JPH08158251A - Production of porous polyamide fiber - Google Patents

Abstract

PURPOSE: To obtain a porous polyamide fiber having excellent water-absorption and light weight by forming a number of fine pores in the inner part or on the surface of a melt-spun fiber composed of specific components. CONSTITUTION: This light-weight porous polyamide fiber is produced by mixing 50-90wt.% of a fiber-forming polyamide component with 10-50wt.% of a copolymerized polyethylene terephthalate component containing ethylene terephthalate unit as a matrix and obtained by reacting a dicarboxylic acid component containing >=1.5 and <9.0 mol% of a sulfoisophthalic acid metal salt with a glycol component containing 3-10wt.% of a polyalkylene glycol having a molecular weight of 400-20,000, spinning the mixture by melt-spinning method and treating the obtained fiber with an alkali to dissolve and remove at least 90wt.% of the copolymerized polyethylene terephthalate and form a number of fine grooved pores. The polyalkylene glycol is preferably polyethylene glycol.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a melt-spun polyamide fiber, and more specifically, by forming fine pores on the surface and inside of the fiber, the water absorption is improved and the weight is reduced. The present invention relates to a polyamide fiber having excellent applicability to general clothing, particularly inner clothing.

[0002]

2. Description of the Related Art From a so-called sea-island type fiber obtained by melt-spinning multi-component polymers having different solubilities, the sea component is removed by dissolution or chemical decomposition, and only the island component is left. Techniques for producing multi-fiber are disclosed in, for example, Japanese Patent Publication No. 55-29166 and Japanese Patent Publication No. 61-1.
No. 3032, JP-A-4-174767, and the like. Here, when the non-dissolved removal component corresponding to the sea part is polyester or polyamide, as an example of the polymer corresponding to the island component, the acid component is replaced with a sulfonic acid metal salt from the standpoint of melt spinnability and heat resistance. Polyesters using aromatic dicarboxylic acids as copolymerization components are well known. (Japanese Patent Publication No. 45-28728, Japanese Patent Publication No. 58-39926, etc.)

On the other hand, contrary to the above-mentioned technique for producing ultra-fine multi-fibers, the island component of the sea-island type fiber is dissolved and removed to form fibrils or voids on the surface or inside of the fiber mainly composed of the sea part. It is also possible to form the fibers to impart water absorbency or hygroscopicity to the fibers, as disclosed in JP-B-58-39926 and JP-A-5-39926.
6-107069, JP-A-4-18112, and the like. In particular, in this case, as a multi-component polymer used for melt-mix spinning, if the mutual affinity of the components is too far apart, uniform mixing will be difficult, and spinning or drawable yarn breakage will occur frequently. It is necessary to have a certain degree of compatibility, since there are adverse effects such as the above, and the size of the fibrils and voids that are formed tend to be rough and non-uniform, and the physical properties and quality of the obtained fiber will be poor. .

In Japanese Patent Laid-Open No. 2-175965, a melt-mixed spun fiber composed of a polyester containing an organic sulfonic acid metal salt and a polyamide is subjected to an alkali weight reduction treatment to elute and remove at least a part of the polyester to lengthen the fiber surface. A porous polyamide fiber is disclosed which forms streak-shaped fine pores in the depth direction. The organic sulfonic acid metal salt-containing polyester used here has a good compatibility with the polyamide and therefore can be mixed in a relatively large amount in the polyamide, has good spinning properties and drawability, and has an improved texture. And suitable for obtaining a polyamide fiber having gloss and water absorption.

[0005]

However, according to the knowledge of the inventor of the present invention, the above-mentioned JP-A No. 2-1759 is present which is present in a dispersed state in the polyamide by the mixed spinning with the polyamide.
The organic sulfonic acid metal salt-containing polyester as described in Japanese Patent Publication No. 65 still has insufficient alkali weight loss processability,
The weight loss rate is slow, which is not advantageous for industrial production. In particular, as shown in Comparative Examples below, under mild alkaline weight loss conditions such as relatively low alkali concentration or low processing temperature, the weight loss rate as far as the theoretical amount was not reached, and especially when the weight loss was within the polyamide fiber, It is considered that the organic sulfonic acid metal salt-containing polyester component remains undissolved.

In consideration of expanding the porous polyamide fiber to be provided in the present invention into a general textile woven or knitted fabric, since it is essential to maintain the dyeability and texture which are the same as those of ordinary polyamide fibers, it is important to maintain the organic Dissolved components such as polyesters containing sulfonic acid metal salts need to be substantially completely dissolved and removed, and if some undissolved parts remain, good dark coloration as expected can be obtained. It is not preferable because it does not occur, causes stains, or deteriorates the physical properties of the fiber.

In order to dissolve and remove the organic sulfonic acid metal salt-containing polyester substantially completely by alkali treatment, it is necessary to increase the alkali concentration of the alkali treatment liquid or to lengthen the treatment time. Is not economically advantageous for the manufacturing process. It is also known that the higher the copolymerization rate of the sulfonic acid metal salt, the higher the solubility, but such a copolyester tends to have a gradual decrease in melting point, which is problematic in terms of stable spinnability. There is. Therefore, industrial production is required to further increase the alkali weight loss rate and improve the treatment efficiency so that the alkali can be completely dissolved and removed under mild treatment conditions.

That is, the object of the present invention is that the compatibility with polyamide is good, spinnability and stretchability are not impaired even when mixed at a high blending ratio, and alkali weight loss is possible in a short time and under mild conditions. Another object of the present invention is to provide a method for producing a porous polyamide fiber, which comprises using a specific copolyester capable of being dissolved and removed substantially completely as a dissolving and removing component. The present inventor does not copolymerize only the sulfonic acid metal salt-containing aromatic dicarboxylic acid described above,
At the same time, the inventors have found that by using polyethylene terephthalate having a specific composition in which the polyalkylene glycol component is used as another copolymerization component, the compatibility with polyamide is extremely high and the alkali weight loss property is further improved, and the present invention has been completed.

[Means for Solving the Problems]

That is, according to the present invention, the fiber-forming polyamide component is 50 to 90% by weight, the ethylene terephthalate unit is the base, and the sulfoisophthalic acid metal salt is 1.5 mol% to 9.0 mol% as the dicarboxylic acid component. Less than less than 400, the glycol component has a molecular weight of 400 to 200
3 parts by weight or more of polyalkylene glycol of 0 or less and 1
At least 90% of the copolymerized polyethylene terephthalate component is treated with an alkali to obtain a melt-mixed fiber obtained by mixing 10 to 50% by weight of a copolymerized polyethylene terephthalate component reacted in an amount of 0% by weight or less and performing melt spinning.
A method for producing a porous polyamide fiber, characterized in that fine groove-shaped porosity is formed on the surface and inside of the fiber by dissolving and removing wt%.

As the polyamide used in the present invention,
Any melt-spinnable fiber-forming polymer may be used, and examples thereof include nylon 6, nylon 66, nylon 610, nylon 6T, nylon 6I, nylon 12, and the like, or a mixture of two or more thereof. Among them, nylon 6 and nylon 66 are particularly preferable because they have good physical properties such as heat resistance and are inexpensive. Further, the polyamide used in the present invention, if necessary, a matting agent such as titanium oxide,
A stabilizer, pigment, antistatic agent, etc. may be added.

The copolymer-modified polyester referred to in the present invention (hereinafter referred to as a copolymer-modified polyester) is a polyethylene terephthalate skeleton into which both metal sulfoisophthalic acid salt and polyalkylene glycol are introduced by copolymerization. , Which is known from, for example, Japanese Patent Laid-Open No. 1-314781. However, such a copolymer-modified polyester has a good compatibility with polyamide even though it is a polyester-based polymer, and it is possible to add and mix it to polyamide at a high concentration and spin it. Found out. In order to achieve the object of the present invention, it is an essential requirement that the composition of the copolyester and the compounding ratio in the polyamide are within the specific ranges as described above.

The metal salt of sulfoisophthalic acid used in the present invention is 5-sodium sulfoisophthalic acid, 5
-Potassium sulfoisophthalic acid is preferable because it has good copolymerization reactivity, is easily available, and has excellent handleability.

In the above copolymerized modified polyester, the copolymerization ratio of the metal salt of isophthalic acid in all the constituent acid components is preferably 1.5 mol% or more and 9.0 mol% or less. If the copolymerization ratio is less than 1.5 mol%, the compatibility with polyamide decreases, resulting in poor mixing spinnability, resulting in increased yarn breakage frequency and non-uniform yarn thickness. Also leads to. Furthermore, the alkali-solubility of the mixed and spun fiber is lowered, and the object of the present invention cannot be effectively exhibited. On the other hand, the copolymerization ratio is 9.
When it exceeds 0%, the affinity with the polyamide is increased and the compatibility is certainly improved, but the melting point of the copolymerized modified polyester is lowered and the heat resistance becomes insufficient, so that the spinnability is also adversely affected. Not preferable.

In the above copolymer modified polyester, the second modifying component, polyalkylene glycol, means polyether glycol such as polyethylene glycol, polypropylene glycol, block or random polyethylene / propylene glycol, among which polyethylene glycol is Optimal. As the polyalkylene glycol, it is preferable to use one having a molecular weight of 400 or more and 20000 or less. If the molecular weight is less than 400, the alkali processability is lowered, and processing under mild conditions cannot be performed. Further, when the molecular weight exceeds 20,000, the melt heat resistance of the copolymer-modified polyester itself is lowered, so that problems such as yarn breakage are likely to occur in melt spinning.

Polyethylene terephthalate obtained by copolymerizing only polyalkylene glycol has a low affinity with the polyamide, has poor alkali solubility in the mixed spun fiber with the polyamide, and has to have a large polyalkylene glycol copolymerization ratio. It is not suitable because good solubility cannot be obtained and the heat resistance of such a copolymer is lowered, which adversely affects the spinnability. Therefore, it is essential to use a polyester modified by copolymerization with a specific composition as in the present invention.

Further, in the above copolymerized modified polyester, the copolymerization ratio of polyalkylene glycol in all the constituent glycol components is preferably 3% by weight or more and 10% by weight or less. When it is less than 3% by weight, the alkali solubility is insufficient, and it becomes difficult to perform treatment under mild conditions.
On the other hand, when the ratio is more than 10% by weight, the melt heat resistance of the copolymer-modified polyester itself is lowered and the stable spinnability is lost.

The proportion of each component in the mixed spinning of the above polyamide component and the above copolymerized modified polyester component is preferably 10 to 50% by weight, and particularly preferably 15 to 40% by weight, of the copolymerized modified polyester component. If this ratio is less than 10% by weight, the number of groove-shaped pores formed after the alkali treatment is small, so that sufficient water absorption and weight reduction cannot be achieved. On the other hand, if this ratio exceeds 50% by weight, the compatibility with the polyamide decreases and the spinnability in mixed spinning becomes poor, which is not preferable.

As a method for obtaining a mixed spun fiber comprising a polyamide component and a copolymerized modified polyester component used in the present invention, pellets of both components may be mixed in advance at a predetermined ratio and melt-spun, or Alternatively, the melted products of both components may be mixed with each other by a known static type or dynamic kneading device, and then spun. The spinning temperature is approximately 275 to 285 ° C., and the winding speed is 50.
0 to 1500 m / min, and the draw ratio is 2.5 to
The stretching speed is 3.5 and the stretching speed is 500 to 1000 m / min. Alternatively, the spun yarn can be produced by a direct spinning method in which the drawn yarn is continuously and immediately drawn without being wound up on a bobbin.

Thus, the dissolving and removing treatment of the copolymer-modified polyester component in the obtained mixed spun fiber with an alkali may be carried out at the stage of the drawn yarn or the processed yarn, but usually for a fabric such as a woven or knitted fabric. It is convenient to carry out the above process, and it may be carried out in accordance with the alkali weight reduction process of the polyester fiber cloth. The alkaline treatment liquid preferably used in the present invention is
It is an aqueous solution of caustic soda or potassium hydroxide, and the treatment conditions are: an alkaline aqueous solution concentration of 0.5 to 5%;
The object to be treated may be immersed in hot water at 0 ° C. In the mixed spun fiber, the modified copolyester has good compatibility with the polyamide and therefore exists in a finely dispersed state on the entire surface of the polyamide. Further, the modified copolyester has an extremely high rate of hydrolysis reaction by alkali. Due to the effects of both, it is assumed that even under a short treatment time or mild treatment conditions, it can be almost completely dissolved and removed through the continuous copolymerized modified polyester portion to the inside of the fiber. Under such conditions, at least 90% by weight of the theoretical amount is dissolved and removed.

By the dissolution treatment, substantially only the polyamide component remains, and in the trace after the dissolution and removal, fine grooves or cavities having a width of 0.01 to 0.1 μm are formed on the fiber surface or inside. It At the same time, as an additional effect, the outer diameter of the fiber is hardly changed even by the dissolution treatment, and the apparent specific gravity is reduced corresponding to the weight loss, so that the weight of the fiber and the product using the fiber can be reduced.

The present invention will be described below with reference to examples. The dissolution removal rate is calculated from the weight of the sample before and after dissolution in alkali. Further, the water absorption rate was calculated from the weight increase amount after the sample was immersed in water under a room temperature environment for 30 minutes and then centrifugally dehydrated for 2 minutes in a dehydrator of a domestic washing machine.

[0022]

【Example】

[Example 1] Nylon 6 chips (semi-dal type having a relative viscosity of 2.58 measured at 25 ° C in a 96% sulfuric acid 1% solution) and polyethylene terephthalate were prepared using sodium sulfoisophthalate and polyalkylene glycol. Chips were mixed with a copolymerized poly (elteru) tip having a composition as shown in Table 1 at a mixing ratio as shown in Table 1, and a spinning temperature of 2 using a spinneret having a round cross section with 24 holes.
Melt spinning was performed at 80 ° C. and a winding speed of 1000 m / min.
Then, it was drawn at room temperature at a draw ratio of 3.35 at a speed of 750 m / min, and a circular knit fabric was prepared using the obtained drawn yarn of 75 denier 24 filaments. After polishing the circular knitted cloth, it was dipped in a 2% boiling aqueous solution of caustic soda. The bath ratio at that time was 1:50. The circular knit fabric was sometimes shaken as it was, and left standing for 60 minutes to dissolve and remove the copolymerized polyelter. After that, the sample was washed with water and naturally dried, and the dissolution removal rate of the copolymerized polyelter was calculated. The results are shown in Table 1.
It can be seen that each of these examples is superior in dissolution and removal property and spinnability to the comparative example shown in the same Table 1.

[0023]

[Table 1]

Example 2 In order to prove that the mixed spun fiber used in the present invention has excellent alkali solubility,
A mixed spun fiber (spun brand: 60 denier / 18) made of the copolymer-modified polyester component having the composition shown in Table 2 and a polyamide component, and prepared in the same manner as in Example 1 except that the number of spinneret holes was 18. (As a filament)
For the circular knitted fabric from No. 3, the dissolution removal rate was measured by changing the alkaline dissolution treatment conditions. Table 2 shows the measurement results. At the same time, it can be seen that the dissolution rate is higher than in the case of using polyethylene terephthalate obtained by copolymerizing and modifying each of sodium sulfoisophthalate and polyethylene glycol. (See Comparative Examples 11 and 12)

[0025]

[Table 2]

Example 3 In order to evaluate the water absorption performance of the porous polyamide fiber obtained by the present invention, copolymerization modification was carried out with 6 nylon, 4.5 mol% of sodium sulfoisophthalate and 8% by weight of polyethylene glycol having a molecular weight of 4000. Mixing ratio with the prepared polyethylene terephthalate 75:
Circular knitting was prepared by using two yarns of mixed spun fibers (70 denier / 24 filaments) having a round cross section of 25 (weight ratio), and dissolved in caustic caustic 2% aqueous solution at about 97 ° C. for 40 minutes. The dissolution removal rate at this time is 94.5% of the theoretical amount.
Met. Table 3 shows the water absorption of the circular knitting after the dissolution treatment. As a control, the nylon 6 round cross section yarn of the same brand was also measured in the same manner. It can be seen that the porous polyamide fiber of the present invention exhibits excellent water absorption performance and is suitable for applications requiring a water absorption function such as inner clothing and towels.

[0027]

[Table 3]

[0028]

EFFECT OF THE INVENTION By using the copolymerized modified polyester having the above-mentioned specific composition, it is possible to obtain a mixed spun fiber which has good compatibility with polyamide and does not impair spinnability even when mixed in a large amount. Further, the copolymer-modified polyester has extremely excellent solubility in alkalis, and has a much higher dissolution rate than conventionally used polyesters which are copolymer-modified with an organic sulfonic acid metal salt or a polyalkylene glycol alone. . As a result, almost all the amount in the fiber can be dissolved and removed under a milder condition in a shorter time than in the past, which is economically advantageous in the processing step. Also,
It does not adversely affect the physical properties and dyeability of the porous polyamide fiber obtained thereby. Further, the fiber thickness after dissolution in alkali is the same as that before dissolution, the apparent density of the entire fiber is lowered, and the effect of weight reduction is naturally exhibited.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location // D06M 101: 32 101: 34

Claims (1)

[Claims] 1. A fiber-forming polyamide component is added in an amount of 50 to 90.
% By weight, and ethylene terephthalate unit as a base, containing 1.5 mol% or more and less than 9.0 mol% of sulfoisophthalic acid metal salt as a dicarboxylic acid component, and 3% of a polyalkylene glycol having a molecular weight of 400 to 20000 as a glycol component. 10 parts by weight or more and 10% by weight or less of the copolymerized polyethylene terephthalate component
The melt-mixed fiber obtained by mixing 50% by weight and melt-spinning is treated with an alkali to dissolve and remove at least 90% by weight of the copolymerized polyethylene terephthalate component to form fine grooves on the surface and inside of the fiber. A method for producing a porous polyamide fiber, which comprises forming a porous polyamide fiber.