CA1153880A

CA1153880A - Suede-like fabric and its manufacture

Info

Publication number: CA1153880A
Application number: CA000367117A
Authority: CA
Inventors: Klaus Gerlach; Nikolaus Mathes; Hans J. Pitowski; Friedbert Wechs
Original assignee: Akzo NV
Current assignee: Akzo NV
Priority date: 1979-12-20
Filing date: 1980-12-18
Publication date: 1983-09-20
Also published as: FR2472051A1; US4612688A; IT8050368A0; DE2951307C2; IT1147073B; FR2472051B1; US4342801A; GB2065732A; JPS5691078A; GB2065732B; DE2951307A1

Abstract

ABSTRACT OF THE DISCLOSURE

Staple fibres made from crimped, in particular compression crimped, multi-component filaments of the matrix/-segment type, the cross-section of which comprises, in addition to the matrix, at least 6 peripheral wedge-shaped or lenticular segments, not completely covered by the matrix, are processed into a web, which is then mechanically bonded, preferably by needling. Subsequently the fabric is subjected to a shrinkage process, by which its density is increased by more than 30%, the multi-component fibres being completely or partly split up into their components. The difference in shrinkage between the components should be at least 10%.
The liquids used for the shrinkage treatment are in particular organic liquids, such as methylene chloride, as well as other liquids producing a difference in shrinkage of at least 20%.
The fabric is then impregnated with a solution of polyurethane on the basis of polyglycols, specifically polytetramethylene glycol, diisocyanates and low-molecular glycols as chain lengtheners, the gelling temperature of the solution being higher than the room temperature and higher than the tempera-ture of the coagulation bath used; the polyurethane is coagulated by cooling and/or treatment with a coagulation bath containing a non-solvent for polyurethane; then the fabric is washed, dried and ground on one or both sides. The suede-like product obtained combines great suppleness with high strength. It is an excellent material for making garments, such as coats, jackets or skirts, offering high wear comfort as well as high breathability.

Description

. ~
1153880 .
The invention relates to a suede-like product, more especially a suede-like product comprising a textile fabric made of multi-component fibres treated with a poly-urethane solution.
A whole series of synthetic products serving as suede substitutes is already known, the relevant literature also contains numerous references to methods for producing such materials.
For example, Federal Republic of Germany Patent ~o.

2,703,654 describes a non-woven textile material for use as a carrier material for artificial leather and including a woven or knitted fabric and at least one bonded fibre fleece.
Also known are numerous other publications in which woven or knitted fabrics are used as linings or inserts in synthetic leather.
U.S. Patent 3,932,687 describes a carrier material said to be suitable for artificial leather. This is a non-woven fleece made out of special composite fibres, so-called island-matrix-composite fibres. A fleece having extremely fine fibres is obtained by dissolving out the matrix component.
The production of such suede-like synthetic mate-rials is complicated and laborious, and the properties thereof leave something to be desired. For instance, pro-ducts in which a knitted or woven fabric is used as a lining or insert are relatively non-resilient. If a fleece is used in a manner hitherto known, the strength thereof is not com-pletely satisfactory. Difficulties also arise in the pro-duction and handling of very fine titers. There are also problems in preventing bonding between the fibres of a textile lining and the polyurethane used as the impregnating agent.

` `` llS3880 There is thus a need for an improved method of producing suede-like products which is simpler, and for a synthetic suede-like material having improved properties.
It is therefore the purpose of the invention to provide a suede-like product which can be made inexpensively and in a simple and uncomplicated manner, which has good mechanical strength and considerable suppleness, exhibits a pronounced writing effect, lends itself to printing, has interesting surface configuration possibilities, has many applications and, above all, may be used as a clothing leather for the widest variety of purposes.
This purpose may be achieved by a suede-like pro-duct based upon a textile fabric impregnated with poly-urethane, in which the textile fabric is a needled fleece made of completely or partly split staple fibres of crimped multi-component filaments of the matrix-segment type, the components thereof suitably being polyester and polyamide, the cross-section of which comprises, in the unsplit condition and in addition to the matrix, at least 6 peripheral segments of wedge-shaped or lenticular cross-section, not completely enclosed in the matrix, the titer of the unsplit fibre being about 0.5 to about 10 dtex, while the titers of the matrix, and of the individual segments, are from about 0.1 to about 1 dtex, the segments displaying, as compared with the matrix, a difference in shrinkage of at least 10%, the multi-component filaments being arranged, at least in part, in the form of bundles in the fleece, the polyurethane being made from polyglycols, diisocyanates, and a low-molecular weight glycol as chain-lengtheners, and at least 30/O of the surface of the fibres having no firm connection with the impregnating polyurethane compound enclosing them.

11S388iV
The titers of the matrix and of the peripheral segments may be different~
The titer of the unsplit fibre amounts to about 1 to 5 dtex, while that of the matrix and of the individual segments is about 0.1 to 0.5 dtex. The amount of the poly-ester component, calculated as the surface area o~ the cross-section of the unsplit fibre, may amount to at least l~/o.
Highly suitable, for the purposes of the invention are staple fibres having polyamide segments which are shrunk, as compared with the polyester matrix, by at least 2~/o.
Also advantageous are multi-component filaments having a polyamide matrix and peripheral polyester segments.
It is desirable for the polyester segments to be shrunk, in relation to the polyamide matrix, by at least 2~/o. Accord-ing to one particularly advantageous embodiment of the invention, the amount of polyester in the multi-component filaments is between 70 and 9~/O, in relation to the cross-section of the unsplit fibres. The polyester components may consist of copolyesters, preferably copolyesters based 20 upon terephthalic acid and ethylene- and butylene-glycol.
The polyamide component may also be made of copolyamides based upon ~-caprolactam and adipic acid hexa-methylene diamine salt.
One highly suitable impregnating compound contains a polyurethane based upon polytetramethylene glycol, ethylene glycol, and 4,4'-diphenylmethane-diisocyanate, The suede-like product according to the invention has, in general, an overall density of at least 0.25 g/cm3, preferably at least 0.3 g/cm3. It is desirable for the product to have a density gradient running from the centre to the outside, i.e., from the centre to the top and bottom surfaces. The impregnating compound in the end product has -` 1153880 a microporous structure and forms a tubular or tunnel-like sheathing, at least partly, around the fibres, the lumen of the section enclosing the fibres being larger than the volume of the sheathed part of the fibre~ The said lumen is prefer-ably at least twice as large as the volume. Within the tubular sheathing, the fibres are preferably arranged largely without firm connection to the impregnating compound sur-rounding them.

In producing a suede-like product according to the invention, use may be made of a method involving the pro-duction of a textile fabric from multi-component fibres impregnated with a polyurethane solution, wherein staple fibres of crimped multi-component filaments of the matrix-segment type, the cross-section of which comprises, in addition to the matrix, at least six peripheral wedge-shaped or lenticular segments, not completely covered by the matrix, are processed into a fleece or non-woven fabric, which may then be mechanically bonded, its density being increased by more than 30/0 by shrinkage, whereby the multi-component fibres are completely or partly split up into theircomponents, the difference in shrinkage between the components amounting to at least 10%t the fleece is then impregnated with a solution of a polyurethane based on polyglycols, diiso-cyanates, and low molecular weight glycols as chain lengthe-ners, the temperature of the solution being higher than room temperature and higher than the temperature of the coagu-lation, the polyurethane is coagulated by, for example by cooling in air and/or treatment with a coagulating bath containing a non-solvent for the polyurethane, and the fleece is ground, on one or both sides after washing and drying.

1153~8C~
The fleece is mechanically bonded or strengthened, preferably by needling. The fleece may be split one or more times before or after impregnation. It is desirable to use staple fibres made of stuffer-crimped multi-component fila-ments or fibres, the components of which, upon being treated with methylene chloride at room temperature, exhibit a shrinkage difference of at least 10%, preferably at least 20~/o. In one form of execution of the method, multi-component filaments are used, the components of which, upon being treated with water, exhibit a shrinkage difference o~ at least 20O/~. It is desirable to use multi-component filaments or fibres having a polyamide matrix-component and polyester peripheral segments. It is desirable for the proportion of polyester in the cross-section of the multi-component fila-ments or fibres to amount of between 70 and 90O/o.
Particularly suitable for impregnating the fleeces is a solution of polyurethane based on polytetramethylene glycol, ethylene-glycol and diphenylmethane-diisocyanate.
It is best for the polyurethane to contain a light-protec-tive agent, more particularly the product available underthe trademark Irganox 1010.
Shrinkage of the fibres in the fleece is preferably accomplished by treatment with methylene chloride, which may contain between 0.5 and 5%, by weight, of a finishing agent soluble in methylene chloride, for example that available under the trademark Soromin AF. It is also possible to use dimethyl formamide at a temperature of above 120C to produce this shrinkage, According to one form of execution, the fleece is impregnated asymmetrically. One particularly suitable method of producing the multi-component filaments or fibres used 1~53880 according to the invention, is disclosed in Canadian Patent Application 322,710, filed March 2, 1979, Klaus Gerlach et al.
Of the cross-sections described in the Canadian Patent Applica-tion, the most suitable is that according to Figure 6, because of its wedge-shaped segments. Cross-sections according to Figure 6 of the Canadian Patent Application make it possible to subject the multi-components filaments of fibres, after spinnning, to various treatments such as stretching, crimping, the application of special preparations, and cutting, without any substantial separation of the matrix from the segments.
Splitting into individual components occurs first when shrink-age is brought about by treatment with a special agent.
Segments having lenticular cross-sections are to be understood as those reproduced in Figures 1 to 4 of the above mentioned Canadian Patent Application. It should be noted, in this connection, that Figure 1 serves merely to explain the term "lenticular cross-section" of the segments. The overall cross-section in the figure is not particularly suitable, since it comprises only three peripheral segments.
?O The multi-component filaments or fibres, produced according to the teaching of the above mentioned patent appli-cation, but not yet split, are then crimped in the usual way, the stuffer-crimping process being particularly suitable.
; In stuffer-crimping, care must be taken to ensure that the scallops or arcs are not too sharp edged since the multi-component filaments or fibres may occasionally be already split into their individual components, to a slight extent, at the bend-locations, and such partly split multi-component filaments or fibres may cause difficulties during formation of the fleece. However, this does not normally occur and the multi-component filaments or fibres therefore remain substan-1~538~

tially unsplit throughout the stuffer-crimping process. In pre-treating the fibres, it is important to ensure that no fixing takes place which will reduce the ability to shrink inherent in the multi-component filaments or fibres because of their previous history. It is therefore not advisable to steam the fibres and dry them at high temperatures. The shrinkage, i.e. the difference in shrinkage between the poly-ester and polyamide components, is best achieved by treatment with methylene chloride, as described in the aforementioned Canadian Patent Application. The shrinkage obtained in methylene chloride should amount to at least more than l~/o preferably even 15 or more than 2~/o.
The components used in producing the multi-compo-nent filaments or fibres may be conventional polyesters and polyamides. Polyethylene-terephthalate is particularly suitable as the polyester component. However, it is also possible to use copolyesters based upon an acid, for example terephthalic acid and two di~ferent glycols, for example ethylene- and butylene glycol. Copolyester components generally dye better and have higher shrinkage.
The polyamides used may be conventional polyamides such as poly-~-caprolactam and polyamide based upon hexa-methylenediamine adipic acid. It is also possible to use copolyamides, especially copolyamides made from ~-caprolactam and hexame~hylenediamine adipic acid salt.
It is possible to build up the multi-components in such a manner that the peripheral segments are made of poly-amide and the matrix of polyester. It is preferable, however, to produce a cross-section in which polyamide forms the matrix and polyester the segments.

llS3880 Conventional additives, for example, pigments, carbon black, fire-proofing agents, delustring agents and the like may be added to the individual components.
After stuffer-crimping, the fibres are cut, in a conventional cutting unit, into staple fibres of a length generally used for fibres of the cotton type, i.e. between 30 and 50, preferably about 40 mm.
A fleece is then produced in the usual manner from the staple fibres thus obtained. This fleece may be obtained aerodynamically, or a carding or combing machine may be used.
The weight of the fleece may be between 50 and 500 g~m2, but is preferably between 100 and 400 g/m2.
The fleece is then needled in a manner known per se.
By selecting the needling conditions it is possible to adapt the fleece to subsequent applications.
Needling is usually carried out with a high number of stitches, preferably between 500 and 1500 stitches~cm2.
~eedling produces a high density fleece with the fibres largely re-oriented into a direction perpendicular to the plane of the fleece. This is of importance to the nap of the end product, among other things.
The fleece thus obtained is then subjected to a treatment whereby the density thereof is increased by more than 30/O by considerable overall shrinkage, and the multi-component filaments or fibres are divided, wholly or partly, into their individual components. This treatment requires an agent, more particularly an organic liquid, in which the individual components exhibit a difference in shrinkage of at least 10%. This is achieved mainly with organic solvents which reduce the zero shrinkage temperature of the polyester used by at least 160C. Among these are the organic solvents ~S388~

appearing in the above mentioned Canadian Patent Application, namely methylene chloride, l,1,2,2-tetrachloroethane, 1,1,2-trichloroethane and chloroform, preference being given to methylene chloride.
Shrinkage, producing satisfactory splitting of the fibres, may also be initiated with dimethyl formamide which has a temperature of at least 120C.
If copolyamides are used, splitting with water is possible. The production of appropriate multi-component filaments or fibres, using copolyamides as one of the compo-nents and splitting the multi-component filaments and fibres with water, is described in Canadian Patent Application 346,426, filed February 26, 1980, Nikolaus Mathes et al, to which reference is hereby expressly made.
In carrying out the treatment with the liquid which is to produce shrinkage and splitting among other things, for example methylene chloride, it is sufficient to pass the needled fleece briefly through a bath containing the treatment agent. However, the solvent may also be sprayed or otherwise applied to the fleece. After this treatment, during which the fibres are wholly or partly split up into their individual components, the solvent is removed from the fleece as far as possible~ for example by squeezing.
The temperature of the treatment liquid is generally between 20 and 40C. The time required for the treatment may be from a few seconds to a few minutes, depending upon the density and thickness of the needled fleece. The squeezing out of the solvent may be governed by the pressure applied, or by the width of the gap between the rolls used for squeez-ing. In certain cases, the solvent may also be removed bysuction, without squeezing.

_ g _ In order to achieve maximal shrinkage, it is essen-tial, during the solvent treatment, that the fleece shall pass through the bath as far as possible free of tension, or that the fleece be under no tension when the solvent is sprayed there onto. This ensures that the longitudinal and transverse shrinkage are generally equal. This treatment produces an area shrinkaye of usually more than 30O/o, preferably even between 35 and 55%. However, the thickness of the fleece remains almost constant. For this reason, there is a sharp increase in density during the shrinkage treatment. It is possible to achieve densities of more than 0.15 g/cm3, preferably even more than 0.25 g/cm3.
This special form of shrinkage produces the following special effects. As compared with an unshrunk, or less shrunk product, the nap-density may be increased by more than 50/
even more than 100%~ In this sense, nap-density is to be understood to mean the number of fine fibres, or hairs per mm2 proiecting from the surface of the end product. Nap-densities attainable are, for example, 450~mm and more.
~oreover, the density of the fleece is high in the interior, and decreases towards the outside, for example the top and bottom surfaces, and the end product therefore has a similar density gradient. This imparts to the end product a firm but supple feel.
Initially the material is easily compressed, but then offers increasing resistance. Because of its high elastic recovery, it returns very easily to its initial position. Its behaviour is therefore substantially that of kid leather.
The total density of the end-product is at least 0.25 g/cm3, preferably more than 0.3 g~cm3.

ilS3138(~

It is possible to include in the treatment-bath, which contains methylene chloride, for example, additives which reduce the adhesion between the polyurethane, to be applied in the next step of the method, and the fibres, this makes it possible to impart a softer feel to the end product, to obtain a more textile draping of the suede and, more particularly, to affect the suppleness of the end product.
For this reason it is advisable to add, to the methylene chloride treatment bath, film-forming finishers which are soluble in methylene chloride. Finishers of this kind are available from BASF (sadische-Anilin und Soda-Fabrik) under the trademark Soromin AF. Finishers of this kind are by nature fatty acid amide condensation products. It is usually sufficient to add to the methylene chloride bath only a very small amount of the finisher, for example between 0.5 and 5%, ~ eedling, which is carried out prior to the shrink-age treatment, serves to bond the fleece mec~anically, thus improving the density and mechanical strength thereof. In addition to this, the fleece may be strengthened by treatment with jets of air or water. However, needling is the preferred method.
After the shrinkage treatment, the fleece is dried, preferably in air, at a temperature of between 50 and 80C., although this may also be increased to about 180C. ~t is desirable, in many cases, subsequently to loosen the fleece structure from the split fibres, for example by subjecting it to a shearing treatment with rolls. The fibre structure may also be loosened by light reneedling, or by fulling.
It is desirable in many cases to enhance the split-ting process by additional mechanical treatment during the il5;3880 shrinkage treatment. It is particularly advantageous to subject the fleece to ultrasonic treatment simultaneously with the shrinkage treatment. A method of this kind is described in Canadian Patent Application SN 322,710, filed March 2, 1979, to which reference is expressly made at this time.
The fleece thus obtained, consisting of wholly or partly divided multi-component fibres, is then impregnated by immersion in a solution based upon polyurethanes. The polyurethanes used are those obtained from polyglycols, diisocyanates, and low molecular weight glycols as chain-lengtheners. Polyurethanes of this kind are preferably produced in accordance with the teaching of Federal Republic of Germany Offenlegungsschrift (Published Patent Application) 2 409 346, the polyglycols used being preferably polytetra-methylene glycol and, as the low molecular weight glycol, ethylene glycol. The preferred diisocyanate is 4,4'-diphenyl-methane-diisocyanate.
The fleece may be impregnated in a variety of ways.
Highly suitable is one method whereby the fleece is passed, substantially without tension, through a tank containing the polyurethane solution, the temperature of which is above room temperature and above the gelling temperature of the solution itself, preferably between 40 and 70C. This makes it possible to reduce the viscosity to about 0.5 Pa.s, leading to rapid and satisfactory impregnation of the fleece.
The fleece is preferably passed from top to bottom through a tank containing the polyurethane to be applied and is removed from the tank by an appropriate detour. It is then passed between a pair of rolls adjusted in such a manner as to allow between 100 and 500% of the polyurethane solution to remain in the fleece.

llS3881U

The fleece is then passed through an air zone at room temperature where the viscosity of the solution under-goes a sharp increase and a certain amount of coagulation already takes place, and which is followed by a coagulation bath containing a non-solve~ for the polyurethane. It is preferable to use a bath containing water and, if necessary, some polyurethane solution.
The gelling temperature, or gel point is the temper-ature at which the polymer solution separates into two phases, the so-called precipitation point, at which polymer droplets are formed. The gel point is governed by the temperature, the concentration and the proportion of non-solvent, for example water, in the solution. It is thus possible to adjust the gel point by adding water to a polymer solution which is homogeneous and constant at room temperature until phase separation takes place. The phase separation may be intensified by adding more water or lowering the temperature.
If a polyurethane solution already separated into two phases is heated, it is possible to convert the two phase mixture back into a homogeneous polymer solution. The poly-urethane solutions used for impregnating are thosewhich form gels upon cooling down to room temperature.
The coagulation initiated by air cooling is completed in a coagulation bath, also known as a precipitation bath. It is preferable to use a plurality of these baths arranged consecu-tively. ~he first may use water heated to about 30C, but it is important for this temperature to be below the gel point, i.e.
below the gelling temperature of the impregnating solution used.
This may be achieved by using a bath consisting, for example, of 800/o of water and 20% of a solvent for the polyurethane, for example dimethyl formamide. This method ensures, among other 1~ .i3~30 things, that the polyurethane acquires a microporous structure and that the adhesion between the polyurethane and the fibres is reduced by the formation of tubular or tunnel-like cavities within which the fibres are largely free to move.
The second precipitation bath need not be heated, but is generally at room temperature. In order to complete the coagulation, it is usually sufficient to pass the fleece, after impregnation, through to further precipitation baths before it reaches the washing bath. Washing is usually carried out in water at a temperature of between 40 and 50C.
It may be desirable to use a plurality of washing baths.
After washing, the impregnated fleece is dried at a temperature preferably not exceeding 100C. The dried fleece is then ground or polished on one or both sides. If necessary, the product may be split one or more times prior to grinding, thus producing a thinner fabric.
In addition to the immmersion process described above, impregnation may bè carried out in other ways, for example by coating, spraying, etc. Also highly suitable is 20 a process whereby coating or impregnation is carried out with the aid of a so-called "reverse-roll coater".
In addition to the polyurethanes in which diphenyl-methyl-diisocyanate is used as the diisocyanate, polyurethanes containing dicyclohexyl-methane-diisocyanate as the diisocya-nate-component are suitable. It is possible to add to the urethane used for impregnating the usual additives, for example pigments, silicone oil, fillers such as calcium carbonate pore-forming agents such as sodium sulphate or stearyl alcohol, light-protective agents such as the product available under the trademark Irganox 1010 from the firm of Ciba Geigy, and other stabilizers.

,' ~

115388() It is also possible to impregnate the fleece asymmetrically, i.e. in a manner such that the concentration of impregnating agent in the fleece varies and sets up an impregnation gradient. This may be achieved by passing the impregnated fleece over a sharp edge or a small-diameter bar.
In this way, the side of the fleece which passes over the sharp edge or the bar is squeezed together so that, when the fleece returns to a straight line, the squeezed areas contain less polyurethane. After coagulation, this side of the fleece also contains less polyurethane than the other side. This makes itpossib~e to control the way in which the suede unrolls, the formation of creases, and ~arious other properties. The coating containing less polyurethane is the nap side of the end-product. Products of this kind are characterized by their asymmetrical structure.
Grinding may be carried out, on one or both sides, in conventional cylinder grinding machines or the like, using corundum or other materials for grinding. Grinding serves not only to control the final thickness of the suede-like product, but also to produce an optimal nap.
Either before or after screwing the surface may be structured and optically sculptured, for example by embossing with calender-rolls.
The product according to the invention may be dyed and dressed by conventional methods. In view of the resis-tance of the polyurethane used to hydrolysis, dyeing may be carried out without any difficulty under HT (high temperature) conditions, and this also improved the feel. Since poly-urethane has a high melting point, transfer printing is also possible with no danger of hardening the product.

~1~38~30 The fabric may be split one or more times, without any difficulty, either before or after dyeing, with conven-tional equipment used in the leather industry. This makes the manufacturing process highly economical and makes it pcssibleto ohtain various thicknesses and surface properties.
The usual final finishing processes, such as brushing, napping, grinding, greasing, tumbling, fulling, waterproofing etc. may be carried out using methods with which those skilled in the art are familiar.
The suede-like product according to the inve~ion possesses a whole range of surprising properties. It has interesting dyeing possibilies enabling different effects to be obtained. For instance the fibres may remain undyed while the polyu.ethane is dyed. Pigmented polyurethane may be used and the fibres left undyed. If dispersion-dyestuffs are used, the polyester can be dyed and the polyamide left undyed. This makes it possible to achieve attractive effects.
The surface makes a very lively, warm impression and has a pronounced writing effect. "Writing effectl' means that when the fabric is stroked, for example with the finger, the position of the nap-hairs is permanently rearranged, leaving a clearly visible trace. This writing effect imparts a very lively aspect to the suede.
Moreover, the product according to the invention is extremely supple and, at the same time, high in strength.
,~ The drapeability is excellent, and the product may be used in a wide variety ofapplications, for example for ~ clothing such as coats, jackets, skirts, caps, or the like, It offers high wear-comfort as well as high breathability.
Because of its high mechanical strength and i38~1U

resistance to abrasion, articles oE clothing made from the product may be worn for long periods of time without looking shabby.
The manufacturing process is uncomplicated, highly economical, and operates in an environmen~ally acceptable manner without causing pollution. For instance, pretreatment of the fibres with polyvinyl alcohol or water-soluble coatings before impregnating with polyurethane, and washing with water after impregnating, are no longer necessary. The splitting of the multi-component filaments or fibres into matrix and segments, combined with an advantageous shrinkage and densification process, is simple, reliable and effective;
there is no loss of material during splitting, processing presents no problems. It should also be emphasized that the method permits rapid and uniform impregnation.
The invention is explained in greater detail by the following example.
According to the method described in the afore-mentioned Canadian Patent Application 322,710, a matrix-segment fibre having the cross-section shown in Figure 6, with a filament-titer of 1.7 dtex, is spun from a 150 hole spinneret from polyethylene-terephthalate (rel.visc.1.63) and polyamide 6 (rel.visc. 2.5) in an 80 : 20 weight ratio.
The spinning pull-off amounts to 1500 m/min and the stretch ratio is 1 : 3.3. The shrinkage of the filament in methylene chloride amounts to about 24%, The bundle of fibres obtained is made into a 51 000 dtex cable, is passed through a finishing bath, and is then stuffer-crimped in a turbo crimper. The cable is crimped with 110 scallops or arcs 100 mm with a crimp contraction of 10.3%. After drying at 50C, it is cut to 40 mm lengths with a fibre cutting machine.

il5;~
A fleece is laid (lay 180 g/m 2 x 12 layers of 7.7 g/m2), by the carding technique, from these as yet un split multi~component filaments or fibres. ~eedling with ~o, 43 needles produces, after about 16 passes, 1000 stitches/- ' cm , a weight of 120 g/m2, and a fleece density of about 0.17 g/cm .
For the purpose of fibrillating the matrix-segment filaments or fibres and compacting, this fleece is subjected to considerable shrinkage, to which end it is passed, loose and without tension, through a methylene chloride bath heated to between 25 and 30C. The process is to allintents and purposes complete after a period of residence of about 30 secO
after which the methylene chloride is squeezed out by passing the fleece through squeezing rolls, but between 100 and 150%
of the weight of the fleece in methylene chloride remains in the fleece. This is removed by drying at about 80C and is recovered.
Fibrillating and shrinking lead to definite densi-fication of the fleece (about 0.27 g~cm3)-, resulting in a compact feel and a dense needle pattern, The uniformity, felting and softness of the fleece are very noticeable after the treatment, but there is no substantial change in thickness.
Longitudinal shrinkage: about l~/o; transverse shrinkage:
24%, surface shrinkage: about 40%. Strength is increased both by felting and by the larger number of fibrils per unit of volume.
The fleece is then passed through a 10% pigmented polyetherurethane solution in dimethyl formamide with an ; addition of 4% of water. The gel point of this solution is about 35C. In order to ensure satisfactory penetration, the polyurethane solution is heated to about 55C,, which 115388C) reduces the viscosity to about 5 poises. A filling of about 300O/o is set by adjusting the squeeze gap. After leaving the impregnating tank, the product is allowed to cool in air below ~ the gel point. This produces immediate stabilization of the fabric, in that the viscosity of the gel rises to above 50 poises and a microporous coagulation structure, with less adhesion of the fibres, is obtained. Coagulation is completed in a bath containing an approximately 20 : 80 mixture of dimethyl formamide and water, at about 30C. Washing is then carried out, first in cold water and then in water at 40C, in order to remove the remaining dimethyl formamide, followed by drying at 100C.
This unfinished product acquires its velvet-like nature by grinding on both sides in a cylinder grinding machine coated with 120 paper. This develops the nap and the velvety surface. The fine fibrils, the large number of needles, and the distinct compacting during the splitting process produce, with this interplay, a dense nap with a lively writing effect.
The p~oduct thus obtained has a density of about 0.4 g/cm and a polyurethane content of about 22%.
By means of HT-dyeing, the fibres of the product are dyed in a jet line and the supple feel is developed.
Brushing and emerging with 180 paper sets the nap up again and provides a product with an attractive appearance and feel and with good wear properties.

Claims

The embodiments of the invention in which an exclu-sive property or privilege is claimed are defined as follows:

1. A suede-like product comprising a textile fabric impregnated with polyurethane, said textile fabric comprising a needled fleece made at least partly of split staple fibres of crimped multi-component filaments of the matrix-segment type, said filaments having a cross-section which comprises, in the unsplit condition, a matrix and at least six peripheral segments of wedge-shaped or lenticular cross-section, not completely enclosed in the matrix, the titer of the unsplit filament being about 0.5 to about 10 dtex, and the titer of the matrix and of the individual segments, being about 0.1 to about 1 dtex; said segments displaying, as compared with the matrix, a difference in shrinkage of at least 10% the multi-component filaments being arranged, at least in part, in the form of bundles in the fleece, said polyurethane being based on polyglycols, diisocyanates, and low molecular weight glycols as chain lengtheners; and at least 30% of the surface of the fibres having no firm connection with the impregnating polyurethane enclosing them.

2. A suede-like product according to claim 1, wherein the unsplit filament has a titer of about 1 to about 5 dtex, and while the matrix and segments have a titer of about 0.1 to about 0.5.

3. A suede-like product according to claim 1, wherein said filament has a polyester content of at least 10%, calculated as a proportion of the surface of the cross-section of the unsplit fibres.

4. A suede-like product according to claim 1, 2 or 3, wherein said staple fibres comprise filaments having polyamide segments and a polyester matrix, said segments being shrunk by at least 20% more than the polyester matrix.

5. A suede-like product according to claim 1, wherein said multi-component filaments have a polyamide matrix and polyester segments.

6. A suede-like product according to claim 5, wherein said polyester segments are shrunk by at least 20% more than the polyamide matrix.

7. A suede-like product according to claim 1, 2 or 3, wherein said multi-component filaments have a 70 to 90%
polyester proportion, as compared with the cross-section of the unsplit fibres.

8. A suede-like product according to claim 1, wherein said filaments have a polyester component which comprises a copolyester.

9. A suede-like product according to claim 8, wherein said copolyester is based upon terephthalic acid and ethylene-and butylene- glycol.

10. A suede-like product according to claim 1, 2 or 3, wherein said multi-component filament comprises a component made from copolyamide based upon .epsilon.-caprolactam and adipic acid/hexamethylene diamine salt.

11. A suede-like product according to claim 1, 2 or 3, wherein said polyurethane is based upon polytetramethylene glycol, ethylene glycol and 4,4'-diphenylmethane-diisocyanate.

12. A suede-liXe product according to claim 1, 2 or 3, having an overall density of at least 0.25 g/cm3.

13. A suede-like product according to claim 1, 2 or 3, having a density of at least 0.3 g/cm3.

14. A suede-like product according to claim 1, 2 or 3, having a density gradient such that the density decreases from the interior to the top and bottom surfaces of the impregnated fleece.

15. A suede-like product according to claim 1, wherein said polyurethane is microporous and at least partly defines tubes enclosing the fibres, the lumen of the tubes being larger than the volume of the enclosed part of the fibres.

16. A suede-like product according to claim 15, wherein said lumen is at least twice as large as the volume of the enclosed part of the fibres.

17. A suede-like product according to claim 15, wherein the enclosed fibres are largely without any firm connection with the polyurethane surrounding them.

18. A suede-like product according to claim 1, 2 or 3, wherein said multi-component filaments are at least partly aligned as bundles in said fleece.

19. A suede-like product according to claim 1, having an overall density of at least 0.25 g/cm3, said product having a density gradient, the density decreasing from the interior to the top and bottom surfaces of the impregnated fleece.

20. A suede-like product according to claim 19, wherein said polyurethane is based on polytetramethylene-glycol, ethylene glycol and 4,4'diphenylmethane diiso-cyanate.

21. A method for producing a suede-like product by producing a textile fabric out of multi-component filaments and impregnating it with a polyurethane solution, which comprises processing stable fibres, made from crimped multi-component filaments of the matrix-segment type, having a cross-section of which comprises a matrix and at least six peripheral wedge-shaped or lenticular segments, not completely covered by the matrix, into a fleece, said fleece being mechanically bonded, the density thereof being increased by more than 30% by shrinkage, the multi-component filaments being at least partly split up into their components, the difference in shrinkage between the said components being at least 10%, impregnating said fleece with a solution of a polyurethane based upon a polyglycol, a diisocyanate and a low molecular weight glycol as a chain lengthener, said solution having a gelling temperature higher than room temperature, coagulating the polyurethane, washing and drying the fleece and grinding on both sides.

22. A method according to claim 21, wherein said coagulating comprises air-cooling the impregnated fleece.

23. A method according to claim 21, wherein said coagulating comprises treatment of the impregnated fleece in a coagulating bath containing a non-solvent for the polyurethane.

24. A method according to claim 21, wherein said coagulating comprises passing the impregnated fleece through an air zone to initiate coagulation and thereafter immersing the imgregnated fleece in a coagulation bath containing a non-solvent for the polyurethane.

25. A method according to claim 21, wherein the fleece is mechanically bonded or strengthened by needling.

26. A method according to claim 21 or 25, wherein the fleece is split one or more times before or after said impregnating.

27. A method according to claim 21, 24 or 25, wherein said staple fibres are made from stuffer-crimped multi-component filaments.

28. A method according to claim 21, wherein the components of said filaments have a shrinkage difference of at least 10% upon treatment with methylene chloride at room temperature.

29. A method according to claim 28, wherein said shrinkage difference in methylene chloride is at least 20%.

30. A method according to claim 21, 24 or 25, wherein the components of said filaments have a shrinkage difference of at least 20% upon treatment with water.

31. A method according to claim 21, wherein said multi-component filaments have a polyamide matrix-component and peripheral segments made from a polyester.

32. A method according to claim 21, wherein the polyester in the cross-section of the multi-component filaments amounts to between 70 and 90%.

33. A method according to claim 21, 24 or 25, wherein said impregnating is carried out with a solution of a poly-urethane based upon polytetramethylene glycol, ethylene glycol and diphenylmethanediisocyanate.

34. A method according to claim 21, 24 or 25, wherein impregnating is carried out with a polyurethane containing a light-protective agent.

35. A method according to claim 21, wherein methylene chloride is used to bring about the shrinkage.

36. A method according to claim 35, wherein the methylene chloride contains between 0.5 and 5%, by weight, of a finishing agent soluble in methylene chloride.

37. A method according to claim 36, wherein said finishing agent is a fatty acid amide condensation product.

33. A method according to claim 21, 24 or 25, wherein dimethyl formamide at a temperature of 120°C is used to bring about the shrinkage.

39. A method according to claim 21, 24 or 25, wherein said impregnating is effected asymmetrically.