CA1075868A - Filament with copolymer component of styrene and higher alcohol ester - Google Patents
Filament with copolymer component of styrene and higher alcohol esterInfo
- Publication number
- CA1075868A CA1075868A CA315,686A CA315686A CA1075868A CA 1075868 A CA1075868 A CA 1075868A CA 315686 A CA315686 A CA 315686A CA 1075868 A CA1075868 A CA 1075868A
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Abstract
ABSTRACT OF THE DISCLOSURE
Sheet-like materials for example for use as synthetic fabrics, comprising a bundle of fine fibers having a maximum deformation ratio of about 12% and a minimum apparent density of 0.21 g/cm3, said fine fibers having a maximum denier of about 0.45 are disclosed. The materials are made by forming a fiber aggregate of multi-component fibers, removing one component from the fibers, eg. by dissolution, to convert each fiber to a bundle of fine fibers consisting of the residual component, shrinking and heat treating the aggregate and impregnating the aggregate with a binder.
Sheet-like materials for example for use as synthetic fabrics, comprising a bundle of fine fibers having a maximum deformation ratio of about 12% and a minimum apparent density of 0.21 g/cm3, said fine fibers having a maximum denier of about 0.45 are disclosed. The materials are made by forming a fiber aggregate of multi-component fibers, removing one component from the fibers, eg. by dissolution, to convert each fiber to a bundle of fine fibers consisting of the residual component, shrinking and heat treating the aggregate and impregnating the aggregate with a binder.
Description
5~8 The invention relates to sheet-like materials and to their pre-paration from multi-component fibers.
~ multi-component fiber is a fiber consisting of at least two components. Various types are known. Specifically these include the sheath-core type composite fiber as shown, for example, in United St~tes patent No.
~ multi-component fiber is a fiber consisting of at least two components. Various types are known. Specifically these include the sheath-core type composite fiber as shown, for example, in United St~tes patent No.
2,989,798 and British patent No. 514,638, the so-called side-by-side type composite fiber as shown in United States patents Nos. 2,428,046, 3,038,239 and 3,117,905, the so-called kidney type composite fiber as shown in United States patents Nos. 2,987,797 and 3,035,235, the "islands-in-a-sea" type composite fiber as shown in British patent No. 1,171,843, the composite fibers having irregularly shaped cores as shown in United States patents Nos.
3,350,488 and 2,932,079 and 3,672,802 and in French patent No. 1,495,835 and polymer blend type fibers as shown in United States patent No. 3,ogg,067, for example. Further, as a special example, a polymer blend may be used as a component of an islands-in-a-sea type composite fiberO
Of these multi-component fibers, typical examples of cross-sections of islands-in-a-sea type composite fibers include islands-in-a-sea ;; type composite fibers having sixteen islands and fibers with 36 islands. In both, some islands are surrounded by other islands. When the number of islands in the fiber is increased, this increases the ratio of islands to the sea, and the stability of the fiber increases.
These multi-component fibers have many uses. However, by removing at least one component from such a fiber, a unique usage is opened up, as in the case of, for example, British patent No. 1,218,191. For example, a component may be removed by dissolution of a conventional multi-component fiber, but this presents problems.
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Th~ following characteristics are often required of a component to be removed by dissolution:
1) Good spinnability; it is intended to be spun together with one or more other components; it must be stably spinnable at the existing spinning la-'~
, - l~l'Y58~8 temperature.
2) It must not react ~ith other components during spinning (es-pecially, it must not gel hy any cross-linking reaction).
3) It ~lust be dra~able cit must not fuse during drawing).
Of these multi-component fibers, typical examples of cross-sections of islands-in-a-sea type composite fibers include islands-in-a-sea ;; type composite fibers having sixteen islands and fibers with 36 islands. In both, some islands are surrounded by other islands. When the number of islands in the fiber is increased, this increases the ratio of islands to the sea, and the stability of the fiber increases.
These multi-component fibers have many uses. However, by removing at least one component from such a fiber, a unique usage is opened up, as in the case of, for example, British patent No. 1,218,191. For example, a component may be removed by dissolution of a conventional multi-component fiber, but this presents problems.
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Th~ following characteristics are often required of a component to be removed by dissolution:
1) Good spinnability; it is intended to be spun together with one or more other components; it must be stably spinnable at the existing spinning la-'~
, - l~l'Y58~8 temperature.
2) It must not react ~ith other components during spinning (es-pecially, it must not gel hy any cross-linking reaction).
3) It ~lust be dra~able cit must not fuse during drawing).
4) It n\ust have f]exibility to some extent ~which is especially necessary when it is to be crimped~.
5) It must be readily soluble.
6) It must be low in cost.
The following are examples of conventional components to be removed by dissolution:
(A) Examples of components having good spinnability, drawability and flexibility while sacrificing solubility:
Polyamides, polyesters and polyacrylonitriles are excellent in respect of spinnability, but ara difficult to remove by dissolution, as has been observed in United States patents Nos. 3,350,4~8 and 3,382,305 and in French patent No. 1,4~5,835.
In case (A), with respect ~o the solvent, there are problems such as dissolving speed and difficult handling. For example, when dissolving ; polyamide in formic acid, the material of the container and the design of the machine for handling formic acid present industrial problems. Almost no mate-~ials satisfactorily resist corrosion by formic acid except titanium alloys, especially when heating is used for increasing solubility. Especially when removal of formic acid from the product after dissolution, and recovery of formic acid are taken into account, the use of formîc acid on an industrial scale is very troublesome.
In the use of ortho-chlorophenol as a solvent for polyester also, danger of using the solvent is great and its dissolving speed is too slow. In the case of acrylonitrile, there is only a limited selection of ; polymers which can be simultaneously spun with acrylonitrile. Also great difficulty is encountered in its removal by dissolution.
; ~B) Examples of components having good solubility while sacrific- -.,, ~ .
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ing spinnability:
Some ~olymers are inferior in drawability and ~lexibility, such as polystyrene, polystyrene-acrylonitril~ copolymers and polystyrene-methyl methacrylate copoly~ers, as reported in British patent No. 1,263,221 and in United States patent ~lo. 2,930,074.
In case (B), solvent which is low in cost and easy to handle, such as a hydrocarbon of the aromatic series or a hydrocarbon of the chlorine series may be selected as a solvent.
However, when such a polymer is used, especially when such a poly-mer occupies at least 40~ of the surface of the multi-component fiber, the drawability and flexibility of the fiber become very poor. The following explanation will elaborate.
Drawbacks in the use of polymers of polystyrene series:
Polystyrene per se is a very brittle polymer; the elongation of undrawn polystyrene yarn at room temperature is at most 6 - 10~. Because it is brittle, polystyrene alone is very difficult to draw. By using polystyrene as one component of multi-component fiber, the polystyrene is reinforced by other components and becomes somewhat easier to handle. ~lowever, the other components become weaker because of the presence of ~he polystyrene, which is most difficult to dra~. Especially when polystyrene is present over at least 40% of the surface of the multi-componen~ fiber, the fiber becomes most difficult to draw. lYhen the temperature is raised so that the polystyrene can be drawn, the polystyrene becomes tacky and the multi-component fibers stick to one another.
In a multi-component fiber, when polystyrene occupies ~t least ~0%
of the fiber surface, it is very difficult to draw the fiber. Polystyrene begins to flow at a temperature of 105 - 115C. As soon as the polystyrene begins to n ow, the multi-component fiber becomes tacky, the fiber fuses on the surface of the heat source Ghot plate~ or the fibers fuse among them-selves. Also, the fiber can be drawn only within a very limited range and ~0~5~1~;8 for a very short p~riod of time. It may be stated~ acco~dingly, that such fibers cannot be dra~n sufficiently, in the industrial sense. Elongation at a lower temperature does not give sufficient r~sults; for example, by drawing with stea~ heat as is ordinarily carried out industrially in staple drawing, the multi-component fiber can be drawn only to 2.0 - 2.5 times its initial length. When drawn more, the polystyrene on the surface whitens, cracks and breaks, and the resulting fiber cannot withstand actual use.
Specifically, since it is impossible sufficiently to draw such a multi-component fiber under normal industrial conditions, this makes it necessary to make a fine denier undrawn yarn, in which case spinning produc-tivity suffers.
Because a complicated spinneret is usually used to obtain a multi-component fiber, it is difficult to effectively increase the number of no~zles on the spinneret. Accordingly, spinning productivity cannot be in-creased which is a fatal drawback with respect to the cost of the fiber as a product.
Further, the physical properties of t~e multi-component fiber product also deteriorate. Because the fiber is not to be drat~ to the desir-ed extent, its elongation is quite high and its Young's modulus is low. The characteristics of the fiber are close to those of undrawn yarn. Such poor drawability and brittleness of polystyrene are particularly troublesome when a highly shrinkable fiber is desired.
In order to obtain a highly contractible fiber, the fiber must be drawn at as low a temperature as possible so as to impart an internal strain to the fiber. When polystyrene is used as the sea component in an island-in-a-sea type composite fiber, such fiber cannot be drawn at as low a temperature as 60 - 70C; at 98~ C or higher drawability begins to some ex-tent, but the resulting fiber does not have a sufficient ~e.g. more than 25%) shrinkage.
And in the case of a contractible fiber, two-stage contractibility is important. When the fiber has been once contracted at a relatively low -- ~t --.: .
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temperature, and is thereafter contracted at a higher temperature, the fiber should still show contractibility. The most ideal relationship in two-stage contractibility is that the sum of the first stage shrinkage and the second stage shrinkage equals the shrinkage that would be obtained if the fiber were suddenly exposed to the higher temperature.
When the fiber is drawn at a high temperature, it is difficult to obtain a fiber having excellent two-stage contractibility. When polystyrene is used, the temperature at which the drawn yarn begins to contract is re-latively high, due partly to the limiting condition that polystyrene must be drawn at a high temperature. It is difficult to carry out stepwise slow con-traction on the low temperature side, it is not possible to provide a wide range of contracting temperature upon carrying out two-stage contraction, and two-stage contraction is accordingly difficult.
As a means for solving the aforementioned problems of drawability and contractibility when polystyrene is used, it is conceivable to add a plasticizer to the polystyrene. However, no anticipated substantial effect is obtained. Further problems arise when a plasticizer is used, including mixing and affinity of the plasticizer with the polymer, bleed-out and evaporation of the plasticizer.
In generalJ plasticizing of a polymer with a plasticizer requires a large amount of the plasticizer. When a large amount of plasticizer is add-ed to the polymer, it is technically difficult to mix the two uniformly, and even if they are mixed, the plasticizer bleeds out and evaporates through the fiber surface during melt spinning of the polymer. The amount of plasticizer remaining in the polymer fiber is sharply reduced and a substantial plasticiz-ing effect cannot be realized.
Further, when such a large amount of the plasticizer is added to the polymer, the melt viscosity of the polymer becomes drastically lower. In the spinning of multi-component fibers, the maintenance of a balance of melt viscosity values among respective components is very important for the stabili-. . .
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zation of spinning. Poor balance results in composite ~mevenness and abnor-mal variations of cross-section and bcnding of the fiber just under the spin-neret.
Further, crystallization of other polymers is sometimes caused by the plasticizer. When crystalli~ation proceeds in an undrawn ya~n, ~he fiber becomes difficult to draw. Depending upon the particular plasticizer, such crystallization may even be accelerated.
Also, with reference to a prob~Lem of evaporation of the plasticizer at the time of spinning, the plasticizer tends to evaporate through the sur-face of a yarn having a large surface area and the plasticizer tends to form bubbles, which tend to cause breakage of the yarn.
As mentioned above, improvement of drawability by adding a plas-ticizer can hardly be expected. Accordingly, it is an object of great desir-ability to develop a novel polymer. Such a novel polymer should be easy to draw at a relatively low temperature, and should not fuse within at least a certain range of temperatures within which other components are drawn. In the case of polystyrene, it fuses simultaneously under normal drawing condi-tions. In the case of polystyrene-acrylonitrile copolymers and polystyrene-methyl methacrylate copolymers, they also present the same problems associated with polystyrene and they do not show any improvement of drawability or flex-ibility.
According to the present invention, there is provided a sheet-like . material comprising a bundle of fine fibers of a thermoplastic polymer and a binder and having a maximum deformation ratio of about 12% and a minimum apparent density of 0.21 g/cm3, said fine fibers having a maximum denier of about 0.45.
Another aspect of the invention provides in a method of making a ; sheet-like material which comprises a fiber aggregate comprising multi-com-ponent fibers comprising at least two components (A~ and (B), one component . ,. ., ~
1~75~3~;8 (B) bcing a copol~ner of about 90 to 70% of styrene and about 10 to 30% of an ester selected from acryl:ic acid and methacrylic acid, and the other component (A) being a fiber-forming thermoplastic polymer~ the steps of removing said component (B) from said component (A) whereby each said fiber becomes a bundle of fine fibers having a maximum denier of about 0.45 and consisting of said component (A); shrinking said aggregate at a time other than the time of re-moving said component (B); subjecting said aggregat~ to a substantial heat ~E~ Q~
IG~ treatment at a temperature ranging from 9~/lto 220 C; and impregnating saidaggregate with a binder at a time other than the time of said heat treatment.
Embodiments of the invention and aspects of the prior art are illu-strated by way of example, in the drawings, in which:
Figures 1 (a) and 1 ~b) are cross-sectional views of islands-in-a-sea type composite fibers.
Figure 2 is a view in side section, showing an apparatus used for measuring the elongation of a polymer~
Figure 3 is a chart showing the relationship between draw ratio and shrinkage in boiling water of composite fibers.
Figure 4 is a chart showing the relationship between copolymerisa-tion ratio and drawability (elongation) of a polymer according to the '~
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present invention.
Figure 5 is a chart showing the heat stabiLizatiorl of a polymer according to the present invention.
Figure 6 is a view in side elevation showing one e~ample of a liquid-bath drawing apparatus preferably used for drawing a fiber according to the present invention.
Figure 7 is a chart showing the deformation of a product of a fiber according to the present invention, plotted against binder con-tent.
Figure 8 is a chart showing the abrasion resistance (chafe number) of a product made of fibers according to the present invention, plotted again-st binder content.
The present invention relates to a multi-component fiber having excellent drawability at a low temperature, which comprises a specified com-ponent of a copolymer of the vinyl series.
~ rom our knowledge of the serious drawbacks associated with con-ventional polystyrene-acrylonitrile copolymers and polystyrene-methyl metha-crylate copolymers, the possibility of improving the properties of the fiber by copolymerization of ~he polystyrene has heretofore seemed to us to be very remote indeed. Actually, we seriously considered abandoning the possibility of improving the properties by this copolymerization procedure, after studying the results of the following examinations.
(1) Copolymeri~ation of polyvinyl ether and styrene:
Polyvinyl ether has been known as a plasticizer of polystyrene.
Accordingly, it was anticipated that remarkable flexibility would be imparted by copolymerization of the two. Methyl-, ethyl-, and butyl-vinyl ethers ~ere selected in trying copolymeri~ation with styrene. However, the product was a waxy brittle copolymer having inferior performance as compared with the homo- polymer of polystyrene.
29 (2) Copolymeri~ation of acrylic acid ester and styrene:
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Methyl acrylate ~ncl ethyl acrylate were selected in carrying out the e~amina-tion. l~hen each copolymer was simultaneously spun ~ith polyethy-lene terephthalate as a multi-component fiber, a gcl was formed which blocked the spinneret. When the spinneret paclc was dismantled, the gel was found to be insoluble in solvents; the spinneret was blocked and became useless. When butyl acrylate was used as the acrylic acid ester, the same result was ob-tained.
Accordingly, polymers of the vinyl series present serious problems in terms of performance and spinning, and cannot be used. It appeared that our study was deadlocked at this point. However, we have now discovered a surprising fact.
We have discovered that, among the polymers of the vinyl series, a particular polymer is thermally stable, surprisingly yielding a copolymer which does not gel, and which possesses excellent drawability at a low temperature, and which combines admirably with other polymers simultaneously spun.
Although gelation occurs especially often with combinations of polyesters with esters of the vinyl series, such gelatin can be avoided when the vinyl polymer is the very particular polymer according to this invention, which is a copolymer of the vinyl series having an HDT (heat deformation temyerature measured by British standard method No. 2782~ of 75 - ~0 C, an elongation in hot water at 70 C of at least 100 % and a shrinkage in hot water at 85C of at least 15 %.
The most simple example of such polymer is a styrene-acrylic acid ester copolymer of the vinyl series containing about 10 - 30 % by weight of acrylic acid ester unit and about 90 - 70 % by weight of the styrene unit.
In referring to elongation in hot water a~ 70 C, this is measured in the following manner:
29 A cylinder having an internal diameter of 10 mm is precisely heated _9_ 1[31'7~8~3 to 220 C. At tlle lower end of this cyl-inder an orifice having a length of 8 mm and a diameter of I mm is provided. The polymer is placed inside the cylinder and allowed to stand there for two minutes. The polymer is then extruded through the orifice from above the cylinder while the load is adj~s-ted to provide a flow rate of 0.3 g/min. Ten undrawn yarns, produced in this manner, are bundled and subjected to a tensile test based on ordinary strain-stress measuring techniques, using the apparatus shown in Figure 2. Elonga-tion at break is the elongation of the polymer at a water temperature of 70C, using a sample length of 1 cm and a tensile speed of 1 cm/min.
In accordance with the method of measuring shrinkage, forty ~mdrawn yarns extruded as just referred to are bundled. A fiber bundle 20 cm long is immersed in hot water at aic, taken out after 3 minutes and the length of the fiber bundle is measured and reported as L centimeters. The shrinkage is Shrinkage = 20 - L x 100 (%) According to this invention, the HDT of the copolymer according to this invention must be not more than about 75 C, which is necessàry, upon imparting crimp to a multi-component fiber comprising the copolymer, for preventing said fiber from cracking or splitting and for increasing the flexibility of the fiber as well. ~owever, when the HDT is too low, various - difficulties are brought about. ~he fibers become apt to fuse and stick to one another at drawing. ~hen subjected only to slight friction, or to heat generated in carding, the fiber fuses. Accordingly, it is necessary that the HDT be not less than about 40 C.
Elongation in hot water at 70 C is important. The elongation re-flects the degree of polymerization and linearity of the molecule, becoming a criterion of spinnability and of drawability. In order that a multi-component fiber may show good drawability at a low temperature~ it is neces-29 sary that the value of this elongation should be at least about 100 %.
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~ s regards contractibility, it is necessary that the shrinkage beat least about 15 % at 85 C. The degree of contractibility becomes especially important ~hen a h-ighly contractible fiber is to be obtained. Contracting stress is not always necessary. It is sufficient for the component to properly follow and not to obstruct the contraction of the other component.
It is important to provide a particular polymer which is a copolymer consisting mainly of a reaction product of styrene and an ester of the vinyl series, containing 90 - 60 % as a whole of the styrene unit, and 10 - 30%, preferably 15 - 20% of the vinyl type ester unit. The foregoing are main components; if desired anoth~r vinyl monomer may be further copolymeri~ed if necessary for adjusting the viscosity and improving the heat stability of the product.
Esters of the vinyl series include the acrylate esters and metha-crylate esters, when such an ester is simultaneously spun with a polyester, an ester having 6 - 20 carbon atoms preferably 8 - 18 is preferred. Such an ester, being a reaction product of acrylic acid or methacrylic acid to form an ester with an alcohol having a boiling point of at least 150 C (at 760 mm Hg~, which is effective to prevent gelation.
In this invention, the configuration of such alcohol is also im-portant. Such alcohol has a side chain which is preferable from the view--- point of the drawability. However, when the heat resistance of the polymer is critical, an alcohol which has a straight chain is preferable. The selec-tion of a particular straight-chain or side-chain alcohol should be judged according to the situation at that time; sometimes it is preferred to use them in admixture.
As specific examples of esters of the vinyl series which may be used in the present invention, they may be classified into those having an . . .
ester group which contains less than 6 carbon atoms such as methyl acrylate, 29 butyl acrylate, methyl methacrylate and butyl methacrylate and those whose `" ' ~07~
ester group contains at :Least 6 carbon atoms such as hexyl acrylate, n-octyl acrylate, 2-ethyl hexyl acrylate, tri-methyl heptyl acrylate, stearyl acrylate, lauryl acrylate, hexyl methacrylate, n-octyl methacrylate, 2-ethylhexyl metha-crylate, tri-methylheptyl methacrylate, stearyl methacrylate and lauryl methacrylate.
When the ester group contains less than 6 carbon atoms, gelation occurs upon simultaneous spinning with polyester, and spinning becomes impos-sible. Accordingly, such esters are limited to combinations with polymers other than polyester.
When the ester group contains at least 6 carbon atoms, gelation does not occur, and spinning may be carried out favourably. However, when the number of carbon atoms is too great, drawability becomes inferior. Ac-cordingly, it is preferred that the number of carbon atoms be not more than about 20, preferably not more than about 18.
Especially preferably examples of esters of the vinyl series in the present invention are those which contain alkyl group at least 6 carbon atoms, having a side chain, namely, 2-ethyl-hexyl acrylate and 3,5,5-tri-~; methylheptyl acrylate.
Regarding the copolymerization ratio, 10 - 30%, preferably 15-25% of such ester of the vinyl series is preferred. Different from thesituation in which a plasticizer is added, the effect begins to appear at about 10% and comes out sharply at about 15%. However, more than 30% is not preferred because there is too much plasticization, spinning becomes difficult due to fusion of chips or pellets ard there is too great a difference of melt viscosity values between the composite components at the time of melting.
Fusion of fiber and fiber characteristics at the time of drawing are greatly influenced by slight fluctuations of temperature.
The polymer according to this invention is ready to reac~ and poly-29 merizable under conditions of ordinary polymerization of styrene, or somewhat-12--1~75~
modified conditions. IndustriaLly, radica-l polymcrization is preferable.
~ppropriate polymerization initiators incLude benzoyl peroxide and ter-butyl-per-benzoic acid.
However, drawability is somewhat influenced by the added amount of polymerization initiator. When the added amount is too great, the degree of polymerization does not increase, which is not desirable. When the added amo~mt is too small, the polymerization rate is too slow. Characteristically, it is preferred to set up a criterion such that the intrinsic viscosity measured at 30 C in toluene is about 0.6 - 1.2.
The present invention relates to a multi-component fiber in which the polymer just described is one component. The component of the present invention is effective when it is intended to be removed by dissolution, especially when it occupies at least 40% of the fiber surface in the multi-~ component fiber.
;~ In general, when the fiber surface occupying ratio of a component that fuses at the time of drawing is as high as 40% or more, difficulties at the time of dra~ing, such as sticking of the fibers, and deposition of residues on the heater plate at the time of drawing, become very serious.
~owever, when the polymer of the present invention is used~ such troubles do not occur. mis is an outstanding feature of this invention.
me most preferable configuration of a fiber in the combination of the present invention is a fiber whose surface is completely surrounded by a component to be removed by dissolution. Specifically, these configurations ` include the islands-in-a-sea type composite fibers, sheath-core type com-; posite fibers, composite fibers with irregular shaped cores, and polymer-blend type fibers at least 60 percent of the surface of which is surrounded by a component which is to be removed by dissolution.
Some of the important characteristics of the present invention 29 consist in imparting softness and flexib ity to a fiber using a low soften-' ~:
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ing point copol~ncr; it has been discovcred that even if such Low softerl-ing point compo--ent is used, the fiber can be clra~m WittlOUt fusion. SpecificaL-ly, a polymer in an l~oriented mo~Lecular state, such as a pellet, tends to fuse easily. Ho~ever, a polymer in the dra~n and oriented state is l~likely to fuse. The discovery that fusion in an amorphous polymer is prevented by o}ientation of large chain-molecules is a characteristic feature of the present invention.
~ s other polymers used in combination with the polymer of -the present invention, in such fiber, mention should be made of polyamides and copolyamides such as poly- -capramide and polyhexamethylene adipamide; poly-esters and copolyesters such as polyethylene terephthalate, polybutylene tere-phthalate, polyoxy benzoate, polyethylene terephthalate-polybutylene-iso-phthalate copolymers, and polyolefins such as polyethylene and polypropylene.
0f these polymers3 polyesters, having a softening point, as defined hereinbelow, of not more than 250 C are especially preferable in regard to preferred balance of drawability with the polymer of the present invention The softening point referred to herein is defined as a temperature measured by a differential scanning calorimeter DSC-II manufactured by Perkin-Elmer Co. at a rate of temperature increase of lo C/min, a sensitivity of 5 cal/sec and a sample amount of 10 mg corresponding to the starting point of a fiber melting peak. Said starting point is an intersecting point of the base line of said peak and a tangent drawn at a point at the intermediate height of said peak.
Such polyesters include polyethylene terephthalate-polyethylene isophthalate copolymers, polyethylene terephthalate-adipic acid copolymers, and copolymers of polyethylene glycol, polyethylene terephthalate and poly-ethylene isophthalate.
The weight ration of the polymer of the present invention to the 29 other polymer in the spinning of a multi-component is preferably within the . . .
~ ' ' '' ~ ' ~75~8 range of about 65/35 - 35/65.
Upon spinning a multi-component fiber using a copolymerization component according to the present invention, the heat career of the copoly-mer prior to spinning becomes very importcmt; it has a remarkable influence upon the thermal decomposition of the copolymer at the time of spinning.
Especially when the copolymer is exposed to a hi~l temperature of at least 240 C before spinning (when the copolymer is pelletized at 240 C), the thermal decomposition of the copolymer at the time of spinning becomes re-markable. Accordingly, it is necessary not to overheat the copolymer prior to spinning, the polymer is likely to fuse and block at a supplying zone of extruding machine. So it is useful to strengthen the cooling of a supplying zone to prevent blocking at the supply opening due to fusion of a bead polymer.
- In order to prevent such difficulties, it is possible to extrude the polymer, after completion of polymerization, directly into pellets by block polymeriza-tion.
In order to prevent thermal decomposition of the polymer, it is also effective to add a thermal decomposition inhibitor. Stabilizers of the phenol series are excellent, for example, 2,6-di-ter-butyl~rdimethyl amino p-cresol; 2,2'-methylene-bis-(4-methyl-6-tert-butylphenol~; 1,3,5-trimethyl-20 2,4,6-tris (3,5-di-ter-butyl-4-hydroxybenzyl) benzene, 4,4'-thiobis-(6-ter-butyl-3-methylphenol) and 2,2'-dihydroxy-3,3'-di (~C-methylcyclohexyl)-5,5'-dimethyl-diphenyl methane.
In the spinning of a multi-component fiber using a component of the present invention, the temperature of the atmosphere below the spinneret is very important. me drawability of the resulting fiber is greatly in-fluenced by atmospheric conditions up to 30 cm below the spinneret. A temp-erature range of about 130 - 320 C is recommended at a point 10 cm directly below the spinneret. ~specially, upon simultaneously spinning a very low 29 softening point polymer with a high softening point polymer of a composite 51~36~3 fiber, by making such ambient temperature higher than the so~tening point ofthe low softening point polymer, but lower than the softening point of the high softening point polymer, it is possible to promote molecular orientation of the high softening point polymer only, and to a-void molecular orientation of the low softening point polymer. When the drawability of the low soften-ing point polymer is poor as compared to that of the high softening point polymer, as in the present invention, such method is very effective for im-parting drawability to a multi-component fiber.
It is preferable not to cool the fiber of the present invention suddenly. Accordingly, upon winding the fiber, it is preferable to control the temperature of the fiber to a value somewhat higher, and to heat the fiber as occasion demands, and to wind the fiber at about 20 - 60 C.
The influence exerted upon the fibers by oiling agents ("spin finishes") is also important. The copolymer of the present invention cracks ~` under the influence of certain kinds of oiling agents. It is recommended to avoid oiling agents containing lower alcohols. Selection of an oiling agent used for the fibers of the present invention is carried out using a tensile tester shown in Figure 2, by pulling an ~mdrawn yarn at 50 C in a 3% solu-tion of the oiling agent to be checked. Oiling agents which in 3 % solution cause fluctuation of the tensile strength of the undrawn yarn, when elongated by 100%, of more than 0.2 g/denier are not preferred.
Upon spinning, the polymer is usually supplied as pellets to the spinning machine~ Upon supplying such pellets it is necessary to control them sufficiently so that their temperature does not become too high. Other-wise the pellet fuses, becomes a block and becomes impossible to supply.
Heat from a melting zone is transmit~ed to a polymer supply zone and the polymer is heated more than expected. In order to prevent such difficulty, it is effective to cool the pellet from without to keep the pellet at a 29 temperature lower than the fusion temperature until the polymer reaches the .. . . .. ..
~0'758G~3 melting zone.
Polymers of the present invention may be melted at ahout 220 -290 C. However, it is preferable to melt the polymer at lower temperature from the viewpoint of melt viscosity and for preventing thermal decomposition.
A fiber according to the present invention may be taken up without any problems under ordinary conditions. However, the advantageous character-istics of the styrene-vinyl ester fiber of the present invention are best developed when the sp~m fiber is taken up at a rate of at least about 1500 ` m/min. At this time, it is effective to keep the spinning temperature low.
Inside the spinneret, the styrene-vinyl ester polymer of the present invention is sufficiently fluid, having a function like a lubricant and smoothing the discharge of the other fiber-forming component. Because of this advantageous characteristic, it is possible to operate effectively with a relatively low spinning temperature.
Such means is especially effective in the case of a fiber having a plurality of independent islands in one fiber, such as islands-in-a-sea type composite fiber. By taking up the fiber at a high speed, the orientation of the fiber is promoted and the subsequent drawing step can be dramatically shortened. When one component is dispersed thinly in another component, the orientation of that component at the time of take-up proceeds more rapidly than when that component is thickly dispersed. This inclination is especially remarkable when a polymer having a low softening point and low elongation at room temperature is used as in the present invention.
Such a fiber is especially effective when it is taken up in the ~ .
form of a sheet, using ~n air jet.
Upon drawing the fiber, it is desirable to establish the drawing temperature at about 50 - 100 C. ~he significance of the fact that the fiber can be drawn at a temperature not higher than 100 C is very great, 29 because drawing by steam heating at atmospheric pressure, as usually carried ~............... '' ~ ':
,:. : ' 5;3~
out in ordinary staple clrawing, becollles practical. Also, drawlng in hot water is practical and effective.
~ s in the past, a yarn using polystyrene cannot be drawn satisfac-torily at a high draw ratio (more than 2.5 times) at a temperature not more than 100C. Nhen the yarn is dral~ at a low temperature the polystyrene cracks, the fiber surface becomes rough and fibrillation and breakage of the fiber tend to occur. In order sufficiently to draw polystyrene, it is neces-sary to heat the same at a temperature above 100 C, actually at least 120C.
In order to do this a hot plate or hot roll is used. However, in the case of polystyrene yarns, when they become easy to draw, they also become easy to fuse and adhere to each othær.
~ hen polystyrene is drawn in such state, if fuses and sticks to the hot plate or fuses by reason of friction between the hot plate and the ~olymer. Accordingly, it is very difficult sufficiently to draw polystyrene on an industrial scale.
In accordance with the present invention, the fiber can be drawn at a temperature not higher than 100 C and, during the drawing step, the - fiber does not fuse and does not stick to the heater.
Drawing according to the present invention may be carried out by steam heating at atmospheric pressure as carried out in usual staple drawing.
However, a preferable method of drawing is based upon the use of a hot liquid as the heating medium. Hot water is ordinarily used. The fiber is passed through hot water kept at a constant temperature, and drawn. However, a still more preferable method of drawing is the method shown in Figure 6. In Figure 6, 11 is a fiber to be drawn and 12 is a liquid kept at a constant temperature and supplied from a tank 14 by a pump 13. This liquid overflows from a draw box 15 and refluxes to 14. 16 is the swollen liquid surface of the over-flowing liquid on or in which the fiber passes to be drawn.
29 Drawing in an overflowing liquid is especially preferable in that ~'~ - ' ~` ' .
:
~:
iO75~
the fiber does rlot contact any solid substance in the draw zone. Abrasion of the fiber surface is prevented and fibcr damage is minimized~
Hot water suffices as the liquid used. }lowever, addi-tion of fiber treating agents such as oiling agents, ("spin finish") and antistatic agents to the hot water gives especially good results because such agents adhere uniformly to the fiber when applied in this manner during the drawing stage.
In the present invention the fiber may be drawn on a hot plate as well. In the present invention for~ation of deposits upon the hot plate, as seen in the case of drawing polystyrene, is not brought about.
Upon carrying out drawing according to the present invention, drawability is sometimes improved remarkably by carrying out preliminary heating before drawing. 30 - 80 C is appropriate as the preliminary heating - temperature. At the time of carrying out preliminary heating, the fiber may either be relaxed or under tension.
The present invention is especially effective in making a multi-component fiber, especially a highly contractible multi-component fiber con-taining polyester. The highly contractible fiber referred to herein is a . .
fiber showing shrinkage of at least 15% to the initial length of 20 cm when it is immersed in hot water at 90 C with a load of 5 mg/denier at one end of the sample.
In order to make a highly contractible fiber containing polyester, two methods are available, as follows:
(A) Lo~ering the draw ratio and utili~ing a 30ne in which the mole-cular orientation is extremely poor.
This is a very effectiYe method when only shrinkage is considered and the practical characteristics of tensile strerlgth and elongation are ignored. However, a fi~er obtained by this method is essentially a so-called undrawn yarn. Upon actually using such a fiber, it undesirably elongates 29 even under small tension, and its tensile strength is low. When such a 1~75~
fiber is further contractcd, its physicaL properties become even worse.
~ ccordingly, a fiber having much better characteristics of molecular orientation is required. For obtaining such fiber the method is:
(B) Carrying out drawing at a high draw ratio at a low temperature.
Drawing at a low temperature causes strain in the fiber. It is necessary to carry out drawing at a temperature not above 100 C as usually carried out industrially. In conventiona:L polystyrene-polyester systems, it has not been possible to draw at a rat:io of at least 2.5 times under this drawing condition.
In accordance with the present invention, the fiber is drawn suf-ficiently at such a low temperature, and a highly contractible fiber having excellent molecular orientation and excellent tensile strength and elongation is obtained.
The draw temperature and draw ratio are important. It is preferable that the draw temperature be about 50 - 100 C, preferably about 60 - 85C and that the draw ratio be about 2.6 - 4.80, preferably 3.0 - 4.3. At a tempera-ture below 50 C, drawing of polyester becomes impossible. At a temperature above 100 C, the internal strain necessary for contraction is not formed in the fiber. It is necessary that the draw ratio be at least about 2.6. For sufficient tensile strength and elongation, it is necessary to use a higher draw ratio. The higher the draw ratio, the more preferable. However, from the industrial viewpoint, an appropriate upper limit is about 4.8.
Crimping conditions are also important. In the crimping operation, the crimper is heated by the friction of the fibers. Partial contraction of the fiber is caused by this heat, reducing the shrinkage of the fiber.
Accordin~ly, it is necessary to repress the heat as much as possible . Speci-fically, it is necessary to keep the temperature of the crimper below 70 C, preferably below 50 C. It is desirable to cool the crimper by an oiling 29 agent applied to the fiber.
, :, . . .
.. . . . ~ .
10'7~8f~8 It is an aclvantage ot the present inventlon that the crimp may be imparted at a low temperature. In a system using poLystyrene as in the past, because polystyrene is hard and brittle, it has not been possible to produce enough crimp at a low temperature, and serious abrasion of the crimper has been experienced. Accordingly, it has been necessary to preheat the fiber and to crimp at a high temperature. Accordingly, e~en if a highly contract-ible fiber is obtained by drawing, it loses its contractibility by reason of the crimping step. However, fibers of the present invention are free from such difficulties.
Upon obtaining a wet, highly con-tractible multi-component fiber, the conditions used in drying the crimped fibers are also important. Hereto-fore, a relatively high drying temperature has been used for heat setting the crimp of the fibers and for the efficiency of drying. High temperatures were necessary to obtain sufficient setting of crimp. However, in a system in which the polymer of this invention is present, the heat setting proper-ties at low temperatures are very good. Accordingly, it is possible to use a low crimp heat setting temperature. When drying is carried out at a high temperature, partial contraction occurs, shrinkage is reduced and the result-ing two-stage contractibility of the fibers is inferior. Accordingly, a temperature as low as possible, such as below 60 C, preferably below 40 C, should be used.
Upon contracting the fiber, its two-stage contractibility is also an important factor. In determining two-stage contraction a fiber placed under a load of S mg/denier is immersed in hot water at 60 C for 1 minute to contract the fiber, and the fiber is then immersed in hot water at 90C
for 3 minutes to contract the fiber further. The ratio of total shrinkage at the end of that time to the initial length of the fiber, to shrinkage obtained when the same fiber is immersed in hot water at 90 C for 4 minutes 9 in one stage, is called the two-stage contraction of the fiber. It is 1~75~
preferable that the shrinkage in two-stage contraction should be at least 60% of the shrinka~re in a single contraction, preferably at least 70%. Two-stage contractibility is especially i~portant when the fiber is contracted as a sheet.
When a sheet is contracted in one stage, creases are formed, the surface becomes lmeven and the commercial value of the product is sharply reduced. In order to carry out uniform contraction, it should occur gradually (stepwise) an~ slowly. To such two-stage contractibility, the polymer of the present invention contributes to contraction at a low temperature at the first s-tage due to its low heat deformation temperature, showing sufficient plast-ici~ation and not obstructing the contraction of any other polymer during the second stage contraction at a high temperature. This gives very good results in two-stage contractibility.
Upon this two-stage contractibility~ the draw ratio, temperature - during crimping and drying temperature and drawing temperature exert a large influence. The two-stage contractibility of the fiber is advantageous only under the aforementioned condit~ons.
For providing a highly contractible multi-component fiber according to the present invention, the combination of a polymer of the vinyl series with a polyester is preferable; the fiber is highly contractible and is unlikely to elongate even after contraction.
` In general, when a fiber is contracted, it tends to elongate cor-responding to the amount of shrinkage, resulting in undergo permanent deforma-tion. The use of such fiber results in processing difficulty and deformation of the product. Upon using a highly contractible fiber, mutually contradict-ory characteristics are required: that the fiber should contract sufficiently and that the fiber should not tend to elongate after contraction. The present invention has resolved this contradiction admirably.
29 By way of summary, the first requirement is to draw the fiber at . ~ .
~75~
a low temperature to increase its shrinkage. ~notller requirement is to draw the fiber at a draw ratio of at least 2.6, preferably at least 3Ø Sti:Ll another requirement is to heat treat the contracted ~iber at a temperature ranging from about 160 C to 220 C. When these three requirements are combin-ed a highly contractible multi-component fiber having good physical proper-ties may be obtained for the first time.
By heat treatment at a temperature not less than about 160 C, the - fiber becomes hard and does not have a -tendency easily to elongate. However, upon carrying out the heat treatment, the fiber should be drawn to adequate extent -- otherwise voluntary elongation of the contracted fiber along with the polyester occurs and the shrinkage of the contracted fiber are diminished by the voluntary elongation of the fiber. When the draw temperature is low, this voluntary elongation tends to occur. In order to repress it, it is necessary to make the draw ratio high.
Heretofore there has been no polymer having excellent solubility and drawability at a low temperature, as in the present invention. merefore, the conditions mentioned above had not been available for use.
Fibers according to the present invention are effective and advan-- tageous when applied to knitted fabrics, woven fabrics and non-woven fabrics~
Because of being drawn to a high extent, the fiber characteristics are excel-lent and the characteristics of the product are greatly improved as compared to conventional products. The component to be removed by dissolution of the ;~ fiber of the present invention is removed as a fiber or fabric.
highly contractible fiber is especially effective for obtaining crepe and non-woven fabrics having compact structures, and these fibers are especially advantageous for products having a nep. The fiber of the present invention exhibits excellent characteristics in carding. In conventional fibers of the polystyrene series, the polystyrene tends to split, the fiber 29 tends to become fibrillated at the time of spinning, neps (lamps) are formed
The following are examples of conventional components to be removed by dissolution:
(A) Examples of components having good spinnability, drawability and flexibility while sacrificing solubility:
Polyamides, polyesters and polyacrylonitriles are excellent in respect of spinnability, but ara difficult to remove by dissolution, as has been observed in United States patents Nos. 3,350,4~8 and 3,382,305 and in French patent No. 1,4~5,835.
In case (A), with respect ~o the solvent, there are problems such as dissolving speed and difficult handling. For example, when dissolving ; polyamide in formic acid, the material of the container and the design of the machine for handling formic acid present industrial problems. Almost no mate-~ials satisfactorily resist corrosion by formic acid except titanium alloys, especially when heating is used for increasing solubility. Especially when removal of formic acid from the product after dissolution, and recovery of formic acid are taken into account, the use of formîc acid on an industrial scale is very troublesome.
In the use of ortho-chlorophenol as a solvent for polyester also, danger of using the solvent is great and its dissolving speed is too slow. In the case of acrylonitrile, there is only a limited selection of ; polymers which can be simultaneously spun with acrylonitrile. Also great difficulty is encountered in its removal by dissolution.
; ~B) Examples of components having good solubility while sacrific- -.,, ~ .
1~'7S8~;~
ing spinnability:
Some ~olymers are inferior in drawability and ~lexibility, such as polystyrene, polystyrene-acrylonitril~ copolymers and polystyrene-methyl methacrylate copoly~ers, as reported in British patent No. 1,263,221 and in United States patent ~lo. 2,930,074.
In case (B), solvent which is low in cost and easy to handle, such as a hydrocarbon of the aromatic series or a hydrocarbon of the chlorine series may be selected as a solvent.
However, when such a polymer is used, especially when such a poly-mer occupies at least 40~ of the surface of the multi-component fiber, the drawability and flexibility of the fiber become very poor. The following explanation will elaborate.
Drawbacks in the use of polymers of polystyrene series:
Polystyrene per se is a very brittle polymer; the elongation of undrawn polystyrene yarn at room temperature is at most 6 - 10~. Because it is brittle, polystyrene alone is very difficult to draw. By using polystyrene as one component of multi-component fiber, the polystyrene is reinforced by other components and becomes somewhat easier to handle. ~lowever, the other components become weaker because of the presence of ~he polystyrene, which is most difficult to dra~. Especially when polystyrene is present over at least 40% of the surface of the multi-componen~ fiber, the fiber becomes most difficult to draw. lYhen the temperature is raised so that the polystyrene can be drawn, the polystyrene becomes tacky and the multi-component fibers stick to one another.
In a multi-component fiber, when polystyrene occupies ~t least ~0%
of the fiber surface, it is very difficult to draw the fiber. Polystyrene begins to flow at a temperature of 105 - 115C. As soon as the polystyrene begins to n ow, the multi-component fiber becomes tacky, the fiber fuses on the surface of the heat source Ghot plate~ or the fibers fuse among them-selves. Also, the fiber can be drawn only within a very limited range and ~0~5~1~;8 for a very short p~riod of time. It may be stated~ acco~dingly, that such fibers cannot be dra~n sufficiently, in the industrial sense. Elongation at a lower temperature does not give sufficient r~sults; for example, by drawing with stea~ heat as is ordinarily carried out industrially in staple drawing, the multi-component fiber can be drawn only to 2.0 - 2.5 times its initial length. When drawn more, the polystyrene on the surface whitens, cracks and breaks, and the resulting fiber cannot withstand actual use.
Specifically, since it is impossible sufficiently to draw such a multi-component fiber under normal industrial conditions, this makes it necessary to make a fine denier undrawn yarn, in which case spinning produc-tivity suffers.
Because a complicated spinneret is usually used to obtain a multi-component fiber, it is difficult to effectively increase the number of no~zles on the spinneret. Accordingly, spinning productivity cannot be in-creased which is a fatal drawback with respect to the cost of the fiber as a product.
Further, the physical properties of t~e multi-component fiber product also deteriorate. Because the fiber is not to be drat~ to the desir-ed extent, its elongation is quite high and its Young's modulus is low. The characteristics of the fiber are close to those of undrawn yarn. Such poor drawability and brittleness of polystyrene are particularly troublesome when a highly shrinkable fiber is desired.
In order to obtain a highly contractible fiber, the fiber must be drawn at as low a temperature as possible so as to impart an internal strain to the fiber. When polystyrene is used as the sea component in an island-in-a-sea type composite fiber, such fiber cannot be drawn at as low a temperature as 60 - 70C; at 98~ C or higher drawability begins to some ex-tent, but the resulting fiber does not have a sufficient ~e.g. more than 25%) shrinkage.
And in the case of a contractible fiber, two-stage contractibility is important. When the fiber has been once contracted at a relatively low -- ~t --.: .
1~3'7586~
temperature, and is thereafter contracted at a higher temperature, the fiber should still show contractibility. The most ideal relationship in two-stage contractibility is that the sum of the first stage shrinkage and the second stage shrinkage equals the shrinkage that would be obtained if the fiber were suddenly exposed to the higher temperature.
When the fiber is drawn at a high temperature, it is difficult to obtain a fiber having excellent two-stage contractibility. When polystyrene is used, the temperature at which the drawn yarn begins to contract is re-latively high, due partly to the limiting condition that polystyrene must be drawn at a high temperature. It is difficult to carry out stepwise slow con-traction on the low temperature side, it is not possible to provide a wide range of contracting temperature upon carrying out two-stage contraction, and two-stage contraction is accordingly difficult.
As a means for solving the aforementioned problems of drawability and contractibility when polystyrene is used, it is conceivable to add a plasticizer to the polystyrene. However, no anticipated substantial effect is obtained. Further problems arise when a plasticizer is used, including mixing and affinity of the plasticizer with the polymer, bleed-out and evaporation of the plasticizer.
In generalJ plasticizing of a polymer with a plasticizer requires a large amount of the plasticizer. When a large amount of plasticizer is add-ed to the polymer, it is technically difficult to mix the two uniformly, and even if they are mixed, the plasticizer bleeds out and evaporates through the fiber surface during melt spinning of the polymer. The amount of plasticizer remaining in the polymer fiber is sharply reduced and a substantial plasticiz-ing effect cannot be realized.
Further, when such a large amount of the plasticizer is added to the polymer, the melt viscosity of the polymer becomes drastically lower. In the spinning of multi-component fibers, the maintenance of a balance of melt viscosity values among respective components is very important for the stabili-. . .
- ' . ' ' ' ~
3LO'75~
zation of spinning. Poor balance results in composite ~mevenness and abnor-mal variations of cross-section and bcnding of the fiber just under the spin-neret.
Further, crystallization of other polymers is sometimes caused by the plasticizer. When crystalli~ation proceeds in an undrawn ya~n, ~he fiber becomes difficult to draw. Depending upon the particular plasticizer, such crystallization may even be accelerated.
Also, with reference to a prob~Lem of evaporation of the plasticizer at the time of spinning, the plasticizer tends to evaporate through the sur-face of a yarn having a large surface area and the plasticizer tends to form bubbles, which tend to cause breakage of the yarn.
As mentioned above, improvement of drawability by adding a plas-ticizer can hardly be expected. Accordingly, it is an object of great desir-ability to develop a novel polymer. Such a novel polymer should be easy to draw at a relatively low temperature, and should not fuse within at least a certain range of temperatures within which other components are drawn. In the case of polystyrene, it fuses simultaneously under normal drawing condi-tions. In the case of polystyrene-acrylonitrile copolymers and polystyrene-methyl methacrylate copolymers, they also present the same problems associated with polystyrene and they do not show any improvement of drawability or flex-ibility.
According to the present invention, there is provided a sheet-like . material comprising a bundle of fine fibers of a thermoplastic polymer and a binder and having a maximum deformation ratio of about 12% and a minimum apparent density of 0.21 g/cm3, said fine fibers having a maximum denier of about 0.45.
Another aspect of the invention provides in a method of making a ; sheet-like material which comprises a fiber aggregate comprising multi-com-ponent fibers comprising at least two components (A~ and (B), one component . ,. ., ~
1~75~3~;8 (B) bcing a copol~ner of about 90 to 70% of styrene and about 10 to 30% of an ester selected from acryl:ic acid and methacrylic acid, and the other component (A) being a fiber-forming thermoplastic polymer~ the steps of removing said component (B) from said component (A) whereby each said fiber becomes a bundle of fine fibers having a maximum denier of about 0.45 and consisting of said component (A); shrinking said aggregate at a time other than the time of re-moving said component (B); subjecting said aggregat~ to a substantial heat ~E~ Q~
IG~ treatment at a temperature ranging from 9~/lto 220 C; and impregnating saidaggregate with a binder at a time other than the time of said heat treatment.
Embodiments of the invention and aspects of the prior art are illu-strated by way of example, in the drawings, in which:
Figures 1 (a) and 1 ~b) are cross-sectional views of islands-in-a-sea type composite fibers.
Figure 2 is a view in side section, showing an apparatus used for measuring the elongation of a polymer~
Figure 3 is a chart showing the relationship between draw ratio and shrinkage in boiling water of composite fibers.
Figure 4 is a chart showing the relationship between copolymerisa-tion ratio and drawability (elongation) of a polymer according to the '~
~C~758~
present invention.
Figure 5 is a chart showing the heat stabiLizatiorl of a polymer according to the present invention.
Figure 6 is a view in side elevation showing one e~ample of a liquid-bath drawing apparatus preferably used for drawing a fiber according to the present invention.
Figure 7 is a chart showing the deformation of a product of a fiber according to the present invention, plotted against binder con-tent.
Figure 8 is a chart showing the abrasion resistance (chafe number) of a product made of fibers according to the present invention, plotted again-st binder content.
The present invention relates to a multi-component fiber having excellent drawability at a low temperature, which comprises a specified com-ponent of a copolymer of the vinyl series.
~ rom our knowledge of the serious drawbacks associated with con-ventional polystyrene-acrylonitrile copolymers and polystyrene-methyl metha-crylate copolymers, the possibility of improving the properties of the fiber by copolymerization of ~he polystyrene has heretofore seemed to us to be very remote indeed. Actually, we seriously considered abandoning the possibility of improving the properties by this copolymerization procedure, after studying the results of the following examinations.
(1) Copolymeri~ation of polyvinyl ether and styrene:
Polyvinyl ether has been known as a plasticizer of polystyrene.
Accordingly, it was anticipated that remarkable flexibility would be imparted by copolymerization of the two. Methyl-, ethyl-, and butyl-vinyl ethers ~ere selected in trying copolymeri~ation with styrene. However, the product was a waxy brittle copolymer having inferior performance as compared with the homo- polymer of polystyrene.
29 (2) Copolymeri~ation of acrylic acid ester and styrene:
~075~
Methyl acrylate ~ncl ethyl acrylate were selected in carrying out the e~amina-tion. l~hen each copolymer was simultaneously spun ~ith polyethy-lene terephthalate as a multi-component fiber, a gcl was formed which blocked the spinneret. When the spinneret paclc was dismantled, the gel was found to be insoluble in solvents; the spinneret was blocked and became useless. When butyl acrylate was used as the acrylic acid ester, the same result was ob-tained.
Accordingly, polymers of the vinyl series present serious problems in terms of performance and spinning, and cannot be used. It appeared that our study was deadlocked at this point. However, we have now discovered a surprising fact.
We have discovered that, among the polymers of the vinyl series, a particular polymer is thermally stable, surprisingly yielding a copolymer which does not gel, and which possesses excellent drawability at a low temperature, and which combines admirably with other polymers simultaneously spun.
Although gelation occurs especially often with combinations of polyesters with esters of the vinyl series, such gelatin can be avoided when the vinyl polymer is the very particular polymer according to this invention, which is a copolymer of the vinyl series having an HDT (heat deformation temyerature measured by British standard method No. 2782~ of 75 - ~0 C, an elongation in hot water at 70 C of at least 100 % and a shrinkage in hot water at 85C of at least 15 %.
The most simple example of such polymer is a styrene-acrylic acid ester copolymer of the vinyl series containing about 10 - 30 % by weight of acrylic acid ester unit and about 90 - 70 % by weight of the styrene unit.
In referring to elongation in hot water a~ 70 C, this is measured in the following manner:
29 A cylinder having an internal diameter of 10 mm is precisely heated _9_ 1[31'7~8~3 to 220 C. At tlle lower end of this cyl-inder an orifice having a length of 8 mm and a diameter of I mm is provided. The polymer is placed inside the cylinder and allowed to stand there for two minutes. The polymer is then extruded through the orifice from above the cylinder while the load is adj~s-ted to provide a flow rate of 0.3 g/min. Ten undrawn yarns, produced in this manner, are bundled and subjected to a tensile test based on ordinary strain-stress measuring techniques, using the apparatus shown in Figure 2. Elonga-tion at break is the elongation of the polymer at a water temperature of 70C, using a sample length of 1 cm and a tensile speed of 1 cm/min.
In accordance with the method of measuring shrinkage, forty ~mdrawn yarns extruded as just referred to are bundled. A fiber bundle 20 cm long is immersed in hot water at aic, taken out after 3 minutes and the length of the fiber bundle is measured and reported as L centimeters. The shrinkage is Shrinkage = 20 - L x 100 (%) According to this invention, the HDT of the copolymer according to this invention must be not more than about 75 C, which is necessàry, upon imparting crimp to a multi-component fiber comprising the copolymer, for preventing said fiber from cracking or splitting and for increasing the flexibility of the fiber as well. ~owever, when the HDT is too low, various - difficulties are brought about. ~he fibers become apt to fuse and stick to one another at drawing. ~hen subjected only to slight friction, or to heat generated in carding, the fiber fuses. Accordingly, it is necessary that the HDT be not less than about 40 C.
Elongation in hot water at 70 C is important. The elongation re-flects the degree of polymerization and linearity of the molecule, becoming a criterion of spinnability and of drawability. In order that a multi-component fiber may show good drawability at a low temperature~ it is neces-29 sary that the value of this elongation should be at least about 100 %.
.. . .
~0'751~ B
~ s regards contractibility, it is necessary that the shrinkage beat least about 15 % at 85 C. The degree of contractibility becomes especially important ~hen a h-ighly contractible fiber is to be obtained. Contracting stress is not always necessary. It is sufficient for the component to properly follow and not to obstruct the contraction of the other component.
It is important to provide a particular polymer which is a copolymer consisting mainly of a reaction product of styrene and an ester of the vinyl series, containing 90 - 60 % as a whole of the styrene unit, and 10 - 30%, preferably 15 - 20% of the vinyl type ester unit. The foregoing are main components; if desired anoth~r vinyl monomer may be further copolymeri~ed if necessary for adjusting the viscosity and improving the heat stability of the product.
Esters of the vinyl series include the acrylate esters and metha-crylate esters, when such an ester is simultaneously spun with a polyester, an ester having 6 - 20 carbon atoms preferably 8 - 18 is preferred. Such an ester, being a reaction product of acrylic acid or methacrylic acid to form an ester with an alcohol having a boiling point of at least 150 C (at 760 mm Hg~, which is effective to prevent gelation.
In this invention, the configuration of such alcohol is also im-portant. Such alcohol has a side chain which is preferable from the view--- point of the drawability. However, when the heat resistance of the polymer is critical, an alcohol which has a straight chain is preferable. The selec-tion of a particular straight-chain or side-chain alcohol should be judged according to the situation at that time; sometimes it is preferred to use them in admixture.
As specific examples of esters of the vinyl series which may be used in the present invention, they may be classified into those having an . . .
ester group which contains less than 6 carbon atoms such as methyl acrylate, 29 butyl acrylate, methyl methacrylate and butyl methacrylate and those whose `" ' ~07~
ester group contains at :Least 6 carbon atoms such as hexyl acrylate, n-octyl acrylate, 2-ethyl hexyl acrylate, tri-methyl heptyl acrylate, stearyl acrylate, lauryl acrylate, hexyl methacrylate, n-octyl methacrylate, 2-ethylhexyl metha-crylate, tri-methylheptyl methacrylate, stearyl methacrylate and lauryl methacrylate.
When the ester group contains less than 6 carbon atoms, gelation occurs upon simultaneous spinning with polyester, and spinning becomes impos-sible. Accordingly, such esters are limited to combinations with polymers other than polyester.
When the ester group contains at least 6 carbon atoms, gelation does not occur, and spinning may be carried out favourably. However, when the number of carbon atoms is too great, drawability becomes inferior. Ac-cordingly, it is preferred that the number of carbon atoms be not more than about 20, preferably not more than about 18.
Especially preferably examples of esters of the vinyl series in the present invention are those which contain alkyl group at least 6 carbon atoms, having a side chain, namely, 2-ethyl-hexyl acrylate and 3,5,5-tri-~; methylheptyl acrylate.
Regarding the copolymerization ratio, 10 - 30%, preferably 15-25% of such ester of the vinyl series is preferred. Different from thesituation in which a plasticizer is added, the effect begins to appear at about 10% and comes out sharply at about 15%. However, more than 30% is not preferred because there is too much plasticization, spinning becomes difficult due to fusion of chips or pellets ard there is too great a difference of melt viscosity values between the composite components at the time of melting.
Fusion of fiber and fiber characteristics at the time of drawing are greatly influenced by slight fluctuations of temperature.
The polymer according to this invention is ready to reac~ and poly-29 merizable under conditions of ordinary polymerization of styrene, or somewhat-12--1~75~
modified conditions. IndustriaLly, radica-l polymcrization is preferable.
~ppropriate polymerization initiators incLude benzoyl peroxide and ter-butyl-per-benzoic acid.
However, drawability is somewhat influenced by the added amount of polymerization initiator. When the added amount is too great, the degree of polymerization does not increase, which is not desirable. When the added amo~mt is too small, the polymerization rate is too slow. Characteristically, it is preferred to set up a criterion such that the intrinsic viscosity measured at 30 C in toluene is about 0.6 - 1.2.
The present invention relates to a multi-component fiber in which the polymer just described is one component. The component of the present invention is effective when it is intended to be removed by dissolution, especially when it occupies at least 40% of the fiber surface in the multi-~ component fiber.
;~ In general, when the fiber surface occupying ratio of a component that fuses at the time of drawing is as high as 40% or more, difficulties at the time of dra~ing, such as sticking of the fibers, and deposition of residues on the heater plate at the time of drawing, become very serious.
~owever, when the polymer of the present invention is used~ such troubles do not occur. mis is an outstanding feature of this invention.
me most preferable configuration of a fiber in the combination of the present invention is a fiber whose surface is completely surrounded by a component to be removed by dissolution. Specifically, these configurations ` include the islands-in-a-sea type composite fibers, sheath-core type com-; posite fibers, composite fibers with irregular shaped cores, and polymer-blend type fibers at least 60 percent of the surface of which is surrounded by a component which is to be removed by dissolution.
Some of the important characteristics of the present invention 29 consist in imparting softness and flexib ity to a fiber using a low soften-' ~:
: , ~ .
1~'7S~
ing point copol~ncr; it has been discovcred that even if such Low softerl-ing point compo--ent is used, the fiber can be clra~m WittlOUt fusion. SpecificaL-ly, a polymer in an l~oriented mo~Lecular state, such as a pellet, tends to fuse easily. Ho~ever, a polymer in the dra~n and oriented state is l~likely to fuse. The discovery that fusion in an amorphous polymer is prevented by o}ientation of large chain-molecules is a characteristic feature of the present invention.
~ s other polymers used in combination with the polymer of -the present invention, in such fiber, mention should be made of polyamides and copolyamides such as poly- -capramide and polyhexamethylene adipamide; poly-esters and copolyesters such as polyethylene terephthalate, polybutylene tere-phthalate, polyoxy benzoate, polyethylene terephthalate-polybutylene-iso-phthalate copolymers, and polyolefins such as polyethylene and polypropylene.
0f these polymers3 polyesters, having a softening point, as defined hereinbelow, of not more than 250 C are especially preferable in regard to preferred balance of drawability with the polymer of the present invention The softening point referred to herein is defined as a temperature measured by a differential scanning calorimeter DSC-II manufactured by Perkin-Elmer Co. at a rate of temperature increase of lo C/min, a sensitivity of 5 cal/sec and a sample amount of 10 mg corresponding to the starting point of a fiber melting peak. Said starting point is an intersecting point of the base line of said peak and a tangent drawn at a point at the intermediate height of said peak.
Such polyesters include polyethylene terephthalate-polyethylene isophthalate copolymers, polyethylene terephthalate-adipic acid copolymers, and copolymers of polyethylene glycol, polyethylene terephthalate and poly-ethylene isophthalate.
The weight ration of the polymer of the present invention to the 29 other polymer in the spinning of a multi-component is preferably within the . . .
~ ' ' '' ~ ' ~75~8 range of about 65/35 - 35/65.
Upon spinning a multi-component fiber using a copolymerization component according to the present invention, the heat career of the copoly-mer prior to spinning becomes very importcmt; it has a remarkable influence upon the thermal decomposition of the copolymer at the time of spinning.
Especially when the copolymer is exposed to a hi~l temperature of at least 240 C before spinning (when the copolymer is pelletized at 240 C), the thermal decomposition of the copolymer at the time of spinning becomes re-markable. Accordingly, it is necessary not to overheat the copolymer prior to spinning, the polymer is likely to fuse and block at a supplying zone of extruding machine. So it is useful to strengthen the cooling of a supplying zone to prevent blocking at the supply opening due to fusion of a bead polymer.
- In order to prevent such difficulties, it is possible to extrude the polymer, after completion of polymerization, directly into pellets by block polymeriza-tion.
In order to prevent thermal decomposition of the polymer, it is also effective to add a thermal decomposition inhibitor. Stabilizers of the phenol series are excellent, for example, 2,6-di-ter-butyl~rdimethyl amino p-cresol; 2,2'-methylene-bis-(4-methyl-6-tert-butylphenol~; 1,3,5-trimethyl-20 2,4,6-tris (3,5-di-ter-butyl-4-hydroxybenzyl) benzene, 4,4'-thiobis-(6-ter-butyl-3-methylphenol) and 2,2'-dihydroxy-3,3'-di (~C-methylcyclohexyl)-5,5'-dimethyl-diphenyl methane.
In the spinning of a multi-component fiber using a component of the present invention, the temperature of the atmosphere below the spinneret is very important. me drawability of the resulting fiber is greatly in-fluenced by atmospheric conditions up to 30 cm below the spinneret. A temp-erature range of about 130 - 320 C is recommended at a point 10 cm directly below the spinneret. ~specially, upon simultaneously spinning a very low 29 softening point polymer with a high softening point polymer of a composite 51~36~3 fiber, by making such ambient temperature higher than the so~tening point ofthe low softening point polymer, but lower than the softening point of the high softening point polymer, it is possible to promote molecular orientation of the high softening point polymer only, and to a-void molecular orientation of the low softening point polymer. When the drawability of the low soften-ing point polymer is poor as compared to that of the high softening point polymer, as in the present invention, such method is very effective for im-parting drawability to a multi-component fiber.
It is preferable not to cool the fiber of the present invention suddenly. Accordingly, upon winding the fiber, it is preferable to control the temperature of the fiber to a value somewhat higher, and to heat the fiber as occasion demands, and to wind the fiber at about 20 - 60 C.
The influence exerted upon the fibers by oiling agents ("spin finishes") is also important. The copolymer of the present invention cracks ~` under the influence of certain kinds of oiling agents. It is recommended to avoid oiling agents containing lower alcohols. Selection of an oiling agent used for the fibers of the present invention is carried out using a tensile tester shown in Figure 2, by pulling an ~mdrawn yarn at 50 C in a 3% solu-tion of the oiling agent to be checked. Oiling agents which in 3 % solution cause fluctuation of the tensile strength of the undrawn yarn, when elongated by 100%, of more than 0.2 g/denier are not preferred.
Upon spinning, the polymer is usually supplied as pellets to the spinning machine~ Upon supplying such pellets it is necessary to control them sufficiently so that their temperature does not become too high. Other-wise the pellet fuses, becomes a block and becomes impossible to supply.
Heat from a melting zone is transmit~ed to a polymer supply zone and the polymer is heated more than expected. In order to prevent such difficulty, it is effective to cool the pellet from without to keep the pellet at a 29 temperature lower than the fusion temperature until the polymer reaches the .. . . .. ..
~0'758G~3 melting zone.
Polymers of the present invention may be melted at ahout 220 -290 C. However, it is preferable to melt the polymer at lower temperature from the viewpoint of melt viscosity and for preventing thermal decomposition.
A fiber according to the present invention may be taken up without any problems under ordinary conditions. However, the advantageous character-istics of the styrene-vinyl ester fiber of the present invention are best developed when the sp~m fiber is taken up at a rate of at least about 1500 ` m/min. At this time, it is effective to keep the spinning temperature low.
Inside the spinneret, the styrene-vinyl ester polymer of the present invention is sufficiently fluid, having a function like a lubricant and smoothing the discharge of the other fiber-forming component. Because of this advantageous characteristic, it is possible to operate effectively with a relatively low spinning temperature.
Such means is especially effective in the case of a fiber having a plurality of independent islands in one fiber, such as islands-in-a-sea type composite fiber. By taking up the fiber at a high speed, the orientation of the fiber is promoted and the subsequent drawing step can be dramatically shortened. When one component is dispersed thinly in another component, the orientation of that component at the time of take-up proceeds more rapidly than when that component is thickly dispersed. This inclination is especially remarkable when a polymer having a low softening point and low elongation at room temperature is used as in the present invention.
Such a fiber is especially effective when it is taken up in the ~ .
form of a sheet, using ~n air jet.
Upon drawing the fiber, it is desirable to establish the drawing temperature at about 50 - 100 C. ~he significance of the fact that the fiber can be drawn at a temperature not higher than 100 C is very great, 29 because drawing by steam heating at atmospheric pressure, as usually carried ~............... '' ~ ':
,:. : ' 5;3~
out in ordinary staple clrawing, becollles practical. Also, drawlng in hot water is practical and effective.
~ s in the past, a yarn using polystyrene cannot be drawn satisfac-torily at a high draw ratio (more than 2.5 times) at a temperature not more than 100C. Nhen the yarn is dral~ at a low temperature the polystyrene cracks, the fiber surface becomes rough and fibrillation and breakage of the fiber tend to occur. In order sufficiently to draw polystyrene, it is neces-sary to heat the same at a temperature above 100 C, actually at least 120C.
In order to do this a hot plate or hot roll is used. However, in the case of polystyrene yarns, when they become easy to draw, they also become easy to fuse and adhere to each othær.
~ hen polystyrene is drawn in such state, if fuses and sticks to the hot plate or fuses by reason of friction between the hot plate and the ~olymer. Accordingly, it is very difficult sufficiently to draw polystyrene on an industrial scale.
In accordance with the present invention, the fiber can be drawn at a temperature not higher than 100 C and, during the drawing step, the - fiber does not fuse and does not stick to the heater.
Drawing according to the present invention may be carried out by steam heating at atmospheric pressure as carried out in usual staple drawing.
However, a preferable method of drawing is based upon the use of a hot liquid as the heating medium. Hot water is ordinarily used. The fiber is passed through hot water kept at a constant temperature, and drawn. However, a still more preferable method of drawing is the method shown in Figure 6. In Figure 6, 11 is a fiber to be drawn and 12 is a liquid kept at a constant temperature and supplied from a tank 14 by a pump 13. This liquid overflows from a draw box 15 and refluxes to 14. 16 is the swollen liquid surface of the over-flowing liquid on or in which the fiber passes to be drawn.
29 Drawing in an overflowing liquid is especially preferable in that ~'~ - ' ~` ' .
:
~:
iO75~
the fiber does rlot contact any solid substance in the draw zone. Abrasion of the fiber surface is prevented and fibcr damage is minimized~
Hot water suffices as the liquid used. }lowever, addi-tion of fiber treating agents such as oiling agents, ("spin finish") and antistatic agents to the hot water gives especially good results because such agents adhere uniformly to the fiber when applied in this manner during the drawing stage.
In the present invention the fiber may be drawn on a hot plate as well. In the present invention for~ation of deposits upon the hot plate, as seen in the case of drawing polystyrene, is not brought about.
Upon carrying out drawing according to the present invention, drawability is sometimes improved remarkably by carrying out preliminary heating before drawing. 30 - 80 C is appropriate as the preliminary heating - temperature. At the time of carrying out preliminary heating, the fiber may either be relaxed or under tension.
The present invention is especially effective in making a multi-component fiber, especially a highly contractible multi-component fiber con-taining polyester. The highly contractible fiber referred to herein is a . .
fiber showing shrinkage of at least 15% to the initial length of 20 cm when it is immersed in hot water at 90 C with a load of 5 mg/denier at one end of the sample.
In order to make a highly contractible fiber containing polyester, two methods are available, as follows:
(A) Lo~ering the draw ratio and utili~ing a 30ne in which the mole-cular orientation is extremely poor.
This is a very effectiYe method when only shrinkage is considered and the practical characteristics of tensile strerlgth and elongation are ignored. However, a fi~er obtained by this method is essentially a so-called undrawn yarn. Upon actually using such a fiber, it undesirably elongates 29 even under small tension, and its tensile strength is low. When such a 1~75~
fiber is further contractcd, its physicaL properties become even worse.
~ ccordingly, a fiber having much better characteristics of molecular orientation is required. For obtaining such fiber the method is:
(B) Carrying out drawing at a high draw ratio at a low temperature.
Drawing at a low temperature causes strain in the fiber. It is necessary to carry out drawing at a temperature not above 100 C as usually carried out industrially. In conventiona:L polystyrene-polyester systems, it has not been possible to draw at a rat:io of at least 2.5 times under this drawing condition.
In accordance with the present invention, the fiber is drawn suf-ficiently at such a low temperature, and a highly contractible fiber having excellent molecular orientation and excellent tensile strength and elongation is obtained.
The draw temperature and draw ratio are important. It is preferable that the draw temperature be about 50 - 100 C, preferably about 60 - 85C and that the draw ratio be about 2.6 - 4.80, preferably 3.0 - 4.3. At a tempera-ture below 50 C, drawing of polyester becomes impossible. At a temperature above 100 C, the internal strain necessary for contraction is not formed in the fiber. It is necessary that the draw ratio be at least about 2.6. For sufficient tensile strength and elongation, it is necessary to use a higher draw ratio. The higher the draw ratio, the more preferable. However, from the industrial viewpoint, an appropriate upper limit is about 4.8.
Crimping conditions are also important. In the crimping operation, the crimper is heated by the friction of the fibers. Partial contraction of the fiber is caused by this heat, reducing the shrinkage of the fiber.
Accordin~ly, it is necessary to repress the heat as much as possible . Speci-fically, it is necessary to keep the temperature of the crimper below 70 C, preferably below 50 C. It is desirable to cool the crimper by an oiling 29 agent applied to the fiber.
, :, . . .
.. . . . ~ .
10'7~8f~8 It is an aclvantage ot the present inventlon that the crimp may be imparted at a low temperature. In a system using poLystyrene as in the past, because polystyrene is hard and brittle, it has not been possible to produce enough crimp at a low temperature, and serious abrasion of the crimper has been experienced. Accordingly, it has been necessary to preheat the fiber and to crimp at a high temperature. Accordingly, e~en if a highly contract-ible fiber is obtained by drawing, it loses its contractibility by reason of the crimping step. However, fibers of the present invention are free from such difficulties.
Upon obtaining a wet, highly con-tractible multi-component fiber, the conditions used in drying the crimped fibers are also important. Hereto-fore, a relatively high drying temperature has been used for heat setting the crimp of the fibers and for the efficiency of drying. High temperatures were necessary to obtain sufficient setting of crimp. However, in a system in which the polymer of this invention is present, the heat setting proper-ties at low temperatures are very good. Accordingly, it is possible to use a low crimp heat setting temperature. When drying is carried out at a high temperature, partial contraction occurs, shrinkage is reduced and the result-ing two-stage contractibility of the fibers is inferior. Accordingly, a temperature as low as possible, such as below 60 C, preferably below 40 C, should be used.
Upon contracting the fiber, its two-stage contractibility is also an important factor. In determining two-stage contraction a fiber placed under a load of S mg/denier is immersed in hot water at 60 C for 1 minute to contract the fiber, and the fiber is then immersed in hot water at 90C
for 3 minutes to contract the fiber further. The ratio of total shrinkage at the end of that time to the initial length of the fiber, to shrinkage obtained when the same fiber is immersed in hot water at 90 C for 4 minutes 9 in one stage, is called the two-stage contraction of the fiber. It is 1~75~
preferable that the shrinkage in two-stage contraction should be at least 60% of the shrinka~re in a single contraction, preferably at least 70%. Two-stage contractibility is especially i~portant when the fiber is contracted as a sheet.
When a sheet is contracted in one stage, creases are formed, the surface becomes lmeven and the commercial value of the product is sharply reduced. In order to carry out uniform contraction, it should occur gradually (stepwise) an~ slowly. To such two-stage contractibility, the polymer of the present invention contributes to contraction at a low temperature at the first s-tage due to its low heat deformation temperature, showing sufficient plast-ici~ation and not obstructing the contraction of any other polymer during the second stage contraction at a high temperature. This gives very good results in two-stage contractibility.
Upon this two-stage contractibility~ the draw ratio, temperature - during crimping and drying temperature and drawing temperature exert a large influence. The two-stage contractibility of the fiber is advantageous only under the aforementioned condit~ons.
For providing a highly contractible multi-component fiber according to the present invention, the combination of a polymer of the vinyl series with a polyester is preferable; the fiber is highly contractible and is unlikely to elongate even after contraction.
` In general, when a fiber is contracted, it tends to elongate cor-responding to the amount of shrinkage, resulting in undergo permanent deforma-tion. The use of such fiber results in processing difficulty and deformation of the product. Upon using a highly contractible fiber, mutually contradict-ory characteristics are required: that the fiber should contract sufficiently and that the fiber should not tend to elongate after contraction. The present invention has resolved this contradiction admirably.
29 By way of summary, the first requirement is to draw the fiber at . ~ .
~75~
a low temperature to increase its shrinkage. ~notller requirement is to draw the fiber at a draw ratio of at least 2.6, preferably at least 3Ø Sti:Ll another requirement is to heat treat the contracted ~iber at a temperature ranging from about 160 C to 220 C. When these three requirements are combin-ed a highly contractible multi-component fiber having good physical proper-ties may be obtained for the first time.
By heat treatment at a temperature not less than about 160 C, the - fiber becomes hard and does not have a -tendency easily to elongate. However, upon carrying out the heat treatment, the fiber should be drawn to adequate extent -- otherwise voluntary elongation of the contracted fiber along with the polyester occurs and the shrinkage of the contracted fiber are diminished by the voluntary elongation of the fiber. When the draw temperature is low, this voluntary elongation tends to occur. In order to repress it, it is necessary to make the draw ratio high.
Heretofore there has been no polymer having excellent solubility and drawability at a low temperature, as in the present invention. merefore, the conditions mentioned above had not been available for use.
Fibers according to the present invention are effective and advan-- tageous when applied to knitted fabrics, woven fabrics and non-woven fabrics~
Because of being drawn to a high extent, the fiber characteristics are excel-lent and the characteristics of the product are greatly improved as compared to conventional products. The component to be removed by dissolution of the ;~ fiber of the present invention is removed as a fiber or fabric.
highly contractible fiber is especially effective for obtaining crepe and non-woven fabrics having compact structures, and these fibers are especially advantageous for products having a nep. The fiber of the present invention exhibits excellent characteristics in carding. In conventional fibers of the polystyrene series, the polystyrene tends to split, the fiber 29 tends to become fibrillated at the time of spinning, neps (lamps) are formed
7~
and the fiber co:ils aroulld the roll of the carcling machine frequently causingtrouble. ~lowever, the fiber of the present invention is remarkably free from such trouble. ~s a spun yarn it is excellent, and the product has only very little fluff (the hairs of the surface of the spun yarn).
~ Irther~ fibers of the present invention may be applied most advan-tageously to the manufacture of synthetic leather-like sheet materials. When a multi-component fiber using polystyrene has been used for making such sheet materials, as in the past, carding has been poor and fiber intertwinement upon needle punching has been poor because the polystyrene tends to split, lacks flexibility and has only a limited capability to produce fiber intertwinement.
Also, the fiber has not been sufficiently drawn, and the product has had a tendency to elongate and to undergo deformation. When the nap was formed on the surface of such fibers, the nap has tended to become entangled and to be lacking in gloss.
Such leather-like material has been found also to be lacking in ; the excellent hand, volume, compact nap and abrasion resistance possessed by natural leather. In order to obtain these characteristics, a high-density intertwined aggregation of fibers is required and the fibers constituting such intertwined aggregation is required to be made of a material having considerable resistance to elongation.
For effecting compact fiber intertwinement, needle punching should be carried out to the maximum extent. However, according to this method, when punching is carried out beyond a certain limit, breakage of the fibers is brought about and the density of the intertwined aggregation of fibers lowers - as well as the tensile strength of such aggregation.
It is not sufficient to increase the density of the aggregation by needle punching and a satisfactory result is not obtained by so doing.
~ nother method is contraction, in which a needle punched felt is 29 caused to contract by heat or chemicals. The fiber intertwinement per unit : . - , ., ,~ . . .
.: .
1(~'75~3~8 volume increases aecord-ing to the contracted volume of the aggreKation.
Accordingly, it is possible to sharply increase the density of the inter-t~ned aggregation of fibers by increasing the volume shrinkage. This in many cases is the most effective means for increasing the amount of fibers per unit volume, and to provide optimum fiber intertwinement.
However, the main drawback of such a method is that the contracted fiber tends to elongate, and that the product tends to elongate and also to become deformed. Upon forming nap, it is necessary to be able to form nap easily, in such a way that the formed nap is unlikely ~co intertwine and is easy to color. A fiber which is capable of solving all of these problems is required, and is provided according to this invention.
Fiber elongation after contraction is diminished and minimized to the extent of practical use by making a felt using a highly contractible multi-component fiber drawn at a high draw ratio (not less than 2.6, prefer-ably not less than 3.0) at a low temperature, then causing the felt to con-tract to form a high-density felt, removing one component of said fibers while in the form of a high-density felt~ and thereafter subjecting the felt to heat treatment at a cemperature ranging from about 160 C to 220 C before or after applying a binder to the fibers of the high-density felt.
In this case, it is preferable that the component to be removed should occupy at least about 60% of the surface of the multi-component fiber used. Otherwise, when the felt is caused to contract to become a high-density felt, the fibers are not likely to be able to move freely or to slide rela-tive to each other inside the felt, and the "hand" of the felt product be-comes remarkably hard. By removing one component occupying a substantial volume around the surface of the fibers in this condition, large voids are formed about and among the remaining fibers, and accordingly movability (slideability) among the remaining fibers increases and the felt product 29 becomes remarkably soft.
1~'75~
~ furttler prcterable multi-component fiber is one that for~s a b~mdle of superfine fibers or the eq~ivalent after removin~ one component. By conversion to a bundle of superfine tïbers, the -fibers per se are further softened, and still more softening oE the felt product may be achieved. When the nap is formed on the surface of the fiber, the nap becomes a soft and compact one, which is highly preferable. Such multi-component fibers include islands-in-a-sea type composite fibers, composite fibers having irregular shaped cores, and certain polymer-blend types of fibers.
Multi-component fibers, one component of which is to be removed and which occupies at least about 60% of the fiber surface are drawn at a low temperature. It is preferred that the draw temperature be not more than about 100 C, preferably abQut ~5 - 60 C, because the temperature must be low in ` order to increase the shrinkage. A shrinkage of at least about 15%, prefer-ably at least about 20%~ is necessary. In order to obtain a high-density felt necessary in the present invention by causing a needle punched felt to cont-ract, shrinkage to this extent is necessary. The shrinkage may be varied within a broad range by varying the draw temperature.
m e required extent of the draw ratio ~aries according to the desired shrinkage of the fibers. In the case the degree of contraction is high, the draw ratio must be large. The following equation must be satisfied:
Draw ratio )2.5 ~ 0.01 x (shrinkage of the fiber [%]) Using such fibers, a felt is formed. The fibers of the present invention may be well carded and may be made into excellent felt by needle punching because the fibers are soft and not likely to split. For making the felt compact a mere contracting means is insufficient. A good end product may not be obtained from a felt which is not characterized by intimate inter-twinement of the fibers. Because the apparent density of the felt decreases upon removal of one component in a subsequent step, it is necessary to 29 increase the apparent density of the felt by needle punching to at least : . .
: ' :
~753~3 about O.l2 g/cm , preferably about O.L~ - 0.25 g/cm3.
The resulting felt is caused to contrclct by heat or by chemicals.
The contraction should be carried out so that the shrinkage per unit area of the felt becomes at least about 27% and the density of the felt becomes at least about 0.2~ g/cm . Contraction may be carried out in one stage, but it is highly desirable to vary the temperature and carry out the contraction procedure stepwise. This prevents creases from forming at the time of con-traction, and produces an especially good, smooth felt. In this case, two-stage contractibility is required of the fiber.
10In order to prevent operating difficulties during the removal of one component before or after contraction, it is preferable to carry out a - sizing operation. Water-soluble sizing agents such as, for example, poly-vinyl alcohol and carboxy methyl cellulose may be used. However, when the density of the felt after contraction is at least about 0.4 g/cm , the operational difficulties during the step of removing one component may be avoided, even if such sizing is not carried out.
One component is removed from the contracted felt~ this may be done easily by immersing the felt in a solvent. After removing one component, the felt is heat treated. The heat treatment is carried out by using heated air or a hot roll. It is preferred to carry out the heat treatment at a temperature ranging from about 160 C to 220 C for about 1 - 10 minutes. A
few seconds suffice as the heat treating time for each fiber per se. However, in the case of a fiber aggregate such as a felt, heat transmission is slow and additional time is necessary to conduct the heat to the interior of the felt. However, because deterioration of the fiber is caused when too much time is allowed, or when the temperature is too high, it is necessary to limit the time and temperature. When a sizing agent is used, it is considered safe to limit the temperature to not more than about 190 C, because the sizing 29 agent becomes insoluble at a higher temperature.
1~375B~;~
A binder is imparted to the fiber before or a-fter such heat trea~-ment. .~ binder o~ the polyurethane series is preferable. When the fibers are to be dyed later, a binder which is capable of withstanding dyeing is required. Preferable binders in this case include polyurethane of the poly-ester series and a part of polyurethane of the polyether series. Specifically, polytetrahydrofuran, polypropylene glycol and polycaprolactone are included.
However, when dyeing is carried out under mild conditions or is not carried out at all, ordinary polyurethane may be used.
Upon applying the binder, it is used as a solution or emulsion.
Solidification of the binder may be carried out either by the wet system or by the dry system. In the dry system, adhesion between the binder and the fiber is quite stron~ as compared to the wet system. Thus, it is preferable to make the amount of the binder somewhat smaller as compared with the case of the wet system. ~hen using a solution~ wet coagulation is preferable from the viewpoint of the "hand" or feel of the end product. When using an emulsion, it is preferred to heat treat the fiber at the s~me tlme, by anneal-ing the emulsion polymer.
Just as in the heat treatment, the amount of the binder incorporated into the felt is very important for decrease of elongation, abrasion resis-tance and hand of the end product. In order to obtain an erld product having a good hand, it is preferred to decrease the amount of binder added. However, when said amount is deereased, the elongation resistance and abrasion resis-tance of the end product become remarkably poor. In order to satisfy all of these characteristics, it is preferred to limit the apparent density of the fiber to about 0.08 - 0.35 g/cm in the end product, the apparent density of the fiber containing the binder to about 0.17 - 0.52 g/cm , preferably 0.20 - 0.40 g/cm , and more preferably, to limit the amount of binder to about 20 - 60%, preferably about 26 - 50%, based on the weight of the fiber.
29 The resulting product is usable per se. However, it is highly s 5t3~3 desirable to but`t` the surface o~ the product to -f`orm a nap. The nap according to the present invention is soft, tends to ~fo~l attractive and realistic finger marks when it is smoothed down by a finger working in different direc-tions, ~ld is lustrous and per~anently entangled. A fiber whose denier is not more than about 0.45 is especially preferable.
The product of the present invention has high quality, improved compactness, and excellent hand, volume, abrasion resistance, elongation resistance and entQnglement of nap.
- In order to practice the present invention very effectively, it is preferable to utili~e a polymer of the polyester series, because by so doing, a highly contractible fiber tends to be produced, and the effect of heat treatment after contraction is remarkable. Of the polymers of the polyester series, a copolymer is especially preferable which is obtained by copolymeriz-ing isophthalic acid or adipic acid in an amount of about 4.5 - 20% based upon the weight of the polyester. When such a polymer is used, not only may the contractibility further be raised, but problems in dyeing may be solved in the same way.
When the nap of a superfine fiber is formed on the felt surface in accordance with the present invention, dyeing of the fibers tends to be-come difficult. That is to say, superfine filaments are dif~icult to colorsufficiently, because of its large curvature to reflect or scatter light to make the color look pale. Accordingly, it is necessary to dye the fiber in a deeper color. However, heretofore, when the concentration of the dyestuff was increased for the purpose of dyeing the fiber in a deeper color, it has not been able to dye the fiber in a deep color. Accordingly, it was con-cluded at one time that it would be impossible to dye such superfine fiber in a deep color. However, as a result of our study conducted after that, it was found that, at the time of dyeing, the dyestuff is mainly absorbed by 29 the binder and not absorbed sufficiently by the fibers. However, after ' - . ' 7~8~3 dyeing, the dyestuf~ falls off ~rom the billder, by washing with water.
AccordingLy, it may be said that however high -the concentration of the dye-stuff may be, excess dyestuff is trapped in the binder and is not sufficiently effective for dyeing the fiber. Raising the concentration of the dyestuff to an extent of more than saturating the adsorbed amount of the dyestuff by the binder means throwing away a large amount of the expensive dyestuff.
We have discovered that such problems may be orercome by using a copolyester containing about 4.5 - 20% of isophthalic acid or adipic acid.
In the simultaneous dyeing of such polymer and binder, the dyestuff increases its affinity for the fiber and part of the dyestuff adheres to the fibers rather than the binder. Accordingly~ it now becomes possible to dye the fibers in a deep color, and the loss of dyestuff becomes very small.
In such dyeing, the dyeing temperature is very important. When the dyeing temperature is raised, the dyestuff tends to prefer to attach itself to the fibers3 but when the dyeing temperature is low, the dyestuff tends to move to the binder side. It is necessary to determine the dyeing temperature by balancing the two factors. Especially, it is preferred to establish the dyeing temperature in the case of such copolymers at about 5 - 25 C lower than the temperature usually adopted for homopolyesters.
Accordingly, when polyethylene terephthalate is selected as the polyester, - its~.ould by dyed at a temperature ranging from about 105 C to 120 C.
The effect of being able to lower the temperature at the time of dyeing is great. Deterioration of elastic binders having poor heat resist-ance may be prevented.
In order to carry out good dyeing, the concentration of the dye-stuff is also important. When a sheet is dyed somewhat more deeply than usual with respect to color, it is recommended to use at least 10% of dye-stuff based on the weight of the sheet.
29 Processing after dyeing is also important. In the case of a sheet - , ,: : -~3'7533f~B
material which is a composite of the binder and the fiber, the adh~sion of the two remarkably influences the hand of` the product. Even after dyeing, the hand andnap quality of the product are remarkably influenced by swelling or contraction of the binder. For instance, treating the sheet after dyeing at a pH of about 7 - 14 and at a temperature of about ~0 - 98C, the hand, volume, softness and dye fastness of the product are remarkabl~ advanced.
The influence of the drying conditions upon the hand of the product is also great. It is better slowly to effect drying at a low temperature and reserve about 0.5 - 2% (based on the ~eight of the product) as the mois-ture content ratio, than suddenly and completely to effect drying at a hightemperature. Also, at the time of drying, the condition of the nap is remarkably influenced. In order to form a soft nap tending to take on realistic finger marks, it is preferred to make the nap into the desired state by brushing or by abrasion when the product is wet, before or at the time of drying, and thereafter to dry the nap.
As mentioned abo~e, according to the present invention, a leather-like sheet material having an apparent density of at least about 0.17 g/cm , preferably about 0.21 - 0.35 g/cm , having excellent hand, volume, dyeability, elon~ation resistance and abrasion resistance is obtained. Especially, when such a sheet material has nap on its surface, the nap becomes compact, tends to be marked with finger marks, and the fibers of the nap are not likely to ` become entangled.
The resistance of the product to elongation may be determined by the following measuring method, and may be expressed as a deformation ratio.
Both ends of a sample (width 2 cm and length 10 cm) are gripped by clamps and pulled by a tensile tester at a tensile speed of 10 cm/min. When the load of the sample becomes 1.5 kg, per perpendicular cross-sectional area, 1 cm of the initial sample, pulling is stopped and the clamps are 29 restored to their original positions. The operation is repeated 5 times.
1~'758f~8 After completion~ the sample is reLeased and aLlowed to stand for 2 hours.Thereafter~ the length of the sample is measured, cmd reported as L (cm).
The deformation ratio is:
Deformation ratio = L 10 :LOO (%) When the deformation ratio is large, the product tends to deform easily and at the -time of using, when the product is used, for example, for clothing, it causes deformation of the clothing. For actual use, it is necessary that this deformation ratio be not more than about 12%, and it should preferably not exceed abowt 8%.
Abrasion resistance of the synthetic leather may be determined as a chafing number, as follows.
On a 90 mm diameter table, a sample of the same shape is fixed by means of a frame. From above onto the entire plane of 90 mm diameter, a brush having 8000 monofilaments of polycaprolactam (diameter 0.3 mm ~, length 20 mm) implanted uniformly is pressed with a load of 8 pounds. This brush is rotated. The rotary axis of the brush and the rotary axis of the table are eccentrically disposed by 15 cm. The table fixed wqth the sample, and the brush itself, are rotated at 62.5 rpm and 58 rpm, respectively in the same direction. The total number of rotations of the brush from the start of rotation until the sample is damaged (wears out and holes are made) is defined as the chafing number. When the chafing num~eris large, abrasion resistance is good.
Susceptibility to entanglement of the nap is measured by a micro-fiber adhering method, as follows.
Both ends of a sample are sewn to make a cylinder having an inner diameter of 4 cm and a length of 13 cm. mis sample is thrown into a 15 cm x 15 cm x 40 cm cuboidal box the interior of which is covered with cork rotat-ing at 30 rpm around an axis in the lengthwise direction, together with 3 g 29 of superfine rayon fiber passing through a 100-mesh sieve. After ro~ating :,'~ ' ' ~75~
the bo~ ~or 10 minutes, the contents are taken out, and droppe(l -t`rom a height of 5 cm onto the floor sllrface twice to eliminate excess fiber dust. There-after, the weight is measured and called W1. Next, after removing thc fiber dust adhering to the surface of the sample completely by using a vacuum absorption apparatus, the weight of the sample is measured. The weight of the sample at this time is called W2. The susceptibi:Lity to entanglement of the nap is determined from -the equation W 1'11 W~
When W is high, it shows that nap tends to become entangled rather readily.
Examples 1 - 8, Controls 1 - 4 These examples and controls show ester interchange reactions and occurrence or otherwise of gelatin caused by such reactions when polyester and vinyl esters group co-exist in the molten state. These examples relate to a composite fiber yarn which is a binary fiber consisting of polyester as one component and a polymer of the vinyl series containing a carboxylic acid ~ aIkyl ester group as the other component in observing stability (whether ; gelation occurs) at the time of melt spinning.
As the polymer of the vinyl series containing a carboxylic acid ;~ 20 alkyl ester group, these examples and controls used a styrene-acrylic acid ester copolymer at a fixed copolymerization ratio (by weight) of 80 parts of styrene and 20 parts of acrylic acid ester. Such systems in which the acrylic acid ester was varied were prepared by block polymerization in am-poules using benzoyl peroxide as an initiator. Each of such polymers was im-mersed in liquid nitrogen and broke into fine pieces and these fine particles and finely cut polyethylene terèphthalate fibers were mixed at a weight ratio of 8.2, the mixture was sealed in a glass tube (ampoule) and heated in a nitrogen atmosphere at 280 C for 4 hours. After cooling, the solid product 29 was taken out and immersed in trichloroe~hylene at a ratio of 4 g of solid .
1(3'7~
per 200 cc of trichloroethylene. The state of dissoLution was observed, to check a gel floatage. The results were as shown in Table 1.
R in Table 1 means the R group of the terminaL -COOR of a carboxylic acid alkyl ester (ROH means an alcohol and -COOR means an ester of that alcohol.
Table 1 ¦ Reference I
Example R Gel Floatage ROH Boiling point _ _ _ Control 1 Ethyl Considerable Ethyl alcohol 78.3 C
(transparent gel) Control 2 Butyl Considerable Butyl alcohol 117.7 C
( transparent _ _ -I
Control 3 Pentyl Slight gel- Pentyl alcohol 137.8 C
_ lin~ occurred _ _ Control 4 3-Pen-tyl Gelling 3-Pentyl alcohol 115.6 C
ocurred _ _ Example 1 Octyl No gelling Octyl alcohol 195 C
Example 2 2-Octyl 2-Octyl alcohol 178 C
Example 3 2-Ethyl- n 2-Ethylhexyl 184.8 C
hexyl _ alcohol ~
Example 4 3,5,5- n 3,5,5_Trimethyl 194 C
Tri- heptyl alcohol methyl heptyl _ ~
Example 5 Nonyl _ Nonyl alcohol 173.3 C
Example 6 Tri- n Trimethyl nonyl 225.2 C
; methyl alcohol nonyl _ _ _ _ _ _ _ Example 7 Cetyl n Cetyl alcohol 344 C
_ . .
Example 8 Stearyl Stearyl alcohol Sufficiently .; , ; NOTE: *at 760 mm Hg ~-29 From the results of Table 1, it may be understood that occurrence ;: i : . ~ . : .
1~7S8~8 or non-occurrence of gelling is influenced by the termina] group ~ of the carboxylic acid ester group. When the boiling points of such a:Lcoho~Ls (ROH) are compared, a boiling point of about 150C can be seen as the boundary between occurrence and non-occurrence of gelling. On the low boiling point side, occurrence of gelling is very noticeable. While on the high boiling point side, occurrence of gelling becomes less, and is eventually not recognizable.
In a system in which a polymer of the vinyl series co-e~ists with a polyester auld the polymer of the vinyl series contains a vinyl es-ter group as in the case of the present invention, it is necessary to select, as said ester, one in which R, when converted into ROH, will have a boiling point of at least 150C.
Examples 9 - 12, Controls 5 - 8 ~` These examples and controls show the stability of polymers of the vinyl series according to the present invention at the time of actual spin-ning, and the drawability at low temperatures of such fibers.
A co-polymer of 2-ethylhexyl acrylate by 20 parts with styrene by 80 parts having an HDT of 60 C, an elongation in hot water at 70 C of 53%
and a shrinkage in hot water at 85 C was used as the sea component of an islands-in-a-sea type composite fiber and polyethylene terephthalate (co-polymeri~ed with 9.9 mol % of isophthalic acid), having an intrinsic viscosity measured in ortho-chlorophenol at 25 C of 0.70 and a softening point of 239 C, was used as the island component of said fiber and spinning was carried out at an islands/sea ratio of 50/50~ with 16 islands present per filament, and using a spinning temperature of 282 C to obtain undrawn filament yarn with 10 denier respecti~ely. me spinning conditions were very stable and bending and instability or vibration of the filaments at the spinneret were not observed. The resulting undrawn yarn was dra~n in a hot bath ~o check 29 its drawability.
~10'75~
Table 2 shows the results o~ this experiment.
Table 2 Drawn isLands-in- Island a-sea composite component~
yarn _ . _ Example Tempera- Maxi- Draw Ten~sile Elonga- Tensile Elonga-ture of mum ratio strength tion strength tion draw draw at bath ratio whhiith-em ng _ 70 C 3.05 2.76 1.93 g/d 19% 2.4 g/d 12.7%
lo ao c 3.32 3.21 2.61 g/d 20% 3-5 g/d 67 %
. _ __ 11 85 C 3.58 3.24 2.85 g/d 28% 3-8 g/d 47 %
9l ~ 4 ~D d ~ 4.01 ~d ~Zl~
NOTE *Whitening is a phenomenon whereby a fiber is devitrified due to the strain of drawing, which is considered to be derived from interphase peeling between the sea component and the island components~ or from - occurrence of micro voids in a sea component which has poor draw-ability. When the fiber whitens, many broken monofilaments are usually mixed.
-VA-~The island component filament remained after the sea component was removed from the drawn islands-in-a-sea type composite yarn by trich-loroethylene.
Table 3 shows examples ~and controls) using ordinary polystryrene instead of using the copolymer according to this invention as the sea com-ponent.
- ~ . . . ' `: :
.: . . - . .
1~'7~ 8 Table 3 Con- Tempera- Maxi- Draw Drawn islands-in- ¦ tsland component trol ture of mum rat-io a-sea composite draw draw at yarn bath ratio which _ _ whit- Tensile Elonga- Tensile Elonga-bnegnang strength tion strength tion __ . .......... . _ C 1.8 1.3 0.9 g/d 14% I.Z g/d 133%
6 80 C 2.1 1.5 1.1 g/d la% 1- 7 g/d 150%
7 85 C 2.78 2.0 1.3 g/d 21% 2.0 g/d ]31%
_ . _ _.. __ a 98 C 3.10 ~.6 1.98 g/d 31% 2.9 g/d 91%
From Tables 2 and 3, it will be understood that the present in-vention is by far superior with reference to drawability. Fibers having high tensile strength and good elongation are obtained according to the present invention.
It is relevant to make a comparison between the elongation in an islands-in-a-sea type composite fiber and the elongation of the island com-ponent after removal of the sea component. In the examples of the present invention, the draw ratio of the composite fiber is sufficiently high to ensure that orientation of the island component proceeds satisfactorily.
On the other hand, in the cases of the comparative examples, the draw ratio cannot be made high enough; it is limited by the fact that poly-styrene has poor drawability. Accordingly, the polyethylene terephthalate, which is the island component, is still almost undrawn, or at best not drawn enough. Accordingly, with reference to the physical properties of island component, the present invention is by far superior.
Example 13_ This example shows a method of effectively utilizing the present 29 invention.
.~ .
1~75~
Polyethylene terephthalate copolymerized with 5 mol percent o-f isophthalic acid was used as the is:Land component of an islands-in-a-sea type composite fiber. The product obtained by copo~ymeri7ing 80 parts of styrene and 20 parts of 2-ethylhexyl acrylate was used as the sea component.
The fiber was sp-m at a ratio of islands/sea of 52/48 and 16 islands/ filament to obtain a 10 denier x 84 filament undrawn yarn. The spinning process was very stable and no traces of gel could be recognized after dismantling khe pack. Using the undrawn yarn, drawing was carried out while varying the drawing conditions. The results are shown in Figure 3.
As will be apparent from Figure 3, the shrinkage was greatly affected by the drawing temperature. In order to make a highly contractible fiber, the fiber had to be drawn at a low temperature, and the object could be achieved easily and effectively by combination of the polymers of the pre-sent invention only.
Control 9 Example 13 was repeated, except using a styrene (80 parts)/ethyl acrylate (20 parts) copolymer as the sea component in spinning.
After spinning for S hours, the pack was dismantled, the spinneret was taken out and cooled. Thereafter, it was in~ersed in trichloroethylene.
Even after 20 hours, the sea component polymer had not dissolved and the spinneret was still blocked with swollen gel.
Example 14 Upon obtaining a sheath-core type composite fiber, polybutylene terephthalate was used as core component and a styrene (90 parts)/stearyl methacrylate (10 parts) copolymer (having an HDT of 53.8 C~ an elongation in hot water at 70 C of 250% and a shrinkage in hot water at 85 C of 58%) was used as the sheath component. They were spun at a ratio of sheath/core of 65/35 to obtain a 12 denier x 24 filament undrawn yarn.
29 This yarn was drawn 3.6 times in a hot bath at 90 C. A trans-, ., ~ .
- :~
10'7~ 8 parent, lllstrous yarn having a good drawability was obtained. After spinning there was no block~ge of the spinneret by gel.
Example 15 30 parts of polyethylene terephthalate copolymerized with 7 mol %
of adipic acid and 70 parts of a terpolymer of 2-ethylhexyl acrYlate (10 parts)/stearyl methacrylate (5 parts)/ styrene (85 parts) (haYing an HDT of 54.7%, an elongation in hot water at 70 C of 149% and a shrinkage in hot water at 85 C of 48%) were so spun that the resultant undrawn yarn had a nebulous cross-section. Such fiber was easily spun by forming a layer com-posite stream and by passing it through a sand layer or the like. me un-drawn ya~n was drawn 3.5 times in a hot bath at 80 C. It showed very good drawability and a good, lustrous yarn free of devitrification was obtained.
Gelation after spinning was not observable.
Example 16 Polyoxy benzoate was used as an island component of an islands-in-a-sea type composite fiber and a terpolymer consisting of 5 parts of nonyl acr~-late, 15 parts of 2-octyl acrylate and 80 parts of styrene (having an HDT of 57.8 C, an elongation in hot water at 70 C of 130% and a shrinkage in hot water at 85 C of 45%) was used as a sea component of composite fiber 20 in carrying out spinning at an islands/sea ratio of 55/45 and 16 islands/
filament. me resulting undrawn yarn was drawn 3.6 times in a hot bath at 85 C to obtained a 3.2 denier transparent staple free of devitrification.
On the other hand, the above procedure was repeated except for using polystyrene as a sea component in carrying out spinning and drawing, in which case the draw ratio was limited to 3.2 and a devitrified yarn having a coarse surface was obtained.
Both of these yarns were repeatedly passed through a card 5 times under the same conditions to observe the coiled arrangement of the fibers 29 around the card. In the case of the copolymer, according to the present invention, as one component, it was observed that the fiber did not coil around the card at aLl. However~ in the case of the -fiber of the conventional example using polystyrene as the sea component, occurrence of neps was rec-ogni3ed from ~nd after the second time the yarn was passecl through the card, and the occurrence of neps bec~me very noticeable from the fourth time the yarn was passed to the card and thereafter. When these neps were observed, the sea component split and the minute i~land components were exposed and entangled to cause the neps.
~xample 17 A polymer consisting of 25 parts of 2-ethy~hexylacrylate, 75 parts of styrene and 0.01 part of diYinyl benzene having an HDT of 50.3 C, an elongation in hot water at 70 C of 1130% and a shrinkage in hot water at 85 C of 68% was used as the sea component of an islands-in-a-sea type com-posite fiber. Polyethylene terephthalate (intrin3ic viscosity 0.70) was the island component of the composite fiber. Spinning was carried out at a ratio of islands/sea of 4~/51 and 16 islands/filament at 278 C. The spinnability was very good; an undrawn yarn was produced having a stable cross-section in which the island components were uniformly distributed. The undrawn yarn was drawn 3.4 times in a hot bath at 70 C to obtain a 3.0 denier highly contractible yarn having a boiling water shrinkage of 33.8%. The yarn was passed through crimping apparatus to have crimps imparted about 10 crimps/
2.54 mm. However, splitting of the sea component at the sharp points of the crimps was not recogni~ed. Using the yarn (cut length 51 mm), a web was formed using a cross lapper. The web had a weight per unit area of 570 g/m2.
; This felt was needle punched to produce a high-density felt having a punch density of 1700 punches/cm and an apparent density of 0.202 g/cm3.
This felt was immersed in hot water at 80 C and thereafter immersed in polyvinyl alcohol solution. Subsequently, being dried, it was immersed in 29 trichloroethylene to dissol~e the sea component of the fiber. Then it was 1~:)'75~3~i8 followed by impregnation with polyurethane, coagulation and a napping treat-ment to create a velour-like leathery sheet material having unprecedented characteristics and properties.
Control 10 Example 17 was repeated, but using polystyrene as the sea component.
The spinning process was good; however, the undrawn yaIn could be drawn only 1.8 times to avoid partial whitening and yarn breakage.
Using the drawn yarn, a web was formed, which was needle punched in the same way as in Example 17; however, even when punching was carried out to a p-mching density of 3000 punches/cm , the apparent density of the felt was saturated at 0.155 g/cm . Using the resulting felt, a velour-like leathery matter was made; however, it was by far inferior to the velour-like leathery material obtained in Example 17. Using the fibers according to the present invention, the felt-forming properties were very good, and the resulting felt became a high-density compacted felt. In the control, the felt-forming property was remarkably poor. Because of the hard properties of polystyrene, the fiber became hard and strong in its repulsive properties, and intertwinement did not take place easily.
Control 11 This example (control) shows the examined results of the case of using a plasticizer for the purpose of improving drawability and flexibility of polystyrene. Although this is one example of the use of a plasticizer, it is a representative example illustrating limitations in the use of plasti-cizers.
DOP (dioctyl phthalate) is used as a plasticizer for styrene. A
` polystyrene polymer~ into which 3% by weight of DOP was added, was spun at 285 C. The spinning pressure at the time of spinning was reduced by about 31% as compared to that of a blank polystyrene polymer containing no DOP.
29 The spun polymer was taken up at a take-up speed of 400 m/min to obtain an ~(~'i'S~3~8 ~mdrawn yarn o~ about LO denier.
This undrawn yarn was pulled thro~lgh a liq~id at 70 C at a speedof 10 m/min and its elongation at break was measured. The increase of elon-gation of the undrawn yarn spun from the polymer containing 3% of DOP was only 1.8%, as compared to an undrawn yarn spun from the polymer which con-tained no DOP, and no substantial plasticizing effect was recognized. Where-as, as a peculiar functional effect of such plastici7er, there was a remark-able, undesirable action of promoting lowering of the viscosity of the molten polymer, not expected from the small plasticizing effect at the time of cooling. Specifically, by adding only 3% of the plasticizer, the pack pres-sure (filter pressure) at the time of spinning decreased by as much as 31%
as compared with that of the blank polymer not containing any plasticizer.
The effect of the plasticizer became very remarkable at the time of melting.
This polystyrene polymer containing 3% of the plasticizer was used : ' .
as the sea component of an islands-in-a-sea type composite fiber, and poly-ethylene terephthalate (intrinsic viscosity 0.72) was used as the island component. They were spun at an islands/sea ratio of 50/50 and by a 16 is-lands/ filament spinneret at 285 C. The spinning was carried out by first discharging the sea component, and later the islands componen~. Immediately after the discharged amounts were mixed, take-up was started. Immediately after the start of the spinning operation, a composite stream extruded smooth and straight from the spinneret orifice and the spun and undrawn yarn had a normal sectional configuration in which the island components were uniformly distributed. However about 3 hours after the start of spinning, the stream began to bend slightly, while a further 4 hours later, the stream bent so extremely as to touch the spinneret surface. Drips began to occur. At this point variation of denier among the holes of the spinneret began to be seen.
When the cross sections of such yarn were observed, the island 29 components adhered to each other, composite unevenness (component ratio un-1~75~8 evenness) was sharp and, in atl cxtreme manner, the island co~ponents and the sea compon~nt e~isted as complete~Ly independent monofilaments in admixture among the holes (toward each hoLe of the spinneret~. In a yarn using a polystyrene homopolymer not containing the plasticizer as the sea component, there was no occurrence of such disorder because, by addition of the plasti-cizer, the viscosity at the time of melting decreased, difference of vis-cosity values between the sland components and the sea component became extremely large and the spinning process became remarkably unstable.
The ~mdra~n yarn obtained immediately after the start of discharging was drawn in a hot bath at 98 C. However, it could be drawm only 2.7 times and no substantial effect of addition of plastici~er on drawing was recognized.
Control 12 A system in which liquid paraffin was added into polystyrene was used in carrying out spinning and drawing as an islands-in-a-sea type com-- posite fiber, otherwise the same as in Control 11.
~- As the ratio of liquid paraffin added to the polystyrene, the various levels of 0, 5, 10, lS and 20% were selected. When 15% of liquid paraffin was added to the polystyrene, the melt viscosity of the polystyrene decreased too much and spinning was impossible. The spinnable limit occurred at a ratio of liquid paraffin of 10%. Accordingly, the undrawn yarns were provided with 0%, 5% and 10% of liquid paraffin. These undrawm yarns were dra~m in a liquid bath at 80 C. The results in terms of draw ratio were 2.0 in the case of 0% (blank), 2.3 in the case of 5% and 2.4 in the case of 10%.
By addition of liquid paraffin, drawability was slightly improved. However, there was no substantial difference between addition of 5% and 10%, and the effect of the amount added per se was small. As reasons for this, it is con-ceivable that by making the polymer into a yarn at the time of spinning, the high temperature surface area becomes very large, from which an excess of 29 plastici~er evaporates. A low boiling point plastici~er evaporates at the 58~8 time ot` spinning, l~aving no effect; a high boiling point plasticizer does notdevelop its effect sufficierltly at the time of drawing.
E mple l8 Using a biaxial extruder-type spinning machine, a mixed chip of 35 parts of polyethylene terephthalate and h5 paIts of astyrene-stearyl acrylate (75/25) copolymer was spun. As a control, mixed chips of 35 parts ofpolyethyleneterephthalate and 65 parts of polystyrene were spun using the same spinning machine. The two different undrawn yarns were drawn in a hot bath at 80 C to check the drawing conditions.
Table 4 - ....... .. _ , .
_ This invention Control Maximum draw ratio 3.4 2.7 Yarn breakage at the time of drawing~ ~ 9.3 times/min .
*Frequency of occurrences in which the yarn coiled around the roller, per minute, when drawing was carried out at a draw ratio of 0.95 x maximum draw ratio.
From these results, the good drawability of the yarns according to the present invention should be understood.
Exam~le 19 A 2-ethylhexyl acrylate (20 parts)/styrene (80 parts) copolymer was used as the sea componènt and a polyethylene terephthalate copolymer ` copolymeri~ed with 5 mol % of isophthalic acid was used as the island com-ponent in carrying out spinning at an islands/sea ratio of 50/50 and 16 islands/filament as an islands-in-a-sea type composite fiber.
No chimney was used in the spinning procedure and the resulting undrawn yarn was taken up through a hot tube provided 1.5 m directly below 29 the spinneret. The atmospheric temperature of said tube was controlled at 1~175~8240 C. The ~mdrawn yarn was drawn ~.2 times at 82 C and a highly contract-ible yarn having a shrinkage in boiling ~ater of 34% was obtained.
The Young's modulus determined from measured strain-stress curve of the sea component filament after dissolving the sea component after con-traction was very high for the shrinkage.
Example 20 In Examples 9 - 19, when the resulting drawn yarns were immersed in trichloroethylene and washed, the sea components dissolved more easily and operations for washing and removing the sea components were easier than in the case of polystyrene alone.
And because the draw ratios were high, the tensile strength of the remaining sea components were remarkably high (see Tables 2 and 3).
Example 21 Example 9 was repeated, except using polyethylene terephthalate as the island component and changing the draw ratio to 3.5 in making a 3.5 denier stream (about 96 - 98C) drawn yarn. This yarn was small in elongation (the island component too) and small in contractibility and was an excellent fiber. About 8 - 12 crimps/in were imparted to the yarn, which was made in-.:
to 51 mm cut staple and 76 mm cut staple. When these staple samples were subjected to ordinary staple system and woolen system spinning to make 16S/2 and 2/12-spun yarns, respectively, they became good spun yarns having very little occurrence of fly and white powder. Used as warps a false twisted filamentary yarn (150 denier) and using as weft, each of the aforesaid spun yarns, these warp and weft yarns were woven into Turkish satin fabrics, respectively.
` It was possible to form a very good nap on the surfaces of these satin fabrics by subjecting them to the action of a napping machine using a card cloth before or after removing the sea component.
29 For information, with reference to fly and white powder7 when the 7~
sea component is substa~tialL~ only polystyrene regard:Less of being mixed or not nuxed with about 0.5% of liquid paraffin, there is a conslderably large amount of fly or white powder at the t:ime of spinning, especially at a yarn uniting or twisting machine and at a spinning winder. On the contrary, in the present invention, because drawing is not carried out to the upper limit, it is possible to avoid the creation of objectionable amounts of fly and white powder.
Example 22 This example shows the importance of the copolymerization ratio.
Polymerization conditions:
- Catalyst: 0.2 parts based on the weight of monomer of benzene peroxide 0.1 parts based on the weight of monomer of ter-butyl perbenzoate Water/monomer: 150/100 (suspension polymerization) Polymerization time: 6 hollrs at 100 C
.
2 hours at 120 C
Making the above conditions constant and varying the copolymeriza-tion ratio of 2-ethylhexyl acrylate/styrene of the charged monomers, poly-merizations were carried out. The drawability ~elongation) of the polymers was checked by the method mentioned in the text of the specification. The results appear in Figure 4. As will be apparent from Figure 4, from a point where the copolymerization ratio is about 10%, the copolymers begin to elon-gate well. From the point where the copolymerization ratio is about 15% as a boundary, the copolymer suddenly begins to elongate well, which is a char-actelistic of the present inven~ion. This fact shows that a copolymerization ratio of not less than 10% is very important for achieving some of the im-portant objects of Athe present invention.
Examples 23 - 28 29 Controls (Comparative Examples) 12 - 14 10'7S~
In E~ample 7, tlle atmospheric temperature at a point 10 cm directly below the spinneret ~as controLled at 40 C, 150 C and 250 C in taking up the undrawn yarn.
Draw tests of the resulting undrawn yarns were carried out. They obtained the follo~ring results:
Table 5 Sample Tempera- Preheat Draw Draw Maximum No.ture tempera- tempera- speed draw spin- ture ture ratio~
. .
10Colnt2rol H-l 40 C R.T. 70 C lmiOnm/ 3.28 times Cln3rl H-2 40 C 40 C 70 ClmiOnm/ 3.33 times Control H-3 40C 70 C 70 C150 m/ 3.5 times 14~ _ min Exa2m3ple H~4150 C R.T. 70 ClmiOnm/ 3.82 times ~xample H-5150 C 40 C 70C150 m/ 3.91 times 24 min Example H-6150 C 70 C 70C150 m/ 4.17 times min ._ .. _ Example H-7250 C R.T. 70C150 m/ 3.88 times 20Exmmple H-8250 C 40 C 70 C150 m/ 4.17 times H-9 50 G 70 C 70 C150 m/ 4.l NOTF: ~'R.T. = room temperature YA-`~Maximum draw ratio = elongation at break From the aforementioned results, it was found that when the tem-perature at a point below the spinneret is high, drawability is good. By increasing the preheat temperature, drawability ad-vances.
Example 29 29 The heat stability of a styrene ~78 parts)/2-e~hylhexyl acrylate . - - . . .. . ,, . - . .
., - ~, ~ . , ~ .
1~75~8 (~2 parts) copol~ner was checkecl.
~lethod of estimating heat stability;
In N2 gas 20 cc/min Amount of the sample: 400 mg Temperature 285 C (temperature was raised from room temperature to 285 C at a rate of 10 C/min) The weight diminished ratio of the polymer in the aforementioned atmosphere was checked. This ratio is defined by ~he formula:
W-Wl X 100 .` 10 W
- where ~ is the weight of polymer before heating and Wl is the weight of the polymer after heating for a particular time. The results are shown in Figure S, wherein:
(A) is a thermal decomposition curve of the sample pelletized at 245 C.
The decomposition ratio is remarkably high.
(B) is a thermal decomposition curve of the sample pelletized at 215 C.
By reducing the temperature to 215 C, the thermal decomposition was remark-ably improved.
(C) is a the~lal decomposition curve of the sample added with a thermal ~ 20 decomposition stabilizer. It was found that a beneficial effect (to this ; polymer) was obtained by addition of a thermal decomposition stabilizer (1,3,5-trimethyl-2,4,6-tris (3,5-di-ter-butyl-4-hydroxyben~yl) benzene).
Example 30, Control 15 A styrene (78 parts)/2-ethylhexyl acrylate (22 parts) copolymer having an HDT of 54.5 C, an elongation in hot water at 70C of 590% and a shrinkage in hot water at 85 C of 58% was used as the sea component of an islands-in-a-sea type composite fiber. An isophthalic acid copolymerized polyethylene terephthalate having a softening point of 235 C was used as the 29 island components o-f said composite fiber in carrying out spinning at an ,. . .
~.~758~
islands/sea ratio o~ 50/50, and with a total o~ 16 islands/fiLament. Theresulting undrawn yarn was wound at a speed of 1070 m/min under such condi-tions that the temperature at a point 10 cm direct:ly below the spinneret was 92 C and 298 C. These undrawn yarns were drawn in hot water at 70 C to check the maximun) draw ratio. The results were as follows:
Atmospheric temperature Maximum directly below spinneret draw ratio Control 15 92 C 3.3 times Example 30 298 C 4.02 times A great difference in maximum draw ratio was observed with changes of atmospheric temperature at a point directly below the spinneret. By raising said temperature, it is possible remarkably to raise orientation of the yarn, and the spinning productivity as well.
- xample 31 In Example 30, the undrawn yarn was drawn at a ratio of 3.92, and crimp was imparted to the drawn yarn. A stuffer box type crimper was used, a fiber oilingagent kept at a constant temperature (15 C) was flowed to cool -the crimper and the roll surface temperature of the crimper was kept at 38 C.
The yarn product showed a shrinkage of 40.3%.
Control 16 As in Example 31, the temperature on the surface of the crimper was changed to 62 C. The resulting yarn had a shrinkage of 2~.7%.
Example 32 The yarn obtained in Example 31 was dried at 40 C. Its shrinkage was 40.2% and no change of shrinkage by drying was observed.
Control 17 ~ -As in Example 32, the drying temperature was 65 C. The shrinkage of the yarn, after drying, was 11.2%.
EXample 33 The yarn in Example 32 was subjected to a card and to a cross 1~7S8~
lapper to form a web. This web was needle punched to make a felt having an apparent density of 0.173 g/cm . A good ~elt in which punched traces were a'most ~recognizable was obtained. This felt was immersed in hot water at 55 C and then in hot water at 85 C, and ligl-tly rolled by rolls to obtain a flat contracted felt. As a result o-f measuring the shrinkage, it was found that the felt contracted by 24% in area at 55 C, and contracted to 56% of the original area at 85 C. The contracted felt was excellent and free from creases.
This fel-t was impregnated with an 18% aqueous solution of poly-vinyl alcohol and dried at 80 C. ~fter drying, the felt was immersed in trichloroethylene and the sea component was dissolved ~d removed. Next, the felt was heat treated in hot air at 180 C for 5 minutes, impregnated with DMF
(dimethyl formamide) solutions of various concentrations of polyurethane whose soft segment was polytetrahydrofuran having a molecular weight of about 2000 and whose hard segment consisted of p,p'-diphenylmethane diisocyanate and p,p'-diaminodiphenyl methane, and then the felt was immersed in hot water at 90 C to remove PVA (polyvinyl alcohol) and sliced along the center into two halves. Both surfaces of the sliced substrate were buffed with sandpaper.
After buffing, the sheets were dyed a chestnut color with a dispersed dyestuff 20 at 115 C.
The product had an apparent density of 0.24 - 0.32 g/cm , a bright color and excellent hand and volume, being free from nap entanglement. The elongation resistance and abrasion resistance were measured, and the results are shown in Figures 7 and 8, respectively.
Figure 7 shows the relation between the binder content ratio and the deformation of the product. It was found that at a binder content ratio of not less than 26%, a remarkable improvement was achieved and the deforma-tion could be controlled to a value of not more than 12%, which is within the 29 range demanded for practical use.
~)758~3 Figure 8 sho~s the results of measuring abrasion resistance. The thickness of the sample upon measuring the chafing number was made the actual thickness. The thickness of this sample was 0.8 mm. It was found that with a binder content ratio of about 33~, the abrasion resistance (chafing number) was remarkably improved.
Control Example 18 Example 33 was repeated except for omitting the heat treatment.
When the deformation ratio was measured at the binder content ratio of 34%, it was 13.2%. And it was found that heat treatment is remarkably effective for inlprOving quality.
Control 19 Example 33 was repeated except for limiting the contraction to one contraction at 55 C. The product had an apparent density of 0.21 g/cm3 and and a binder content ratio of 34%. The thickness of the sample at this time was 0.8 mm and the chafing number was 118, which was quite poor.
Example 34 The amount of the minute fibers adhered in the sample whose binder content ratio was 34% of Example 33, was measured by the minute fiber adhesion method. The value was 73 mg.
Control 20 Example 33 was repeated except for omitting the heat treatment.
The amo~mt of minute fiber adhered, in the resulting sample having a binder content ratio of 33%, was measured. The value was 213 mg, which was increased '~
remarkably as compared to the value in Example 34. ~;
In a multi-component fiber according to the present invention, for - example, an islands-in-a-sea type composite fiber, when polyethylene tereph-thalate is used as the island component, when the draw ratio is raised, a filament is obtainec which is unlikely to contract. When a woven fabric 29 having a superfine nap is macle using such a composite fiber, the destruction 1~758~8 of the sea component at the time of spinning is small as compared to a con-ventional -is~lands-in-a--sea t~pe composite fiber using a sea co~ponent con-sisting of a polymer of the polystyrene series. Because of that, coiling of fibers around the rolls in the drawing step and the spinning step is ]ess, the luster of tlle nap of the res~lting fabric is excellent, the nap is un-likely to curl and, because of that, the fabric has an excellent hand.
Examples of steps for making such woven fabrics are as follows:
(1) (a) Spinning of an islands-in-a-sea type staple fiber to be used as weft.
; 10 (b) Woolly, processed, latent crimped or ordinary filament yarn, to be used as warp (c) Satin fabric is made -- 4, 5 and 8-ply (d) Contracting treatment or desizing (when the warp was sized, desizing is carried out) ` (e) Removal of the sea component (dissolving) ~ f) Oiling (for napping) and/or crimp developing treatment (heat treatment) ~ g) Napping (h) Adding an anti-pilling, balancing agent (a high mo]ecular ~eight elastomer such as polyurethane) (emulsion or solution) (including solidification and drying) (i) Napping ~buffing) (j) Dyeing (including reduction washing and/or drying) (An example of reduction washing is use of a dilute hot aqueous solution of sodium hydro-` sulfite (Na3S204) and caustic soda (NaOH) (k) Finishing (imparting a finishing oiling agent, brushing and/
or buffing of the back surface) (2) (a) Spinning of islands-in-a-sea type staple fiber (as weft) 29 (b) Woolly processed, latent crimped or ordinary filament (as warp) 1 1:)75868 (c) Sat:in fabnic (d) Cont~acting treatment or~ desiz:ing (e) Remova.l. of` ~ea component (f) Oiling and/or cri~p de~e10ping treatment (heat treatment) (g) Napping (h) Imparting a sizing agent ~dr~ing) (i) Imparting an ~mt,:i-pilling'ba~ancing agent (emu~sion or solu-tion Removal of the sizing agent (desizing) - 10 (k) Napping (buffing) '` (1) Dyeing and dyeing finishing (m) Finish processing of woven fabric (3) (a) Spun yarn or filament of an islands-in-a-sea type stap~.e fiber las a napped fiber) ,., (b) Spun yarn or filament (as warp and weft of the base) (c) Seal woven fabric (d) Backing (solution or emulsion) (e) Removal of the sea component (preferab],y buffing the back ' ' surface) (f) Dyeing :~
(g) Finishing (preferably buffing the surface and the back surface) '; ~en the islands-in-a-sea type fiber is highly contractible, the aforesaid step (3) is further improved and the woven fabric made a napped fabric having short nap.
(4) (a) Spun yarn or filament of an islands-in-a-sea type staple fiber (as a napped fiber~
(b) Spun yarn or filament (as warp and weft of the base) (c) Seal woven fabric 29 (d) Backing : - ~. . .
. .-. :
~0~5~
(e) Contracting step af`ter (c) or (d) (f`or shortening nap) (f) Rc~lovaL of sea componen-t (g) Dyeing (h) Finishing Example 35 A total 150 denier x 48 filament woolly false twisted yarn of : ~ polyethylene terephthalate was used as warp ~ncl a spun ya~n from an is~a~ds-in-a-sea type stap].e fiber whose island componellt was polyethy.Lenc terephtha~
late and whose sea component was a copolymer of 72 parts of styrene and 28 parts of 2-ethylhexyl acrylate, was used as weft in weaving a fabric.
The islands-in-a-sea type staple fiber had the following character-istics:
Number of islands 16 (see Figure 1) Island component ratio 55% by weight Sea component ratio 45% by weight Denier 3.0 - Fiber length 51 mm . Number of crimps 8 - 12 per inch Draw ratio at the time of drawing 3.2 This staple was spun into a 20/28 spun yarn.
The spinnability at this time was good, the staple fiber was pro-cessed favorably through carding, drafting, roving and spinning steps, and coiling of the staple around the card, drafting rollers and spinning rollers took place very seldom, and good spinning could easily be carried out.
Further, the aforesaid yarns were used as warp and weft, respective-ly, and they were woven into a 5-ply satin fabric to produce a weaving den-sity of 100 warps/in and 60 wefts/in. At this time, an.-edge of about 1 cm was made and a basket weave was selected as the woven pattern.
29 The fabric was washed with hot water at 80 C. After it was dried, .. .
s~
the fabric wa~ thoroughly washed 5 t-imes ~ith trich~oroethylene, and the sea component ot` thc weft was remo~ed. After it was driedJ the fabric was passed through hot water containing an ordinary oiling agent for napping, and dried.
The resulting fabric was passed 7 times through a rotary card cloth napping machine to nap the surface, to obtain a napped fabric in which super~
fine fibers were thoroughly napped. This fabric had wonderful smooth touch.
~lowever, it had poor pilling resistance and hand, and the firmness that re-sulted when it was bent longitudinally was greatly different from that which resulted when it was bent transversely. When it was bent transversely, creases were left behind. The fabric was out of balance.
is fabric was impregnated with a 10% dilute polyurethane emulsion consisting mainly of polypropylene glycol, toluylene diisocyanate and hexa-methylene diamine prepared according to known methods of polymerization, namely, according to the method disclosed in Japanese Patent No. 242 577 (James E. ~aloney), and dried. The amount that adhered, calculated as pure polyurethane, was 21 g/cm . The resulting fabric was napped ~buffed~ by #150 mesh sandpaper. The front surface was buffed thrice and the back surface ;
was buffed once by a belt sander buffing machine. As a result of this buff-ing, the fabric became a sue~e-like fabric whose surface was covered with compact superfine nap. It was heat treated at 170 C for 3 minutes in hot air.
Next the fabric was dyed in a brown color by a circular type pres-sure dyeing machine; washed with water, a finishing oiling agent was applied and dried in hot air at 90 C according to known methods. The back surface was buffed to remove ugly naps raised here and there, and the surface was brushed and finished. When the naps were brought down to one side and the fabric was so dried that the surface of the fabric could contact the surface of a dryer roll at 90 C, the fabric developed excellent surface gloss and brilliance. -29 The resulting fabric was a suede-like abric, the texture of which :1~7S~8 was hal~lly v:is:ible, hav:ing a wondcrt`u:lly sott and smooth surface touch and soft hand, and it was so weL:L ba:lanced that any direct.ional d:ifference i.n hand when it was bent longitud:inally and transverseLy was a:l.most ~lnoticeable.
Because the fiber was well drawn in this fabr:ic, super:t`ine naps were in evidence, having almost no -tendency to be entangled, and they had excellent gloss.
Example 36 Example 33 was repeated except for using a polyethylene terephtha late copolymer having a softening point of 231 C, copolymeri~ed with adipic acid in an amount of 11% based on the weight of the polymer, as an island component in fibers used for preparing artificial leather.
The resulting artificial leather was dyed at a temperature of 105 C.
The resulting dyed artificial leather had an excellent appearance in which any color difference between the binder and the fiber was virtually undetect-able and inconspicuous. The defor~ation ratio was 7% and the chafing number was 320.
. . .
:' '
and the fiber co:ils aroulld the roll of the carcling machine frequently causingtrouble. ~lowever, the fiber of the present invention is remarkably free from such trouble. ~s a spun yarn it is excellent, and the product has only very little fluff (the hairs of the surface of the spun yarn).
~ Irther~ fibers of the present invention may be applied most advan-tageously to the manufacture of synthetic leather-like sheet materials. When a multi-component fiber using polystyrene has been used for making such sheet materials, as in the past, carding has been poor and fiber intertwinement upon needle punching has been poor because the polystyrene tends to split, lacks flexibility and has only a limited capability to produce fiber intertwinement.
Also, the fiber has not been sufficiently drawn, and the product has had a tendency to elongate and to undergo deformation. When the nap was formed on the surface of such fibers, the nap has tended to become entangled and to be lacking in gloss.
Such leather-like material has been found also to be lacking in ; the excellent hand, volume, compact nap and abrasion resistance possessed by natural leather. In order to obtain these characteristics, a high-density intertwined aggregation of fibers is required and the fibers constituting such intertwined aggregation is required to be made of a material having considerable resistance to elongation.
For effecting compact fiber intertwinement, needle punching should be carried out to the maximum extent. However, according to this method, when punching is carried out beyond a certain limit, breakage of the fibers is brought about and the density of the intertwined aggregation of fibers lowers - as well as the tensile strength of such aggregation.
It is not sufficient to increase the density of the aggregation by needle punching and a satisfactory result is not obtained by so doing.
~ nother method is contraction, in which a needle punched felt is 29 caused to contract by heat or chemicals. The fiber intertwinement per unit : . - , ., ,~ . . .
.: .
1(~'75~3~8 volume increases aecord-ing to the contracted volume of the aggreKation.
Accordingly, it is possible to sharply increase the density of the inter-t~ned aggregation of fibers by increasing the volume shrinkage. This in many cases is the most effective means for increasing the amount of fibers per unit volume, and to provide optimum fiber intertwinement.
However, the main drawback of such a method is that the contracted fiber tends to elongate, and that the product tends to elongate and also to become deformed. Upon forming nap, it is necessary to be able to form nap easily, in such a way that the formed nap is unlikely ~co intertwine and is easy to color. A fiber which is capable of solving all of these problems is required, and is provided according to this invention.
Fiber elongation after contraction is diminished and minimized to the extent of practical use by making a felt using a highly contractible multi-component fiber drawn at a high draw ratio (not less than 2.6, prefer-ably not less than 3.0) at a low temperature, then causing the felt to con-tract to form a high-density felt, removing one component of said fibers while in the form of a high-density felt~ and thereafter subjecting the felt to heat treatment at a cemperature ranging from about 160 C to 220 C before or after applying a binder to the fibers of the high-density felt.
In this case, it is preferable that the component to be removed should occupy at least about 60% of the surface of the multi-component fiber used. Otherwise, when the felt is caused to contract to become a high-density felt, the fibers are not likely to be able to move freely or to slide rela-tive to each other inside the felt, and the "hand" of the felt product be-comes remarkably hard. By removing one component occupying a substantial volume around the surface of the fibers in this condition, large voids are formed about and among the remaining fibers, and accordingly movability (slideability) among the remaining fibers increases and the felt product 29 becomes remarkably soft.
1~'75~
~ furttler prcterable multi-component fiber is one that for~s a b~mdle of superfine fibers or the eq~ivalent after removin~ one component. By conversion to a bundle of superfine tïbers, the -fibers per se are further softened, and still more softening oE the felt product may be achieved. When the nap is formed on the surface of the fiber, the nap becomes a soft and compact one, which is highly preferable. Such multi-component fibers include islands-in-a-sea type composite fibers, composite fibers having irregular shaped cores, and certain polymer-blend types of fibers.
Multi-component fibers, one component of which is to be removed and which occupies at least about 60% of the fiber surface are drawn at a low temperature. It is preferred that the draw temperature be not more than about 100 C, preferably abQut ~5 - 60 C, because the temperature must be low in ` order to increase the shrinkage. A shrinkage of at least about 15%, prefer-ably at least about 20%~ is necessary. In order to obtain a high-density felt necessary in the present invention by causing a needle punched felt to cont-ract, shrinkage to this extent is necessary. The shrinkage may be varied within a broad range by varying the draw temperature.
m e required extent of the draw ratio ~aries according to the desired shrinkage of the fibers. In the case the degree of contraction is high, the draw ratio must be large. The following equation must be satisfied:
Draw ratio )2.5 ~ 0.01 x (shrinkage of the fiber [%]) Using such fibers, a felt is formed. The fibers of the present invention may be well carded and may be made into excellent felt by needle punching because the fibers are soft and not likely to split. For making the felt compact a mere contracting means is insufficient. A good end product may not be obtained from a felt which is not characterized by intimate inter-twinement of the fibers. Because the apparent density of the felt decreases upon removal of one component in a subsequent step, it is necessary to 29 increase the apparent density of the felt by needle punching to at least : . .
: ' :
~753~3 about O.l2 g/cm , preferably about O.L~ - 0.25 g/cm3.
The resulting felt is caused to contrclct by heat or by chemicals.
The contraction should be carried out so that the shrinkage per unit area of the felt becomes at least about 27% and the density of the felt becomes at least about 0.2~ g/cm . Contraction may be carried out in one stage, but it is highly desirable to vary the temperature and carry out the contraction procedure stepwise. This prevents creases from forming at the time of con-traction, and produces an especially good, smooth felt. In this case, two-stage contractibility is required of the fiber.
10In order to prevent operating difficulties during the removal of one component before or after contraction, it is preferable to carry out a - sizing operation. Water-soluble sizing agents such as, for example, poly-vinyl alcohol and carboxy methyl cellulose may be used. However, when the density of the felt after contraction is at least about 0.4 g/cm , the operational difficulties during the step of removing one component may be avoided, even if such sizing is not carried out.
One component is removed from the contracted felt~ this may be done easily by immersing the felt in a solvent. After removing one component, the felt is heat treated. The heat treatment is carried out by using heated air or a hot roll. It is preferred to carry out the heat treatment at a temperature ranging from about 160 C to 220 C for about 1 - 10 minutes. A
few seconds suffice as the heat treating time for each fiber per se. However, in the case of a fiber aggregate such as a felt, heat transmission is slow and additional time is necessary to conduct the heat to the interior of the felt. However, because deterioration of the fiber is caused when too much time is allowed, or when the temperature is too high, it is necessary to limit the time and temperature. When a sizing agent is used, it is considered safe to limit the temperature to not more than about 190 C, because the sizing 29 agent becomes insoluble at a higher temperature.
1~375B~;~
A binder is imparted to the fiber before or a-fter such heat trea~-ment. .~ binder o~ the polyurethane series is preferable. When the fibers are to be dyed later, a binder which is capable of withstanding dyeing is required. Preferable binders in this case include polyurethane of the poly-ester series and a part of polyurethane of the polyether series. Specifically, polytetrahydrofuran, polypropylene glycol and polycaprolactone are included.
However, when dyeing is carried out under mild conditions or is not carried out at all, ordinary polyurethane may be used.
Upon applying the binder, it is used as a solution or emulsion.
Solidification of the binder may be carried out either by the wet system or by the dry system. In the dry system, adhesion between the binder and the fiber is quite stron~ as compared to the wet system. Thus, it is preferable to make the amount of the binder somewhat smaller as compared with the case of the wet system. ~hen using a solution~ wet coagulation is preferable from the viewpoint of the "hand" or feel of the end product. When using an emulsion, it is preferred to heat treat the fiber at the s~me tlme, by anneal-ing the emulsion polymer.
Just as in the heat treatment, the amount of the binder incorporated into the felt is very important for decrease of elongation, abrasion resis-tance and hand of the end product. In order to obtain an erld product having a good hand, it is preferred to decrease the amount of binder added. However, when said amount is deereased, the elongation resistance and abrasion resis-tance of the end product become remarkably poor. In order to satisfy all of these characteristics, it is preferred to limit the apparent density of the fiber to about 0.08 - 0.35 g/cm in the end product, the apparent density of the fiber containing the binder to about 0.17 - 0.52 g/cm , preferably 0.20 - 0.40 g/cm , and more preferably, to limit the amount of binder to about 20 - 60%, preferably about 26 - 50%, based on the weight of the fiber.
29 The resulting product is usable per se. However, it is highly s 5t3~3 desirable to but`t` the surface o~ the product to -f`orm a nap. The nap according to the present invention is soft, tends to ~fo~l attractive and realistic finger marks when it is smoothed down by a finger working in different direc-tions, ~ld is lustrous and per~anently entangled. A fiber whose denier is not more than about 0.45 is especially preferable.
The product of the present invention has high quality, improved compactness, and excellent hand, volume, abrasion resistance, elongation resistance and entQnglement of nap.
- In order to practice the present invention very effectively, it is preferable to utili~e a polymer of the polyester series, because by so doing, a highly contractible fiber tends to be produced, and the effect of heat treatment after contraction is remarkable. Of the polymers of the polyester series, a copolymer is especially preferable which is obtained by copolymeriz-ing isophthalic acid or adipic acid in an amount of about 4.5 - 20% based upon the weight of the polyester. When such a polymer is used, not only may the contractibility further be raised, but problems in dyeing may be solved in the same way.
When the nap of a superfine fiber is formed on the felt surface in accordance with the present invention, dyeing of the fibers tends to be-come difficult. That is to say, superfine filaments are dif~icult to colorsufficiently, because of its large curvature to reflect or scatter light to make the color look pale. Accordingly, it is necessary to dye the fiber in a deeper color. However, heretofore, when the concentration of the dyestuff was increased for the purpose of dyeing the fiber in a deeper color, it has not been able to dye the fiber in a deep color. Accordingly, it was con-cluded at one time that it would be impossible to dye such superfine fiber in a deep color. However, as a result of our study conducted after that, it was found that, at the time of dyeing, the dyestuff is mainly absorbed by 29 the binder and not absorbed sufficiently by the fibers. However, after ' - . ' 7~8~3 dyeing, the dyestuf~ falls off ~rom the billder, by washing with water.
AccordingLy, it may be said that however high -the concentration of the dye-stuff may be, excess dyestuff is trapped in the binder and is not sufficiently effective for dyeing the fiber. Raising the concentration of the dyestuff to an extent of more than saturating the adsorbed amount of the dyestuff by the binder means throwing away a large amount of the expensive dyestuff.
We have discovered that such problems may be orercome by using a copolyester containing about 4.5 - 20% of isophthalic acid or adipic acid.
In the simultaneous dyeing of such polymer and binder, the dyestuff increases its affinity for the fiber and part of the dyestuff adheres to the fibers rather than the binder. Accordingly~ it now becomes possible to dye the fibers in a deep color, and the loss of dyestuff becomes very small.
In such dyeing, the dyeing temperature is very important. When the dyeing temperature is raised, the dyestuff tends to prefer to attach itself to the fibers3 but when the dyeing temperature is low, the dyestuff tends to move to the binder side. It is necessary to determine the dyeing temperature by balancing the two factors. Especially, it is preferred to establish the dyeing temperature in the case of such copolymers at about 5 - 25 C lower than the temperature usually adopted for homopolyesters.
Accordingly, when polyethylene terephthalate is selected as the polyester, - its~.ould by dyed at a temperature ranging from about 105 C to 120 C.
The effect of being able to lower the temperature at the time of dyeing is great. Deterioration of elastic binders having poor heat resist-ance may be prevented.
In order to carry out good dyeing, the concentration of the dye-stuff is also important. When a sheet is dyed somewhat more deeply than usual with respect to color, it is recommended to use at least 10% of dye-stuff based on the weight of the sheet.
29 Processing after dyeing is also important. In the case of a sheet - , ,: : -~3'7533f~B
material which is a composite of the binder and the fiber, the adh~sion of the two remarkably influences the hand of` the product. Even after dyeing, the hand andnap quality of the product are remarkably influenced by swelling or contraction of the binder. For instance, treating the sheet after dyeing at a pH of about 7 - 14 and at a temperature of about ~0 - 98C, the hand, volume, softness and dye fastness of the product are remarkabl~ advanced.
The influence of the drying conditions upon the hand of the product is also great. It is better slowly to effect drying at a low temperature and reserve about 0.5 - 2% (based on the ~eight of the product) as the mois-ture content ratio, than suddenly and completely to effect drying at a hightemperature. Also, at the time of drying, the condition of the nap is remarkably influenced. In order to form a soft nap tending to take on realistic finger marks, it is preferred to make the nap into the desired state by brushing or by abrasion when the product is wet, before or at the time of drying, and thereafter to dry the nap.
As mentioned abo~e, according to the present invention, a leather-like sheet material having an apparent density of at least about 0.17 g/cm , preferably about 0.21 - 0.35 g/cm , having excellent hand, volume, dyeability, elon~ation resistance and abrasion resistance is obtained. Especially, when such a sheet material has nap on its surface, the nap becomes compact, tends to be marked with finger marks, and the fibers of the nap are not likely to ` become entangled.
The resistance of the product to elongation may be determined by the following measuring method, and may be expressed as a deformation ratio.
Both ends of a sample (width 2 cm and length 10 cm) are gripped by clamps and pulled by a tensile tester at a tensile speed of 10 cm/min. When the load of the sample becomes 1.5 kg, per perpendicular cross-sectional area, 1 cm of the initial sample, pulling is stopped and the clamps are 29 restored to their original positions. The operation is repeated 5 times.
1~'758f~8 After completion~ the sample is reLeased and aLlowed to stand for 2 hours.Thereafter~ the length of the sample is measured, cmd reported as L (cm).
The deformation ratio is:
Deformation ratio = L 10 :LOO (%) When the deformation ratio is large, the product tends to deform easily and at the -time of using, when the product is used, for example, for clothing, it causes deformation of the clothing. For actual use, it is necessary that this deformation ratio be not more than about 12%, and it should preferably not exceed abowt 8%.
Abrasion resistance of the synthetic leather may be determined as a chafing number, as follows.
On a 90 mm diameter table, a sample of the same shape is fixed by means of a frame. From above onto the entire plane of 90 mm diameter, a brush having 8000 monofilaments of polycaprolactam (diameter 0.3 mm ~, length 20 mm) implanted uniformly is pressed with a load of 8 pounds. This brush is rotated. The rotary axis of the brush and the rotary axis of the table are eccentrically disposed by 15 cm. The table fixed wqth the sample, and the brush itself, are rotated at 62.5 rpm and 58 rpm, respectively in the same direction. The total number of rotations of the brush from the start of rotation until the sample is damaged (wears out and holes are made) is defined as the chafing number. When the chafing num~eris large, abrasion resistance is good.
Susceptibility to entanglement of the nap is measured by a micro-fiber adhering method, as follows.
Both ends of a sample are sewn to make a cylinder having an inner diameter of 4 cm and a length of 13 cm. mis sample is thrown into a 15 cm x 15 cm x 40 cm cuboidal box the interior of which is covered with cork rotat-ing at 30 rpm around an axis in the lengthwise direction, together with 3 g 29 of superfine rayon fiber passing through a 100-mesh sieve. After ro~ating :,'~ ' ' ~75~
the bo~ ~or 10 minutes, the contents are taken out, and droppe(l -t`rom a height of 5 cm onto the floor sllrface twice to eliminate excess fiber dust. There-after, the weight is measured and called W1. Next, after removing thc fiber dust adhering to the surface of the sample completely by using a vacuum absorption apparatus, the weight of the sample is measured. The weight of the sample at this time is called W2. The susceptibi:Lity to entanglement of the nap is determined from -the equation W 1'11 W~
When W is high, it shows that nap tends to become entangled rather readily.
Examples 1 - 8, Controls 1 - 4 These examples and controls show ester interchange reactions and occurrence or otherwise of gelatin caused by such reactions when polyester and vinyl esters group co-exist in the molten state. These examples relate to a composite fiber yarn which is a binary fiber consisting of polyester as one component and a polymer of the vinyl series containing a carboxylic acid ~ aIkyl ester group as the other component in observing stability (whether ; gelation occurs) at the time of melt spinning.
As the polymer of the vinyl series containing a carboxylic acid ;~ 20 alkyl ester group, these examples and controls used a styrene-acrylic acid ester copolymer at a fixed copolymerization ratio (by weight) of 80 parts of styrene and 20 parts of acrylic acid ester. Such systems in which the acrylic acid ester was varied were prepared by block polymerization in am-poules using benzoyl peroxide as an initiator. Each of such polymers was im-mersed in liquid nitrogen and broke into fine pieces and these fine particles and finely cut polyethylene terèphthalate fibers were mixed at a weight ratio of 8.2, the mixture was sealed in a glass tube (ampoule) and heated in a nitrogen atmosphere at 280 C for 4 hours. After cooling, the solid product 29 was taken out and immersed in trichloroe~hylene at a ratio of 4 g of solid .
1(3'7~
per 200 cc of trichloroethylene. The state of dissoLution was observed, to check a gel floatage. The results were as shown in Table 1.
R in Table 1 means the R group of the terminaL -COOR of a carboxylic acid alkyl ester (ROH means an alcohol and -COOR means an ester of that alcohol.
Table 1 ¦ Reference I
Example R Gel Floatage ROH Boiling point _ _ _ Control 1 Ethyl Considerable Ethyl alcohol 78.3 C
(transparent gel) Control 2 Butyl Considerable Butyl alcohol 117.7 C
( transparent _ _ -I
Control 3 Pentyl Slight gel- Pentyl alcohol 137.8 C
_ lin~ occurred _ _ Control 4 3-Pen-tyl Gelling 3-Pentyl alcohol 115.6 C
ocurred _ _ Example 1 Octyl No gelling Octyl alcohol 195 C
Example 2 2-Octyl 2-Octyl alcohol 178 C
Example 3 2-Ethyl- n 2-Ethylhexyl 184.8 C
hexyl _ alcohol ~
Example 4 3,5,5- n 3,5,5_Trimethyl 194 C
Tri- heptyl alcohol methyl heptyl _ ~
Example 5 Nonyl _ Nonyl alcohol 173.3 C
Example 6 Tri- n Trimethyl nonyl 225.2 C
; methyl alcohol nonyl _ _ _ _ _ _ _ Example 7 Cetyl n Cetyl alcohol 344 C
_ . .
Example 8 Stearyl Stearyl alcohol Sufficiently .; , ; NOTE: *at 760 mm Hg ~-29 From the results of Table 1, it may be understood that occurrence ;: i : . ~ . : .
1~7S8~8 or non-occurrence of gelling is influenced by the termina] group ~ of the carboxylic acid ester group. When the boiling points of such a:Lcoho~Ls (ROH) are compared, a boiling point of about 150C can be seen as the boundary between occurrence and non-occurrence of gelling. On the low boiling point side, occurrence of gelling is very noticeable. While on the high boiling point side, occurrence of gelling becomes less, and is eventually not recognizable.
In a system in which a polymer of the vinyl series co-e~ists with a polyester auld the polymer of the vinyl series contains a vinyl es-ter group as in the case of the present invention, it is necessary to select, as said ester, one in which R, when converted into ROH, will have a boiling point of at least 150C.
Examples 9 - 12, Controls 5 - 8 ~` These examples and controls show the stability of polymers of the vinyl series according to the present invention at the time of actual spin-ning, and the drawability at low temperatures of such fibers.
A co-polymer of 2-ethylhexyl acrylate by 20 parts with styrene by 80 parts having an HDT of 60 C, an elongation in hot water at 70 C of 53%
and a shrinkage in hot water at 85 C was used as the sea component of an islands-in-a-sea type composite fiber and polyethylene terephthalate (co-polymeri~ed with 9.9 mol % of isophthalic acid), having an intrinsic viscosity measured in ortho-chlorophenol at 25 C of 0.70 and a softening point of 239 C, was used as the island component of said fiber and spinning was carried out at an islands/sea ratio of 50/50~ with 16 islands present per filament, and using a spinning temperature of 282 C to obtain undrawn filament yarn with 10 denier respecti~ely. me spinning conditions were very stable and bending and instability or vibration of the filaments at the spinneret were not observed. The resulting undrawn yarn was dra~n in a hot bath ~o check 29 its drawability.
~10'75~
Table 2 shows the results o~ this experiment.
Table 2 Drawn isLands-in- Island a-sea composite component~
yarn _ . _ Example Tempera- Maxi- Draw Ten~sile Elonga- Tensile Elonga-ture of mum ratio strength tion strength tion draw draw at bath ratio whhiith-em ng _ 70 C 3.05 2.76 1.93 g/d 19% 2.4 g/d 12.7%
lo ao c 3.32 3.21 2.61 g/d 20% 3-5 g/d 67 %
. _ __ 11 85 C 3.58 3.24 2.85 g/d 28% 3-8 g/d 47 %
9l ~ 4 ~D d ~ 4.01 ~d ~Zl~
NOTE *Whitening is a phenomenon whereby a fiber is devitrified due to the strain of drawing, which is considered to be derived from interphase peeling between the sea component and the island components~ or from - occurrence of micro voids in a sea component which has poor draw-ability. When the fiber whitens, many broken monofilaments are usually mixed.
-VA-~The island component filament remained after the sea component was removed from the drawn islands-in-a-sea type composite yarn by trich-loroethylene.
Table 3 shows examples ~and controls) using ordinary polystryrene instead of using the copolymer according to this invention as the sea com-ponent.
- ~ . . . ' `: :
.: . . - . .
1~'7~ 8 Table 3 Con- Tempera- Maxi- Draw Drawn islands-in- ¦ tsland component trol ture of mum rat-io a-sea composite draw draw at yarn bath ratio which _ _ whit- Tensile Elonga- Tensile Elonga-bnegnang strength tion strength tion __ . .......... . _ C 1.8 1.3 0.9 g/d 14% I.Z g/d 133%
6 80 C 2.1 1.5 1.1 g/d la% 1- 7 g/d 150%
7 85 C 2.78 2.0 1.3 g/d 21% 2.0 g/d ]31%
_ . _ _.. __ a 98 C 3.10 ~.6 1.98 g/d 31% 2.9 g/d 91%
From Tables 2 and 3, it will be understood that the present in-vention is by far superior with reference to drawability. Fibers having high tensile strength and good elongation are obtained according to the present invention.
It is relevant to make a comparison between the elongation in an islands-in-a-sea type composite fiber and the elongation of the island com-ponent after removal of the sea component. In the examples of the present invention, the draw ratio of the composite fiber is sufficiently high to ensure that orientation of the island component proceeds satisfactorily.
On the other hand, in the cases of the comparative examples, the draw ratio cannot be made high enough; it is limited by the fact that poly-styrene has poor drawability. Accordingly, the polyethylene terephthalate, which is the island component, is still almost undrawn, or at best not drawn enough. Accordingly, with reference to the physical properties of island component, the present invention is by far superior.
Example 13_ This example shows a method of effectively utilizing the present 29 invention.
.~ .
1~75~
Polyethylene terephthalate copolymerized with 5 mol percent o-f isophthalic acid was used as the is:Land component of an islands-in-a-sea type composite fiber. The product obtained by copo~ymeri7ing 80 parts of styrene and 20 parts of 2-ethylhexyl acrylate was used as the sea component.
The fiber was sp-m at a ratio of islands/sea of 52/48 and 16 islands/ filament to obtain a 10 denier x 84 filament undrawn yarn. The spinning process was very stable and no traces of gel could be recognized after dismantling khe pack. Using the undrawn yarn, drawing was carried out while varying the drawing conditions. The results are shown in Figure 3.
As will be apparent from Figure 3, the shrinkage was greatly affected by the drawing temperature. In order to make a highly contractible fiber, the fiber had to be drawn at a low temperature, and the object could be achieved easily and effectively by combination of the polymers of the pre-sent invention only.
Control 9 Example 13 was repeated, except using a styrene (80 parts)/ethyl acrylate (20 parts) copolymer as the sea component in spinning.
After spinning for S hours, the pack was dismantled, the spinneret was taken out and cooled. Thereafter, it was in~ersed in trichloroethylene.
Even after 20 hours, the sea component polymer had not dissolved and the spinneret was still blocked with swollen gel.
Example 14 Upon obtaining a sheath-core type composite fiber, polybutylene terephthalate was used as core component and a styrene (90 parts)/stearyl methacrylate (10 parts) copolymer (having an HDT of 53.8 C~ an elongation in hot water at 70 C of 250% and a shrinkage in hot water at 85 C of 58%) was used as the sheath component. They were spun at a ratio of sheath/core of 65/35 to obtain a 12 denier x 24 filament undrawn yarn.
29 This yarn was drawn 3.6 times in a hot bath at 90 C. A trans-, ., ~ .
- :~
10'7~ 8 parent, lllstrous yarn having a good drawability was obtained. After spinning there was no block~ge of the spinneret by gel.
Example 15 30 parts of polyethylene terephthalate copolymerized with 7 mol %
of adipic acid and 70 parts of a terpolymer of 2-ethylhexyl acrYlate (10 parts)/stearyl methacrylate (5 parts)/ styrene (85 parts) (haYing an HDT of 54.7%, an elongation in hot water at 70 C of 149% and a shrinkage in hot water at 85 C of 48%) were so spun that the resultant undrawn yarn had a nebulous cross-section. Such fiber was easily spun by forming a layer com-posite stream and by passing it through a sand layer or the like. me un-drawn ya~n was drawn 3.5 times in a hot bath at 80 C. It showed very good drawability and a good, lustrous yarn free of devitrification was obtained.
Gelation after spinning was not observable.
Example 16 Polyoxy benzoate was used as an island component of an islands-in-a-sea type composite fiber and a terpolymer consisting of 5 parts of nonyl acr~-late, 15 parts of 2-octyl acrylate and 80 parts of styrene (having an HDT of 57.8 C, an elongation in hot water at 70 C of 130% and a shrinkage in hot water at 85 C of 45%) was used as a sea component of composite fiber 20 in carrying out spinning at an islands/sea ratio of 55/45 and 16 islands/
filament. me resulting undrawn yarn was drawn 3.6 times in a hot bath at 85 C to obtained a 3.2 denier transparent staple free of devitrification.
On the other hand, the above procedure was repeated except for using polystyrene as a sea component in carrying out spinning and drawing, in which case the draw ratio was limited to 3.2 and a devitrified yarn having a coarse surface was obtained.
Both of these yarns were repeatedly passed through a card 5 times under the same conditions to observe the coiled arrangement of the fibers 29 around the card. In the case of the copolymer, according to the present invention, as one component, it was observed that the fiber did not coil around the card at aLl. However~ in the case of the -fiber of the conventional example using polystyrene as the sea component, occurrence of neps was rec-ogni3ed from ~nd after the second time the yarn was passecl through the card, and the occurrence of neps bec~me very noticeable from the fourth time the yarn was passed to the card and thereafter. When these neps were observed, the sea component split and the minute i~land components were exposed and entangled to cause the neps.
~xample 17 A polymer consisting of 25 parts of 2-ethy~hexylacrylate, 75 parts of styrene and 0.01 part of diYinyl benzene having an HDT of 50.3 C, an elongation in hot water at 70 C of 1130% and a shrinkage in hot water at 85 C of 68% was used as the sea component of an islands-in-a-sea type com-posite fiber. Polyethylene terephthalate (intrin3ic viscosity 0.70) was the island component of the composite fiber. Spinning was carried out at a ratio of islands/sea of 4~/51 and 16 islands/filament at 278 C. The spinnability was very good; an undrawn yarn was produced having a stable cross-section in which the island components were uniformly distributed. The undrawn yarn was drawn 3.4 times in a hot bath at 70 C to obtain a 3.0 denier highly contractible yarn having a boiling water shrinkage of 33.8%. The yarn was passed through crimping apparatus to have crimps imparted about 10 crimps/
2.54 mm. However, splitting of the sea component at the sharp points of the crimps was not recogni~ed. Using the yarn (cut length 51 mm), a web was formed using a cross lapper. The web had a weight per unit area of 570 g/m2.
; This felt was needle punched to produce a high-density felt having a punch density of 1700 punches/cm and an apparent density of 0.202 g/cm3.
This felt was immersed in hot water at 80 C and thereafter immersed in polyvinyl alcohol solution. Subsequently, being dried, it was immersed in 29 trichloroethylene to dissol~e the sea component of the fiber. Then it was 1~:)'75~3~i8 followed by impregnation with polyurethane, coagulation and a napping treat-ment to create a velour-like leathery sheet material having unprecedented characteristics and properties.
Control 10 Example 17 was repeated, but using polystyrene as the sea component.
The spinning process was good; however, the undrawn yaIn could be drawn only 1.8 times to avoid partial whitening and yarn breakage.
Using the drawn yarn, a web was formed, which was needle punched in the same way as in Example 17; however, even when punching was carried out to a p-mching density of 3000 punches/cm , the apparent density of the felt was saturated at 0.155 g/cm . Using the resulting felt, a velour-like leathery matter was made; however, it was by far inferior to the velour-like leathery material obtained in Example 17. Using the fibers according to the present invention, the felt-forming properties were very good, and the resulting felt became a high-density compacted felt. In the control, the felt-forming property was remarkably poor. Because of the hard properties of polystyrene, the fiber became hard and strong in its repulsive properties, and intertwinement did not take place easily.
Control 11 This example (control) shows the examined results of the case of using a plasticizer for the purpose of improving drawability and flexibility of polystyrene. Although this is one example of the use of a plasticizer, it is a representative example illustrating limitations in the use of plasti-cizers.
DOP (dioctyl phthalate) is used as a plasticizer for styrene. A
` polystyrene polymer~ into which 3% by weight of DOP was added, was spun at 285 C. The spinning pressure at the time of spinning was reduced by about 31% as compared to that of a blank polystyrene polymer containing no DOP.
29 The spun polymer was taken up at a take-up speed of 400 m/min to obtain an ~(~'i'S~3~8 ~mdrawn yarn o~ about LO denier.
This undrawn yarn was pulled thro~lgh a liq~id at 70 C at a speedof 10 m/min and its elongation at break was measured. The increase of elon-gation of the undrawn yarn spun from the polymer containing 3% of DOP was only 1.8%, as compared to an undrawn yarn spun from the polymer which con-tained no DOP, and no substantial plasticizing effect was recognized. Where-as, as a peculiar functional effect of such plastici7er, there was a remark-able, undesirable action of promoting lowering of the viscosity of the molten polymer, not expected from the small plasticizing effect at the time of cooling. Specifically, by adding only 3% of the plasticizer, the pack pres-sure (filter pressure) at the time of spinning decreased by as much as 31%
as compared with that of the blank polymer not containing any plasticizer.
The effect of the plasticizer became very remarkable at the time of melting.
This polystyrene polymer containing 3% of the plasticizer was used : ' .
as the sea component of an islands-in-a-sea type composite fiber, and poly-ethylene terephthalate (intrinsic viscosity 0.72) was used as the island component. They were spun at an islands/sea ratio of 50/50 and by a 16 is-lands/ filament spinneret at 285 C. The spinning was carried out by first discharging the sea component, and later the islands componen~. Immediately after the discharged amounts were mixed, take-up was started. Immediately after the start of the spinning operation, a composite stream extruded smooth and straight from the spinneret orifice and the spun and undrawn yarn had a normal sectional configuration in which the island components were uniformly distributed. However about 3 hours after the start of spinning, the stream began to bend slightly, while a further 4 hours later, the stream bent so extremely as to touch the spinneret surface. Drips began to occur. At this point variation of denier among the holes of the spinneret began to be seen.
When the cross sections of such yarn were observed, the island 29 components adhered to each other, composite unevenness (component ratio un-1~75~8 evenness) was sharp and, in atl cxtreme manner, the island co~ponents and the sea compon~nt e~isted as complete~Ly independent monofilaments in admixture among the holes (toward each hoLe of the spinneret~. In a yarn using a polystyrene homopolymer not containing the plasticizer as the sea component, there was no occurrence of such disorder because, by addition of the plasti-cizer, the viscosity at the time of melting decreased, difference of vis-cosity values between the sland components and the sea component became extremely large and the spinning process became remarkably unstable.
The ~mdra~n yarn obtained immediately after the start of discharging was drawn in a hot bath at 98 C. However, it could be drawm only 2.7 times and no substantial effect of addition of plastici~er on drawing was recognized.
Control 12 A system in which liquid paraffin was added into polystyrene was used in carrying out spinning and drawing as an islands-in-a-sea type com-- posite fiber, otherwise the same as in Control 11.
~- As the ratio of liquid paraffin added to the polystyrene, the various levels of 0, 5, 10, lS and 20% were selected. When 15% of liquid paraffin was added to the polystyrene, the melt viscosity of the polystyrene decreased too much and spinning was impossible. The spinnable limit occurred at a ratio of liquid paraffin of 10%. Accordingly, the undrawn yarns were provided with 0%, 5% and 10% of liquid paraffin. These undrawm yarns were dra~m in a liquid bath at 80 C. The results in terms of draw ratio were 2.0 in the case of 0% (blank), 2.3 in the case of 5% and 2.4 in the case of 10%.
By addition of liquid paraffin, drawability was slightly improved. However, there was no substantial difference between addition of 5% and 10%, and the effect of the amount added per se was small. As reasons for this, it is con-ceivable that by making the polymer into a yarn at the time of spinning, the high temperature surface area becomes very large, from which an excess of 29 plastici~er evaporates. A low boiling point plastici~er evaporates at the 58~8 time ot` spinning, l~aving no effect; a high boiling point plasticizer does notdevelop its effect sufficierltly at the time of drawing.
E mple l8 Using a biaxial extruder-type spinning machine, a mixed chip of 35 parts of polyethylene terephthalate and h5 paIts of astyrene-stearyl acrylate (75/25) copolymer was spun. As a control, mixed chips of 35 parts ofpolyethyleneterephthalate and 65 parts of polystyrene were spun using the same spinning machine. The two different undrawn yarns were drawn in a hot bath at 80 C to check the drawing conditions.
Table 4 - ....... .. _ , .
_ This invention Control Maximum draw ratio 3.4 2.7 Yarn breakage at the time of drawing~ ~ 9.3 times/min .
*Frequency of occurrences in which the yarn coiled around the roller, per minute, when drawing was carried out at a draw ratio of 0.95 x maximum draw ratio.
From these results, the good drawability of the yarns according to the present invention should be understood.
Exam~le 19 A 2-ethylhexyl acrylate (20 parts)/styrene (80 parts) copolymer was used as the sea componènt and a polyethylene terephthalate copolymer ` copolymeri~ed with 5 mol % of isophthalic acid was used as the island com-ponent in carrying out spinning at an islands/sea ratio of 50/50 and 16 islands/filament as an islands-in-a-sea type composite fiber.
No chimney was used in the spinning procedure and the resulting undrawn yarn was taken up through a hot tube provided 1.5 m directly below 29 the spinneret. The atmospheric temperature of said tube was controlled at 1~175~8240 C. The ~mdrawn yarn was drawn ~.2 times at 82 C and a highly contract-ible yarn having a shrinkage in boiling ~ater of 34% was obtained.
The Young's modulus determined from measured strain-stress curve of the sea component filament after dissolving the sea component after con-traction was very high for the shrinkage.
Example 20 In Examples 9 - 19, when the resulting drawn yarns were immersed in trichloroethylene and washed, the sea components dissolved more easily and operations for washing and removing the sea components were easier than in the case of polystyrene alone.
And because the draw ratios were high, the tensile strength of the remaining sea components were remarkably high (see Tables 2 and 3).
Example 21 Example 9 was repeated, except using polyethylene terephthalate as the island component and changing the draw ratio to 3.5 in making a 3.5 denier stream (about 96 - 98C) drawn yarn. This yarn was small in elongation (the island component too) and small in contractibility and was an excellent fiber. About 8 - 12 crimps/in were imparted to the yarn, which was made in-.:
to 51 mm cut staple and 76 mm cut staple. When these staple samples were subjected to ordinary staple system and woolen system spinning to make 16S/2 and 2/12-spun yarns, respectively, they became good spun yarns having very little occurrence of fly and white powder. Used as warps a false twisted filamentary yarn (150 denier) and using as weft, each of the aforesaid spun yarns, these warp and weft yarns were woven into Turkish satin fabrics, respectively.
` It was possible to form a very good nap on the surfaces of these satin fabrics by subjecting them to the action of a napping machine using a card cloth before or after removing the sea component.
29 For information, with reference to fly and white powder7 when the 7~
sea component is substa~tialL~ only polystyrene regard:Less of being mixed or not nuxed with about 0.5% of liquid paraffin, there is a conslderably large amount of fly or white powder at the t:ime of spinning, especially at a yarn uniting or twisting machine and at a spinning winder. On the contrary, in the present invention, because drawing is not carried out to the upper limit, it is possible to avoid the creation of objectionable amounts of fly and white powder.
Example 22 This example shows the importance of the copolymerization ratio.
Polymerization conditions:
- Catalyst: 0.2 parts based on the weight of monomer of benzene peroxide 0.1 parts based on the weight of monomer of ter-butyl perbenzoate Water/monomer: 150/100 (suspension polymerization) Polymerization time: 6 hollrs at 100 C
.
2 hours at 120 C
Making the above conditions constant and varying the copolymeriza-tion ratio of 2-ethylhexyl acrylate/styrene of the charged monomers, poly-merizations were carried out. The drawability ~elongation) of the polymers was checked by the method mentioned in the text of the specification. The results appear in Figure 4. As will be apparent from Figure 4, from a point where the copolymerization ratio is about 10%, the copolymers begin to elon-gate well. From the point where the copolymerization ratio is about 15% as a boundary, the copolymer suddenly begins to elongate well, which is a char-actelistic of the present inven~ion. This fact shows that a copolymerization ratio of not less than 10% is very important for achieving some of the im-portant objects of Athe present invention.
Examples 23 - 28 29 Controls (Comparative Examples) 12 - 14 10'7S~
In E~ample 7, tlle atmospheric temperature at a point 10 cm directly below the spinneret ~as controLled at 40 C, 150 C and 250 C in taking up the undrawn yarn.
Draw tests of the resulting undrawn yarns were carried out. They obtained the follo~ring results:
Table 5 Sample Tempera- Preheat Draw Draw Maximum No.ture tempera- tempera- speed draw spin- ture ture ratio~
. .
10Colnt2rol H-l 40 C R.T. 70 C lmiOnm/ 3.28 times Cln3rl H-2 40 C 40 C 70 ClmiOnm/ 3.33 times Control H-3 40C 70 C 70 C150 m/ 3.5 times 14~ _ min Exa2m3ple H~4150 C R.T. 70 ClmiOnm/ 3.82 times ~xample H-5150 C 40 C 70C150 m/ 3.91 times 24 min Example H-6150 C 70 C 70C150 m/ 4.17 times min ._ .. _ Example H-7250 C R.T. 70C150 m/ 3.88 times 20Exmmple H-8250 C 40 C 70 C150 m/ 4.17 times H-9 50 G 70 C 70 C150 m/ 4.l NOTF: ~'R.T. = room temperature YA-`~Maximum draw ratio = elongation at break From the aforementioned results, it was found that when the tem-perature at a point below the spinneret is high, drawability is good. By increasing the preheat temperature, drawability ad-vances.
Example 29 29 The heat stability of a styrene ~78 parts)/2-e~hylhexyl acrylate . - - . . .. . ,, . - . .
., - ~, ~ . , ~ .
1~75~8 (~2 parts) copol~ner was checkecl.
~lethod of estimating heat stability;
In N2 gas 20 cc/min Amount of the sample: 400 mg Temperature 285 C (temperature was raised from room temperature to 285 C at a rate of 10 C/min) The weight diminished ratio of the polymer in the aforementioned atmosphere was checked. This ratio is defined by ~he formula:
W-Wl X 100 .` 10 W
- where ~ is the weight of polymer before heating and Wl is the weight of the polymer after heating for a particular time. The results are shown in Figure S, wherein:
(A) is a thermal decomposition curve of the sample pelletized at 245 C.
The decomposition ratio is remarkably high.
(B) is a thermal decomposition curve of the sample pelletized at 215 C.
By reducing the temperature to 215 C, the thermal decomposition was remark-ably improved.
(C) is a the~lal decomposition curve of the sample added with a thermal ~ 20 decomposition stabilizer. It was found that a beneficial effect (to this ; polymer) was obtained by addition of a thermal decomposition stabilizer (1,3,5-trimethyl-2,4,6-tris (3,5-di-ter-butyl-4-hydroxyben~yl) benzene).
Example 30, Control 15 A styrene (78 parts)/2-ethylhexyl acrylate (22 parts) copolymer having an HDT of 54.5 C, an elongation in hot water at 70C of 590% and a shrinkage in hot water at 85 C of 58% was used as the sea component of an islands-in-a-sea type composite fiber. An isophthalic acid copolymerized polyethylene terephthalate having a softening point of 235 C was used as the 29 island components o-f said composite fiber in carrying out spinning at an ,. . .
~.~758~
islands/sea ratio o~ 50/50, and with a total o~ 16 islands/fiLament. Theresulting undrawn yarn was wound at a speed of 1070 m/min under such condi-tions that the temperature at a point 10 cm direct:ly below the spinneret was 92 C and 298 C. These undrawn yarns were drawn in hot water at 70 C to check the maximun) draw ratio. The results were as follows:
Atmospheric temperature Maximum directly below spinneret draw ratio Control 15 92 C 3.3 times Example 30 298 C 4.02 times A great difference in maximum draw ratio was observed with changes of atmospheric temperature at a point directly below the spinneret. By raising said temperature, it is possible remarkably to raise orientation of the yarn, and the spinning productivity as well.
- xample 31 In Example 30, the undrawn yarn was drawn at a ratio of 3.92, and crimp was imparted to the drawn yarn. A stuffer box type crimper was used, a fiber oilingagent kept at a constant temperature (15 C) was flowed to cool -the crimper and the roll surface temperature of the crimper was kept at 38 C.
The yarn product showed a shrinkage of 40.3%.
Control 16 As in Example 31, the temperature on the surface of the crimper was changed to 62 C. The resulting yarn had a shrinkage of 2~.7%.
Example 32 The yarn obtained in Example 31 was dried at 40 C. Its shrinkage was 40.2% and no change of shrinkage by drying was observed.
Control 17 ~ -As in Example 32, the drying temperature was 65 C. The shrinkage of the yarn, after drying, was 11.2%.
EXample 33 The yarn in Example 32 was subjected to a card and to a cross 1~7S8~
lapper to form a web. This web was needle punched to make a felt having an apparent density of 0.173 g/cm . A good ~elt in which punched traces were a'most ~recognizable was obtained. This felt was immersed in hot water at 55 C and then in hot water at 85 C, and ligl-tly rolled by rolls to obtain a flat contracted felt. As a result o-f measuring the shrinkage, it was found that the felt contracted by 24% in area at 55 C, and contracted to 56% of the original area at 85 C. The contracted felt was excellent and free from creases.
This fel-t was impregnated with an 18% aqueous solution of poly-vinyl alcohol and dried at 80 C. ~fter drying, the felt was immersed in trichloroethylene and the sea component was dissolved ~d removed. Next, the felt was heat treated in hot air at 180 C for 5 minutes, impregnated with DMF
(dimethyl formamide) solutions of various concentrations of polyurethane whose soft segment was polytetrahydrofuran having a molecular weight of about 2000 and whose hard segment consisted of p,p'-diphenylmethane diisocyanate and p,p'-diaminodiphenyl methane, and then the felt was immersed in hot water at 90 C to remove PVA (polyvinyl alcohol) and sliced along the center into two halves. Both surfaces of the sliced substrate were buffed with sandpaper.
After buffing, the sheets were dyed a chestnut color with a dispersed dyestuff 20 at 115 C.
The product had an apparent density of 0.24 - 0.32 g/cm , a bright color and excellent hand and volume, being free from nap entanglement. The elongation resistance and abrasion resistance were measured, and the results are shown in Figures 7 and 8, respectively.
Figure 7 shows the relation between the binder content ratio and the deformation of the product. It was found that at a binder content ratio of not less than 26%, a remarkable improvement was achieved and the deforma-tion could be controlled to a value of not more than 12%, which is within the 29 range demanded for practical use.
~)758~3 Figure 8 sho~s the results of measuring abrasion resistance. The thickness of the sample upon measuring the chafing number was made the actual thickness. The thickness of this sample was 0.8 mm. It was found that with a binder content ratio of about 33~, the abrasion resistance (chafing number) was remarkably improved.
Control Example 18 Example 33 was repeated except for omitting the heat treatment.
When the deformation ratio was measured at the binder content ratio of 34%, it was 13.2%. And it was found that heat treatment is remarkably effective for inlprOving quality.
Control 19 Example 33 was repeated except for limiting the contraction to one contraction at 55 C. The product had an apparent density of 0.21 g/cm3 and and a binder content ratio of 34%. The thickness of the sample at this time was 0.8 mm and the chafing number was 118, which was quite poor.
Example 34 The amount of the minute fibers adhered in the sample whose binder content ratio was 34% of Example 33, was measured by the minute fiber adhesion method. The value was 73 mg.
Control 20 Example 33 was repeated except for omitting the heat treatment.
The amo~mt of minute fiber adhered, in the resulting sample having a binder content ratio of 33%, was measured. The value was 213 mg, which was increased '~
remarkably as compared to the value in Example 34. ~;
In a multi-component fiber according to the present invention, for - example, an islands-in-a-sea type composite fiber, when polyethylene tereph-thalate is used as the island component, when the draw ratio is raised, a filament is obtainec which is unlikely to contract. When a woven fabric 29 having a superfine nap is macle using such a composite fiber, the destruction 1~758~8 of the sea component at the time of spinning is small as compared to a con-ventional -is~lands-in-a--sea t~pe composite fiber using a sea co~ponent con-sisting of a polymer of the polystyrene series. Because of that, coiling of fibers around the rolls in the drawing step and the spinning step is ]ess, the luster of tlle nap of the res~lting fabric is excellent, the nap is un-likely to curl and, because of that, the fabric has an excellent hand.
Examples of steps for making such woven fabrics are as follows:
(1) (a) Spinning of an islands-in-a-sea type staple fiber to be used as weft.
; 10 (b) Woolly, processed, latent crimped or ordinary filament yarn, to be used as warp (c) Satin fabric is made -- 4, 5 and 8-ply (d) Contracting treatment or desizing (when the warp was sized, desizing is carried out) ` (e) Removal of the sea component (dissolving) ~ f) Oiling (for napping) and/or crimp developing treatment (heat treatment) ~ g) Napping (h) Adding an anti-pilling, balancing agent (a high mo]ecular ~eight elastomer such as polyurethane) (emulsion or solution) (including solidification and drying) (i) Napping ~buffing) (j) Dyeing (including reduction washing and/or drying) (An example of reduction washing is use of a dilute hot aqueous solution of sodium hydro-` sulfite (Na3S204) and caustic soda (NaOH) (k) Finishing (imparting a finishing oiling agent, brushing and/
or buffing of the back surface) (2) (a) Spinning of islands-in-a-sea type staple fiber (as weft) 29 (b) Woolly processed, latent crimped or ordinary filament (as warp) 1 1:)75868 (c) Sat:in fabnic (d) Cont~acting treatment or~ desiz:ing (e) Remova.l. of` ~ea component (f) Oiling and/or cri~p de~e10ping treatment (heat treatment) (g) Napping (h) Imparting a sizing agent ~dr~ing) (i) Imparting an ~mt,:i-pilling'ba~ancing agent (emu~sion or solu-tion Removal of the sizing agent (desizing) - 10 (k) Napping (buffing) '` (1) Dyeing and dyeing finishing (m) Finish processing of woven fabric (3) (a) Spun yarn or filament of an islands-in-a-sea type stap~.e fiber las a napped fiber) ,., (b) Spun yarn or filament (as warp and weft of the base) (c) Seal woven fabric (d) Backing (solution or emulsion) (e) Removal of the sea component (preferab],y buffing the back ' ' surface) (f) Dyeing :~
(g) Finishing (preferably buffing the surface and the back surface) '; ~en the islands-in-a-sea type fiber is highly contractible, the aforesaid step (3) is further improved and the woven fabric made a napped fabric having short nap.
(4) (a) Spun yarn or filament of an islands-in-a-sea type staple fiber (as a napped fiber~
(b) Spun yarn or filament (as warp and weft of the base) (c) Seal woven fabric 29 (d) Backing : - ~. . .
. .-. :
~0~5~
(e) Contracting step af`ter (c) or (d) (f`or shortening nap) (f) Rc~lovaL of sea componen-t (g) Dyeing (h) Finishing Example 35 A total 150 denier x 48 filament woolly false twisted yarn of : ~ polyethylene terephthalate was used as warp ~ncl a spun ya~n from an is~a~ds-in-a-sea type stap].e fiber whose island componellt was polyethy.Lenc terephtha~
late and whose sea component was a copolymer of 72 parts of styrene and 28 parts of 2-ethylhexyl acrylate, was used as weft in weaving a fabric.
The islands-in-a-sea type staple fiber had the following character-istics:
Number of islands 16 (see Figure 1) Island component ratio 55% by weight Sea component ratio 45% by weight Denier 3.0 - Fiber length 51 mm . Number of crimps 8 - 12 per inch Draw ratio at the time of drawing 3.2 This staple was spun into a 20/28 spun yarn.
The spinnability at this time was good, the staple fiber was pro-cessed favorably through carding, drafting, roving and spinning steps, and coiling of the staple around the card, drafting rollers and spinning rollers took place very seldom, and good spinning could easily be carried out.
Further, the aforesaid yarns were used as warp and weft, respective-ly, and they were woven into a 5-ply satin fabric to produce a weaving den-sity of 100 warps/in and 60 wefts/in. At this time, an.-edge of about 1 cm was made and a basket weave was selected as the woven pattern.
29 The fabric was washed with hot water at 80 C. After it was dried, .. .
s~
the fabric wa~ thoroughly washed 5 t-imes ~ith trich~oroethylene, and the sea component ot` thc weft was remo~ed. After it was driedJ the fabric was passed through hot water containing an ordinary oiling agent for napping, and dried.
The resulting fabric was passed 7 times through a rotary card cloth napping machine to nap the surface, to obtain a napped fabric in which super~
fine fibers were thoroughly napped. This fabric had wonderful smooth touch.
~lowever, it had poor pilling resistance and hand, and the firmness that re-sulted when it was bent longitudinally was greatly different from that which resulted when it was bent transversely. When it was bent transversely, creases were left behind. The fabric was out of balance.
is fabric was impregnated with a 10% dilute polyurethane emulsion consisting mainly of polypropylene glycol, toluylene diisocyanate and hexa-methylene diamine prepared according to known methods of polymerization, namely, according to the method disclosed in Japanese Patent No. 242 577 (James E. ~aloney), and dried. The amount that adhered, calculated as pure polyurethane, was 21 g/cm . The resulting fabric was napped ~buffed~ by #150 mesh sandpaper. The front surface was buffed thrice and the back surface ;
was buffed once by a belt sander buffing machine. As a result of this buff-ing, the fabric became a sue~e-like fabric whose surface was covered with compact superfine nap. It was heat treated at 170 C for 3 minutes in hot air.
Next the fabric was dyed in a brown color by a circular type pres-sure dyeing machine; washed with water, a finishing oiling agent was applied and dried in hot air at 90 C according to known methods. The back surface was buffed to remove ugly naps raised here and there, and the surface was brushed and finished. When the naps were brought down to one side and the fabric was so dried that the surface of the fabric could contact the surface of a dryer roll at 90 C, the fabric developed excellent surface gloss and brilliance. -29 The resulting fabric was a suede-like abric, the texture of which :1~7S~8 was hal~lly v:is:ible, hav:ing a wondcrt`u:lly sott and smooth surface touch and soft hand, and it was so weL:L ba:lanced that any direct.ional d:ifference i.n hand when it was bent longitud:inally and transverseLy was a:l.most ~lnoticeable.
Because the fiber was well drawn in this fabr:ic, super:t`ine naps were in evidence, having almost no -tendency to be entangled, and they had excellent gloss.
Example 36 Example 33 was repeated except for using a polyethylene terephtha late copolymer having a softening point of 231 C, copolymeri~ed with adipic acid in an amount of 11% based on the weight of the polymer, as an island component in fibers used for preparing artificial leather.
The resulting artificial leather was dyed at a temperature of 105 C.
The resulting dyed artificial leather had an excellent appearance in which any color difference between the binder and the fiber was virtually undetect-able and inconspicuous. The defor~ation ratio was 7% and the chafing number was 320.
. . .
:' '
Claims (8)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a method of making a sheet-like material which comprises a fiber aggregate comprising multi-component fibers comprising at least two components (A) and (B), one component (B) being a copolymer of about 90 to 70% of styrene and about 10 to 30% of an ester selected from acrylic acid and methacrylic acid, and the other component (A) being a fiber-forming thermoplastic polymer, the steps of removing said component (B) from said component (A) whereby each said fiber becomes a bundle of fine fibers having a maximum denier of about 0.45 and consisting of said component (A); shrinking said aggregate at a time other than the time of removing said component (B); subjecting said aggregate to a substantial heat treatment at a temperature ranging from 160°C to 220°C;
and impregnating said aggregate with a binder at a time other than the time of said heat treatment.
and impregnating said aggregate with a binder at a time other than the time of said heat treatment.
2. A method according to claim 1 wherein the contractibility of said aggregate is at least about 27% with respect to the area of the aggregate.
3. A sheet-like material comprising a bundle of fine fibers of a thermo-plastic polymer and a binder and having a maximum deformation ratio of about 12% and a minimum apparent density of 0.21 g/cm3, said fine fibers having a maximum denier of about 0.45.
4. A sheet-like material according to claim 3, wherein the binder con-tent ratio, based on the weight of fiber, ranges from about 20% to 60%.
5. A sheet-like material according to claim 3 which has a nap of maxi-mum denier of about 0.45 on at least one surface thereof.
6. A sheet-like material according to claim 3, wherein said bundle of fine fibers consists of polyester.
7. A sheet-like material according to claim 3 which has a chafing number of at least 150.
8. A sheet-like material according to claim 3, wherein said bundle of fine fibers consists of polyester containing an acid selected from the group consisting of isophthalic acid and adipic acid, in an amount ranging from about 4.5% to 20% based on the weight of polyester.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA315,686A CA1075868A (en) | 1973-04-05 | 1978-10-31 | Filament with copolymer component of styrene and higher alcohol ester |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP48038218A JPS5013849B2 (en) | 1973-04-05 | 1973-04-05 | |
| CA196,822A CA1049728A (en) | 1973-04-05 | 1974-04-04 | Filament with copolymer component of styrene and higher alcohol ester |
| CA315,686A CA1075868A (en) | 1973-04-05 | 1978-10-31 | Filament with copolymer component of styrene and higher alcohol ester |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1075868A true CA1075868A (en) | 1980-04-22 |
Family
ID=27163408
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA315,686A Expired CA1075868A (en) | 1973-04-05 | 1978-10-31 | Filament with copolymer component of styrene and higher alcohol ester |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1075868A (en) |
-
1978
- 1978-10-31 CA CA315,686A patent/CA1075868A/en not_active Expired
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