JPS5953365B2 - Water-absorbing acrylic fiber - Google Patents

Description

[Detailed description of the invention] The present invention relates to water-absorbing acrylic fibers.

Acrylic fiber has a texture similar to wool.

It is a fiber that has many characteristics that make it excellent as a clothing fiber, such as excellent color development.

However, compared to natural fibers such as wool and cotton, acrylic fibers have significantly lower water absorption and hygroscopicity.

It is said that the reason fiber products made of wool and cotton feel comfortable to wear even when sweating or in high humidity environments is because these fibers have excellent water absorption and moisture absorption performance.

Recently, acrylic fibers have been proposed that have improved water absorption properties and have a water absorption capacity similar to that of natural fibers.

For example, JP-A-52-70113 discloses dry-spun fibers having a sheath-core structure with a moisture content of at least 2% and a water retention degree of at least 10% at 65% relative humidity/21°C. .

In addition, Japanese Patent Application Laid-Open No. 54-23723 has a range of 100 to 300
Consisting of a porous core layer and a dense skin layer with a microstructure of 0.5%, and a water retention rate of at least 35% and a temperature of 100℃.
Discloses a fiber whose water retention rate decreases by 20% or less when subjected to dry heat treatment for 1 hour.

All of these acrylic fibers have a sheath-core structure in which the center is porous and the outer periphery forms a dense layer. It is characterized by its ability to absorb water by inhaling it.

However, the above-mentioned acrylic fibers are simply fibers with a large number of fine holes, and the acrylic fibers themselves do not have an affinity for water.

Therefore, although it does have water absorption performance in terms of sucking water into its fine pores, it is essentially different from the water absorption and moisture absorption performance of fibers that have an affinity for water, such as wool and cotton.

For this reason, the textile products made of the above-mentioned acrylic fibers are not necessarily comfortable to wear in high humidity environments such as when sweating, and there is still room for improvement.

The present inventors have completed the present invention as a result of extensive research in order to improve these drawbacks.

That is, the present invention provides an acrylic polymer containing at least 80% by weight of acrylonitrile and 0% by weight of the polymer.
．． It is an acrylic fiber comprising 3 to 30% by weight of polyalkylene oxide having a number average molecular weight of 100,000 or more, and is characterized by having fine pores.

The object of the present invention is to provide an acrylic fiber that has excellent water absorbency and hygroscopicity and has improved wear performance in high humidity environments.

The present invention will be explained in more detail below.

The acrylic polymer constituting the acrylic fiber of the present invention is a copolymer of at least 80% by weight of acrylonitrile and up to 20% by weight of a monomer having an unsaturated double bond that is copolymerizable with acrylonitrile, or It is a mixture of two or more polymers containing a total of at least 80% by weight acrylonitrile.

The acrylic polymer may include, for example, acrylonitrile and 2
0% by weight or less of methyl acrylate, methyl methacrylate, vinyl acetate, vinyl chloride, vinyl bromide, vinylidene chloride, vinylidene bromide, styrene, acrylamide,
A polymer with at least one selected from dimethylaminoethyl methacrylate, vinylpyridine, acrylic acid, methacrylic acid, acrylsulfonic acid, methallylsulfonic acid, styrenesulfonic acid, and salts of these acids, or
A mixture of at least two of these polymers,
It is not limited to these polymers.

The molecular weight of polyalkylene oxide, which is another component constituting the acrylic fiber of the present invention, has a number average molecular weight of 10.
It needs to be 10,000 or more; if it is smaller than this, the effect will be less pronounced.

On the other hand, there is no particular restriction on the upper limit of the number average molecular weight of the polyalkylene oxide, as long as it is within a practically obtainable range.

The amount of the above-mentioned polyalkylene oxide contained in the fiber is required to be 0.3 to 30% by weight based on the acrylic polymer in order to exhibit the effects of the present invention.
If it is less than % by weight, the effect will not be sufficiently expressed.

On the other hand, if the content of polyalkylene oxide exceeds 30% by weight based on the acrylic polymer, the strength and elongation properties of the fiber will be impaired, which is not preferable.

The preferred content is 0.5 to 10% by weight.

Specific examples of the polyalkylene oxide include polyethylene oxide, polypropylene oxide, polypropylene oxide, polyoxyethylene polyoxypropylene block polymer, etc. having a number average molecular weight of 100,000 or more.

This polyalkylene oxide compound itself is hydrophilic, and by mixing it with the acrylic polymer, the acrylic fibers have an affinity for water.

However, the water performance of acrylic fibers made hydrophilic by mixing polyalkylene oxide, that is, the water absorption and moisture absorption performance, is extremely low, and it is not possible to obtain hydrophilic acrylic fibers of practical value with this alone.

This is exactly the same as the fact that hydrophilic acrylic fibers mixed with other hydrophilic substances, which have been proposed in the past, have not been practically successful.

However, when a polyalkylene oxide with a number average molecular weight of 100,000 or more is mixed and pores are created in the acrylic fiber itself, the polyalkylene oxide with a number average molecular weight of 100,000 or more is simply mixed. The water absorption and hygroscopic properties of acrylic fibers are greater than the sum of the acrylic fibers that simply have holes in them, and in addition, products made from these fibers in high humidity environments are superior to conventional pore-only acrylic fibers. This provides a comfortable wearing experience that is not found in products made from acrylic fibers.

This effect is apparently due to the interaction between the polyalkylene oxide and the pores, and cannot be obtained when the compound is replaced with another hydrophilic substance.

Although it is not clear why the acrylic fiber, which contains polyalkylene oxide with a number average molecular weight of 100,000 or more and has pores, exhibits the unique effects, it is possible to Alkylene oxide itself mainly absorbs water, but the state of this water absorption differs greatly when there are pores inside the fiber.In short, it has a good affinity with water and absorbs water quickly, and the amount of water absorbed increases. This is extremely common.

The mechanism for this is not clear, but it is not because when the polyalkylene oxide in the fiber absorbs water and swells, if there are pores, it can absorb enough water and swell to fill the pores. It is estimated that.

In short, the mechanism is thought to be similar to the mechanism by which cotton absorbs water and swells.

The reason why these fibers are so comfortable to wear is that when you sweat, water moves quickly from the surface of your body to the inside of the fibers, and the water disappears from the skin surface, resulting in a dry touch without a damp feeling, making it uncomfortable to wear. Seems like a good thing.

Another feature of the acrylic fiber of the present invention is that it has fine pores in the fiber.

Because the acrylic fiber has these fine pores, interaction with the polyalkylene oxide occurs, resulting in the acrylic fiber having unique water absorption and hygroscopic properties as described above.

The above-mentioned fine pores possessed by the acrylic fiber of the present invention are
It may be in the form of a simple bubble or may have a certain length along the fiber axis direction.

These fine pores may be uniformly distributed in the cross section of the fiber, or may be concentrated in the center or outer periphery.

Furthermore, some of these fine pores may open from the inside of the fiber to the surface.

Its pore size is 0.1-5μ.

If the pore diameter is less than 0.1 μm, the water absorption and moisture absorption performance will decrease, which is not preferable.

However, finer pores may be mixed than in the present invention.

On the other hand, if the pore diameter is larger than 5 μm, physical properties such as fiber strength and elongation are impaired, which is not preferable.

Next, the method for producing acrylic fibers of the present invention will be explained.

The acrylic fiber of the present invention is produced by spinning a spinning dope containing an acrylic polymer and polyalkylene oxide from a spinneret into a coagulation bath compatible with a solvent, and then passing through processes such as water washing, stretching, drying, and heat treatment. Manufactured.

A spinning stock solution containing an acrylic polymer and a polyalkylene oxide can be prepared by mixing them simultaneously in the solvent for the acrylic polymer, or by dissolving one of them first and adding the other later. You can adjust it by using any of the following methods.

The solvent for preparing the spinning stock solution of acrylic polymer is
A solvent for polyalkylene oxide or a solvent for acrylic polymer that can finely disperse the polyalkylene oxide is preferred.

As such a solvent, a conventionally known acrylic polymer solvent can be used.

Examples of such solvents include organic solvents such as dimethylformamide, dimethylacetamide, and dimethyl sulfoxide, concentrated aqueous solutions of inorganic salts such as rhodan salt or zinc chloride, and inorganic salt-based or inorganic acid-based solvents such as aqueous nitric acid. can be mentioned.

The above spinning dope is then extruded through the pores of the spinneret into a coagulation medium and coagulated to form a filament.

In this case, the coagulation medium may be a dilute aqueous solution of a solvent (referred to as a wet spinning method), a combination of a gas such as air and water or a dilute aqueous solution of a solvent (referred to as a semi-dry spinning method), or a gas alone (referred to as a dry spinning method). is used as appropriate.

In the present invention, the amount of polyalkylene oxide added to the spinning stock solution may be appropriately selected depending on the spinning method, the amount of the above-mentioned compound contained in the acrylic fiber, target water absorption, moisture absorption performance, etc.

The coagulated filament produced by the above-described spinning method is washed with water to remove the solvent, and then subjected to processes such as stretching, applying an oil agent, drying, etc., and then, if necessary, a heat treatment process to become the final product.

All of these steps are carried out by appropriately selecting known methods.
Recruitment is a good idea.

Although it is not clear why pores are formed in the above method, the polyoxyalkylene oxide in the spinning solution mainly exists in the form of blocks, and these blocks exist as they are in the coagulated filament. It is thought that the block shrinks in volume more than the yarn at the same time as the yarn dries during the drying process, and as a result, voids are formed in several blocks.

The acrylic fiber of the present invention is characterized by excellent water absorption and hygroscopicity, but it also improves other fiber physical properties such as strength,
It is an excellent acrylic fiber that retains the original characteristics of acrylic fiber in terms of elongation, color development, fibrillation resistance, etc.

Hereinafter, the acrylic fiber of the present invention will be explained with reference to Examples.

In addition, the polyethylene oxide (PEO) in the stock solutions and fibers in Examples is expressed in weight % with respect to the acrylic polymer.

The method for measuring each performance is as shown below.

Diameter of pores: Freeze cut the fiber, take a 400x photograph with a transmission electron microscope, and determine from this photograph.

Water absorption rate: Thoroughly open approximately 1 dir of the fiber for measurement and soak it in water at room temperature for 10 min.
Soak for minutes.

After soaking for 10 minutes, centrifugal acceleration 1000 in a centrifuge
Dehydrate at X g for 3 minutes.

Find the weight of this dehydrated fiber.

(51 g) This fiber was further dried in a hot air dryer at 120° C. for 3 hours.

Determine the fiber weight after drying.

(32g) Water absorption rate Q (%owt) is determined from the following formula.

Moisture absorption rate: Moisture absorption rate (%) is determined by drying the fiber at 80℃ and determining the fiber weight (53g).
After leaving for 4 hours, the fiber weight is determined again (84 g) and the moisture absorption rate is determined from the following formula.

Example 1 Acrylonitrile 92% by weight, methyl acrylate 7.7%
70% by weight of polyethylene oxide (abbreviated as PEO) with a number average molecular weight of 600,000.
A spinning stock solution was prepared by dissolving it in nitric acid.

In the spinning dope, it was observed from the results of observation using an optical microscope that polyethylene oxide had a particle size of 0.3 to 13 μm and was dispersed in the form of islands.

This spinning stock solution was cooled to -3°C, and the pore diameter was 0.08 mm.
32% by weight kept at 3℃ using a spinneret with 30,000 holes
It was spun into a nitric acid aqueous solution and coagulated.

The coagulated filaments were washed with water, stretched 8.5 times in hot water, dried, and then set in steam at 105°C to obtain a fineness of 3d.
acrylic fibers were obtained.

Table 1 shows the string properties of the obtained fibers.

It is clear from Table 1 that the acrylic fiber of the present invention has excellent water absorption and hygroscopicity, and at the same time, the physical properties such as fiber strength and elongation are comparable to those of ordinary fibers. there were.

In addition, both color development and texture were good, and no devitrification was observed.

On the other hand, the fiber of Comparative Example 1 has a low PEO content and is inferior to the fiber of the present invention in water absorption and moisture absorption performance, lacking practical utility.
Due to the excessive amount of EO, there were problems with the strength and elongation of the fibers, resulting in a lack of practical physical properties.

Figure 1 is an electron micrograph of the fiber cross section of Invention Example 2 (2500x magnification)
shows.

Example 2 Acryloni I.Ryl 92.2% by weight, vinyl acetate 7.3%
% by weight, an acrylic polymer consisting of 0.5% by weight of sodium styrene sulfonate, and polyethylene oxide (denoted as PEO) having the number average molecular weight shown in Table 2 at 55°C.
A spinning stock solution was prepared by dissolving it in a 40% by weight zinc chloride aqueous solution maintained at A filament was obtained.

The obtained filamentous body was washed with water, stretched, dried, and heat treated to obtain a fiber having a fineness of 1.5 d.

The results are shown in Table 2.

Fibers obtained using polyethylene oxide with a low number average molecular weight (generally, those with a low number average molecular weight are called polyethylene glycol) have small pore diameters and a low amount of PEO in the fibers. The effect of the present invention was not observed.

Example 3 94% by weight acrylonitrile, 5.5% methyl acrylate
wt% and sodium styrene sulfonate 0.5 wt%
A spinning stock solution was prepared by mixing the acrylic polymer consisting of the above with dimethylformamide containing various polymer compounds shown in Table 3, which was kept at 62°C.

These spinning stock solutions were dry-spun in air at 160°C through a spinneret with a hole diameter of 0.1 mm and a number of holes of 1000, stretched 3.5 times while washing in hot water, further washed with water, and then dried and heat treated. The fibers were obtained.

Table 3 shows the physical properties of each fiber obtained.

It is clear from Table 3 that the fibers using the polypropylene oxide of the present invention with a number average molecular weight of 120,000 have excellent water absorption and hygroscopicity, and the physical properties of the fibers are comparable to those of ordinary fibers. In addition, the color development was also excellent.

Moreover, the polyoxyethylene polyoxypropylene block polymer (number average molecular weight 150,000) referred to in the present invention had similar physical properties.

On the other hand, fibers to which substances other than those of the present invention were added had small pore diameters, almost no pores were observed, and water absorption and moisture absorption performance were not observed.

[Brief explanation of drawings]

FIG. 1 is an electron micrograph showing a cross section of a water-absorbing acrylic fiber according to an embodiment of the present invention.

Claims (1)

[Scope of Claims] 1. Comprised of an acrylic polymer containing at least 80% by weight of acrylonitrile, and a polyalkylene oxide having a number average molecular weight of 100,000 or more in an amount of 0.3 to 30% by weight based on the polymer; A water-absorbing acrylic fiber characterized by having pores. 2 Claim 1 in which the pores have a pore diameter of 0.1 to 5 μm
The water-absorbing acrylic fiber described in Section 1. 3. The water-absorbing acrylic fiber according to claim 1, wherein the polyalkylene oxide is polyethylene oxide, polypropylene oxide, or polyoxyethylene polyoxypropylene block polymer.