Pile fabric production process

Pile fabric having excellent softness and high tear strength which has short fibers planted and adhered to a base with an adhesive, is obtained by applying an adhesive and planting the short fibers to the base, drying or curing the adhesive, and removing at least 5 weight % of the fibers of the base.

Field of the Invention 
The present invention relates to a process for production of soft pile 
fabrics. 
BACKGROUND OF THE INVENTION 
Conventionally so-called pile fabrics are used for various purposes. They 
are obtained by adhering short fibers to a base, using gravity or static 
electricity. Many of them are producible only by applying an adhesive to 
the base, planting dyed short-fiber piles therein, and hardening the 
adhesive. The piles to be implanted had been limited both in thickness and 
length. Fine, long fiber piles had been generally difficult to implant. 
However, it is proposed to flock separable type composite fibers such as 
islands-in-a-sea type composite fibers or multi-core type composite fibers 
composed of polyester or polyamide and to separate the separable fibers 
after flocking. By this method a flocked fabric with an 
extremely-fine-denier touch surface may be obtained. However, the adhesive 
must be used in great quantities to prevent falling out of the pile 
fibers. Large amounts of the adhesive and high bonding strength are 
necessary when a solvent or a swelling agent is used to separate the pile 
fibers and when thicker and longer piles are used, as in a fur like 
fabric. Hard texture of the flocked fabric has also been one of the 
important defects. 
On the other hand, Canadian Pat. No. 895611 and U.S. Pat. No. 3,865,678 
teach removing one of the fiber components after impregnating an elastomer 
to make the fabric soft. Further, Canadian Pat. No. 167512 teaches the use 
of raised fabric as a base of the pile fabric. However, even using a soft 
fabric as a base for a pile fabric, the resulting pile fabric becomes hard 
owing to the large amount of adhesive needed to fix the piles firmly. 
Therefore, such a method has not been used for making clothing, which 
requires a soft texture. 
SUMMARY OF THE INVENTION 
This invention relates to a process for producing a soft pile fabric in 
which the piles are fixed to a fiber base with an adhesive, wherein a part 
of the base is removed after hardening the adhesive. 
Through this process the product is a very soft, highly-drapable pile 
fabric with a high tear strength, with no real decrease of falling out 
resistance of the pile fabric. It is therefore suitable for clothing which 
requires softness in particular, as well as for various non-clothing uses 
(e.g., seat covers, wall coverings, curtains, bags, automobile fittings, 
etc.) 
The effect of the present invention is not limited by the structure of the 
short-fiber piles. Soft, fine short-fiber piles, however, ensure a high 
commodity value, particularly the ones with less than 1 denier which are 
preferably used. On the other hand, the present invention makes it 
possible to produce an artificial fur which is soft enough for use as 
clothing.

DETAILED DESCRIPTION OF THE INVENTION 
The pile fabric in accordance with the present invention can be obtained by 
planting short fibers by electrostatic flocking or needle punching and 
raising, for example. 
The short fibers in accordance with the invention include polyester, 
polyamide, acrylic or other synthetic fibers; rayon or other regenerated 
fibers; and natural fibers; but are not limited thereto. 
Also, the thicknesses and lengths of the short-fiber piles to be implanted 
are not limited. Even superfine fiber piles can be produced through 
implanting separable fibers. 
Soft, fine short-fiber piles, however, ensure a high commodity value, 
particularly the ones with 0.3 to 5.0 mm length and less than 1 denier, 
especially 0.01 to 0.5 denier, which are preferably used. In such cases, 
separable fibers such as islands-in-sea type fibers, or multi-core 
composite fibers whose cores are located at the surface of the fiber, are 
preferably used. Of course, the separable fibers of ordinary denier are 
separated after implantation. 
On the other hand, this invention is also preferably applied to an 
artificial fur, in which the guard hair component preferably uses both end 
tapered short fibers of 10 to 200 denier at the body portion and of 20 to 
200 mm length, and the down hair component preferably uses short fibers of 
0.1 to 5 denier and of 10 to 100 mm length. 
In the pile fabric in accordance with the present invention, the adhesive 
is left with many narrow continuous spaces which are brought about by 
removing a part of the fiber base. The continuous narrow spaces make the 
adhesive layer very soft without reducing the adherence between the piles 
and the fiber base. The fibers of the base are not necessarily adhered to 
the adhesive and are preferably only bound with the adhesive along the 
fiber axes, allowing free movement of the fibers in the intervening 
spaces. This structure is obtained by removing a part of the fiber of the 
base, as by dissolving a component of a sheath-core fiber with a solvent, 
or separating a multi-core composite fiber with a swelling agent, or 
removing a surface portion of a polyester fiber base with an alkali 
reagent. Especially, removing the sea components of islands-in-sea type 
composite fibers creates spaces along the fiber axes and allows movement 
as between the individual island fibers and between the fiber bundle and 
the point of adherence to the base. 
This is considered to be the reason for the fabric's soft texture and high 
tear strength. On the other hand, the bundles themselves are securely held 
by the adhesive. The base and adhesive therefore do not peel off from each 
other, i.e., the adhesive is impregnated into the base to some extent and, 
in that portion, surrounds and holds each fiber of the base. 
The materials and structures of the base in accordance with the present 
invention are not limited, provided that at least 5% by weight of its 
component is removable through dissolution or decomposition by an 
appropriate method. The materials include polyester, polyamide, acrylic 
and other synthetic fibers; rayon and other semi-synthetic fibers; 
cellulose, wool and other natural fibers; and mixtures thereof (blended 
during spinning, doubling, weaving or knitting). In terms of structures 
various kinds of fabrics such as woven, knitted and unwoven fabrics are 
included. 
The method for removing by dissolving or decomposing more than 5% by weight 
of the base in accordance with the present invention includes: 
(1) Dissolution or decomposition of one component of composite filaments, 
(2) Mixing with the fiber destined ultimately to form the base, a further 
fiber dissoluble or decomposable by an appropriate method, 
(3) Use of a fiber which is dissoluble or decomposable from the surface, 
and 
(4) Impregnation in the base of more than 5% by weight of a removable 
material before applying the adhesive. 
Methods (1) include those for carrying out the dissolution or decomposition 
removal and the fining treatment of the pile fiber of an islands-in-a-sea 
type composite fiber at the same time; methods (2) the dissolution or 
decomposition removal out of the blended fabrics comprising water- and/or 
alkali soluble fibers; methods (3) utilization of alkali hydrolysis of 
polyesters; and methods (4) removal of a sizing agent or a resin added to 
the fabrics. 
Methods for dissolution or decomposition removal in accordance with the 
present invention are not limited to those mentioned above. 
It is preferable in accordance with the present invention to remove by more 
than 5% by weight of the base by dissolution or decomposition. Otherwise, 
sufficient softening effect as in the present invention cannot be 
expected. It is not necessary to fix the upper limit of dissolution or 
decomposition ratio. It is however preferable to remove less than 60% by 
weight, particularly less than 40% by weight to ensure sufficient base 
strength and adequate peel strength of the adhesive layer. 
The adhesives to be used in the present invention are not limited but 
required to withstand the chemicals and conditions to be adopted for the 
dissolution or decomposition removal of a part of the base. 
In view of the foregoing, the use of an islands-in-a-sea type fiber which 
comprises the same sea component as the fibers of the base and the pile is 
most preferable for the present invention, since it provides a soft 
texture for flocked fabrics and enables removal of the base components and 
the fining process of the pile components to be effected simultaneously. 
Further, the use of a polyurethane type adhesive is preferable from the 
standpoint of dissolution resistance treatment and texture. 
The amount and penetration depth of the adhesive in the base influences the 
softness of the fabric. An excess amount or excessively deep penetration 
of the adhesive often results in too hard a fabric. The preferable amount 
of adhesive is 30 to 150 g/m.sup.2. The penetration depth of the adhesive 
may be controlled by changing the viscosity of the adhesive, the coating 
condition, the drying temperature or by pretreatment of the base cloth, 
such as raising or with water or oil-repellent agent. 
Crumpling of the fabric during or after dissolution or decomposition 
removal of a component of the base is preferable because it increases the 
softening effect. Further, the process in accordance with the present 
invention has been found to improve the tear strength of the flocked 
fabric. 
It is preferable to use an islands-in-a-sea type fiber base that enables 
removal of a part of the base and fining of the pile to be carried out at 
the same time. For separable composite fiber bases, where components are 
recovered by peeling, and where fining does not bring about removal, only 
a small softening effect can be obtained; thus the softening effect must 
be attained by another method. 
Through this process, an exceptionally soft, highly-drapable pile fabric is 
obtained with a high tear strength. The implanted fibers encounter no real 
decrease in falling out resistance. The fabric is therefore suitable for 
clothing which requires softness in particular, and is also suitable for 
various non-clothing uses (e.g., seat covers, wall coverings, curtains, 
bags, automobile fittings, etc.) 
The present invention will be described hereinafter in connection with the 
following examples: 
EXAMPLE 1 and COMATIVE EXAMPLE 1 
Piles were obtained by cutting into lengths of 1.0 mm an islands-in-a-sea 
type fiber whose sea and island components were polystyrene and 
polyethylene terephthalate (4 denier, sea/island ratio=20/80, number of 
islands=16). The cut fibers were subjected to 60.degree. C..times.15 min. 
scouring in a bath containing 1 g/ of a non-ionic surface active agent; 
hydroextraction; 40.degree. C..times.20 min. immersion in a bath 
containing 2% by weight of sodium silicate, 3% by weight of colloidal 
silica ("SNOWTEX C" made by Nissan Kagaku K.K.), and 0.2% by weight of 
potassium chloride (modified at pH4 with acetic acid); hydroextraction; 
and drying. 
The pile was electrostatically implanted to form a flocked fabric 
(voltage=30,000 V, distance between electrodes=10 mm) at a rate of 120 
gr./m.sup.2 by flocking upwardly after applying a solvent type 
polyurethane adhesive (25% polyether type polyurethane DMF solution) to a 
needle punch felt base (unit weight=200 gr./m.sup.2, thickness=1 mm) of a 
similar islands-in-a-sea type fiber (4 denier, sea/island ratio=30/70, 
number of islands=36) at a rate of 300 g/m.sup.2 with a knife coater. The 
flocked fabric thus obtained was subjected to 100.degree. C. drying, 
130.degree. C..times.3 min. curing, and immersion in trichloroethylene (3 
times at room temperature) for removing 29% of the whole fiber base. The 
flocked fabric thus obtained was much softer than that before the removal 
of the sea component. It was further subjected to conventional dyeing at 
120.degree. C. with a liquid-flow dyeing machine. The flocked fabric thus 
obtained became softer and was highly drapable and gave a high-grade 
feeling. It had a cantilever method softness value of 31 mm (compared to 
140 mm immediately after flocking) and a high tear strength of 3,500 gr. 
(mean value of lateral and longitudinal tear strengths). 
FIG. 1 is a scanning type electron-microscope photograph of the flocked 
fabric. It indicates that the monofilament bundles of its base are not 
completely bonded but have a structure with voids at the section where the 
adhesive and base are bonded. A represents pile fibers, B represents an 
adhesive layer and C represents the base fabric. 
At the same time, a comparative example was prepared by a process according 
to Example 1 except that the sea component removal was carried out before 
flocking. 
Compared with the Example, the flocked fabric thus obtained was much harder 
and had a softness value of 82 mm and a tear strength of 1,700 gr, which 
were considerably inferior to the example. As a result of observations 
with a scanning type electron-microscope, it was found that the adhesive 
has penetrated into the fiber bundles of the base, with practically no 
void structure. 
EXAMPLE 2 and COMATIVE EXAMPLE 2 
A plain weave base (weight: 140 g/m.sup.2) made of blended yarn composed of 
25 weight % of a readily alkali soluble polyester fiber (a copolymer of 7 
mol % of 5-sodium sulfoisophthalate and 93 mol % of ethylene 
terephthalate) and 75 weight % of ordinary polyethlene telephthalate fiber 
was subjected to the same manner of flocking as Example 1. The sea 
component of its pile was removed in trichlorethylene, and the readily 
alkali soluble polyester in its base was removed with a 3% NaOH solution 
at 95.degree. C. 26 weight % of the base was removed. The softness of the 
flocked fabric thus obtained was measured by the cantilever method. At the 
same time, a comparative example was prepared wherein the readily alkali 
soluble fibers of the base were removed before flocking and then flocking 
according to example 1 was applied. 
As the result, the flocked fabric in accordance with the present invention 
showed a much higher softness of 35 mm than that before the removal of the 
alkali readily removable fibers (135 mm) and the fabric of the comparative 
example (95 mm). 
EXAMPLE 3 
A pile was obtained through a process wherein an islands-in-a-sea type 
fiber (3.5 denier, sea/island ratio=15/85, number of islands=6) whose sea 
and island components were a readily alkali soluble polyester (a copolymer 
of 7 mol % of 5-sodium sulfoisophthalate and 93 mol % of ethylene 
terephthalate) and polyethylene terephthalate. The fiber was cut to 
lengths of 1 mm and electrostatic flocking was applied in Example 1. 
Flocking was carried out after applying a solvent type polyurethane binder 
(obtained by adding one part of a diphenylmethane-bis-4,4'-N, 
N'-ethyleneurea bridging agent to a 25% polyether polyurethane DMF 
solution) to a twill fabric base (unit weight 130 gr./m.sup.2) whose warp 
and weft were made from the above said islands-in-a-sea type fiber 
filaments to 300 gr./m.sup.2. The flocked fabric thus obtained was 
subjected to 100.degree. C. drying, 140.degree. C..times.2 min. curing, 
and 80.degree. C..times.1 hour treatment with a 3% NaOH solution for 
removing the sea component of the pile and base, and conventional 
120.degree. C. dyeing with a circular liquid flow dyeing machine. The 
flocked fabric thus obtained was soft and highly-drapable and gave a 
high-grade feeling. 
EXAMPLE 4 
A guard hair component was made with both end tapered fibers of 
polybutyleneterephthalate (35 denier, 17 mm length) having a flat 
cruciform cross-section (large diameter/ short diameter=2.5. It was 
prepared according to the method of U.S. Pat. No. 4,381,325. A down hair 
component was prepared with both end tapered fibers of 
polybutyleneterephthalate (5 denier, 17 mm length) having round cross 
sections. 
The guard hair component was dyed black with Samaron Black BBL-liq. 10% owf 
(disperse dye supplied by HOECHST AG) and Samaron Brown 2GSL-N 12% owf 
(disperse dye supplied by HOECHST AG) at 120.degree. C., 60 minutes. The 
down hair component was dyed dark brown with Miketon Polyester Orange 3% 
owf (supplied by Mitsui Toatsu Kagaku Co. Ltd.), Foron Rubine S-2GFL 0.5% 
owf (disperse dye supplied by Sand Co. Ltd.) and Sumikalon Blue S-BG 1.5% 
owf (disperse dye supplied by Sumitomo Kagaku Co. Ltd.). 
The same weights of both components were well mixed by air. 
As a base, a needle punched felt was made having a weight of 200 g/m.sup.2 
composed of islands-in-sea type fibers (3.5 denier, number of islands: 20, 
thickness of each island: 0.1 denier, islands component: polyethylene 
terephthalate, sea component: polystyrene). The mixed hair component was 
spread uniformly on the base at a weight of 1200 g/m.sup.2 and implanted 
in the base by needle punching using needle FPD-1.sup.# 36 (supplied by 
Organ Co. Ltd.). Then the undersurface of the implanted base was treated 
with 25 weight % of an aqueous solution of polyvinylalcohol. After drying 
the treated surface, the implanted surface was raised and the 
polyvinylalcohol was removed with hot water at 50.degree. C., and then the 
fabric was dried. After shearing the hair fibers which protruded from the 
undersurface, the undersurface of the raised fabric was treated by knife 
coating with Sunplen LQ-T1502 (polyurethane solution in dimethyformamide 
supplied by Sanyo Kasei Co. Ltd.). 
The polystyrene which constituted a component of the base was removed with 
trichlorethylene at room temperature. Next, the fabric was subjected to 
reduction clearing with NaOH 1g/l, Na.sub.2 S.sub.2 O.sub.4 2H.sub.2 O, 
1g/l, surface active agent 1g/l at 80.degree. C. 30 min. The obtained 
artificial fur was very soft and looks similar to black mink fur.