tissue sheet product wherein use is made of said tissues 4 to inseparably 
plant the same on the basic clothing sheet 2 by means of static 
electricity induction so as to plant the tissues 4 uniformly throughout 
the whole surface area of the basic clothing sheet 2 at regularly 
spaced-apart intervals, additionally to an advantage that one extremity of 
each tissue 4 is deeply pierced into the adhesive surface area layer of 
the basic clothing sheet 3, as definitely illustrated in FIG. 2(B) of the 
drawings. 
A still further object of the invention is to provide a semi-leather 
fibrous tissue sheet product planted on the basic clothing sheet wherein, 
since the product is composed of said fibrous tissues planted to stickly 
and inseparably to easily come off by mere repetition of touching, 
polishing or cleaning frictions, a seeming and touching tone or so-called 
"the tone of slipperiness" of an animals' leather sheet product in the 
field of leather industry is reproducible to its full extent through the 
above-mentioned treating operations. 
As has been clearly evident from the foregoing description, the 
semi-leather fibrous tissue sheet product of the present invention is 
uniformly planted on a basic clothing sheet throughout the whole outer 
surface area layer thereof in a stickly inseparable state, without causing 
sporadical density and parti-colour dyeing of the planted tissues so that 
when dyed, said fibrous tissues are seemingly quite equal to the natural 
color of an animal leather fibrous tissues, being far superior in strength 
and durability compared with a natural leather product sheet thereby to 
provide semi-leather fibrous tissue sheet product exceeding the existing 
similar one.

DETAILED DESCRIPTION OF INVENTION 
Referring now in detail a preferred embodiment of the present invention in 
conjunction with the accompanying drawings, in which an original raw 
material in the form of odd flocks and other hackled pieces of an animal's 
leather is in the first instance dehydrated (at this stage, the raw 
material is called "a shaving layer") until the water content thereof is 
lowered approximately to the range between 20 and 40 percent by weight 
either by being exposed to natural and ambient drying conditions or by 
subjecting same to mechanical drying operations. Secondly, the original 
raw material thus dried is smashed into short length of pieces by means of 
a sharp blade-edge cutter, then said pieces being set to a cyclone 
separator through which to produce a second raw material. Thereafter the 
second raw material is taken out of the cyclone separator and put into a 
mixer wherein a proper quantity of water is added to the second raw 
material until the latter gets to water content of approximately 50 to 70 
percent by weight by fully agitating both the material and the quantity of 
water together within the mixer. Simultaneously therewith, it is to be 
noted that to the percentage of water there is added a suitable quantity 
of sodium bicarbonate solution. The solution is adapted to uniformly 
readjust the irregularities of Ph of the second raw material lot thereby 
making it effective to carry on such treatments for example as enhances 
the effect of a dyeing operation that directly follows. Preferably, Ph of 
the second raw material lot is raised upto the range between Ph 6.5 and Ph 
7.0. 
After Ph density of the second raw material lot has been adjusted by 
permeating plenty of water thereinto in the above-mentioned manner, the 
same material is set to a mill whose rotational number is pre-set to less 
than 4000 rpm and smashed therein into shorter length of pieces until the 
latter pieces are ground down and finally formed into shapes of bundles or 
tissues of fibrous unit. In this case, a quantity of water added to the 
second raw material is fully permeated deep into each inside of the fiber 
elements and the fibrils both being component elements of leather fibrous 
tissue portions. Moreover, between each of the bundles and each of the 
fibers there exists so great a boundary space that the quantity of water 
serves to facilitate separation of these bundles and fibers from one 
another, whereas between each of the fiber elements and each of the 
fibrils there exists so small a boundary space that said quantity serves 
to facilitate adhering function of said elements sticking to the fibrils. 
To reiterate, said second raw material is easily separable into each state 
of bundles and fibers by being ground down within the mill. But on the 
contrary, the fiber elements and the fibrils are both prevented from being 
pulverized, thus there being neither bristling nor branching off in the 
midway of said elements and said fibrils, respectively. 
The second raw material that has been treated in the above-mentioned manner 
is then taken out of the mill and further set to a cyclone separator 
thereafter being taken out of the cylone separator in the form of a third 
raw material. 
The third raw material contains a large quantity of water when just taken 
out of the cyclone separator so that it must be left to be dried up in 
exposition to natural ambient drying conditions or otherwise forcibly 
dehydrated until the water content is lowered down to the range between 32 
and 38 percent by weight. The third raw material thus naturally dried up 
or mechanically dehydrated is now in a state of solid lump so that the 
lump must be pulverized and the filtered through a filter to be assorted 
into quantities of powder having two different diameters by means of 
different mesh netting filters. Namely, a quantity of powder which passes 
through a filter having a netting between 30 and 100 meshes is assorted in 
the form of leather fibrous tissues capable of adhering to a basic 
clothing sheet inducibly by means of static electricity whereas another 
quantity which passes through a filter having a netting more than 100 
meshes is assorted in the form of leather fibrous powder. 
Our accepted result of leather fibrous tissue manufacturing operations in 
factory proves that the amount of the tissues employable as a static 
electricity inducible raw material is approximately 50 percent while the 
amount of a little more than 30 percent of the remain is employable as 
leather fibrous powder. 
It is clearly understood from the preceding description of the invention 
that the leather fibrous tissues embodying the invention provides a 
semi-leather fibrous tissue sheet product which can be almost prevented 
from being bent in excess, without occurence of bristling and 
branching-off phenomena so that by using the raw material of the 
invention, high quality semi-leather fibrous tissue sheet products can be 
obtained that are uniformly and inseparably attached on the whole outer 
surface area of a basic clothing sheet, subsequently making it possible to 
provide any kinds of semi-leather fibrous tissue sheet products quite 
equal to those made of animals' leather itself from viewpoints of 
appearance and touching sense.