JPH04241114A - Polyester conjugate fiber - Google Patents

Abstract

PURPOSE:To obtain high-density polyester conjugate fiber, excellent in stretchability and extension recovery and having latent crimpability suitable for obtaining nonwoven, woven or knitted fabrics. CONSTITUTION:Polyester conjugate fiber is obtained by joining (A) a polyethylene terephthalate-based polyester in which 2,2-bis[4-(2-hydroxyethoxy) phenyl]propane in an amount within the range of >=2 to <=10mol% is copolymerized with 5-sodium sulfoisophthalic acid in an amount within the range of >=1 to <=3mol% to (B) a polyethylene terephthalate component in a side-by-side type.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester conjugate fiber which has excellent stretchability and elongation recovery rate and has latent crimp ability suitable for obtaining highly densified non-woven fabrics or woven or knitted fabrics.

0002

[Prior Art] A side-by-side type polyester composite fiber having latent crimp ability uses polyethylene terephthalate (intrinsic viscosity 0.40 to 0.60) with a low degree of polymerization as the polymer component on the low shrinkage side, and Polyethylene terephthalate with a high degree of polymerization (intrinsic viscosity 0.70 to 0.80) is used as the polymer component on the high shrinkage side of fibers. As a result, it was not possible to obtain high elasticity and elongation recovery power sufficient to overcome the weaving force, that is, the binding force between fibers, and the fit was poor in terms of texture and fit.

[0003] Furthermore, JP-A No. 62-78214 discloses a composite fiber using a copolyester having a copolymerization rate of 3 mol % or more and 6 mol % or less with 5-sodium sulfoisophthalic acid (SIP), or a composite fiber made from this fiber. However, in this case, since the copolymerization rate of SIP is too high, the melt viscosity of the polymer becomes too high, making it difficult to obtain an appropriate degree of polymerization in the polycondensation reaction. In addition, the cost will be high, and
The crystallinity of the spun yarn becomes too high, making it susceptible to changes over time, leading to a decrease in drawability and the strength of the composite fiber.

0004

[Problems to be Solved by the Invention] The present invention solves the drawbacks of conventional polyester composite fibers, and provides latent crimp fibers that are suitable for obtaining high-density nonwoven fabrics or woven or knitted fabrics with excellent elasticity and elongation recovery rate. The purpose of the present invention is to provide a polyester composite fiber having the following properties.

[0005]

[Means for Solving the Problems] As a result of intensive research to solve the above problems, the present inventors have developed a three-dimensional crimping method using eccentric core-sheath type or side-by-side type composite fibers of two specific types of polyester. The present invention has been achieved by discovering that the above object can be achieved by having the ability to express the film and performing a specific heat treatment in the stretching process.

That is, the present invention is characterized in that the main component is composed of ethylene terephthalate units, and 2,2-bis[4-(2-hydroxyethoxy)phenyl]propane is contained in an amount of 2 mol% or more and 10 mol% as a copolymer component. 1 mol% of aromatic dicarboxylic acid having the following and metal sulfonate groups:
The polyester composite fiber is characterized in that a polyester component (A) copolymerized in an amount of 3 mol% or less and a polyester component (B) substantially consisting of ethylene terephthalate units are eccentrically joined.

In the present invention, the polyester component (A)
is a copolyester whose main constituent unit is ethylene terephthalate unit, and 2,2-
A polyethylene terephthalate copolyester modified using bis[4-(2-hydroxyethoxy)phenyl]propane or an ester-forming derivative thereof and an aromatic dicarboxylic acid having a metal sulfonate group or an ester-forming derivative thereof. .

Here, 2,2-bis[4-(2-hydroxyethoxy)phenyl]propane (hereinafter abbreviated as BPE) is represented by the structural formula of Chemical Formula 1.

[0009]

[Chemical formula 1]

Aromatic dicarboxylic acids having a metal sulfonate group include, for example, isophthalic acid, phthalic acid,
, 6-naphthalene dicarboxylic acid, etc., which has a metal sulfonate group on the aromatic ring, and the metal is an alkali metal such as lithium, sodium, potassium, etc. Specifically, 5-sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid, 5-
Examples include lithium sulfoisophthalic acid, 4-sodium sulfoisophthalic acid, 4-sodium sulfo-2,6-naphthalene dicarboxylic acid, and ester-forming derivatives thereof may also be used. In the present invention, 5-sodium sulfoisophthalic acid or its ester-forming derivatives are preferably used.

In the present invention, the copolymerized units (hereinafter abbreviated as (a-1) units) formed in the polymer by the above-mentioned BPE or its ester-forming derivative are 2 mol % or more and 10 mol % or more in the polyester component (A). % or less, and the copolymerized units (hereinafter abbreviated as (a-2) units) formed by the aromatic dicarboxylic acid having a metal sulfonate group or its ester-forming derivative are present in the polyester component (A). It is mol% or more and 3 mol% or less. If the (a-1) unit is less than 2 mol %, not only the shrinkage properties will be insufficient, but also the bulk density will not be sufficient when made into a nonwoven fabric or the like. Moreover, if it exceeds 10 mol %, it becomes difficult to stably obtain an appropriate degree of polymerization in the polycondensation reaction necessary to maintain the melt viscosity of the polymer at a constant level, and the crimp fastness is significantly reduced. In addition, when the amount exceeding 10 mol % is made into chips and the chips are melted and used again, there is a drawback that there is a high possibility that sticking will occur when the chips are dried. The (a-1) unit is preferably 4 mol% or more and 8 mol% or less.

(a-2) The aromatic dicarboxylic acid having a metal sulfonate group constituting the unit imparts shrinkage force during heat treatment, maintains the melt viscosity at a certain level during polymerization, and maintains the ability to develop crimp over a certain level. It is necessary to make it latent. If the amount of (a-2) units is less than 1 mol %, the ability to develop crimp is small, and it is insufficient to obtain the target shrinkage stress, resulting in insufficient crimp development. If it exceeds 3 mol %, the melt viscosity of the polymer becomes too high, making it difficult to obtain an appropriate degree of polymerization in the polycondensation reaction, and at the same time increasing the cost. Furthermore, the crystallinity of the spun yarn becomes too high, which is undesirable because it tends to change over time, resulting in a decrease in drawability and a decrease in the strength of the composite fiber. The unit (a-2) is present in the polyester component (A) preferably in an amount of 1.5 mol% or more and 2.8 mol% or less, more preferably 1.5 mol% or more and 2.5 mol% or less.

[0013] The intrinsic viscosity of the polyester components (A) and (B) is not particularly limited, but each has a viscosity of 0.
It is sufficient if it is about 45 to 0.60 and 0.55 to 0.70. Further, the polyester components (A) and (B) may contain other copolymer components within a range that does not impair the objective effects of the present invention. Furthermore, in the composite fiber of the present invention, various property-imparting agents and additives such as flame retardants, deodorants, antibacterial agents, fragrances, pigments, and ceramics may be optionally added to the components (A) and/or (B). be able to.

[0014] In the present invention, when a polyester containing a specific amount of the above-mentioned (a-1) units and (a-2) units is used as one component of the conjugate fiber, and a nonwoven fabric is obtained using the conjugate fiber as raw cotton. , it is possible to surprisingly increase the bulk density of the nonwoven fabric.

[0015] When producing the composite fiber of the present invention, it is possible to use a spinneret having any hole shape such as a round cross section, a triangular cross section, a cross cross section, a T-shaped cross section, etc. Either an eccentric core-sheath type or a side-by-side type may be used, but the latter is preferable because it has excellent crimp development ability.

In particular, in the present invention, (A) and (
B) Using a side-by-side type nozzle for the two-component polymer,
It is desirable to perform composite spinning at a composite ratio of (A):(B)=40-60:60-40. However, the composite ratio (
As the ratio deviates from A):(B)=50:50, the kneeing phenomenon becomes more likely to occur at the nozzle discharge part (A)
:(B)=45-55: 55-45 is most preferred. In addition, the melt viscosity of the two components during spinning is always (A)>(B), and the difference in melt viscosity between the two is within the range of 300 to 1500 poise, which provides excellent latent crimp ability. desirable. If the melt viscosity difference is small, it is difficult to develop a sufficient number of crimps, while if it is too large, spinnability tends to be poor, which is not preferable. The term "difference in melt viscosity" used in the present invention refers to the difference in melt viscosity between polyester components (A) and (B) at about 285°C. For other spinning conditions, the spinning conditions for conventional polyester composite fibers can be adopted almost as they are.

In addition, when spinning the composite fiber of the present invention, for the polyester component (A), a polyester having a high content of units (a-1) and (a-2) is diluted with a homopolyester, and a predetermined amount of polyester is prepared. It may be adjusted by a master batch method such that the content of (a-1)
The polyester component (A) may be prepared by blending a polyester containing only the unit (a-2) with a polyester containing only the (a-2) unit, but in order to maximize the effects of the present invention, BPE and metal sulfonate must be blended. It is preferable to use a modified polyester obtained by adding an aromatic dicarboxylic acid having a group to the reaction system during polymerization of the polyester.

Next, in order to obtain a fabric such as a nonwoven fabric having stretchability and stretch recovery property, it is important that the latent crimpable composite fiber of the present invention has three-dimensional crimp after heat treatment. After dry heat treatment at °C, three-dimensional crimp of 40 to 90 crimp/25 mm, preferably 50 to 90 crimp/25 mm is developed, and the crimp ratio at this time is preferably 30% or more. If the number of crimps is less than 40 crimps/25 mm, the stretchability will be significantly reduced and the stretch recovery will be low. on the other hand,
If the number of crimps exceeds 90 crimps/25 mm, the irregularities on the surface of the nonwoven fabric will be noticeable and the texture will be poor, resulting in low practicality.

[0019] In addition to the number of crimps, the shape of the crimps (the state of the loops produced by the crimps) is also one of the factors for improving the elongation recovery properties of nonwoven fabrics. It is preferable that In other words, the shape of the loop is closely related to crimp fastness, and in the present invention, the shape of the loop is closely related to crimp fastness.
Preferably it is a composite fiber with a crimp fastness of 40%. When it is within this range, especially when it is made into a nonwoven fabric, the elongation recovery property and texture will be good.

[0020] The composite fiber of the present invention has a shrinkage rate of 20% or less, preferably 3 to 18%, when subjected to free shrinkage dry heat treatment at 170°C. It has an important relationship with the texture, bulkiness, and elasticity of fabrics. When the shrinkage rate exceeds 20%, the fabric becomes extremely hard, and its stretching properties, particularly its stretch recovery, are extremely poor, resulting in low durability.

[0021] The stretchable conjugate fiber having such a specific latent crimp ability and heat shrinkability is produced by the difference in melt viscosity between the polyester component (A) and the polyester component (B), and the difference in B of the component (A).
It can be obtained by appropriately selecting the copolymerization ratio of PE and an aromatic dicarboxylic acid having a metal sulfonate group, the composite ratio of (A) and (B), the stretching conditions and heat treatment conditions in the post-spinning stretching step, etc. The stretching ratio is determined by the breaking elongation of the spun yarn, that is, by stretching at 60 to 70% of the maximum stretching ratio, the latent crimp ability can be efficiently expressed. By doing so, high crystallinity can be maintained and high stretching strength can be cultivated. If the temperature is lower than 130°C, the shrinkage rate will be satisfied, but the shrinkage force will be insufficient and the elasticity will be poor. On the other hand, if the temperature exceeds 180° C., the fiber orientation will be significantly relaxed, resulting in a decrease in elasticity, durability, and strength of the fiber itself.

In addition, since the composite fiber of the present invention is passed through a carding process, it can be crimped using a conventional push-type crimper to the extent that no neps or unopened fiber troubles occur during the carding process. It is preferable to use raw cotton with a number of crimps of 8 to 20/25 mm.

[0023]

[Examples] The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these in any way. In the examples, the melt viscosity difference was measured with a flow tester.
The difference in melt viscosity (poise) between component (A) and component (B) at 85°C is shown. Further, the method of measuring other characteristic values at that time is as follows.

(1) Fineness: JIS L-1015-7-5-1A (
2) Number of crimp, crimp rate, crimp fastness: JIS L-10
15-7-12-1 (3) Free shrinkage rate: JIS L-1015-7-15
Measured according to the method of 30 minutes in a 170°C atmosphere with a load of 300mg per denier.

[Example 1] The polyester component (A) was mainly composed of ethylene terephthalate units, and 5.0 mol% of 2,2-bis[4-(2-hydroxyethoxy)phenyl]propane (BPE) and 5- A modified polyester (melt viscosity: 3300 poise) copolymerized with 2.5 mol% sodium sulfoisophthalic acid (SIP) and a polyester (melt viscosity: 2300 poise) consisting essentially of ethylene terephthalate units as the polyester component (B).
) was used to form a side-by-side type with a composite ratio of 50:50 at 285°C from a round-section spinneret using a composite melt-spinning device, and was wound at a discharge rate of 380 g/min and a speed of 1050 m/min to obtain a single yarn denier of 6.2 d. An undrawn yarn was obtained. After converging these undrawn yarns, they were drawn at a drawing ratio of 2.8 times (75% of the maximum drawing ratio) at a drawing temperature of 70°C, heat treated at a tension heat treatment temperature of 155°C, and then crimped using a push-in crimping machine. After mechanical crimping, the fibers were cut into 51 mm pieces to obtain short fibers with 12 crimps/25 mm.

[Examples 2 and 3] Polyester component (A) and polyester component (A) having different melt viscosities were prepared by changing the polycondensation reaction time of polyester.
B) was produced, and side-by-side composite fibers with a composite ratio of 50:50 were spun using the combinations shown in Table 1,
The fibers were stretched under the same conditions as in Example 1 except that the stretching ratio was as shown in Table 1, mechanically crimped, and then cut to obtain short fibers with 12 crimps/25 mm.

[0027]

[Table 1]

[Examples 4 to 7 and Comparative Examples 1 to 4] Using terephthalic acid as the main dicarboxylic acid component as the polyester component (A), the amount of copolymerization of BPE and the amount of copolymerization of SIP were combined as shown in Table 2, Other conditions were the same as in Example 1, and the fibers were spun and drawn, mechanically crimped, and then cut to obtain short fibers with 8 to 12 crimps/25 mm.

[0029]

[Table 2]

[Example 8] After drawing the undrawn yarn spun in Example 1, the procedure was repeated in the same manner as in Example 1 except that the tension heat treatment temperature was set at 170° C. The cut length was 51 mm and the number of mechanical crimp was 1.
Two short fibers/25 mm were obtained.

Table 3 shows the results of evaluating various properties of the short fibers obtained in the above Examples and Comparative Examples.

[0032]

[Table 3]

[0033]

Effects of the Invention According to the present invention, B is used as one component of the two types of polymers of the polyester latent crimp composite fiber.
By using a modified polyester made by copolymerizing a specific amount of aromatic dicarboxylic acid with PE and metal sulfonate groups, there is no significant increase in cost compared to ordinary polyethylene terephthalate fibers, and it has improved stretchability, stretch recovery, and texture. It is possible to provide polyester latent crimpable composite fibers suitable for obtaining fabrics such as nonwoven fabrics with excellent properties.

The fibers having the excellent properties of the present invention greatly contribute to improving the performance of sports and medical nonwoven fabrics, especially base fabrics for skin patches. In addition, when this property is utilized to make woven or knitted fabrics, it is possible to obtain fabrics that are not only highly stretchable but also soft to the touch and have an improved feel.

Claims (1)

[Claims] Claim 1: The main component is composed of ethylene terephthalate units, and the copolymerization component is 2,2-bis[4-(2-hydroxyethoxy)phenyl]propane in an amount of 2 mol% or more and 10 mol% or less, and a metal sulfonate. 1 mol% or more of aromatic dicarboxylic acid having a group of 3 mol%
A polyester composite fiber characterized in that a polyester component (A) copolymerized in the following range and a polyester component (B) substantially composed of ethylene terephthalate units are eccentrically joined.