JPS5812940B2 - Manufacturing method of bulky yarn - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a bulky yarn having a special texture using undrawn polyethylene terephthalate yarn.

More specifically, it consists of a core and a sheath, and the fibers that make up the sheath part bulge out in a fluff-like manner, and they have excellent cohesiveness.
This invention relates to a method for manufacturing a processed yarn that has the appearance and feel of spun yarn, and when knitted into a double jersey and given a special finish, gives it the feel of a wool product.

Various proposals have been made for this purpose in the past; for example, Japanese Patent Application Laid-Open No. 136952/1983 proposes a method with a birefringence of 80×.
A method has been proposed in which two undrawn polyethylene terephthalate yarns of 10-3 or less are drawn together and subjected to simultaneous drawing and false twisting at a drawing ratio below the breaking tension point.

One of the problems with this method is that the excellent bulkiness required of the finished yarn is contradictory to the strong binding properties of the core and both parts of the yarn.

That is, in order to obtain excellent bulkiness, it is necessary to increase the difference in yarn length between the core and sheath yarns, but this also leads to a decrease in the cohesiveness of both yarns. During false twisting and knitting and weaving, the threads become loose, resulting in lower operability and quality deterioration.

The present invention is an improvement on the conventional method, and aims to harmonize the contradictory characteristics of bulkiness and encapsulation, and is aimed at harmonizing the conflicting characteristics of bulkiness and encapsulation, and uses an oriented method having a difference in birefringence of 30 to 45 x 10-3. Production of a bulky yarn characterized by aligning two different types of undrawn polyethylene terephthalate yarns, stretching them at a stretching ratio DR expressed by the following formula, and simultaneously false-twisting them using a circumscribed friction disk. It's a method.

0.7(1+ε)≦DR≦0.74(1+ε) (However, ε
is the elongation at break of the undrawn yarn with the larger birefringence index.) As mentioned above, the present invention targets yarns with a two-layer structure of core and sheath, and undrawn yarns of polyethylene terephthalate are used in correspondence with each of them. use

According to research conducted by the present inventors, it has been found that a certain difference in birefringence must exist between these two types of undrawn yarns.

In the present invention, the bulkiness of the yarn increases as the difference in yarn length between the core and sheath yarns in the finished yarn increases, and in order to ensure the yarn length difference to obtain the desired bulkiness, the birefringence must be 30× 10-
A difference of 3 or more is required.

If the birefringence difference is less than this, only thin threads can be obtained.

However, if the bulkiness becomes too large, the cohesiveness of both the core and sheath yarns will be weakened, and the sheath yarns will become loose and the yarn structure will be destroyed by mechanical straining.

This limit, expressed as a difference in birefringence, is 45.times.10@-3, and if this limit is exceeded, problems will occur.

Next, both of these undrawn yarns are subjected to stretching and simultaneous false twisting, and the stretching ratio DR at that time gives complete stretching to the undrawn yarn A (which constitutes the core yarn) having the larger birefringence index. It is necessary that the other undrawn yarn B (which constitutes the sheath yarn) is in a range that gives incomplete stretching.

As a result of determining this based on the breaking elongation ε of the yarn A, the following empirical formula was obtained.

0.7(1+ε)≦DR≦0.74(1+ε) (1) If this DR is less than the above range, the strength of the yarn under heating is insufficient and yarn breakage often occurs in the false twisting heater. I don't like it.

If the diameter exceeds this range, it is undesirable because the number of single filament breaks will increase, and at the same time, the core and both yarns will become less compatible, making it easier for the two portions to separate.

In addition, the temperature of the heater is within the range used in the production of ordinary polyester filament processed yarn, that is, 200 to 24°C.
Any temperature of 0° C. can be applied to the present invention.

A further feature of the present invention is that a friction type, particularly a circumscribed friction disk type, is employed as the false twisting means.

In a spindle-type false twisting device in which the yarn is wound around a twist pin and rotated, the yarn is squeezed by the twist pin, so the sheath yarn slips on the core yarn and is partially accumulated, making it impossible to obtain a uniform yarn shape. Not only that, but thread breakage is likely to occur, making it unsuitable.

Even in the case of a friction type bushing method in which the yarn is inscribed in a hollow cylinder, a force acts on the yarn in a direction that impedes its progress, resulting in a large passage resistance, so defects similar to those with twist pins are likely to occur.

In the biaxial disk circumscribing system shown in Fig. 1, even if a disk made of elastomer such as urethane has a high coefficient of friction with the yarn, the contact with the yarn is smooth and it is easy to twist. It is suitable because the thrust in the advancing direction works and allows the thread to pass through with reasonable flexibility, and in the case of a triaxial type, ceramic discs have better workability than elastomer discs. It is.

In the method of the present invention, during the false twisting process, the yarn A with a high degree of orientation change is false twisted while generating high tension by drawing, resulting in a thermally and mechanically strong crimping method, and the core yarn is On the other hand, yarn B, which has a lower degree of orientation, is incompletely drawn while being coiled around yarn A under tension.

Therefore, there is a difference in length between the two yarns, and when the false twist is released in the untwisting zone, both yarns are not untwisted uniformly at the same time, and as a result, yarn B is twisted around yarn A as an axis. The shape has a mixture of untwisted parts and untwisted parts in the length direction.

This is shown in FIG. The untwisted portion of yarn B is tightly entangled with yarn A, maintaining the shape stability of both yarns, and the untwisted portion protrudes outward from the yarn in a fluff-like appearance, giving an appearance similar to that of spun yarn.

The characteristic structure of the above-mentioned A and B yarns was determined by comparing the S-S curve of the yarn obtained by the method of the present invention with that of the conventional drawn and simultaneously false-twisted yarn, as shown in Figures 3 and 4. is also clear.

That is, in the yarn of the present invention, it is clear that the A yarn forming the core breaks first, and then the B yarn forming the sheath breaks.

After the yarn obtained by the method of the present invention is made into knitted fabrics such as double jersey, etc., it is subjected to the usual finishing process for synthetic fiber fabrics, and then the finishing method for wool products such as fulled wool and steamed wool products is applied. By doing so, it is possible to create a high-quality product with a texture that is not seen in conventional synthetic fiber products.

Next, the features of the present invention will be explained in more detail based on examples.

Each characteristic value in the examples was determined by the following measurement method.

1. Yarn length ratio S is an index of the bulkiness of the yarn, and is 5% under a load of 0.1 g/d.
Using a 0cm trial length as a scale, separate this into core yarn and sheath yarn, and measure the length (L1, L
2) Measure.

This is done for 50 samples, and the yarn length difference S is measured using the following formula.

2. This is an indicator of the strength of the binding force between the core and sheath of the binding yarn.The yarn to be measured was stretched horizontally with a load of 1 g/d, and then placed between rubber plates with a hardness of 30 degrees at a thickness of 5 g/cm2. After holding the rubber plate under a pressure of 100 cm and making the rubber plate reciprocate 10 times over a distance of 50 cm at a speed of 50 cm/min, the appearance of the yarn is observed and judged.

Those in which the core and pod were separated, and those in which the pod was squeezed and partially formed into a dumpling shape were rated ×, and those with no change were rated ○.

3. Breaking elongation of composite yarn after processing This indicates the difficulty of processing the yarn during knitting and weaving, and is determined by the SS curve.

If this value is less than 0.20, yarn breakage in the knitting machine will increase, resulting in poor knitting quality.

4. Fabric thickness: Initial load according to JISL1079-5.18: 50 g/
Indicates the thickness of the fabric in cm2.

5. 6. Elastic modulus of fabric according to JISL1079-5.18. Bending resistance of fabric JISL1079-5.17 Example using cantilever method 1 Undrawn polyethylene terephthalate yarn 114d/36fA with a birefringence of 51 x 10-3 and various undrawn polyethylene terephthalate yarns with a birefringence smaller than this B was pulled together and simultaneously subjected to stretching and false twisting.

The processing conditions were as follows. Processing speed: 500m/m
in Stretching ratio (DR): 1.55 False twisting device: 2-axis circumscribed friction disk (made of urethane) yarn speed/friction surface speed: 0.35 Heater temperature: 230°C Target processed yarn fineness: 225d The elongation at break of the drawn yarn A is 1.15, and the stretching ratio of 1.55 is within the range of formula (1).

Table 1 shows the properties of the processed yarn obtained.

From this result, in the case of a combination of undrawn yarns with a difference in birefringence of 30 x 10-3 or less, the yarn form is similar to a normal false twisting system, and the core and sheath parts are not clearly defined.
Therefore, it has been found that the encapsulation property is poor, and in combinations in which the number exceeds 45 x 10-3, the protrusion of the sheath threads is too large, resulting in a deterioration of the embedding property.

Example 2 Test No. shown in Example 1. A combination of the same undrawn yarns as in 3, i.e. polyethylene terephthalate undrawn yarn 114 d/36fA with a birefringence of 51 x 10-3 and the same undrawn yarn B with a birefringence of 10 x 10-3 smaller than this. In the combination, the drawing ratio was changed and other processing conditions were kept the same as in Example 1, and drawing and false twisting was performed to obtain textured yarns.

The results are shown in Table 2. Note that the elongation at break of the undrawn yarn A is 1.15, and the range of the appropriate stretching ratio according to the above formula (1) is calculated as 0.7 (1 + ε)≦DR≦0.7.
4(1+ε)0.7(1+1.15)≦DR≦0.74
(1+1.15)1.505≦DR≦1.591, which is in the range of about 1.51 to 1,59.

Furthermore, the elongation at break in Table 2 indicates the likelihood of breakage of the obtained textured yarn, and as mentioned above, if it is less than 0.20, there will be many yarn breakages in the knitting machine, resulting in poor fabrication. .

If the stretching ratio is outside the range of the present invention, the number of thread breaks during false twisting will increase, which is undesirable.

This is because if the stretching ratio is too high, the elongation at break of the yarn decreases,
On the other hand, if it is too low, the heat resistance will decrease and this will cause yarn breakage.

Example 3 The false twisting device was changed in various ways, and other conditions were the same as in Test No. 1 shown in Example 1. Processed yarn was obtained in the same manner as in 3.

The results are shown in Table 3.

From this table, it was found that the circumscribed friction disk type gave good results, and the two-axis type using a urethane friction disk was particularly excellent.

Example 4 Test No. shown in Example 1. A single pristar gray fabric was knitted using a circular knitting machine using the yarn produced in step 3, and finished by the following method.

Test no. A Gray fabric → Relax (95℃ x 15 seconds) → Widening set (1
50℃ x 30 seconds) → napping → finishing set (160℃ x 30 seconds)
seconds) → Shearing test No. B Test No. The finished fabric of A was further subjected to the following steaming process.

Flat press (100℃ x 5 seconds) → Steam treatment (120℃
℃ x 6 minutes) The characteristic values of these finished fabrics were measured.

This is shown in FIG.

From these results, it was found that the fabric using the yarn produced by the method of the present invention increases in thickness by steaming and has a feel similar to that of a wool product.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a circumscribed biaxial friction disk false twisting device used in the method of the present invention, FIG. 2 is an external view of processed yarn obtained by the method of the present invention, and FIGS. 3 and 4 shows the SS curves of the processed yarn according to the present invention and the conventional processed yarn.

Claims (1)

[Claims] 1. Two types of polyethylene terephthalate undrawn yarns with different orientations having a difference in birefringence of 30 to 45 x 10-5 are aligned, and the drawing ratio DR is expressed by the following formula. A method for producing a bulky yarn, characterized in that it is stretched and at the same time subjected to false twisting using a circumscribed friction disk. 0.7(1+ε)≦DR≦0.74(1+ε) (However, ε
is the elongation at break of the undrawn yarn with the larger birefringence)