JPH0583663B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a method for producing flexible acrylic synthetic fibers, and more specifically, the present invention relates to a method for producing flexible acrylic synthetic fibers. The present invention relates to a method for producing flexible acrylic synthetic fibers. <Prior art> Conventionally, methods for peeling and reducing the weight of acrylic synthetic fibers include a solvent method in which the surface layer is dissolved using a solvent for acrylic synthetic fibers, and an alkali metal hydroxide and/or its Acrylic synthetic fibers are immersed in an aqueous solution of salt, only the surface layer of the fibers is dissolved and diffused in the aqueous solution, and then taken out.
Alkaline hydrolysis methods are known in which the material is washed with water and then brought into contact with an acid solution. However, in the case of the solvent method, as the skin is peeled off, the eluted polymer accumulates in the solvent solution. Polymer concentration is 0.2%
(wt%, hereinafter all expressed in wt%), this dissolved polymer adhering to the fiber surface during washing with water re-solidifies and adheres to the fiber, resulting in a disadvantage that the texture becomes hard. In addition, in the case of the solvent method, a highly concentrated solvent solution is required to remove the skin (for example, in the case of sulfuric acid, 65 ~
80%, 80-100% for dimethylformamide).
Therefore, when put into practical use, there are many problems in handling, corrosion resistance, waste liquid treatment, and cost. In addition, as a peeling reduction processing method using alkaline hydrolysis of acrylic synthetic fibers, JP-A-58
-91866 and JP-A-58-186670 are known. However, the skin-reduced products obtained by this method had the disadvantage that the texture was hardened by steam ironing. <Problems to be Solved by the Invention> In view of the above-mentioned prior art, an object of the present invention is to provide a method for producing flexible acrylic synthetic fibers whose texture does not change due to steam ironing. The present inventors have conducted intensive research on a method for manufacturing peeled acrylic synthetic fibers that does not have the above-mentioned problems, and have found that alkali metal hydroxide and/or alkali metal hydroxide and/or which have a dissolving action on acrylic synthetic fibers have been found. Or, after applying an aqueous solution of the salt to acrylic synthetic fibers and dissolving and removing the surface layer of the fibers,
The fibers are treated with an alkali metal salt of phosphoric acid selected from alkali metal salts of orthophosphoric acid, pyrophosphoric acid, polyphosphoric acid, or polymetaphosphoric acid, and condensed phosphates consisting of phosphorus pentoxide and an alkali metal oxide (hereinafter referred to as an alkali metal salt of phosphoric acid). The inventors have discovered that flexible acrylic synthetic fibers can be obtained by treating them with an aqueous solution (referred to as salt) to remove the swelling layer remaining on the surface, and have arrived at the present invention. <Means for Solving the Problems> The present invention provides a method for producing flexible acrylic synthetic fibers, and this method uses an alkali metal hydroxide and an alkali metal hydroxide having a dissolving action on acrylic synthetic fibers. / or an aqueous solution of its salt (hereinafter referred to as
Step A, in which the surface layer is dissolved and removed by applying an aqueous alkali solution) to the acrylic synthetic fiber, and Step B, in which the fiber treated in Step A is further treated with an aqueous solution of an alkali metal salt of a phosphorus compound. It is characterized by 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 are also possible. Also, process A can be performed in a multi-stage manner,
In that case, it is also possible to change the conditions of each stage as necessary. For example, by carrying out the first stage at a high concentration, the rate of weight loss can be increased, and by carrying out the second stage at a low concentration, the rate of weight loss can be precisely controlled. When carrying out a multi-stage process like this, it is preferable to carry out the process at a higher concentration at the beginning and at a lower concentration towards the end. 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. The steaming method is carried out by applying an alkaline aqueous solution to acrylic synthetic fibers, steaming the fibers to make only the fiber surface layer solubilized, and then removing the surface layer by washing with water. Also, the above A and B
It is preferable to add a step C to the process, 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. Also, filament made of acrylic fiber defined above, bulky processed yarn, tow, cut cotton,
Slivers, rovings, spun yarns, fiber webs, non-woven fabrics, knitted fabrics, woven fabrics, and blends and weaves with natural fibers, synthetic fibers other than acrylic fibers, and semi-synthetic fibers,
This also applies to intertwisted and knitted fabrics. 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 substance that exhibits hydrolyzability for acrylic synthetic fibers can be used in the present invention. Mixtures of these substances can also be used, but in the case of mixtures, the peeling effect is particularly enhanced when sodium hydroxide is the main component and sodium rhodanate or potassium rhodanate is used in combination as described below. was recognized. 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.
2-20% at °C, 10-40% for sodium carbonate
%. 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 alkaline fiber used. When the concentration of the alkaline solution is lower than point a, it has little dissolving effect on the alkaline fibers, and therefore almost no peeling effect is observed. Furthermore, when the concentration becomes higher than point b, the dissolution rate begins to decrease, and even though hydrolysis progresses, the elution rate of the polymer in the treatment solution becomes extremely slow.When the concentration exceeds point c, hydrophilic crosslinked fibers are formed and The fibers become swellable and have a hard texture, similar to when the swelling layer is not sufficiently removed by general solvent treatment. As mentioned above, in the peeling process of acrylic fibers using the dipping treatment method, 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, 1% of the fiber weight after elution and peeling
It is relatively easy to suppress the uneluted hydrolyzed polymer below, and a product with a fairly soft texture can be obtained. In the immersion treatment method, since an aqueous alkali solution is present in excess in the treatment solution, hydrolysis and dissolution proceed proportionally. 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, for sodium hydroxide, 80
~120℃ steaming temperature (for saturated steam)
2-30% for sodium carbonate, 10-50% for sodium carbonate
It is. The steam used for steaming may be either saturated steam or superheated steam, but steaming conditions vary depending on the type of steam used. For example, when using saturated steam, the temperature
The temperature is preferably 80°C or higher. On the other hand, if the temperature exceeds 120°C, the fibers tend to be hydrophilically crosslinked 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.
This is in the water washing step after the steaming treatment (this step is referred to as 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 controlled. 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 only present in a limited amount on the fibers, so if it is consumed in the hydrolysis reaction, it will cause damage. 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 that obtained using the dipping method remains after the completion of step A. 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%, based on the initial fiber weight.
%. The degree 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. Also in the steaming method, the preferred range of weight loss rate is:
As with the immersion treatment method, it is 2 to 50%, preferably 5 to 30%. The fibers treated in step A have an uneluted hydrolyzed polymer (swelling layer) on the 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 an alkali metal salt of phosphoric acid is performed.
By this aqueous alkali metal salt solution treatment of phosphoric acid,
After step A, the undissolved hydrolyzed polymer (swelling layer) remaining on the fiber surface layer is completely dissolved and removed. The uneluted hydrolyzed polymer (swelling layer) remaining on the fiber surface layer after this step A can be completely dissolved and removed only by an aqueous solution of an alkali metal salt of phosphoric acid. In alkali metal salt aqueous solution treatment, under conditions where the swelling layer is removed, new hydrolysis occurs, weight loss progresses, and a new swelling layer is generated, making it impossible to achieve the objective. However, in the treatment with an aqueous alkali metal salt solution of phosphoric acid, only the weight loss of the swollen layer produced in step A did not occur, indicating that no new hydrolysis occurred. The alkali metal salts of phosphoric acid used in step B of the present invention include alkali metal salts of polyphosphoric acids such as orthophosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, and tetrapolyphosphoric acid, and alkali metal salts of polymetaphosphoric acids such as trimetaphosphoric acid and hexametaphosphoric acid. salt. Examples include condensed phosphates consisting of phosphorus pentoxide and alkali metal oxides. Examples of the alkali metal of these alkali metal phosphates include lithium, sodium, potassium, and the like. In addition, it is also possible to use together with inorganic salts such as mirabilite and common salt, and surfactants such as sodium alkylbenzenesulfonate and sodium alkylsulfate. The concentration of the aqueous solution of these alkali metal phosphates is suitably 0.1 to 7%, preferably 0.2 to 5%.
Used in %. In addition, the processing temperature and processing time are 70℃
It is suitable that the temperature is 5 minutes or more, preferably 10 minutes or more at a temperature of 130°C to 130°C, preferably 90°C to 100°C. As for the treatment time, a sufficient effect can be obtained within 30 to 60 minutes, and the effect does not change even if the treatment time is extended beyond that. In the present invention, the treatment with an alkaline aqueous solution in step A is usually accompanied by yellowing of the fibers, but most of the yellowing is removed in step B of the present invention.
However, since yellowing is not completely removed, when dyeing to a fluorescent color or bright color, after step B, it is preferable to carry out step C, which brings the dye 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. Preferably PH without
Any acid that can be controlled to 3.5 or less is fine. In addition, the processing temperature is usually 50℃ or higher, preferably
The temperature is 80-100℃. 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, more preferably 1.5 to 2.5.
It is. Step C can also be carried out during the dyeing process if there is no problem in dyeing. 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. By treating the acrylic synthetic fibers as described above with the method of the present invention, synthetic fibers having 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 during dyeing, but these drawbacks can be solved by applying this method, and silk-like fit and gloss can be obtained. <Function> Such an excellent modification effect is due to the fact that the surface layer of the fiber is peeled, 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. In addition, all percentages in the examples are by weight.
It is. Example 1 A plain woven fabric made of 75d/38f Pieuron (trade name of acrylic long fiber manufactured by Asahi Kasei Industries, Ltd.) was soaked in a 7% aqueous solution of sodium hydroxide (90°C) for 60 minutes as step A.
After being immersed for a minute, as step B, it was treated in an aqueous solution of an alkali metal salt of phosphoric acid under the conditions listed in Table 1, washed with water, and treated with a cationic dye using a conventional method.
After staining at 100°C for 60 minutes, it was washed with water and dried. Table 1 shows the results obtained by the above processing. In Table 1, No. 1 is dyed without performing B step after A step, No. 2 to 18 is dyed with an aqueous alkali metal salt solution of phosphoric acid as B step,
Nos. 23 to 26 are cases in which an alkali metal salt other than a phosphorus compound was used in the B step.

[Table] Among the samples of this example, Nos. 1, 23, 24, 25, and 26 were significantly hardened in texture by steam ironing. In addition, the texture of Nos. 2, 3, and 9 was slightly hardened by steam ironing. For other items, no change in texture was observed due to steam ironing. In addition, when treated with an alkali metal salt of phosphoric acid, an equilibrium value was observed in the weight loss rate. This indicates that in the case of an alkali metal salt of phosphoric acid, it acts only on the swollen layer produced by the A-step treatment, and does not affect the inner layer. In the case of this example, the swelling layer caused by the treatment in step A is approximately 1%, but caustic soda other than the alkali metal salt of phosphoric acid,
In the case of soda carbonate, the weight loss progresses beyond the amount of the swelling layer created in step A, thereby creating a new swelling layer, making it possible to obtain a product that does not harden the texture by steam ironing. do not have. Example 2 20% plain woven fabric similar to that used in Example-1
The sample was immersed in a concentrated sodium hydroxide solution, squeezed with a mangle to a liquid content of 120%, and then 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. After dehydrating this sample, it was treated under the conditions listed in Table 2, washed with water, and treated with a cationic dye using a conventional method.
After staining at 100°C for 60 minutes, it was washed with water and dried.

[Table] No hardening of the texture was observed in Nos. 2 to 5 in this example due to the steam iron treatment. <Effects of the Invention> The effects of the method of the present invention are that by removing only the swelling layer produced by the A process treatment, the acrylic material is reduced in weight and has a soft texture that does not harden in texture during steam ironing. The aim is to obtain synthetic fibers.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the relationship between the concentration of an aqueous solution of an alkali metal hydroxide and/or its salt and the solubility of an acrylic synthetic fiber.

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; The fibers treated in step A are further treated with an aqueous solution of an alkali metal salt of phosphoric acid selected from alkali metal salts of orthophosphoric acid, pyrophosphoric acid, polyphosphoric acid, or polymetaphosphoric acid, and condensed phosphates consisting of phosphorus pentoxide and an alkali metal oxide. 1. A method for producing flexible acrylic synthetic fibers, comprising step B of treating with. 2. The method according to claim 1, wherein in step A, acrylic synthetic fibers are immersed in the aqueous solution to dissolve and diffuse the surface layer of the fibers into the aqueous solution. 3. The step A is characterized in that after the aqueous solution is attached to the acrylic synthetic fiber, a steaming treatment is performed to remove the water-soluble surface layer by washing with water. the method of.