JPH03234819A - Lightweight sea-island conjugate type polyester yarn - Google Patents

Abstract

PURPOSE:To obtain the title lightweight polyester yarn having small flexural rigidity and soft handle by dispersing a polyolefin having a specific density as an island component into a polyester. CONSTITUTION:A polyolefin (e.g. polypropylene) having 1.1g/cm<3> density and <=5.0mu dispersion diameter as an island component is dispersed into a polyester as a sea component in a ratio of (96:4)-(80:20) to give the objective polyester yarn having >=5% void content after treatment at 160 deg.C for 5 minutes.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to lightweight polyester fibers, and more particularly to lightweight sea-island composite polyester fibers that are lightweight by dispersing polyolefins in polyester in the form of islands.

[Prior Art] Polyester fibers have excellent functionality and are inexpensive to manufacture, so they are widely used for clothing, textile materials, and industrial applications.

However, polyester, especially polyethylene terephthalate 1~, has a high density of the polymer itself and also has a high degree of crystallinity, so the fibers have high density and high rigidity, so they are particularly required to be lightweight and have a soft texture. It was not suitable as a material to be used in the field where it is used.

In order to solve these problems, many inspections have been carried out in the past. For example, JP-A-52-77228 discloses that the fibers are made hollow to lower the fiber density. However, since this fiber is made by adding one or several hollow parts to a normal fiber, it has higher rigidity than normal polyester fiber when compared at the same fineness, and therefore, it is difficult to fabricate. When made into knitted or nonwoven fabrics, they have a strong rough and hard feel, and on the other hand, when the hollowness ratio is increased to reduce weight, the hollow parts have the disadvantage of being crushed. Therefore, it has not been possible to obtain polyester fibers that are lightweight and have a soft texture using hollow technology. In addition, JP-A-59
Publication No. 76971 discloses a method of dispersing and blending a substance different from polyethylene terephthalate in the form of streaks to make polyester fibers, and then eluting out a part of the blended substances through alkali M reduction treatment, etc., to reduce the weight. has been done.

This fiber had the disadvantage that the fiber surface would become fibrillated even with slight friction because of the presence of long voids in the direction of the m-ring ring and the presence of the compounded substance. Furthermore, JP-A-55-137208@ describes microporous fibers made by blending polymers with relatively low affinity between the polymers, and a method thereof. This fiber does have micropores and is therefore lightweight, but since it is intended for filter use, it has the stiffness, firmness and softness required for clothing, as well as texture and dyeability. It cannot be said that it has physical properties such as tensile strength.

The main application of the present invention is for clothing, in which case light weight as well as the above-mentioned balance and physical properties are essential requirements. Furthermore, in clothing applications, various heat treatments such as heat setting and dyeing are performed after fiber formation, so the substrate polymer must be able to sufficiently withstand heat treatments at temperatures below 200'C. Furthermore, the physical properties of the polymer to be blended are also important.

Furthermore, Japanese Patent Application Laid-Open No. 57-47912 proposes an invention in which polyester is blended with polyolefin for the purpose of improving the spinning productivity of polyester. However, the invention does not describe the formation of voids in the fibers to reduce weight.

[Problems to be Solved by the Present Invention] The present invention was achieved as a result of intensive studies aimed at eliminating the above-mentioned drawbacks and achieving weight reduction.

[Means for Solving the Problems] The object of the present invention is to provide a seabird composite polyester fiber consisting of a sea component and an island component, in which (A) the island component has a density of 1;
．． It is made of polyolefin with a diameter of 19/cm or less, the sea component is polyester, and the dispersion diameter of the islands is 5.0! is less than or equal to i,
(B) The M ratio of sea and island components in the sea-island junction is 96:4-8
This can be achieved by using lightweight sea-island composite polyester fibers having a void content of 5% or more after heat treatment at 160° C. for 5 minutes.

In order to reduce the weight of polyester, it is advantageous to have a lower density of the polymer to be blended, and it is preferable to reduce the amount of staining with the base polymer polyester or to reduce the weight by creating voids during stretching. . It is necessary that the density of the polyolefin blended is 1.19/cffl or less. It is preferably 1.09/cm or less, particularly preferably 0.99/cd or less.

A polyolefin is required as a material that satisfies these requirements. Examples of polyolefins include polyethylene, polypropylene, polystyrene, and polymethylpentene, but they have poor compatibility with polyethylene terephthalate (PE), which is particularly useful among polyesters, have a relatively high melting point, and have a low density. Of these, polypropylene and polymethylpentene are preferred. When polyester is used for clothing, it is generally heat treated at about 160° C., so it is important that the voids generated by this heat treatment do not become too large. The melting point of the polyolefin is preferably 200°C or higher, more preferably 220°C or higher. In particular, polymethylpentene is P
``It is preferable because it has a low affinity with Ding and has a high melting point.

In order to reduce the weight of the fibers, it is necessary to have a low density of the polyolefin blended and at the same time to contain as many voids as possible in the fibers. The void content is required to be 5% or more, preferably 10% or more, more preferably 20% or more, particularly preferably 30% or more. In order to reduce weight, it is preferable to have a high void content, but
In terms of physical properties of t, fibers containing 50% or more of voids are not preferred.

Moreover, it is not a problem even if polyolefin and substances other than polyolefin are combined together, as long as they do not impede weight reduction. Rather, it is preferable to use them in combination as long as they promote weight reduction. For example, it is preferable to include calcium carbonate, which is a substance with poor compatibility with PET, because it helps to form voids in the fibers. However, if the blending amount is too large, the spinning properties will be poor, so the blending amount of other than polyolefin is 1.
The content is preferably 0% by weight or less.

The amount of polyolefin to be blended varies depending on the target degree of weight reduction of the fiber, but it is required to be 4% by weight or more in order to impart a sufficiently lightweight feel. The content is preferably 8% by weight or more, particularly preferably 11% by weight or more. If the blending amount of polyolefin is too large, the spinning property will deteriorate, and PE
Since T's original functionality is lost, it should be kept at 20% by weight or less. Preferably it is 15% by weight or less.

In order not to impair the original characteristics of polyester, it is necessary that the polyolefin is dispersed in the fiber cross section in the form of islands in the sea of polyester. Here, the sea is a part that extends continuously throughout the fiber when observing an arbitrary cross section, and
An island is a part that exists almost independently in the polyester sea. When the islands are continuous, the boundary area between the two becomes small, which reduces the occurrence of voids, which is not preferable.

The dispersion size of the polyolefin is important because it affects the size of the micropores that occur at the interface between the polyester and the polyolefin. If the size of the dispersion is too small, the specific surface area will increase, but the amount of voids will decrease, which is not preferable. On the other hand, if it is too large, it is not preferable because not only the spinning properties become poor, but also various kinds of irregularities such as dyeing irregularities occur.

It is necessary that the size of the polyolefin islands is 5.0 μm or less. Preferably it is 2 μm or less and 0.1 μm or more.

In order to maintain the desired size of the polyolefin islands, the melt viscosity of the polyolefin is preferably higher than the melt viscosity of the polyester, particularly preferably at least twice the melt viscosity of the polyester.

The fibers of the present invention are mainly suitable for clothing, but in textile applications, they are generally heat treated at 200°C or less for the purpose of imparting dimensional stability, and fibers that can withstand temperatures of at least 160°C are Preferably, the fibers can withstand temperatures of 200°C or higher. For this purpose, the melting point of the fiber is preferably 240°C or higher, more preferably 250°C or higher.

In the present invention, the melting point refers to PFRKIN-ELMAR D
This is a value measured using SC-4 at a heating rate of 16°C/min. At this time, when melting peaks occur on multiple layers, it refers to the peak temperature of the one with the greater heat of fusion. In this sense, the polyester of the present invention is preferably polyethylene terephthalate, but it may also contain a commonly used copolymer composition or blend as long as it satisfies the above-mentioned melting point, and the amount of the polyester to be blended with the polyolefin It may be contained in an amount of 12% by weight or less based on other compositions.

Since the fiber of the present invention is used for clothing, and texture is also important, the fineness is preferably in the range of 0.5 denier or more and 5 denier or less. Since the fibers of the present invention contain voids, they are lighter than ordinary polyethylene terephthalate fibers with the same cross-sectional area, have low bending rigidity, and have a soft texture.

The fiber cross-sectional shape of the present invention is not particularly limited, and can be applied to commonly used shapes. Further, by forming the cross section into a hollow shape, the effects of the present invention can be further enhanced.

The fiber of the present invention can be produced, for example, as follows.

4 to 20% by weight of polymethylene pentene, which has a melt viscosity higher than that of PET, is blended into PET in a molten state and stirred thoroughly, and then the blended polymer is formed into particles. 160% of this blend polymer
After drying under reduced pressure at °C, it is melt-spun. In this case, it is preferable that the shear stress at the time of discharge from the spinneret hole be 10 x 106 or less in order to prevent the particle size of the polymethylpentene from being dispersed more than necessary. Furthermore, from the same point of view, the deformation ratio after discharge (the value obtained by dividing the undrawn yarn take-off speed by the flow speed in the die hole) is more preferably 200 or less, preferably 80 or less.

The obtained undrawn yarn is drawn to an elongation of 50% or less by employing a low drawing temperature of less than 80°C to generate voids, and then heat-treated to improve dimensional stability. .

[Example] The present invention will be explained in more detail with reference to Examples below. The measurement method used in the Examples is as follows.

Dispersion size: This value is determined by the average diameter of polyolefin islands scattered in a sea of polyester when the Ishin surface is observed with a transmission electron microscope.

Void content: After heat-treating the fibers at 160°C for 5 minutes at normal pressure, 20 arbitrary cross-sections and 20 arbitrary side cross-sections of the fibers were observed using a transmission electron microscope, and the ratio of the void area to the entire fiber area was calculated. Expressed as an average. However, substantially infinitely continuous voids in the fiber axis direction, so-called hollow portions, are not included in either the area of the entire fiber or the voids.

Example 1 86% by weight of a polyester consisting essentially of polyethylene terephthalate 1 was melt-blended with 14% by weight of polymethylpentene to give an average dispersion diameter of 35 μm. This polymer was discharged from a circular cross-section hollow nozzle to form an undrawn yarn, and then stretched. The stretching temperature at this time was 30°C, and subsequent to the stretching, a heat treatment at 125°C was performed. The residual elongation was 23%. The properties of the drawn yarn obtained in this experiment are shown in Table 1. The fabric made of the fibers was soft, and its softness remained almost unchanged even after heat treatment at 1602°C. Incidentally, the hollowness ratio after heat treatment was 15.6%.

Example 2 86% by weight of a polyester consisting essentially of polyethylene terephthalate was melt blended with 14% by weight of polymethylpentene to give an average dispersion diameter of 35 μm. This polymer was discharged from a circular cross-section hollow nozzle to form an undrawn yarn, and then stretched. The stretching temperature at this time was 30°C, and the residual elongation was 23%. The properties of the drawn yarn obtained in this actual test are shown in Table 1. The fabric made of the fibers was soft, and its softness remained almost unchanged even after heat treatment at 160°C.

Example 3 18% by weight of polymethylpentene was melt-blended with 86% by weight of a polyester in which 98% by mole of repeating units consisted of polyethylene terephthalate 1 to 1 to give an average dispersion diameter of 35% by weight.
It was set to μm. This polymer was used as the core component, while the sheath component 3 was a polymer consisting of polyethylene terephthalate 1 to 98 mol%, which was used as an undrawn core-sheath composite yarn (core/sheath-90/10), and then stretched. I did it. The stretching temperature at this time was 30°C, and the residual elongation was 23%. During the production of this fiber, there was no yarn breakage at all during spinning and drawing, and the spinning performance was extremely good. The properties of the drawn yarn obtained in this experiment are shown in Table 1. The properties of the fibers are as shown in Table 1, and the fabric made of the fibers was soft, and its softness remained almost unchanged even after heat treatment at 160°C.

Example 4 A drawn yarn was obtained by spinning yarn in the same manner as in Example 1 except that the amount of polymethylpentene was changed to 8% by weight. The fiber properties were as shown in Table 1, but the softness was slightly inferior to that of the fiber of Example.

Example 5 Chip 8 consisting essentially of polyethylene terephthalate
6% by weight and 4% by weight of polymethylene pentene were chip blended and melt spun. In this spinning, a static mixer was used immediately before the discharge hole in order to improve dispersibility. It was the same as Example 1 except that a chip blend and static mixer were used.

The properties of the drawn yarn obtained in this experiment were as shown in Table 1, but the void content was low and the yarn spinnability was slightly poor.

Example 6 Example 1 except that polyethylene was used as the blended polymer
A similar experiment was conducted. There were no particular problems during the spinning process, but the fiber properties are as shown in Table 1. The void content of the fiber was as high as 18% before heat treatment, but the void content decreased after heat treatment after making it into a fabric. Therefore, the effect of weight reduction was not very large.

Comparative Example 1 An experiment was carried out in the same manner as in Example 1 except that polymethylpentene was changed to 3% by weight. Although the dispersion of Polyme5-Tylpentene was also good, the void rate was low;
The object of the present invention could not be satisfied.

Comparative Example 2 Example 3 except that no static mixer was used
I conducted the same experiment. However, yarn breakage occurred frequently during melt spinning, and yarn production could not be completed.

(The following is a blank space) 6 [Effects of the Invention] Since the light weight fiber according to the present invention is made of polyethylene terephthalate with a void content of 5% or more, it has low bending rigidity, has a soft texture, and is lightweight. Because it has micropores, it has a texture suitable for general clothing use. Furthermore, since it has an immovable air layer, its heat retention properties are improved, making it a material for soft clothing that is especially suitable for autumn and for multiple uses.

Claims (1)

[Claims] In a sea-island composite polyester fiber consisting of a sea component and an island component, (A) the island component is made of polyolefin with a density of 1.1 g/cm^3 or less, the sea component is polyester, and the dispersed diameter of the islands is (B) The weight ratio of the sea and island components of the sea-island composite is 96:4 to 8.
A lightweight sea-island composite polyester fiber having a ratio of 0:20 and a void content of 5% or more after heat treatment at 160°C for 5 minutes.