JPS6139431B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is a microporous acrylic staple (hereinafter referred to as acrylic staple) that has both excellent spinnability and water absorption performance.
related to science fiction). Traditionally, acrylic fibers, like other polyamide or polyester fibers, have poor water absorption, so they are rarely used as fiber materials for underwear, towels, sheets, or summer clothing; Only natural fibers such as or blends with cellulose fibers are used. Many studies have been made to improve the water absorbency of this acrylic fiber, but no one has been proposed that has water absorption and moisture absorption performance comparable to the above-mentioned natural fibers. On the other hand, recently, when acrylic fibers are manufactured by wet spinning, it is possible to obtain water-absorbing acrylic fibers by fixing the porous structure of the swollen gel-like yarn obtained during the manufacturing process. It was noted that the
Many proposals such as 70113 have been made. However, the porous structure of the water-absorbing acrylic fibers obtained by these methods tends to disappear when the gel-like yarn is dried, and the porous structure is not easily changed by ironing, etc. However, it has the disadvantage of reduced water absorption. Furthermore, the method of reinforcing the porosity by spinning a spinning stock solution mixed with a low boiling point liquid, etc. is difficult to obtain fibers with a reproducible and uniform porous structure, resulting in large variations in water absorption performance and recovery of additives. As an industrial method, there are many limitations and drawbacks such as deterioration of the working environment. The present inventors have discovered a method for producing acrylic fibers with improved water absorption properties with good reproducibility by eliminating the above-mentioned drawbacks, and proposed this method in Japanese Patent Application No. 53-4473. However, in the process of further investigation, the present inventors discovered that acrylic SF, which has excellent water absorption, cannot be spun unless a much larger amount of antistatic oil is attached than normal acrylic SF. I found it. In other words, due to the excellent water absorption properties of water-absorbing acrylic SF, the spinning oil penetrates into the fibers, and if the amount of adhesion is comparable to that of normal acrylic SF, static electricity is generated and spinning cannot be performed. On the other hand, if there is too much spinning oil, the antistatic properties will be good, but roller binding will occur during the spinning process, so it is necessary to control the amount of antistatic oil applied depending on the water absorption level of the water-absorbing acrylic SF. After discovering this fact and conducting extensive research, we have arrived at the present invention. That is, an object of the present invention is to provide a water-absorbent acrylic SF that has excellent spinnability and blendability without impairing the water absorption performance of the microporous water-absorbent acrylic SF, and other purposes. The purpose of the present invention is to provide a water-absorbing acrylic SF product with high water-absorbing performance, particularly high water-absorbing speed, and improved antistatic properties. The object of the present invention is to provide the invention as described in the claims above, in particular, a microporous acrylic SF having a water retention rate in a specific range, and an anionic and nonionic oil agent in a specific range amount with respect to the water retention rate. This can be achieved by attaching at least one of the following. The water-absorbing acrylic SF of the present invention must first have a water retention rate of 20% or more, preferably within the range of 25 to 60%; if the water retention rate is less than 20%, the water absorption performance is simply insufficient. Therefore, it is possible to spin with an oil adhesion amount close to that of normal acrylic SF. On the other hand, if it exceeds 60%, not only the spinnability decreases, but also the strength and elongation properties decrease, resulting in more flies during spinning, and the whiteness and brightness after dyeing also deteriorate. Further, there is no need to provide more water absorbency. Water-absorbing acrylic type with water retention rate in the above range
SF can be produced by known methods, but in order to industrially produce products with almost constant water retention with good reproducibility, the method previously proposed by the present inventors, that is, the method detailed below. is preferred. The acrylonitrile (hereinafter abbreviated as AN) polymer constituting the acrylic SF of the present invention is not particularly limited as long as it is used in the production of conventionally known acrylic fibers, but preferably at least 90 mol%, preferably 95 mol% of AN and a vinyl monomer copolymerizable to AN 10
A copolymer with mol %, preferably 5 mol % or less is preferable. Vinyl monomers include acrylic acid, methacrylic acid, itaconic acid and their lower alkyl esters or ammonium salts, monoethylenic vinyl monomers such as vinyl acetate, vinyl chloride, and styrene, allylsulfonic acid, methallylsulfonic acid, and vinylbenzenesulfonic acid. Examples include sulfonic acid group-containing monomers such as alkali metal salts or ammonium salts thereof, and 0 to 10 mol%, preferably 0 to
It is preferable to copolymerize the sulfonic acid group-containing monomer in an amount of 0 to 0.3 mol%, preferably 0 to 0.2 mol%. In other words, copolymerization of sulfonic acid group-containing monomers imparts dyeability with cationic dyes, etc., but if the copolymerization ratio exceeds 0.3 mol%, not only will the formation of pores be suppressed during the coagulation process, but This is not preferable because the pores formed during the stretching or drying process tend to disappear. Furthermore, copolymerization of monoethylene-based vinyl monomers is effective in improving polymer solubility, stock solution stability, and spinnability, but if the copolymerization rate exceeds 10 mol%, network fibrils will fuse during the drying process. This is not preferable because it tends to cause pores to disappear and pores to disappear. Also voids of 100 to 3000 angstroms and 0.5 to 2
In order to obtain AN-based fibers that have excellent water absorption properties with a wide void distribution including micron-order voids, are highly stable against heat, and have little change in water absorption properties over time, they are mixed with the AN-based polymer. It is preferable to mix and spin a thermoplastic polymer that has no compatibility and is soluble in the solvent of the AN polymer, but is insoluble in water. In other words, when the thermoplastic polymer is not miscible with the AN polymer or is insoluble in the solvent for the AN polymer, a stable spinning solution with good spinnability cannot be obtained, and the drawability of the coagulated yarn may be affected. Because of the poor strength, it is not possible to obtain fibers that satisfy practical strength and physical properties. In addition, it is important that the thermoplastic polymer has substantially no compatibility with AN-based polymers, and if it is compatible with AN-based polymers, voids on the order of 0.5 to 2μ will be present in the fibers. This makes it difficult to form, and it becomes difficult to achieve a sufficient improvement in water absorbency. Furthermore, when the thermoplastic polymer is soluble in water, generally an aqueous coagulation bath or drawing bath is used for wet spinning of acrylic fibers, so the thermoplastic polymer may be eluted into the bath during the coagulation and drawing steps. This is not preferable because the water resistance of the resulting fibers deteriorates. Examples of such thermoplastic polymers include dimethyl sulfoxide (DMSO), dimethylformamide (DMF), and dimethylacetamide (DMA), although they differ depending on the type of solvent for the AN polymer.
When using an organic solvent such as acrylonitrile-styrene copolymer, cellulose acetate, polymethyl methacrylate, etc., AS resins are particularly preferred. These thermoplastic polymers have a softening point of at least 100% from the viewpoint of thermal stability of the water absorbent fibers obtained.
℃, preferably 110℃ or higher. The proportion of the thermoplastic polymer to the AN polymer is 90 wt% or more of the AN polymer, preferably 90 to 99.9%, and 10 wt% or less of the thermoplastic polymer, preferably 10 to 0.1%. egoism,
If it is outside this range, the stability, spinnability, or drawability of the spinning dope decreases, making it impossible to stably spin the yarn or to obtain fibers with good physical properties, which is not preferable. In addition to the above-mentioned organic solvents, solvents for AN polymers include inorganic solvents such as concentrated sulfuric acid, zinc chloride aqueous solution, and rhodan soda aqueous solution, but considering conditions such as solubility for thermoplastic polymers, organic solvents are It's advantageous. The organic solvent solution containing the AN polymer and the thermoplastic polymer, that is, the spinning dope, is spun, stretched,
Water-absorbent fibers can be made by performing known wet spinning, which includes the steps of washing with water, oil treatment, and drying, but wet spinning conditions using an organic solvent will be described below as a representative example. First, regarding the coagulation conditions, if the bath temperature is low, voids will not be formed enough and water absorption will decrease, while if the bath temperature is high, stable spinning will become difficult.
The bath temperature is preferably 30-75°C, preferably 35-55°C. Regarding the coagulation bath temperature, the higher the temperature, the easier it is to impart a porous structure, but conversely, the strength and elongation properties also tend to decrease. If measures such as setting the spinning draft high or setting the spinning stock solution concentration low are used in combination, water absorption can be imparted even at a relatively low coagulation bath temperature of 30 to 50°C. From the viewpoint of strength and elongation properties, it is desirable to set the spinning draft high and the first bath temperature low. The stretching ratio should normally be at least 5 times, but it is preferable to perform a wet heat treatment using hot water or steam to stabilize the structure of the drawn yarn prior to drying. Regarding drying conditions, if the drying temperature is too high, the porous structure of the fibers will be easily lost during drying, resulting in a decrease in water absorption, while if the drying temperature is too low, productivity will decrease.
At least 100
Drying is preferably carried out at a temperature of 120-170°C. The thus obtained water-absorbing acrylic SF having a water retention rate of 20% or more cannot be spun as it is because of the generation of static electricity. In other words, even with normal acrylic SF, it is necessary to apply approximately 0.1 to 0.5% of the spinning oil to suppress the generation of static electricity, and if an amount exceeding this adheres, the acrylic science fiction
It is known that the binding becomes significant during the drawing process, etc. However, in the case of the water-absorbing acrylic SF according to the present invention, no matter what kind of spinning oil agent is used, static electricity is generated and spinning cannot be performed within the range of the amount normally used. This is because the water-absorbing acrylic SF according to the present invention has excellent water-absorbing performance, so that the oil agent that adheres to the surface immediately penetrates into the inside of the microporous structure, increasing the amount of oil agent that adheres to the surface that contributes to antistatic properties. It is presumed that this is because the amount of Therefore, as water absorption performance increases, unless the amount of oil deposited is increased, troubles due to static electricity clinging will occur during the spinning process. However, the microporous acrylic SF according to the present invention
In this case, the amount of the spinning oil applied to the acrylic
When the amount of SF is deposited in an amount 0.033 to 0.1 times the water retention rate based on the water retention rate of SF, the antistatic effect during spinning is significantly improved, and troubles such as binding during each spinning process are significantly reduced. Normally, in the case of polyester staples, if the amount of oil attached exceeds 0.2%, it will cause binding during the spinning process, and in the case of acrylic staples, if it exceeds 0.7%, the amount of clearer cotton in the spinning process will increase, causing roller binding, and the acrylic It was completely unthinkable to have more than about 1% of the oil adhere to staples. However, in the case of the microporous water-absorbing acrylic staple according to the present invention, due to the obtained water absorbency, spinning is possible only with a coating amount of oil agent that is unimaginable according to conventional common sense. Furthermore, since the acrylic SF of the present invention has a large amount of oil attached, the oil gradually oozes out onto the fiber surface. The oil has the advantage of improving the water absorption rate of the acrylic SF of the present invention, and this effect is semi-permanent. Furthermore, the oils used in the present invention include anionic and nonionic amphoteric oils, such as aliphatic sulfonates, higher alcohol (EO adducts) sulfate ester salts, higher alcohol (EO adducts) phosphate ester salts, higher alcohol EO adducts, Examples include polyethylene glycol fatty acid ester, polyhydric alcohol fatty acid ester, betaine type amphoteric surfactant, etc., but in particular, the electrical resistivity at 20°C and 65% RH after adhesion is 10 ⁸ Ω・cm or less, preferably 5×10 ⁷ Ω.・
It is preferable to use an oil agent that is less than cm. In other words, it has excellent antistatic effects such as lauryl alcohol (EO adduct) phosphate potassium salt, lauryl alcohol EO adduct sulfate potassium salt, octyl alcohol EO adduct phosphate potassium salt, etc. It is preferable to use an oil agent that does not easily penetrate inside the fibers. When a cationic oil agent is used, it is not preferable because it not only inhibits the water absorption performance of the water-absorbing acrylic SF but also impairs the excellent feel of the water-absorbing acrylic SF. The present invention will be specifically explained below using Examples. In the following examples, the water retention rate, electrical resistance, and amount of oil adhesion were measured by the following methods. (Water retention rate measurement method) Boil raw cotton in water for 30 minutes to remove adhering oil. The obtained raw cotton was thoroughly opened, soaked in water for 10 minutes, and then centrifuged using a centrifuge with a diameter of 18 cm.
The sample was dehydrated for 5 minutes at a rotation speed of 200 rpm, and the weight difference between the dehydrated sample and the dried sample was expressed in %, that is, the value was calculated using the following formula. Water retention rate = Wet fiber weight after dehydration - Dry fiber weight / Dry fiber weight x 100 (Electrical resistance measurement method) A fully opened sample was pre-dried at 35℃ x 10 hours,
After leaving it in the air at ±2°C and 65±2% for more than 2 hours, insert 10 g of the sample into a cylinder with a volume of 100 cm ³ (electrode plate diameter: 8 cm) and measure R using a super megohmmeter. (Method for measuring oil amount) Weigh 5 g of the sample and place it in a Soxhlet extractor. Add 120 ml of a mixture of benzene and ethanol (2:1) to a Soxhlet extraction flask, and perform extraction by repeating reflux under boiling for 4 hours. From the obtained amount of oil, the amount of oil adhered to the fibers is determined. Example 1 A copolymer spinning stock solution of AN, methyl acrylate (MEA), and sodium methallylsulfonate (SMAS) was obtained by solution polymerization in DMSO. The polymer composition of the blank product is AN/MEA/SMAS.
(94.65/5.0/0.35) mol %, and the water-absorbing polymer of the present invention was AN/MEA/SMAS (95.9/4.0/0.1) mol %. AN/MEA/SMAS (95.9/4.0/0.1) mol%
AN/styrene (abbreviated as ST) 24/76wt in the spinning dope
% AS resin was added and mixed with 2 wt % of acrylic polymer to create a spinning dope. This spinning dope and blank spinning dope are
Using a 0.065 mmφ nozzle, it was discharged into a 50% DMSO aqueous solution, stretched 6 times in hot water, washed with water, and dried.
At this time, by changing the coagulation bath temperature from 20°C to 65°C, various fibers with different water absorption levels can be obtained. For these fibers with different water absorption levels, potassium salt of lauryl alcohol phosphate ester was used as the spinning oil to create fibers with different amounts of the spinning oil attached. A dip method was used to apply the oil, and after preheating with steam, crimping was applied, drying, and cutting (38 mm) were performed to perform a spinning test. The results are summarized in Figure 1, which shows that if the amount Y of attached spinning oil is less than 0.033X, spinning is impossible due to the generation of static electricity, while on the other hand, the amount Y of attached spinning oil is too large than 0.1X. This indicates that roller binding occurs due to oil falling off. From the above results, the amount of oil adhering for good spinning properties is
It will be specified within the range of 0.033X≦Y≦0.1X. Example 2 Using the water-absorbing acrylic fibers with a water retention capacity of 45% obtained in Example 1, the electrical resistance of raw cotton was investigated by changing the spinning oil in various ways. The results are shown in Table 1, and it can be seen that lauryl alcohol phosphoric acid ester potassium salt, lauryl alcohol EO adduct sulfate potassium salt, lauric acid amidopropyl dimethyl betaine, etc. have excellent antistatic properties.

[Table] The fibers obtained in Example 1 with water retention rates of 7, 20, 30, and 45% were spun, and underwear was made using spun yarn with a count of 33. Figure 2 shows the results of comparing the water absorption rates of the obtained underwear after washing them. It can be seen that the water-absorbing acrylic of the present invention has almost the same water-absorbing performance as cotton.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the influence of the water retention rate and the amount of oil adhering on the spinnability of the water-absorbing microporous acrylic fiber obtained according to one example of the present invention, and FIG. FIG. 2 is a diagram showing the relationship between water retention and water absorption rate of water-absorbing microporous acrylic fibers obtained in Examples. In the figure, A: Straight line indicating the upper limit of the amount of oil adhered: Y
=0.1X, B... Straight line indicating the lower limit of the amount of oil adhered:
Y=0.033X, C...Water absorption rate of fibers with a water retention rate of 45%, D...Water absorption rate of fibers with a water retention rate of 30%, E...
Water absorption rate of cotton, F... Water absorption rate of fiber with a water retention rate of 20%, G... Water absorption rate of fiber with a water retention rate of 7% (blank).

Claims (1)

[Scope of Claims] 1. Has a water retention rate of 20% or more, and has a water retention rate of 20% or more;
A water-absorbing microporous acrylic fiber staple with excellent spinnability, to which at least one oil selected from the group consisting of anionic, nonionic and amphoteric oils is adhered in an amount of 0.033 to 0.1 times. 2 20℃, 65% in Claim 1
A water-absorbing microporous acrylic fiber staple with an electrical resistivity of 10 ⁸ Ω・cm or less at RH.