GB1584313A

GB1584313A - False twisted yarns and processes for producing them

Info

Publication number: GB1584313A
Application number: GB3882977A
Authority: GB
Original assignee: Toray Industries Inc
Current assignee: Toray Industries Inc
Priority date: 1976-10-06
Filing date: 1977-09-16
Publication date: 1981-02-11
Also published as: FR2367127B1; IT1091252B; FR2367127A1; JPS5927407B2; JPS5345444A

Description

(54) FALSE TWISTED YARNS AND PROCESSES FOR PRODUCING THEM (71) We, TORAY INDUSTRIES INC., a corporation organized and existing under the laws of Japan, of 2 Nihonbashi-Muromachi 2-chome, Chuo-ku, Tokyo, 103 Japan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to false-twisted yarns and processes for their manufacture, employing "islands-in-a-sea" type composite filaments. The invention relates to falsetwisted yarns composed essentially of "islands-in-a-sea" type composite filaments and yarns of superfine fibres made of such filaments.

The yarn according to the invention firstly provides a false-twisted yam comprising a plurality of "islands-in-a-sea" type composite filaments, said filaments each comprising a plurality of island components each having a predetermined melting point, and a sea component having a melting point below that of said island components, in which the cross-sectional configuration of each of the island components in said filaments is substantially free from any deformation caused by the application of the false twist to the yarn.

The substantial freedom of deformation can be established by contrasting any deformation with the substantial deformation occurring in normal false twisting filaments without embedding the filaments in a sea component. Normal false twisting not only results in crimping of the filament but also in altering the filament crosssection as it becomes sufficiently plastic to be crimped. Using the invention such cross-section deformation is primarily imparted to composite filaments whereas the individual island filaments are relatively unaffected. However the individual filaments do follow the crimps imparted to the composite filament as a whole.

The invention also provides a process for producing a false-twisted yarn which comprises false-twisting "islands-in-a-sea" type composite filaments, which each comprise a plurality of higher melting point island components and a lower melting point sea component, at a temperature Q, wherein Q satisfies the relationship P + 10 < Q! < R C wherein P is the melting point of the sea component and R is the melting point of the island components, the false twisting of the yarn being controlled so that the cross-sectional configuration of each of the island components in said filaments is substantially free from any deformation caused by the application of the false twist to the yarn.

"Islands-in-a-sea" type composite filaments for false-twisting according to the invention are each composed of a plurality of superfine filamentary constituents (island component) in a matrix of a different constituent (sea component). The shape or configuration of the island components within the sea component is not particularly limited. Composite filaments in which the island components are partly exposed as in Figures 2 and 3 of the accompanying drawings are within the scope of the present invention. Also included are composite filaments as shown in Figure 2 of the accompanying drawings in which islands components are connected at very narrow constricted portions which may yield under subsequent treatment to allow the island components to become wholly separated.

Various polymers may be utilized for the island components. These may include thermoplastic polymers for clothing such as a polyester, including polyethylene terephthalate, or polyamide. However, for the sea component, a thermoplastic polymer whose melting point is lower than that of the island component by at least 1000C, preferably at least 1200 C, such as polystyrene or co-polystyrene is suitable.

When the difference between the respectlve melting points is less than 100go, the island components may be deformed to some extent as a result of false-twisting.

The percentage by weight of the island components to the total yarn weight is preferably within the range of 65 to 90%. When the weight percentage of the island components exceeds 90%, and the sea component is subsequently removed, there is less space between the island components, resulting in increased friction among the monofilaments in the final product. The product is inferior in repulsion, and it becomes difficult to obtain a product with a good balance with respect to drapability and repulsion. On the other hand, when the weight percentage of the island com ponents is less than about 65% based upon the total, the space that is provided among the monofilaments after removal of the sea component becomes large, the fabric resistance may be lost and an organizational abberation called thread slippage tends to occur.The preferred range of the weight ratio is from 75 to 90%.

The denier of each of the island components may have an average value within the range of from 0.001 to 10 denier (d). Preferably it is from 0.5 to 0.9 d. When the denier is too high, it is difficult to obtain a product having mild lustre, soft surface touch and pliant drapability. On the other hand, when the denier is too low, diffusion and reflection of the fibre becomes excessive, with the result that the colour appears pale and it is not feasible to obtain the deep shades often required for clothing.

The number of island components (monofilaments) is preferably from 3 to 10.

When the number exceeds 10, the rigidity of the composite filaments may be high.

When filaments are then formed into a product the yarn does not bend easily and it becomes difficult to produce a product having high density. When the number of filaments in the yarn is less than 3, the filaments become very fine and the incidence of yarn breakage during subsequent warping, re-winding or drawing operations increases.

As stated, the composite filaments used in the invention are deformable. Preferably, at least two island components are used which differ with respect to degree of cross-sectional deformation before application of a false twist to the yarn. Such com posite filaments, when separated from the sea component and made into a product, change the bulkiness, feel and lustre of the product and produce a product having a unique hand. The degree of deformation referred to above is defined as the diameter of the circumscribed circle which may be drawn about the cross-sectional shape of the fibre so as to touch the extremities of the fibre divided by the diameter of the inscribed circle which may be drawn within the cross-sectional shape of the fibre so as to touch the sides of the fibre.

It is especially preferable for such composite filaments to contain at least two island components that have degree of deformation which differ by at least 0.2.

False-twisted yarn according to the invention may be produced as follows: "Islands-in-a-sea" type composite filaments (30--250 d) are subjected to the action of a conventional false-twisting spindle utilizing friction with a friction-type spindle where it is false-twisted to the extent of at least 1000 t/m. This twist is fixed using a hot plate or hot cube, and the composite filaments are detwisted on the untwisting side. If necessary, the composite filaments may be subjected to a secondary heat set under low tension while being overfed after detwisting, and may be made into a processed yarn having no stretch, which is ordinarily called a bulky yarn. The number of twists and the processing tension are exactly the same as in an ordinary falsetwisted yarn.

In the present invention, it is necessary to carry out the false-twisting step at a temperature Q within the following range to give island component filaments substantially free of deformation: P+ 10Q < R0C wherein P is the melting point of the sea component and R is the melting point of the island components.

The exact range may be selected having regard to the following considerations.

Referring to Figure 7 of the accompanying drawings, the change of crimp rigidity when a multifilament yarn consisting of six 50 d/12 fil. polyester island components and a polystyrene sea component (melting point 100 C) are twisted by 2700 t/m and the temperature of a heating zone is varied, as shown. In the expression 'six 50d/12 fil., '12' refers to the number of 'island-in-a-sea' type composite filaments making up the multifilament yarn; '30 d' refers to the denier of the multifilament yarn; and 'six' refers to the number of 'island' components in each composite filament.

The crimp rigidity referred to above is measured by the following method based on JIS Japanese Industrial Standard (L1077, 1966): a. The sample is wound up on a hank winder having a frame periphery of about 80 cm. It is wound under a tension of 0.1 g/d at a constant velocity to prepare a small hank having 10 windings.

b. The hank so obtained is immersed in hot water at 90"C for 20 minutes in order to maintain the hank in an orderly configuration, and in order not to obstruct the contraction of the yarn. Thereafter the water is drained off by means of filter paper and the hank is allowed to stand in a horizontal arrangement for over 5 hours, so that the hank is not disturbed and the water is balanced.

c. At one end of the hank, an initial load of 2 mg/d and a load of 0.1 g/d are placed. The loads are quickly hung down into water at a temperature of 200C (plus or minus 20C) so that no shock is applied thereto, and the upper end of the hank is hooked and fixed.

d. After the hank has been allowed to stand in water for 2 minutes, the hank length (a) is measured and the load (0.1 g/d) is immediately removed.

e. Two minutes after the load (0.1 g/d) has been removed, the hank length (b) is again measured.

f. From the hank lengths (a) and (b), the crimp rigidity is calculated according to the following equation: a - b Crimp rigidity = -------- X 100 a The bulkiness expressed in crimp rigdity is preferably at least 7%.

Accordingly, as will be apparent from Figure 7, the proper false-twist temperature is at least 1100C, namely, at least the sum of the melting point of the sea component plus 100C. Further, by adding a plasticizer and varying the amount of the plasticizer (such as polyethylene glycol) added to the polystyrene, "islands-in-a-sea" type multi filament yarn (containing six to 50 d/12 fil. polyester island components) the melting point of the sea component varies from 800C to llO"C are produced, that are false twisted (2700 t/m) and thereafter the temperature of a heating zone which would give a crimp rigidity of at least 7% is determined. The results are shown in Figure 8 of the accompanying drawings.

As will be apparent from Figure 8, in each case, by establishing the temperature of the heating zone at a value at least 100 higher than the melting point of the sea components it is possible to obtain a crimp rigidity of at least 7%. However, when the temperature of the heating zone is at least (P + 40"C), the yarn becomes a fused yarn in which the composite filaments adhere to one another. Because this fused yarn is mainly used for crepe woven fabric, the crimp rigidity need not necessarily be at least 7%.

In Figure 10 of the accompanying drawings the side elevation and cross-section of yarns are shown. The "islands-in-a-sea" type composite filaments consisting of six 50 d/12 fil. polyester island components and a polystyrene sea component (melting point 100 C). The side elevation and cross-section, for each selected temperature, is shown. As appears in Figure 10, when the temperature of the heating zone is at least 1400 C, namely, higher than the melting point of the sea component by at least 400 C, fusion of the composite filaments takes place as is shown in Figures 5 and 6 of the accompanying drawings.

As is shown in Figure 8, the melting point of the sea component can be varied from 800C to 1100C by adding a plasticizer to the polystyrene sea component.

"Islands-in-a-sea" composite filaments containing these sea components are false twisted, and the temperatures at which the composite filaments fuse are measured.

The results are shown in Figure 9 of the accompanying drawings. When Q becomes higher than the melting point of the island components, they are completely deformed.

This is undesirable. From the foregoing results, it will be clear that surprising results are obtained when the range of the temperature Q of the heating zone in the false twist process is: P + 10'5 R C P being the melting point of the sea component and R the melting pbint of the island components. The range of the temperature Q of the heating zone P + 10 it Q : < P + 40 assists in avoiding fusion of the composite filaments.

The invention is more particularly described with reference to the drawings in which: Figures 1 to 3 are cross-sections of "islands-in-a-sea" type composite filaments comprising embodiments suitable for the invention, prior to false-twisting; Figures 4 to 6 are cross-sections, respectively, of the filaments of Figure 1 after false-twisting at different temperatures; Figure 7 is a graph showing the relationship between the temperature of a false-twisting heating zone and the crimp rigidity of a false-twist yarn; Figure 8 is a graph showing a zone in which the crimp rigidity exceeds 7%; Figure 9 is a graph showing a zone in which a false-twist yarn fuses; and Figure 10 is a diagram showing the relationship between the temperature of the heating zone and the cross-section and side-elevational configurations of resulting false twist varns.

Typical examples of islands-in-a-sea type composite filaments or fibres appear in Figures 1 to 3 of the drawings, wherein the island components are designated as A and the sea component is designated as B. As shown in the figures, the island components A need not be completely enclosed or encompassed by the sea component B.

By utilizing a false-twist process on the "islands-in-a-sea" type composite filaments of Figures 1 to 3 it is possible to produce a processed, false-twist yarn without deforming the initially established cross-sectional configuration as shown in Figures 4 to 6 which show non-fused, partlty fused and nearly wholly fused composite filaments resnectively. Nevertheless, the yarns have essentially the same performance, after the removal of the sea component, as a normal fine denier false-twist yarn or a non-detwisted yarn for crepe woven fabric. These yarns may be used to make knitted or woven fabrics for clothing, furniture or bedding.

The filaments are not crushed, have a good feel and lustre even when the crosssection is triangular or penta-lobal. Bulkiness and stretchability are good as they can be handled easily for knitting and weaving.

The invention is illustrated by reference to the Examples. Parts and percentages are by weight unless otherwise indicated.

EXAMPLE 1.

"Islands in-a-sea" type multifilament yarn consisting of 80% of six 50 d/12 fil.

polyester island components (melting point 2650C) and 20% of a polystyrene sea component (melting point 100"C) were twisted 3300 turns per metre (t/m), falsetwisted over a heater while the temperature of the heater was varied between 600C and 2000C. The false twist characteristics of the resulting yarns were observed. The twisting tension was 7 g and the dewisting tension was 21 g. Further, using each of these yarns as weft, and using an ordinary polyester stretch yarn (50 d/36 fil.) as warp on a loom, taffeta fabrics were woven. The polystyrene sea component was dissolved out in trichloroethylene from these fabrics, and they were finished.

As a result, in the yarns obtained at false-twisting temperatures of P + 10 < Q r < P + 40 "C as disclosed in this specification, the initially established cross sectional configurations of the original multifilaments were not deformed and the yarns had the same performances as did false-twisted yarns without embedding of filaments in a sea component. The fabrics had excellent bulkiness and feel and, more over, had mild lustre and a unique hand. Fabrics obtained at false-twisting tempera tures of R > Q > P + 40 OC had excellent crimp development, and soft fabrics were obtained from the yarns. They were not restricted by any substantial degree of fusion. The observed results appear in Table 1.

TABLE 1

Deformation Crimp Rigidity of the cross- False Before After sectional Twist removing removing configuration Temp. the sea the sea Occurrence Crimped of the island Crimp ( C) component component of fusion condition component Appearance 60 1.9 0.8 No fusion Weakly No Poor crimped yarn 80 2.4 1.1 100 3.5 -1.8 ,, " 110 8.6 7.7 " Ordinary Fair false twist yarn 120 11.4 9.6 " 130 12.1 10.8 " " " " 140 9;8 7.2 Partly Non-de- ., Good fused twisted yarn 150 7.9 5.6 Wholly ., " fused 160 i 5.4 4:1 " " Very good 180 1 5.3 4:9 " 200 3.2 4:9 Partly " ,, Good fused EXAMPLE 2.

"Islands-in-a-sea" type multifilament yarn consisting of 85% of six 75 d/18 fil.

nylon island components (melting point 235 C) and 15% af a polystyrene sea component (melting point 900C) were twisted to 2800 t/m, false-twisted while the temperature of the heater was varied between 60 C and 1700C, and the false-twist characteristics of the resulting yarns were observed. At this time, the twisting tension was 10 g and the detwisting tension was 30 g. Further, using each of these yarns as weft, and using a conventional nylon stretch yarn (50 d/17 fil.) as warp, taffeta fabrics were woven. Polystyrene was removed from these fabrics by dissolution in perchloroethylene and the fabrics were finished.

As a result, in the yarns obtained at false twist temDeratures of P + 10 < Q < P + 40 C as disclosed herein, the initially established cross-sectional configurations of the original filaments were not deformed and the yarns had the same performances as yarns false twisted without being embedded in a sea component. The fabrics had unique hand, and had excellent lustre, bulkiness and drapability.

Those fabrics whose wefts were from the yarns obtained at false-twist temperatures of R > Q 2 P + 40 C had excellent crimp develonment. Gcod scft pebbled fabrics, not restricted by substantial fusion, were obtained. The results of these observations are tabulated in Table 2.

TABLE 2

Deformation Crimp Rigidity of the cross False Before After sectional Twist removing removing configuration (OC) component component of fusion State component Appearance 60 2.1 0.9 No Weakly No poor crimped yarn 80 3.9 2.1 100 9:7 7.4 ,, Ordinary .. Fair false twist yarn 110 10.6 8.0 120 11.5 9.6 130 8.8 7.1 Partly fused Non-de- .. Good twisted yarn 140 6.7 5.5 Wholly fused 150 6.3 5.1 " .. .. Very good 160 5.2 4:3 .. " 170 4:8 4:1 " WHAT WE CLAIM IS: 1.A false twisted yarn comprising a plurality of "islands-in-a-sea" type composite filaments, said filaments each comprising a plurality of island components each having a predetermined melting point, and a sea component having a melting point below that of said island component, in which the cross-sectional configuration of each of the island components in said filaments is substantially free from any deformation caused by the application of the false twist to the yarn.

2. A false-twisted yarn according to Claim 1, in which the composite filaments are not fused to one another and the crimp rigidity of the yarn is at least 7%.

3. A false-twisted yarn according to Claim 1 in which the composite filaments are fused to one another.

4. A false-twisted yarn according to any of the preceding claims in which the difference between the melting point of each of the island components and that of the sea component is at least 100"C.

5. A false-twisted yarn according to any of the preceding Claims in which the difference is at least 1200C.

6. A false-twisted yarn according to any of the preceding Claims in which the island components are of polyester or polyamide, and the sea component is of polystyrene.

7. A false-twisted yarn according to any of the preceding Claims, in which the percentage weight of said island components, based upon the total yarn weight, is within the range of from 65 to 90%.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

TABLE 2

Deformation Crimp Rigidity of the cross False Before After sectional Twist removing removing configuration (OC) component component of fusion State component Appearance 60 2.1 0.9 No Weakly No poor crimped yarn 80 3.9 2.1 100 9:7 7.4 ,, Ordinary .. Fair false twist yarn 110 10.6 8.0 120 11.5 9.6 130 8.8 7.1 Partly fused Non-de- .. Good twisted yarn 140 6.7 5.5 Wholly fused 150 6.3 5.1 " .. .. Very good 160 5.2 4:3 .. " 170 4:8 4:1 " WHAT WE CLAIM IS: 1.A false twisted yarn comprising a plurality of "islands-in-a-sea" type composite filaments, said filaments each comprising a plurality of island components each having a predetermined melting point, and a sea component having a melting point below that of said island component, in which the cross-sectional configuration of each of the island components in said filaments is substantially free from any deformation caused by the application of the false twist to the yarn.
2. A false-twisted yarn according to Claim 1, in which the composite filaments are not fused to one another and the crimp rigidity of the yarn is at least 7%.
3. A false-twisted yarn according to Claim 1 in which the composite filaments are fused to one another.
4. A false-twisted yarn according to any of the preceding claims in which the difference between the melting point of each of the island components and that of the sea component is at least 100"C.
5. A false-twisted yarn according to any of the preceding Claims in which the difference is at least 1200C.
6. A false-twisted yarn according to any of the preceding Claims in which the island components are of polyester or polyamide, and the sea component is of polystyrene.
7. A false-twisted yarn according to any of the preceding Claims, in which the percentage weight of said island components, based upon the total yarn weight, is within the range of from 65 to 90%.
8. A false-twisted yarn according to any of the preceding Claims in which the

number of the island components is from 3 to 10.
9. A false twisted yarn according to any of the preceding Claims in which the denier of each of the island components is on average from 0.5 to 0.9.
10. A false-twisted yarn according to any of the preceding Claims in which at least two island components are used which differ as to the degree of deformation of cross-sectional configuration before application of false twist to the yarn.
11. A process for producing a false-twisted yarn which comprises false-twisting "islands-in-a-sea" type composite filaments, which each comprise a plurality of higher melting point island components and a lower melting point sea component, at a tem perature Q, wherein Q satisfies the relationship P + 10 Fizz Ql R C R0C wherein P is the melting point of the sea component and R is the melting point of the island components, the false twisting of the yarn being controlled so that the cross sectional configuration of each of the island components in said filaments is substan tially free from any deformation caused by the application of the false twist to the yarn.
12. A process according to Claim 11 in which the difference between the melting point of said island components and that of said sea component is at least 1000C.
13. A process according to Claim 11 or Claim 12 in which the difference between the melting point of each of the island components from that of the sea component is at least 1200C.
14. A process according to any of Claims 11 to 13 in which the island components are of polyester or polyamide and the sea component is of polystyrene.
15. A process according to any of Claims 11 to 14 in which Q is within the following range: P + 10 Q1 < P + 40 CC.
16. A process according to any of Claims 11 to 15 in which Q is within the following range: P + 40 Q < R 0C.
17. A process for producing false twist yarn substantially as described in any one of the Examples.
18. A false twisted yarn made by a process according to any of Claims 11 to 17.
19. A false twisted yarn made by a process according to any of Claims 11 to 16 from which the sea component has been removed.
20. A false twisted yarn substantially as described in any one of the Examples.