JPS59216974A - Production of flexible acrylic synthetic fiber - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION 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, and more specifically, the surface of the acrylic synthetic fibers is
The present invention relates to a method for producing flexible acrylic synthetic fibers that is treated with an aqueous solution of alkali metal hydroxide and/or its salt.

Conventionally, as a method for peeling and reducing the weight of acrylic synthetic fibers, a solvent method is known in which the surface layer of the acrylic synthetic fibers is physically melted using a solvent. However, with this method, as the surface layer peels off, the eluted polymer accumulates in the solvent solution, resulting in a polymer concentration of 0.2%.
(all percentages by weight), the dissolved polymer re-solidifies and adheres to the fibers during washing with water, resulting in a hard texture. In addition, in the case of a solvent method, it is necessary to use a highly concentrated solvent solution (for example, 65 to 80% in the case of sulfuric acid, 80 to 1% in the case of dimethylformamide) in order to remove the skin sufficiently.
00%) is required, and there will be many problems in handling, contact resistance, waste liquid treatment, and cost when putting it into practical use.

On the other hand, a method of treating the surface of acrylic synthetic fibers with an aqueous solution such as caustic soda has been known for a long time. The fiber surface is chemically modified by decomposition, or the outer layer of the fiber is hydrophilically crosslinked by treatment with a highly concentrated alkali metal hydroxide aqueous solution as described in JP-A-54-138693. However, there was no known method of using an alkaline aqueous 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 producing flexible acrylic synthetic fibers by peeling the surface of acrylic synthetic fibers using an aqueous solution of an alkali metal hydroxide and/or its salt. There is a particular thing.

The inventors of the present invention have conducted extensive research into improving the manufacturing method of peeled acrylic synthetic fibers, which does not have the above-mentioned problems. An aqueous solution of an oxide and/or its salt is applied to an 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 form a swelling layer that remains on the surface. It was discovered that a flexible acrylic synthetic fiber could be obtained by fixing the fibers, and the present invention was developed based on this discovery.

In the present invention, an aqueous solution of an alkali metal hydroxide and/or its salt (hereinafter sometimes referred to as an aqueous alkali solution) having a dissolving effect on acrylic synthetic fibers is applied to the acrylic synthetic fibers to form a surface layer of the acrylic synthetic fibers. A to melt and remove
and a step B in which the fibers treated in step A are 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. This method is carried out by a method (steaming method) in which the fiber surface layer is removed by washing with water after the fibers are coated with aqueous alkaline solution. It may be a method.

The above-mentioned immersion treatment method is specifically performed by immersing acrylic synthetic fibers in an alkaline aqueous solution under appropriate conditions and then washing with water, while the steaming method involves attaching an alkaline aqueous solution to the acrylic synthetic fibers. After drying, steaming is performed to make only the surface layer of the fiber solubilized in water, and then the surface layer is removed by washing with water. Also, the above A,
It is preferable to add to step B a step C 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, filaments, bulky processed yarns, tows, cut cotton, slivers, rovings, spun yarns, fiber webs, non-woven fabrics, knitted fabrics, woven fabrics, and natural fibers made of acrylic fibers as defined above, and other types of acrylic fibers. Blending with fibers, interweaving, intertwisting, intermixing knitting, etc. are also covered.

Examples of the alkali metal hydroxide used in Step A of the present invention include sodium hydroxide, potassium hydroxide, and lithium hydroxide; examples of its salts include sodium carbonate, sodium phosphate,
Examples include sodium rhodanate, crystalline potassium rhodanate, and other salts of strong bases and weak acids. The substances listed here are examples of rinsing, and in addition to these substances, any substance that exhibits hydrolyzability for 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 the 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 2 to 20% at 80 to 100°C. and 10 to 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.

The concentration of alkali metal hydroxides and their salts and the solubility of fibers in the immersion treatment method of the present invention show a tendency as shown in Figure 1. (point b indicates the point at which the dissolving action is lost, and point b indicates the point at which the dissolution rate reaches its maximum), and the concentration of the alkaline solution in the present invention must be in the range of points a - "C. Practically speaking, point a
It is preferable that there be G between points -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, there is little dissolving effect on the acrylic fibers, so almost no peeling 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 became extremely slow, and when the C point was exceeded, hydrophilic cross-linked fibers were formed, causing water-swellable fibers to swell, and removal of the swelling layer by general solvent treatment was insufficient. The texture becomes stiff just like when it was used.

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. Treatment method for hydrolyzed polymer
Although elution into a liquid is possible by selecting conditions, it is quite difficult to achieve 100% elution in terms of reproducibility. However, 1% of the fiber weight after elution and peeling
It is relatively easy to suppress uneluted hydrolyzed polymer, and a product with a fairly soft texture can be obtained. In the immersion treatment method, hydrolysis and melting proceed linearly because an aqueous alkaline solution is present in excess in the treatment liquid. 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 a steaming method, the concentration range of the alkaline aqueous solution varies depending on the type of alkali metal hydroxide and its salt and the steaming conditions. For example, in the case of sodium hydroxide, it is 2 to 30% at a steaming temperature of 80 to 120°C (in the case of saturated steam), and in the case of sodium carbonate, it is 10 to 50%. Either saturated steam or superheated steam may be used for steaming, 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 preferable, but if the temperature exceeds 120.degree. 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 off in the washing process after the steaming treatment (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 melting at the same time, the method using steaming treatment reaches its peak after a certain period of time, so it is easy to use by controlling the amount of aqueous alkaline solution attached. The weight loss rate can be 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 remains after the completion of the A process as when using the dipping treatment method.

In step A using the dipping treatment method, the N (weight loss rate) of the fibers to be dissolved and diffused is preferably 2 to 50%, more preferably 5 to 30%, based on the initial fiber weight. The extent of this melting 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 preferable range of weight loss rate in the steaming method is 2 to 50%, and preferably 5 to 30%, as in the immersion treatment method.
It is.

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,
The polymer surface becomes non-stick and stabilized.

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 total ion will also bond with the acidic group that is the dyeing seat in the fiber. , which 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 generates a polyvalent metal ion with a valence of 2 or more in an aqueous solution.
Preferably, calcium, magnesium, halium, aluminum chlorides, sulfates, nitrates, phosphates, borates, etc. are used. The amount of the polyvalent metal compound used should theoretically be equal to or more than the equivalent 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 involves energization and yellowing of the fibers, in the present invention, it is preferable to perform step C without contacting with an acid solution to restore the original color after peeling treatment. . 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 processing temperature is suitably 50°C or higher, preferably 80 to 100°C. When processing at pH 3.5 or higher, the time required to remove yellowing increases. The appropriate pH depends on the type of acid, treatment temperature,
Although it varies depending on the time, approximately 0°5 to 3 is good.
More preferably it is 1.5 to 2.5.

The order of the B process and the C process is that when dyeing is performed, it is preferable to perform the dyeing after performing the C process of contacting with an acid solution, and then perform the B process, but after treating with a polyvalent metal compound, It is also possible to dye it.

In addition, in the method of the present invention, the history of the fiber to be treated, such as edge line conditions, heat setting conditions, oil agent used, and glue agent,
Needless to say, the concentration range in which peeling is possible differs depending on the deposit, and the degree of effect obtained by peeling also differs.

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 streaks are improved.

The present invention is applicable to all acrylic synthetic fibers, but is particularly effective in the case of acrylic filaments. In other words, acrylic filament products have the drawbacks of being hard to the touch and prone to streaks during dyeing, but these drawbacks can be overcome by applying Kenpo, resulting in a silk-like texture and luster.

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 this is because peeling of the fibers constituting the textile product creates appropriate voids in the tissue, improving the hand and drape properties.

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.

Example 1 Pieuron (trade name of acrylic long fiber manufactured by Asahi Kasei Corporation)
A 75 dl/38 f plain woven fabric was immersed in an aqueous sodium hydroxide solution (98°C) having the concentration shown in Table 1 for 15 minutes, and then washed with water. This sample was kept at 98℃ with 0.5%
After being immersed in a phosphoric acid aqueous solution for 15 minutes, it was washed with water and dyed using a cationic dye at 100° C. for 60 minutes using a conventional method.

This dyed product was immersed in aluminum chloride at the concentration shown in Table 1 at a bath ratio of 1/20 at 30° C. for 20 minutes, then washed with water and dried.

Table 1 shows the results obtained by the above processing.

As is clear from Table 1, 11kL6.7.9.10
Samples No. 11, 13, 14, and 15 had particularly silk-like luster and texture, and almost no staining spots occurred. Moreover, no tackiness or adhesion was observed in these samples.

Below is the margin in Table 1 *1 Flexibility evaluation: ◎ Very softer than untreated ○ Softer than untreated △ Same as untreated × Harder than untreated × × Much harder than untreated Ta.

*2 Weight reduction rate = (A-B/A) x 100A:
Sample bone dry weight before treatment B: Sample bone dry weight after treatment Example 2 A plain woven fabric similar to that used in Example 1 was immersed in a sodium hydroxide solution with the concentration listed in Table 2, and soaked with a mangle. After squeezing at a rate of 120%, steaming treatment was performed 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, it was immersed in a 1% sulfuric acid aqueous solution kept at 98° C. for 10 minutes, and then washed with water and dried. This acid treatment restored the whiteness of the sample to the same level as that of the untreated fabric. This sample was dyed using a cationic dye in a conventional manner at 100° C. for 60 minutes.

The obtained dyed products were immersed in an aqueous calcium chloride solution (bath ratio 1/20) at a concentration shown in Table 2 for 20 minutes at 30°C, followed by washing with water and drying.

The results obtained by the above processing are shown in Table 2.

From the results in Table 2, N016.11.13.14.15
The sample had a particularly silk-like luster and texture, and almost no staining spots occurred. Moreover, no tackiness or adhesion was observed in these samples.

The following is a blank Table 2. The above measurements of flexibility and weight loss rate are the same as in Example 1.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the relationship between the aqueous alkaline solution concentration and the melting rate of acrylic synthetic fibers in the dipping method. Agent Patent Attorney Takeshi Kawakita

Claims (1)

[Claims] (1) An aqueous solution of an alkali metal hydroxide and/or its salt that has a dissolving action on acrylic synthetic fibers is applied to the acrylic synthetic fibers to dissolve and remove the surface layer. A method for producing flexible acrylic synthetic fibers, comprising a step A and a step B in which the fiber treated in step A is further treated with an aqueous solution of a polyvalent 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) In any one of claims (1) to 3), the feature is 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. A method for producing flexible acrylic synthetic fibers.