JPH049228B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing flexible acrylic synthetic fibers, and more specifically, a method for producing flexible acrylic synthetic fibers in which the surface of the acrylic synthetic fibers is treated with an aqueous solution of an alkali metal hydroxide and/or its salt. It is related to. Conventionally, as a method for peeling and reducing the weight of acrylic synthetic fibers, a solvent method is known in which the surface layer is physically dissolved using a solvent for acrylic synthetic fibers. However, with this method, as the surface layer peels off, the dissolved polymer accumulates in the solvent solution. The disadvantage was that it re-coagulated and adhered to the fibers, resulting in a hard texture. In addition, in the case of the solvent method,
In order to remove the skin sufficiently, a highly concentrated solvent solution (e.g. 65-80% for sulfuric acid, 80-100% for dimethylformamide) is required.
There are many problems in handling, corrosion resistance, waste liquid treatment, and price. On the other hand, a method of treating the surface of acrylic synthetic fibers with an aqueous solution of caustic soda or the like has been known for a long time. However, in this method, the nitrile groups on the very surface of the fibers are partially hydrolyzed to chemically modify the fiber surface, or as described in JP-A-54-138693, a highly concentrated alkali This is a method in which the outer layer of the fiber is hydrophilically crosslinked by treatment with an aqueous metal hydroxide solution, and there was no known method of using an aqueous alkaline solution to peel the surface layer of acrylic synthetic fibers. In view of the above prior art, an object of the present invention is to provide a method for manufacturing flexible acrylic synthetic fibers by peeling acrylic synthetic fibers using an aqueous solution of an alkali metal hydroxide and/or its salt. It is in. The inventors of the present invention have conducted extensive research on improving the manufacturing method of peeled acrylic synthetic fibers that does not have the above-mentioned problems, and have found that an alkali metal hydroxide and a /Or an aqueous solution of the salt is applied to the acrylic synthetic fiber to dissolve and remove the surface layer of the fiber, and then the fiber is treated with an aqueous solution of a polyvalent metal compound to fix the swelling layer remaining on the surface. The inventors have discovered that flexible acrylic synthetic fibers can be obtained by this method, and have arrived at the present invention. The present invention involves applying an aqueous solution of an alkali metal hydroxide and/or its salt (hereinafter sometimes referred to as an aqueous alkali solution) that has a dissolving effect on acrylic synthetic fibers to the acrylic synthetic fibers,
It is characterized by comprising a step A in which the surface layer is dissolved and removed, and a step B in which the fiber treated in step A is further treated with an aqueous solution of a polyvalent metal compound. In the present invention, the step A includes a method of immersing the acrylic synthetic fiber in the alkaline aqueous solution and dissolving and diffusing the surface layer of the fiber into the aqueous solution (immersion treatment method), or applying the aqueous solution to the acrylic synthetic fiber. It is carried out by a method (steaming method) in which the fiber surface layer is removed by washing with water after being attached to the fiber by steaming treatment, but if the fiber surface layer is dissolved and removed by an alkaline aqueous solution, ,
Other methods may also be used. Specifically, the above-mentioned immersion treatment method involves immersing acrylic synthetic fibers in an alkaline aqueous solution under appropriate conditions.
This is done by washing with water, and in the steaming method, an alkaline aqueous solution is applied to acrylic synthetic fibers, and then steamed to make only the fiber surface layer solubilized. This is done by washing away with water. Further, it is preferable to add a step C to the above steps A and B, in which the yellowed fiber surface is treated with an acid solution to restore the original color. In the present invention, the acrylic synthetic fiber refers to an acrylic synthetic fiber containing at least 40% or more of acrylonitrile units in its components. This naturally includes composite fibers made of polymers with different copolymerization components and yarns with irregular cross-sections having a non-circular fiber cross section. In addition, filaments, bulky textured yarns, tows, cut cotton, slivers, rovings, spun yarns, fiber webs, nonwoven fabrics, knitted fabrics, woven fabrics, and natural fibers made of acrylic fibers as defined above, as well as other types of acrylic fibers, Blended spinning, mixed weaving, mixed twisting and knitting are also covered. The alkali metal hydroxides used in step A of the present invention include sodium hydroxide, potassium hydroxide,
Lithium hydroxide and its salts include sodium carbonate, sodium phosphate, sodium rhodanate, potassium rhodanate, and other salts of strong bases and weak acids. The substances listed here are only examples, and any other substances that exhibit hydrolyzability to acrylic synthetic fibers can be used in the present invention. Mixtures of these substances can also be used; however, as described below, mixtures containing sodium hydroxide as the main component and combined with sodium rhodanate or potassium rhodanate may particularly enhance the peeling effect. Admitted. The concentration range of an alkaline aqueous solution that has a dissolving effect on acrylic synthetic fibers varies depending on the type of alkali metal hydroxide and its salt and the temperature of the aqueous solution, but for example, in the case of sodium hydroxide, it is 80 to 100°C.
2-20% for sodium carbonate, 10-40% for sodium carbonate
It is. The temperature of the aqueous solution is preferably 80°C or higher, but if it exceeds 100°C, it becomes difficult to control the amount of peeling. In the dipping treatment method of the present invention, the concentration of alkali metal hydroxide and its salt and the solubility of the fiber are determined by the first
The alkali in the present invention exhibits a tendency as shown in the figure (point a in the figure indicates the concentration at which the dissolving effect occurs, point c indicates the point at which the dissolving effect is lost, and point b indicates the point at which the dissolution rate becomes the highest). The solution concentration needs to be in the range of points a to c, and practically it is preferably between points a and b. The above points a, b, and c can be appropriately determined by experiment for the alkaline solution and acrylic fiber used. When the concentration of the alkaline solution is lower than point a, it has little dissolving effect on the acrylic fibers, so almost no stripping effect is observed, and when the concentration is higher than point b, the dissolution rate begins to decrease and hydrolysis progresses. However, the elution rate of the polymer in the treatment solution becomes extremely slow, and when the point C is exceeded, hydrophilic cross-linked fibers are formed, resulting in water-swellable fibers, and the removal of the swelling layer by general solvent treatment is insufficient. The texture becomes stiff, just like when it was washed. When peeling acrylic fibers using the dipping treatment method as described above, it is a practical requirement that the hydrolyzed polymer be eluted into the treatment solution at the same time as hydrolysis with an alkaline aqueous solution. It is possible to elute the hydrolyzed polymer into the treatment solution by selecting the conditions;
Achieving 100% elution is quite difficult in terms of reproducibility. However, it is relatively easy to suppress the amount of uneluted hydrolyzed polymer to 1% or less based on the weight of the fiber after leaching and peeling, and a material with a fairly soft feel can be obtained. In the immersion treatment method, since an excessive amount of alkaline aqueous solution is present in the treatment liquid, hydrolysis and solution proceed linearly. For this reason, the fiber weight loss rate is generally controlled by the processing time. On the other hand, when step A is performed by the steaming method,
The concentration range of the alkaline aqueous solution varies depending on the type of alkali metal hydroxide and its salt and steaming conditions. For example, in the case of sodium hydroxide, 80~
At a steaming temperature of 120°C (for saturated steam) it is 2-30%, and for sodium carbonate it is 10-50%. The steam used for steaming may be either saturated steam or heated steam, but steaming conditions vary depending on the type of steam used. For example, when using saturated steam, the temperature is 80°C.
C. or more is preferred, but if the temperature exceeds 120.degree. C., there is a strong tendency for the fibers to undergo hydrophilic crosslinking and become water-insoluble water-swellable fibers, although this varies depending on the type of alkali metal hydroxide and/or its salt. In the case of the steaming treatment method, only hydrolysis occurs during steaming to make the fiber surface layer water-soluble, and the surface layer is dissolved and peeled off in the washing process after steaming (here The steps up to this point are called step A in the steaming method). Unlike the above-mentioned immersion treatment method, which performs hydrolysis and dissolution at the same time, the steaming treatment method is different from the above-mentioned immersion treatment method, in which the hydrolysis reaction reaches its peak after a certain period of time. Weight loss rate can be easily managed. In other words, in the case of steaming treatment, the aqueous alkaline solution is not present in excess around the fibers as in the dipping treatment method, but is present only in a limited amount on the fibers, so if it is consumed in the hydrolysis reaction, it The reaction no longer progresses, and therefore it becomes possible to control the weight loss rate only by controlling the amount of adhesion. Note that even when using the steaming method, a swollen layer of the same extent as the dipping treatment method remains after the A step is completed. In step A using the dipping treatment method, the amount of fiber to be dissolved and diffused (reduction rate) is preferably 2 to 50%, more preferably 5 to 30% of the initial fiber weight.
%. The extent of this dissolution and diffusion can be appropriately determined experimentally depending on the type, concentration, and time of the alkali metal hydroxide. The dissolution and diffusion may be carried out by leaving the fibers still in the solution or by shaking them. Alternatively, the solution itself may be stirred. The preferred range of weight loss rate in the steaming method is 2 to 50%, preferably 5 to 50%, as in the immersion treatment method.
It is 30%. The fibers treated in step A have an uneluted hydrolyzed polymer (swelling layer) on their surface and have a sticky surface, but in the present invention, in order to remove this, step B, That is, a step of treating the fiber surface with an aqueous solution of a polyvalent metal compound is performed. This polyvalent metal compound generates metal crosslinks between polymers having carboxyl groups on the fiber surface, making the polymer surface non-adhesive and stabilizing. As a method for this step B, preferably used is a method in which the fibers are immersed in an aqueous solution of a polyvalent metal compound or a method in which the aqueous solution is sprayed onto the fibers. The treatment temperature is preferably around room temperature; if the treatment is too high, when dyeing is performed after treatment with a polyvalent metal compound, the polyvalent metal ions will also bond with the acidic groups that are the dyeing sites in the fiber. Reduces the dyeability of cationic dyes when dyeing is performed after treatment. The polyvalent metal compound used in the present invention may be any compound that produces polyvalent metal ions of divalent or higher valence in an aqueous solution, and preferably calcium, magnesium, barium, or aluminum chloride, sulfate, nitrate, or phosphoric acid. Salts, borates, etc. are used. Theoretically, the polyvalent metal compound should be used in an amount equivalent to or more than the amount of carboxyl groups in the hydrolyzed polymer slightly remaining on the fiber surface, but it is practically preferable to use more than this amount. In the present invention, since the treatment with an alkaline aqueous solution in step A is usually accompanied by yellowing of the fibers, in the present invention, after the peeling treatment, it is preferable to perform step C in which the fibers are brought into contact with an acid solution to restore the original color. Acids used to remove yellowing include inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid, and organic acids such as formic acid, acetic acid, malic acid, oxalic acid, and succinic acid, but are not limited to these acids. Any acid may be used as long as the pH can be controlled preferably to 3.5 or less. Further, the treatment temperature is usually 50°C or higher, preferably 80 to 100°C. When processing at a pH of 3.5 or higher, it takes longer to remove yellowing. Appropriate pH varies depending on the type of acid, treatment temperature, and time, but generally 0.5 to 3 is good, and 1.5 to 2.5 is more preferable. The order of the B process and the C process is, when dyeing is performed, it is preferable to carry out the dyeing after carrying out the C process of contacting with an acid solution, and then carrying out the B process, but after the treatment with a polyvalent metal compound, , it is also possible to dye it. In addition, in the method of the present invention, the concentration range that can be peeled differs depending on the scouring conditions, heat setting conditions, history of the fiber to be treated such as the oil and sizing agent used, and deposits, and the degree of the effect obtained by peeling also varies. Needless to say, they are different. As described above, by treating acrylic synthetic fibers with the method of the present invention, synthetic fibers with extremely soft texture and elegant luster can be obtained. Furthermore, according to the method of the present invention, the level dyeing properties of fibers are improved and dyeing spots are improved. The present invention is applicable to all acrylic synthetic fibers, but is particularly effective in the case of acrylic filaments. That is, acrylic filament products have the drawbacks of being hard to the touch and prone to staining when dyed, but these drawbacks can be overcome by applying this method, and a silk-like texture and luster can be obtained. Such an excellent modification effect is due to the fact that the surface layer of the fiber is peeled off, thereby smoothing the fiber surface and changing the physical properties of the fiber. Furthermore, it is thought that peeling of the fibers constituting the textile product creates appropriate voids in the tissue, improving the texture and drape properties. EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the scope of the present invention is not limited thereby. Note that all percentages in the description of Examples are percentages by weight. Examples 1 to 8, Comparative Examples 1 to 11 Puron (trade name of acrylic long fiber manufactured by Asahi Kasei Industries, Ltd.) 75d/38f plain woven fabric was soaked in an aqueous sodium hydroxide solution (98°C) at the concentration shown in Table 1. After soaking in water for 15 minutes, it was washed with water. This sample was immersed in a 0.5% phosphoric acid aqueous solution kept at 98℃ for 15 minutes, washed with water, and treated with a cationic dye using a conventional method at 100℃.
Stained for 60 minutes. This dyed product was added to aluminum chloride at the concentration listed in Table 1 at a bath ratio of 1/20 at 30°C.
After being immersed for a minute, it was washed with water and dried. Table 1 shows the results obtained by the above processing. As is clear from Table 1, Examples 1, 2,
Samples 3, 4, 5, 6, 7, and 8 had particularly silk-like luster and texture, and almost no staining spots occurred. Moreover, no tackiness or adhesion was observed in these samples.

【table】

[Table] Examples 9 to 20, Comparative Examples 12 to 18 A plain woven fabric similar to that used in Example 1 was immersed in sodium hydroxide at the concentration listed in Table 2, and then woven with a mangle at a liquid content of 120%. After squeezing the liquid, it was steamed at 105°C for 10 minutes. This treated cloth was sufficiently washed with warm water at 80°C to dissolve and remove the surface. The sample after washing with water was colored yellow. After dehydrating this sample, 98
Immerse it in a 1% sulfuric acid aqueous solution kept at ℃ for 10 minutes,
After that, it was washed with water and dried. This acid treatment restored the whiteness of the sample to that of the untreated fabric. This sample was stained using a cationic dye at 100° C. for 60 minutes in a conventional manner. The obtained dyed product was added to a calcium chloride aqueous solution (bath ratio 1/20) at the concentration listed in Table 2 for 30 minutes.
After immersion treatment at ℃ for 20 minutes, washing with water and drying were performed. The results obtained by the above processing are shown in Table 2. From the results in Table 2, the samples of Examples 9 to 20 had particularly silk-like luster and texture, and almost no staining spots occurred. Furthermore, no tack or adhesive properties were observed in these samples. Among the examples, examples
The reason why the flexibility of samples 18 to 20 was not ◎ despite the large weight loss rate is thought to be that the NaOH concentration was too high and the hydrolyzed polymer was not dissolved and removed, but remained partially as swollen fibers. This is compared to Comparative Example 17.
You can see this by comparing 18. That is, Comparative Example 18 has a higher weight loss rate than Comparative Example 17, but is inferior in flexibility. This is also due to the formation of a swelling layer in Comparative Example 18. In addition, comparative example 17 had a weight loss rate of 30%.
Because of its large size, it is more flexible than the blank Comparative Example 12, but it is less flexible than Examples 11, 12, and 13, which were treated with calcium chloride using the same alkali treatment.

[Table] The above evaluation of flexibility and weight loss rate was the same as in Example 1.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the relationship between the concentration of aqueous alkali solution and the dissolution rate of acrylic synthetic fibers in the dipping method.

Claims (1)

[Scope of Claims] 1. A step of applying an aqueous solution of an alkali metal hydroxide and/or its salt that has a dissolving action to acrylic synthetic fibers to the acrylic synthetic fibers to dissolve and remove the surface layer; A method for producing flexible acrylic synthetic fibers, comprising a step B in which the fibers treated in step A are further treated with an aqueous solution of a multivalued metal compound. 2 In claim 1, the step A includes:
A method for producing flexible acrylic synthetic fibers, comprising immersing acrylic synthetic fibers in the aqueous solution and dissolving and diffusing the surface layer of the fibers into the aqueous solution. 3 In claim 1, the step A includes:
A method for producing flexible acrylic synthetic fibers, which comprises applying the aqueous solution to the acrylic synthetic fibers and then subjecting the fibers to a steaming treatment to remove the water-solubilized surface layer by washing with water. 4. A flexible acrylic composition according to any one of claims 1 to 3, characterized in that a step C is added to the above step in which the yellowed fiber surface is further treated with an acid solution to restore the original color. Fiber manufacturing method.