JP2000054262A - Hygroscopic polyester fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce hygroscopic polyester fibers excellent in hygroscopictiy and laundering resistance by forming fibers of a polyester compounded with a specific polyalkylene oxide and then graft-polymerizing a polyalkylene glycol derivation on the surfaces of the fibers. SOLUTION: The hygroscopic polyester fibers are produced by spinning poly(ethylene terephthalate) compounded with 0.1-15 wt.% polyalkylene oxide (e.g. polyethylene oxide) having >=100,000 (pref. 500,000-4,000,000) weight average molecular weight to form fibers, forming cloth with the fibers and then graft- polymerizing a polyalkylene glycol derivative (e.g. a polyalkylene glycol diacrylate and/or a polyalkylene glycol dimethacrylate) having <100,000 (pref. 250-1,500) weight average molecular weight on the surfaces of the cloth.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hygroscopic polyester fiber having extremely high practical properties such as hygroscopicity and washing durability. More specifically, the present invention relates to a moisture-absorbing polyester fiber suitably used for clothing applications requiring moisture absorption, for example, sportswear and underwear which directly touches the skin.

[0002]

2. Description of the Related Art Polyester fibers are widely used in clothing and industrial applications because of their excellent mechanical and chemical properties. However, polyester fibers have a very low hygroscopicity due to their hydrophobicity, and are not suitable for use in clothing that directly touches the skin. Therefore, the emergence of polyester fibers having both high moisture absorption and practical properties such as washing durability is strongly desired.

Conventionally, as a method for imparting water absorbency or hygroscopicity to polyester fiber, a method of blending or copolymerizing a polyester with a hydrophilic compound before forming into a fiber or a method of forming a hydrophilic fiber on a fiber surface after forming into a fiber. For example, a method of performing a conversion process has been proposed.

As the former hydrophilic compound to be blended or copolymerized, PAG having Mw of 1,000 to 20,000 has been generally used. However, PAG has poor water resistance due to its water solubility and poor compatibility with the matrix polymer, so that it has a problem that the PAG easily falls off from the matrix polymer and the moisture absorbing effect of the final product decreases with time.

[0005] In order to solve the drawback of the PAG dropping,
It is known to employ a PAG having a hydrophobic function. For example, JP-B-45-17547 and JP-B-46-7461 disclose a random block copolymer of a PAG block and a polyamide block.
158429 proposes a random block copolymer of polytetramethylene glycol and polybutylene terephthalate. However, these proposals have a problem that the PAG becomes water-insoluble, but the hydrophilicity of the PAG decreases.

[0006] The latter method of hydrophilizing the fiber surface also has the disadvantage that the glycol is liable to fall off simply by coating the fiber with a PAG hydrophilic compound.

In order to solve this drawback, instead of simply coating a hydrophilic compound on the fiber surface, the compound is graft-polymerized to a matrix polymer on the fiber surface,
A method has been proposed for increasing the bonding force at the interface between the two.
Specifically, PA having two or more vinyl groups added to PAG
JP-A-48-27066 and JP-B-54-27066 disclose a method in which a G derivative and a matrix polymer are subjected to steam heat treatment in a wet state in the presence of a radical polymerization catalyst to carry out graft polymerization.
No. 40680.

In this case, it is necessary to graft-polymerize most of the fiber surface in order to obtain the desired hygroscopicity. But,
Along with this, the fibers are coated in the form of a film, and the texture of the obtained fabric is hardened. That is, the surface area of the fiber is limited, and as long as the texture of the fiber itself is not impaired, a sufficient hygroscopic effect cannot be obtained only by graft polymerization.

In view of the above, there has been proposed a method of improving the hygroscopicity by combining the compounding of the hydrophilic compound into the fiber and the graft polymerization on the fiber surface. Specifically, it is possible to knead a PAG having Mw of 1,000 to 20,000 into the fiber and graft-polymerize the fiber surface with acrylic acid, methacrylic acid and / or ethylene glycol monomethacrylate. 59-
No. 17224, for example. In this method, by using kneading and graft polymerization together, the hydrophilic compound is present both inside and on the surface of the fiber, so that at first glance only the hygroscopicity is additionally improved, and practical properties such as washing durability are not improved. It is imagined that PAG does not decrease because the PAG exists separately inside and on the surface of the fiber.

[0010] However, the hydrophilic compounds present inside and on the surface of the fiber are closely related to maintain practical properties such as washing durability. That is, when the sports clothing made of the hygroscopic fiber is subjected to, for example, washing, the fiber surface tends to be pulled into water due to the good affinity between the hydrophilic compound present on the fiber surface and the water molecule. However, the fiber morphology is maintained by the strong bonding force between the matrix polymers inside the fiber. However, when the PAG is present inside the fiber, there is no bonding force between the matrix polymers in that portion, that is, a groove is formed in the matrix polymer. Further, the PAG in the inside also has a good affinity for water and thus tends to fall into the water, and destruction from inside the fiber is also added. As described above, when PAG is present inside the fiber, the bonding force for fixing the surface of the fiber on which the hydrophilic compound has been graft-polymerized is reduced, and the PAG is applied from inside and outside the fiber.
Is also destroyed by falling into water, and the practical properties such as washing durability are significantly reduced. In particular, when the PAG to be blended is within the range of conventional Mw of 1,000 to 20,000, a PAG having a lower viscosity than the matrix polymer is easily bleed out to the outer layer of the fiber while being spun from the die and stretched, and is close to the fiber surface. PAGs gather in the outer layer,
The bonding force between the matrix polymers fixing the fiber surface is further reduced. Also, falling off from the inside of the internal PAG,
The closer to the fiber surface, the easier it is to drop off, and the higher the destruction from inside the fiber.

Therefore, at present, no hygroscopic fiber having sufficient hygroscopicity and practical properties such as washing durability has been provided yet.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a moisture-absorbing fiber which overcomes the above-mentioned problems of the prior art and has both practical properties such as sufficient moisture absorption and washing durability. is there.

[0013]

Means for Solving the Problems The present inventors have conducted intensive studies in order to achieve the above object, and found that PAO having a weight-average molecular weight of 100,000 or more was contained in the fiber in an amount of 0,000 or more based on the weight of the fiber.
Provided is a moisture-absorbing polyester fiber which is blended in an amount of 1 to 15% by weight and has a PAG derivative graft-polymerized on the fiber surface.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The term "hygroscopic agent" to be added to the hygroscopic fiber of the present invention means P
It is a PAO having an ultrahigh molecular weight of 100,000 or more, particularly 100,000 to 5.5 million, which far exceeds the number average molecular weight of AG.
It has been found that the incorporation of such an ultra-high molecular weight PAO into the matrix polymer significantly improves the washing durability of the obtained fiber. Conventionally, the molecular weight of the PAG compounded in the polyester is from several thousands to at most about 20,000 as described above, and none of them exceed 50,000.

Usually, Mw (weight average molecular weight) of 20,000 or less is referred to as polyalkylene glycol (PAG), and those having Mw higher than that are polyalkylene oxide (PAG).
O), in this document, PAO is a polyalkylene oxide having a Mw of 100,000 or more, and PAG is a polyalkylene glycol having a lower molecular weight than Mw 100,000 in order to easily understand the difference from the prior art.

In this regard, conventionally formulated low Mw PAGs are bleed-out to the outer layer of the fiber due to their low viscosity while being spun from a die and stretched. However, PA with Mw exceeding 100,000
O becomes difficult to bleed out to the outer layer because O has a high viscosity with an increase in Mw. Therefore, it is presumed that the ratio of the PAO existing in the central portion of the fiber is increased, and the concentration of PAO in the outer layer near the fiber surface is suppressed. That is,
Because the ratio of PAO existing in the center of the fiber cross section is high,
It is presumed that the decrease in the bonding force between the matrix polymers in the outer layer portion close to the fiber surface was small, the PAO was easy to fall off, and the washing durability was improved. Therefore, when the Mw is less than 100,000, the viscosity is small and the matrix polymer bleeds out to the outer layer, and the washing durability does not reach a practical level. As a preferable range of Mw, Mw is 100,000 or more, especially 100,000 to 400.
A range of 10,000 is preferable because the viscosity becomes sufficiently high with an increase in Mw. However, when Mw exceeds 5.5 million, the effect becomes saturated.

By the way, the fact that PAO is more present in the interior of the fiber means that the probability of contact with moisture existing outside the fiber is reduced, and a decrease in hygroscopicity is expected. However,
The problem is that a hydrophilic compound is graft-polymerized on the fiber surface, and the expected decrease in hygroscopicity is not exhibited. This is presumably because the hydrophilic compound on the fiber surface increased the moisture content on the fiber surface and facilitated the transmission of moisture to the PAO at the center of the fiber.

Specific examples of the above-mentioned PAO to be blended include polyethylene oxide, polypropylene oxide, polytetramethylene oxide, methoxy polyethylene oxide, phenoxy polyethylene oxide, polyethylene oxide-polypropylene oxide block copolymer, and functional groups thereof. Derivatives and the like are preferred, and polyethylene oxide is particularly preferred from the viewpoint of hydrophilicity. These PAOs can be obtained by any polymerization method, for example, by coordination ring-opening polymerization of an alkylene oxide until a desired molecular weight is reached using an alkoxide of an alkaline earth metal or the like as a catalyst. In particular, in the case of polyethylene oxide, it is obtained in the form of a white powder at room temperature.

The proportion of PAO to be blended in the fiber of the present invention is 1 to 15% by weight based on the weight of the fiber. 1
If the amount is less than 15% by weight, a sufficient hygroscopic effect is not exhibited, and
If the content exceeds wt%, even if the bleed-out is small, the proportion of PAO present in the outer layer close to the fiber surface increases, so that not only the improvement of practical properties such as washing durability is not exhibited, but also the mechanical strength is reduced. Would.

The polyester in the present invention is a polymer composed of a polymer having an ethylene terephthalate chain and / or a butylene terephthalate chain in an amount of 60% or more of all repeating units. Mixing or copolymerizing an agent for adding various functions such as properties and color development is a preferable embodiment without any problem.

Here, taking as an example a polyester fiber blended with PAO having a molecular weight of 400,000, under a condition (30 ° C. × 90% RH) where the inside of the clothes feels uncomfortable due to stuffiness, the PAO can absorb about 20 wt% of moisture. The PAO is 15 wt.
%, The fiber as a whole absorbs only about 3% at most. Therefore, in order to achieve sufficient hygroscopicity, it is necessary to use the PAG derivative together with a surface treatment for graft-polymerizing the PAG derivative onto the fiber surface.

PA graft-polymerized on the fiber surface of the present invention
Examples of the G derivative include those in which a compound having a vinyl group at the terminal or side chain of PAG is added.
Polyalkylene glycol diacrylate or polyalkylene glycol dimethacrylate in which acrylic acid or methacrylic acid is added to both ends of the polymer is preferred. Specific examples are shown below.

[0023]

Embedded image

In the above PAG derivative, the molecular weight of the polyalkylene glycol segment is from 250 to 1
500 is preferable, and 400 to 900 is more preferable. If the molecular weight is less than 250, it is insoluble in water and is not suitable for improving the hygroscopicity, which is the object of the present invention. Even if it exceeds 1500, the effect is not remarkably improved. The amount of these PAG derivatives attached to the fibers is 1.0 to 30 wt.
% Is preferred. If the amount is less than 1 wt%, the desired sufficient hygroscopic effect cannot be obtained, and if the amount exceeds 30 wt%, the texture of the obtained fabric is hardened or practical characteristics are deteriorated.

The method of applying the PAG derivative to the fiber may be any method such as a dipping treatment or a spraying method, and it is preferable to carry out steaming heat treatment immediately in a wet state without drying. As for the conditions of the steaming heat treatment, the steam content is better as it approaches saturation, and is at least 70% or more, preferably 90% or more. The processing temperature is 90 to 130.
C is preferable, and 100 to 115C is more preferable. If the treatment temperature is lower than 90 ° C., the reaction does not proceed sufficiently,
C. is not practically preferable, for example, the color fastness is lowered. As the graft polymerization catalyst used in the present invention,
Ammonium persulfate, potassium persulfate, sodium persulfate and / or benzoyl peroxide are preferably employed.

The form of the moisture-absorbing polyester fiber of the present invention is not limited to continuous filaments and tows, but may be arbitrarily selected from staples, spun yarns, woven fabrics, knitted fabrics and nonwoven fabrics. In particular, in the case of a cloth, it is preferable that the fiber is constituted by 100% from the aspect of hygroscopicity.
It is no problem at all to use a part of other fibers having a function to be added, and it is a preferable embodiment. As a particularly preferred range, the proportion of the hygroscopic polyester fiber in the fabric is 30 to 100% by weight.

[0027]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited to these Examples.

The moisture absorption (MR) and the difference (ΔMR) in the examples and comparative examples are calculated by the following equations.

[0029]

(Equation 1)

[0030]

(Equation 2)

Example 1 90 wt. Of polyethylene terephthalate (intrinsic viscosity = 0.64) obtained according to a conventional method
% Of polyethylene oxide (Mw = 400,000) was melt-spun to obtain a yarn having a single yarn fineness of 1.3 dtex. Next, the short fiber obtained by cutting into 38 mm was spun to produce a 30-count single yarn. Using this yarn, a thin woven fabric having a warp of 103 / in and a weft of 61 / in was woven and dyed, and then reduced by 10% by weight with an alkali.

In the obtained fabric, 20 wt% of polyethylene glycol diacrylate having a molecular weight of polyethylene glycol segment of 600 and 0.1% of potassium persulfate were added.
After padding, the mixed aqueous solution adjusted to be wt% was steam-heat treated with steam at 100 ° C. for 2 minutes to perform graft polymerization. The graft ratio at this time was 10 wt% based on the weight of the fabric before the graft. Table 1 shows the results.

Example 2 The same procedure as in Example 1 was carried out except that the blending amount of polyethylene oxide was reduced to 3% by weight, and the spun yarn was woven with a standard such that the yarn was 40-count single yarn and had the same weight. did. Table 1 shows the results.

Comparative Example 1 An experiment was carried out in the same manner as in Example 2 except that the graft polymerization with the PAG derivative was not carried out.
Table 1 shows the results.

Comparative Example 2 The same operation as in Example 2 was carried out except that a general polyethylene terephthalate polymer containing no polyoxyalkylene glycol was used.
Table 1 shows the results.

Comparative Example 3 The same operation as in Comparative Example 1 was carried out except that a normal polyethylene terephthalate polymer containing no polyoxyalkylene glycol was used.
Table 1 shows the results.

Comparative Example 4 The same operation as in Example 2 was carried out except that the polyethylene oxide to be blended was changed to a polyalkylene glycol having a molecular weight of 20,000. Table 1 shows the results.

Comparative Example 5 The same operation as in Comparative Example 4 was carried out except that the graft polymerization with the PAG derivative was not carried out.
Table 1 shows the results.

[Comparative Example 6] As a comparative sample of 100% cotton, a U.S. cotton comber yarn was used, woven according to the same weaving standard as in Example 2, and then dyed and finished under ordinary cotton fabric finishing conditions. did. However, the alkali reduction step and the surface modification step by graft polymerization were not performed. Table 1 shows the results.

The MR of the example is lower than that of the cotton of Comparative Example 6, but is incomparably improved with that of Comparative Example 3, and is much higher than that of kneading or surface treatment alone. MR is obtained, and the effect on the target hygroscopicity is confirmed. Further, although there is almost no difference in the ΔMR of Comparative Example 5 in which the hydrophilic compound is likely to fall off due to alkali weight loss compared to Comparative Example 1, there is a difference between Example 2 and Comparative Example 4 in which both were subjected to graft polymerization. In △ MR (L0),
Example 2 is higher, and the effect of hygroscopicity by the combined use of the kneading agent with a higher molecular weight and graft polymerization is also confirmed. Furthermore, despite the increase in the amount of the hydrophilic agent added due to the combination of kneading and surface treatment, no significant decrease in ΔMR was observed at L0 to L20 as compared with Comparative Examples 4 and 5,
Maintenance of washing durability has also been achieved.

[0041]

[Table 1]

[0042]

The hygroscopic polyester fiber of the present invention includes:
Because it contains ultra-high molecular weight polyoxyalkylene, which has never been imagined, such as in conventional fibers, even if the PAG derivative is graft-polymerized on the fiber surface, there is no decrease in practical properties such as washing durability, and It also has extremely high hygroscopicity. Therefore, in clothing applications that require moisture absorption, for example, in sportswear or inners that directly touch the skin, it has the effect of reducing discomfort such as stuffiness felt during high summer and greatly improving wearing comfort.

Claims (4)

[Claims] 1. A hygroscopic polyester fiber characterized in that PAO having an Mw of 100,000 or more is blended in the fiber in an amount of 0.1 to 15% by weight based on the weight of the fiber, and a PAG derivative is graft-polymerized on the fiber surface. Here, PAO is a polyalkylene oxide having a Mw (weight average molecular weight) of 100,000 or more, and PAG is a polyalkylene glycol having a Mw of less than 100,000. 2. The hygroscopic polyester fiber according to claim 1, wherein the weight average molecular weight of the PAO blended inside the fiber is from 500,000 to 4,000,000. 3. The hygroscopic polyester fiber according to claim 1, wherein the PAG derivative on the fiber surface is polyalkylene glycol diacrylate and / or polyalkylene glycol dimethacrylate. 4. The hygroscopic polyester fiber according to claim 3, wherein the weight average molecular weight of the PAG segment in the PAG derivative on the fiber surface is from 250 to 1500.