JPS6342916A - Sheath-core type conjugated fiber - Google Patents

Abstract

PURPOSE:To obtain a sheath-core type conjugated fiber having high color- developing properties, frosting resistance and high tenacity, by conotituting the core component and sheath component, respective, of specific polymers. CONSTITUTION:As a core component, sufficiently color-developing copolyester containing more than 3mol% of 5-sodium sulfoisophthalate is used, while a low color-developing copolyester containing 5-sodium sulfoisophthalate less than in the core component is used as the sheath component. The copolyesters are mainly composed of ethylene terephthalate units and butylene terephthalate units. The weight ratio of the core to the sheath is preferably 90/10-40/60.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a core-sheath type composite fiber having high color development, frosting resistance, and high strength.

[Conventional technology]

Cationically dyeable polyester fibers using polyesters containing 5-sodium sulfoisophthalate units as a copolymerization component are known.

However, if the content of this copolymer component is increased in order to obtain sufficient color development, the fiber strength becomes low.
For ultrafine fibers suitable for use in suede-like artificial leather and silky-like fabrics that have a high-class appearance and touch, it is necessary to combine ultrafine fibers made of the copolymer alone with sufficient color development and strength. It was extremely difficult to use it.

Japanese Patent Publication No. 61-6165 proposes, for example, the following configuration as a means to solve this problem.

That is, the ultrafine fibers have a core-sheath type groove structure, and the sheath component is a copolymerized polyester containing a high content of the above-mentioned copolymerized components and has sufficient coloring properties, while the core component is made of a copolymerized polyester with a high degree of polymerization. The aim is to strengthen the fibers by using polyester.

By adopting this configuration, ultrafine fibers having high color development and strength suitable for practical use can be obtained.

However, this configuration still has the following problems.

In other words, if the high degree of polymerization polyester used as the core component is a homopolymer, a portion of the homopolymer will not be dyed when dyed with cationic dyes, so if this fiber is used in areas that are frequently subjected to friction, such as the hem of clothes, it will be difficult to dye the fabric. Sting is likely to occur. When viewed with the naked eye, this phenomenon appears as whitening that looks like frost on the friction site, but when observed in more detail under a microscope, the two components that make up the ultra-fine fibers peel off and a portion of the homopolymer is exposed. It turned out that it was.

[Problem that the invention seeks to solve]

An object of the present invention is to provide a core-sheath type composite fiber that has high color development and frosting resistance and is also high in strength.

[Means for solving problems]

The inventors of the present invention have made extensive studies to solve the above drawbacks, and as a result, have found that the problems can be solved by the following means, and have arrived at the present invention.

The present invention has the following configuration.

In the core-sheath type composite fiber, the core component is a polymer mainly composed of 1 to 1 unit of ethylene terephthalate or butylene terephthalate, and 5-sodium sulfoisophthalate component units contain 3 mol% or more of the total acid component units. It is a copolymer in which the sheath component is a polymer mainly composed of polyethylene terephthalate or polybutylene terephthalate and contains fewer 5-sodium sulfoisophthalate component units than the core component. Characteristic core-sheath type composite fiber.

In other words, the gist of the present invention is to use a copolyester containing a high content of 5-sodium sulfoisophthalate component with sufficient color development in the core and a small amount of 5-sodium sulfoisophthalate in the sheath. - Using a copolymerized polyester containing a sodium sulfoisophthalate component that has low color development but has a high degree of polymerization.

With this structure, the present invention surprisingly provides a fiber that does not impair color development, has excellent frosting resistance, and has strength comparable to that of the ultrafine composite fiber using the aforementioned highly polymerized homopolymer as the core. I need it because it happened.

In addition, during the study process of the present inventors, it was confirmed that the following two methods are also effective if only the frosting is to be improved.

(2) As a core component, a mixture of a high degree of polymerization homopolymer and a small amount of a cationic dyeable copolymer is used.

(2) A polyester copolymerized with a small amount of 5-sodium sulfoisophthalate component is used as the core component.

However, regarding (■), the silk-spinning operability is extremely unstable, and regarding (■), the polyester copolymerized with the 5-sodium sulfoinphthalate component is abnormal because it is presumed to be caused by a metal crosslinking reaction. The melt viscosity increases. For this reason, it is difficult to spin a polymer whose degree of polymerization is high enough to have a reinforcing effect on the sheath component. There is also some high polymerization in the core component.

The use of thinned polymers also does not produce the expected effect.

In the end, it was found that it is extremely difficult to improve the strength of composite fibers by such a method compared to the case where a homopolymer is used.

When understood as an extension of the conventional technology, the present invention, in common sense, first exposes a large amount of a highly color-forming component on the outer periphery of the fiber in order to obtain color-forming property, and then exposes a high degree of polymerization component inside the fiber for the purpose of reinforcing the strength. It is expected that it is essential to balance the color development and reinforcing effect, and this method has been used in practice, but as mentioned earlier, such a combination does not meet the objectives of both. I can't get a satisfactory result.

The inventors of the present invention completely reversed the idea and found that under certain conditions, even if a component with low coloring property was brought to the outer sheath component, the coloring property would not be impaired, but rather it would be superior in terms of fiber strength and other aspects. I have confirmed that I can get what I want.

The core-sheath type structure referred to in the present invention is not necessarily limited to the cross-sectional structure illustrated in FIG.
Various shapes such as a circular shape and a polygonal shape can be used for this sacrocoronal sheath shape.

Further, the cross section of the core-sheath type can be arranged not only concentrically as shown in FIG. 1 but also eccentrically, and in this case, the effect of crimp generation due to fiber contraction is also reduced by 1q.

The core-sheath type composite fiber of the present invention can be produced by, for example, spinning a sea-island type fiber having core-sheath type islands as shown in FIG. 2 by a three-component spinning method, drawing it, and then removing the sea component (q
It will be done.

In the present invention, the core component is a copolymer containing 5-sodium sulfoisophthalate component units in a proportion of 3 mol% or more based on the total acid component units in a polymer mainly composed of ethylene terephthalate units or butylene terephthalate units. is important.

If the content of the 5-sodium sulfoisophthalate component unit is less than 3 mol %, it will be difficult to achieve high color development sufficient to compensate for the decrease in color development due to the low fineness when ultrafine fibers are used.

Furthermore, if the intrinsic viscosity of the polymer used for the core component is too low, sufficient strength cannot be obtained even if the composite fiber is reinforced with a sheath of a highly polymerized polyester copolymer. For this reason, the intrinsic viscosity of the core component is preferably 003 or higher, particularly preferably 0.35 or higher. However, depending on the purpose, it is not limited to this range.

Furthermore, in the present invention, a copolymer mainly composed of polyethylene terephthalate or polybutylene terephthalate, in which 5-sodium sulft isophthalate component units are copolymerized in a smaller proportion than the core component, is used as the sheath component. is particularly important.

By copolymerizing a small amount of 5-sodium sulfoisophthalate component units in the sheath component, it becomes possible to fully exhibit the high coloring property of the core component, and the coloring property of the composite fiber of the present invention as a whole can be improved. It can be made extremely high. In the present invention, the reason why the fiber as a whole has high coloring property even though the highly coloring core component is covered with a relatively low coloring sheath component is currently unknown. Although it is not fully understood yet, by copolymerizing even a small amount of 5-sodium sulfoisophthalate component units, the sheath component has a fine 4M structure that is easily permeable to dye molecules. It is assumed that the thickness (diameter) of the highly color-forming component on the inside is large compared to the mold temperature ratio, so that a substantial color-forming effect can be obtained.

When the copolymerization ratio of 5-sodium sulfate inphthalate component units to the sheath component polymer is necessarily high,
As shown in (e), the increase in melt viscosity becomes an obstacle, making it difficult to achieve a high degree of polymerization, resulting in a decrease in the strength of the composite fiber as a whole. Therefore, the copolymerization ratio of the above-mentioned copolymer is set lower than that of the core component to suppress the increase in melt viscosity, while maintaining a high intrinsic viscosity of 0.4 or more for polyethylene terephthalate and 0.5 or more for polybutylene terephthalate. It is preferable to use a polymer having a degree of polymerization.
Note that the ultrathin viscosity is measured at 25° C. using orthochlorophenol as a solvent.

The upper limit of the intrinsic viscosity of the polymer used in the present invention is naturally determined by the increased difficulty of polymerization and spinning techniques due to increased melt viscosity.

One of the outstanding features of the fiber of the present invention is its high fiber strength. This is because in the fiber of the present invention,
This is one of the surprising effects, as it is at a level that cannot be achieved with fibers with a structure in which the core and sheath components are arranged in reverse. Although the cause of this is not clear, it seems to be related to some kind of difference in the molecular orientation state of the core component and the sheath component in the undrawn yarn spun from the composite spinneret.

In the fiber of the present invention, the weight ratio of the core component and the sheath component is appropriately determined depending on the balance between color development and strength, and is particularly preferably in the range of 90/'to to 40/60. However, it is not limited to this. In particular, as the fiber denier decreases, surface reflection increases and coloring performance decreases significantly, so in order to overcome this problem, it is effective to focus not only on the weight ratio of the core and sheath, but also on the thickness of the sheath itself. In some cases, the thickness is preferably 2 μm or less, and particularly preferably 1 μm or less.

The polymer used in IT of the present invention has both core and sheath components mainly composed of ethylene terephthalate units or butylene terephthalate units, which are copolymerized with a certain amount of 5-sodium sulfoisophthalate units. However, depending on the purpose, other components may also be copolymerized. For example, by copolymerizing a small amount of polyethylene glycol, it is possible to increase the intrinsic viscosity and increase fiber strength while suppressing an increase in melt viscosity, and the fiber structure is relaxed, which greatly increases the effective utilization rate of dyed sheets. increases.

Further, among the characteristics of the fiber of the present invention, its high color development is particularly remarkable in the ultrafine region of 0.5 denier or less. This is a region where ordinary polyester fibers show a significant decrease in color development due to surface reflection.

On the other hand, the high strength effect and frosting resistance of the fibers of the present invention are obtained not only in the ultra-fine region but also in the normal denier region.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to examples. Example 1 A three-component spinning machine was used to spin fibers having a cross section as shown in FIG. The composition and spinning conditions of each polymer are as follows.

Component A: Polyethylene terephthalate obtained by copolymerizing 5-sodium sulfoisophthalate units in an amount of 5.2 mol% based on the total acid component units.

Intrinsic viscosity: 0.42 Component B = polyethylene terephthalate obtained by copolymerizing 2.5 mol% of 5-sodium sulfoisophthalate units based on the total acid component units.

Intrinsic viscosity 0.59 Component C: Heavy ratio of 2B to polystyrene = 37:20:43 Spinning humidity: 2
85°C Take-up speed: 1250 m/min The obtained undrawn yarn was drawn by liquid bath heating in two stages at 3° to 1 times the following conditions.

The drawn composite fibers are washed with trichlorethylene and C
components were removed. After that, when the strength was measured, it was 3.
．． It had a high strength of 6 g/d. The single fiber fineness of the core-sheath fiber was 0°17d.

In addition, the drawn composite fibers are crimped and then cut, and the resulting raw cotton is used to create artificial leather! ! A) According to the known method of Fi, wear formation, needle punching, shrinkage, PVA application, trichlorethylene washing, polyurethane application, napping treatment were performed, and black yarn was dyed with cationic dye for 12
When dyed at 0°C, a suede-like sheet with a full black color, high color development, and excellent texture, appearance, and touch was obtained.

Work pants were made from this suede-like sheet and worn for 500 hours, but no frosting was observed in any part of the pants.

Comparative Example 1 In Example 1, the A component was replaced with polyethylene terephthalate-1 having an intrinsic viscosity of 0.85, and the C component was replaced with Example 1.
The spinning, stretching, and suede-like sheet production was carried out under the same conditions as in Example 1, except that component A was replaced with Component A in Example 1.

When a wear test similar to that in Example 1 was conducted using this suede-like sheet, it was found that 200
Over time, frosting appeared near the pocket opening.

Comparative Example 2 The A-8 components in Example 1 were replaced with each other in a core-sheath arrangement, and spinning was performed under the same conditions as in Example 1 except for the other components. When the obtained undrawn yarn was tried to be stretched under the same conditions as in Example 1, when the total stretching ratio exceeded 2.90 times, yarn breakage frequently occurred during stretching, and stable stretching could not be continued. There wasn't. The composite fiber obtained by setting the total draw ratio to 2.80 times was washed with 1-lichlorethylene to remove the C component, and the strength was measured. As a result, the strength was as low as 2.9 g/d.

Comparative Example 3 The core component and sheath component in Comparative Example 1 were replaced with each other,
Spinning, stretching, and sheet production were performed under the same conditions.

The resulting sheet had low color development and could not be dyed deep with cationic dyes.

〔Effect of the invention〕

The composite fiber of the present invention has excellent color development and frosting resistance, and also has high strength. Plus, 5-sodium sulfoisophthalate! - Dimethylformamide and Ca often pose a problem in polyurethane application processes, etc., compared to those in which components with a relatively high copolymerization ratio of units are exposed on the fiber surface.

It also exhibits high resistance to deterioration in color development due to the action of metal ions such as Mg. Furthermore, due to the high temperature and strongly acidic conditions during dyeing, there is a large decrease in strength over time after the dyeing process, which often occurs with polyester fibers with a relatively high copolymerization ratio of 5-sodium sulfoisophthalate units. Improved.

[Brief explanation of drawings]

FIG. 1 shows a preferred example of a cross section of an ultrafine composite fiber having a core-sheath type structure according to the present invention. FIG. 2 shows an example of a cross section of a three-component conjugate fiber for obtaining a core-sheath type ultrafine conjugate fiber according to the present invention. △: Core component B: Sheath component C: Sea component

Claims (1)

[Claims] In the core-sheath type composite fiber, the core component is a copolymer containing 5-sodium sulfoisophthalate component units in an amount of 3 mol% or more based on the acetic acid component units in a polymer mainly composed of ethylene terephthalate units or butylene terephthalate units. A core-sheath type characterized in that the sheath component is a copolymer in which a polymer mainly composed of polyethylene terephthalate or polybutylene terephthalate contains fewer 5-sodium sulfoisophthalate component units than the core component. Composite fiber.