JPS6147873A - Production of novel water swellable 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 provides an outer layer of a hydrophilic crosslinked aggregate (hereinafter referred to as hydroglu) and an inner layer of a 7-crylonitrile derivative polymer (hereinafter referred to as ANM polymer) and/or other polymers. TonotaN
The present invention relates to a method for producing a novel water-swellable fiber having a structured structure, high water-swellability, and high physical properties.

In recent years, highly water-swellable polymers have attracted attention for their special functions and are being applied to a wide range of fields of use. For example, by utilizing the instantaneous water absorption ability of such polymers, diapers
It can be used in sanitary products, soil improvement materials, innutant sandbags, etc. due to its moisture retention ability, and soft contact lenses, artificial organs, surgical suture materials, etc. due to its affinity with human tissue. Some of these applications have already entered the practical stage.

It is often preferable for water-swellable polymers (hydrogel), which have a wide range of potential applications, to be in the form of fibers depending on the intended use, and some such fibrous hydrogels are known. . However, although such existing natural or synthetic fibers have a certain degree of water swelling ability, their water swelling degree is extremely low or they are water soluble). The material was far from the water-swellable fibers, which absorb and retain several times as much water and are water-insoluble. Furthermore, Japanese Patent Publication No. 52-42916 describes a highly swellable fibrous structure formed by incorporating a specific crosslinked structure and a large amount of carboxyl groups in the form of salt into acrylic fibers. However, in such a fibrous structure, an extremely large amount of salt-form calhoki groups are introduced, and the hydrogel is formed over the inner and outer parts of the fc fiber, so it is true that the structure has a high degree of On the other hand, it is extremely brittle and the concept of fiber is poor.

It was just a distant physical property. In other words, the reality is that water-swellable fibers with satisfactory performance still do not exist, and imparting a high degree of water-swellability and maintaining fiber physical properties are contradictory issues.

As a result of intensive studies to overcome the above-mentioned essential difficulties and impart high water swelling properties while retaining the physical properties of the fibers, the present inventors have discovered that fibers made of AN-based polymers (hereinafter referred to as 11-based polymers) By applying a specific aqueous alkali metal hydroxide solution to the fibers (abbreviated as "fibers"), only the outer layer of the fibers is selectively hydrophilically crosslinked (hydrogel-ized).
The present invention was achieved by discovering that Jli fiber properties can be advantageously imparted with water swelling performance.

That is, an object of the present invention is to provide a novel method for producing water-swellable fibers that have both high water-swellability and high physical properties.

6. The water-swellable fiber according to the present invention to achieve the above-mentioned purpose has a water-swellable fiber of AN-based fiber. Omol/1000g
The outer layer of the fiber is made into a hydrogel by applying a high concentration alkali metal hydroxide aqueous solution higher than the solution or a low concentration alkali metal hydroxide aqueous solution coexisting with electrolyte salts having a concentration higher than 0.5 moJ/1000g solution. By converting the salt type carboxylic group represented by -COOX (X: alkali metal or NH4) into
ojl/g, outer layer made of hydrogel and ANN
It can be advantageously manufactured by forming the fiber into a fiber composed of a polymerized material and/or an inner layer made of another polymer.

Therefore, the ANN-based polymer according to the present invention is a general term for polymers containing AN as a copolymerization component, and the ANN single association is composed of muN and other ethylene. comonomers with systemically unsaturated compounds, or AN and other polymers, such as starch, duraft copolymers such as polyvinyl 7-CoI, huBy polymers and other polymers, such as polyvinyl chloride/L Examples include mixed polymers with /yarn, polyamide, polyolefin, polyurethane, linutylene, polyvinyl alcohol, and sylose. like (like A)
The content of AN in the M-based polymer is preferably 30ffi% or more, preferably 50% or more, and when using fibers made of a polymer with an AI content that is less than this recommended range as a is not preferred because it is not sufficiently hydrophilized by alkaline hydrolysis treatment, or even if it can be made hydrophilic, it is difficult to form water-swellable fibers.

In addition, there are no particular restrictions on the polymer composition such as the Mi of the ethylenically unsaturated compound that is a copolymerization component of the AN polymer or the molecular weight of the polymer, and the required performance of the final product and the monomer It can be arbitrarily selected depending on the copolymerizability of the polymer and the like. Furthermore, regarding methods for producing these polymers and methods for forming fibers from the polymers, known methods (
For example, it can be arbitrarily selected from single-component spinning, sheath-core composite spinning, etc.]. In other words, the AN employed in the present invention has an hMB7BM body as a sheath component, which is easily decomposed by AN, and an hxQ polymer that is difficult to hydrolyze as a core component, or
A sheath-core type spun fiber can be produced, such as one in which an N-polymer is used as a sheath component and another polymer (for example, the above-mentioned polyamide, polyolefin, etc.) is used as a core component. In addition, A
It can be used as the starting material of the present invention, AN-based fiber, as long as it has a cross-sectional structure with a small amount of N-based monomerization (some of which are exposed on the fiber surface, for example, random polymers of two to three or more components). It does not depart from the gist of the present invention to use special spun fibers such as composite spun fibers, seabird-type composite fibers, two-component laminated composite fibers, or sand-inch composite fibers as starting materials. isn't it.

(The fibers produced by this process are short fibers, long fibers, fiber tow,
Any form of waste fiber such as yarn, knitted fabric, non-woven fabric, etc., can be subjected to subsequent hydrolysis treatment, and waste fiber 1 or waste fiber discarded in the AN-based fiber manufacturing process, etc. It goes without saying that products in the process (eg, hot-stretched fibers, etc.) can be used as the starting material.

In order to obtain a water-swellable fiber having high water-swellability and high physical properties as a starting material for AM-based woven fibers, only the outer layer of the AN-based fiber is selectively hydrogelated and the outer layer of the hydrogel is combined with the Allll threads. It is necessary to form fibers having a long structure with/or other polymer inner layers.

It is necessary that the degree of water swelling of the thus produced fiber having a two-layer structure or multi-layer structure is in the range of 13 to 300 oc/g%, more preferably 5 to 200 ca/g, and In order to have a swelling degree and maintain sufficient fiber physical properties, the proportion of the hydrogel outer layer is controlled to 55% or less, more preferably within the range of 5 to 40%, based on the total volume of the fiber when dry. It's hard to do. If the proportion of the hydrogel exceeds the upper limit of the recommended range of the present invention, sufficient fiber properties will not be maintained, and if the proportion exceeds the lower limit of the preferred range, the salt-type carboxylic acid will not exhibit sufficient water swelling performance. /l/ group ■ is 0.5
~4. Qmmol/g, more preferably 0.5 to 3.5
It is necessary to adjust the amount within the range of mmol/g. If the salt-type force μ oxyl group poison is outside the lower limit of the recommended range of the present invention, the water swelling performance will be insufficient, and if it exceeds the upper limit of the range, the fiber physical properties will deteriorate and the fiber will have poor flexibility. Only brittle products can be obtained (which is not preferable).As for the type of the above-mentioned salt type carboxyl group, L
The salt may be a salt of an alkali metal such as ", K1Ma, or N2H4, or a mixture of two or more thereof.

Next, a method for hydrolyzing AN-based fibers will be described in detail. R
If water-swellable fibers consisting of an outer hydrogel layer and an inner layer such as ANN aggregates are ultimately obtained, there are no restrictions on the hydrolysis method, but only the outer layer of AM-based woven fibers can be selectively hydrogelized. In the present invention, as a one-step hydrolysis and crosslinking treatment method that can easily control the proportion of the outer layer, the following method was employed in the present invention.

Uchi1 hxAmim, 6.0 mob/1000
A highly concentrated alkali metal hydroxide aqueous solution (hereinafter referred to as method A) is applied to the solution (hereinafter referred to as method A).
One of the methods (hereinafter abbreviated as method B) in which a low concentration alkali metal hydroxide aqueous solution coexisting with a concentrated W(')m solution of 1,000 g or more was used. 16.0 when adopting method A above
When an alkaline aqueous solution with a degree of less than mol/1000 g of solution is applied, the AN-based fiber becomes hydrophilic through a hydrolysis reaction, but becomes water-soluble, resulting in the formation of the outer layer of the hydrogel, which is the objective of this article. cannot be made to form. Also, 6.25-8.85 theory + 1/1000g solution, further tm 6.25-8.50 moJ/1000
The present invention can be more effectively achieved by using an alkaline aqueous solution in the concentration range of g solution. Under conditions exceeding the upper limit of the preferred range, the activity of the alkali metal hydroxide decreases, requiring high-temperature treatment to increase the reaction rate, and making it difficult to remove residual alkali, making it undesirable from a practical standpoint. do not have. In addition, when adopting method B, the amount of salt to coexist is 0.5 nov.
In the case of a low Ω degree of less than 1000g solution, the AN-based fiber becomes hydrophilic through a hydrolysis reaction, but most of it becomes water-soluble, and the outer layer of the hydrogel is formed in a single step in a low-concentration alkaline aqueous solution. You can't force it. Also, 1. QmoJ/1000g Salt concentration above the solution, or the salt 6 degrees and 0.25 to 6.0 moJ/100
0 g solution, more preferably 0.5-5.0 moJt
By using an alkaline aqueous solution with an alkali metal hydroxide concentration of /1000 g solution! llS The present invention can be implemented more industrially advantageously. 1. The method A is described in more detail in Japanese Patent Application No. 158423/1983 filed by the present applicant.

Here, examples of the alkali metal hydroxide used in the present invention include hydroxides of alkali metals such as Na5K1Li or mixtures thereof, and examples of electrolyte salts include hydroxides of alkali metals such as Na5K1Li and mixtures thereof. Any salt can be used as long as it is stable, and the cation components constituting the raw salt are, for example, alkali metals such as Na5K1Li, alkali metals such as Na5K1Li, alkali metals such as Be% Mg% Ck, Ba, etc., and metals. Class+CuqZn1Al, Mn, I'es Co
Other metals such as sNi, 1NH4, etc., and salts composed of acid groups such as folic acid, organic acid, organic sulfonic acid, etc., or a mixture of 2g1 or more can be mentioned. In addition, when using electrolyte salts in which the above-mentioned cationic component is an element with a valence of 2 or more, the outer layer of the resulting hydrogel may aggregate or
It is preferable to use a salt containing an alkali metal or HH- as a cationic component because it is easy to coalesce and the degree of swelling is reduced. Furthermore, as a solvent in place of water, water such as methanol, ethanol, propatool, 2-methquine ethanol, 2-ethoxyethanol, dimethylformamide, dimethy/l/nup oxide, etc. can be used as long as it does not dissolve the AN fibers to be treated. An aqueous mixed solvent of a miscible organic solvent and water can be used, and it is also possible to coexist other inorganic substances or organic substances as necessary.

Here, the specific conditions of method A or B recommended for the present invention are adopted, even though in fact only a water-soluble polymer is produced when alkaline hydrolysis treatment is performed under the conditions of known technology. This produces hydrogels in a single step and in high yields, which are significantly different from the results expected from reactions under known conditions. This mechanism of action is particularly related to = t! in the outer fiber layer. This can be explained by the fact that, accompanying the hydrolysis reaction of the tv group, side reactions that form intermolecular crosslinks or intramolecular cyclic structures proceed specifically under the above-mentioned specific conditions. However, the details have not yet been elucidated.

It is impossible to unambiguously define the range of suitable conditions for forming microgrooves in polymers depending on factors such as alkali concentration, etc., such as the morphology of the polymer and crystallinity. Preferably, the temperature is 50° C. or higher, more preferably 80° C., since the speed can be increased and the processing effect can be advantageously achieved.
The present invention can be effectively carried out by using temperature conditions of .degree. C. or higher.

Further, although there is no strict limit on the amount of alkaline aqueous solution treated with ANJj fibers, it is recommended to use at least 3 m dish parts, preferably 4 parts by weight or more, of the aqueous solution per 1 part by weight of the fibers. Desirably, under such conditions, the contact between the fiber and the aqueous solution can be facilitated, and the hydrophilization reaction and crosslinking reaction of the present invention can proceed effectively.

Furthermore, as a method for applying an alkaline aqueous solution to the AM:A fibers, short fibers cut to an arbitrary fiber length are suspended in an aqueous solution, and then cut using a shearing device such as a Nuclue-type stirring field or mixer, or Two methods, long fiber, fiber tow,
A method in which continuous U & fibers such as yarn, knitted fabrics, non-woven fabrics, etc. are run under tension or under no tension in the aqueous solution, or the short fibers, long fibers, etc. are filled in a mesh container and run in the aqueous solution. A wide range of known heterogeneous treatment methods can be selected, such as a method in which the treatment method is oscillated in a vacuum.

As mentioned above, when producing a fiber having a multilayer W4 structure consisting of an outer layer and an AMM polymer and/or other polymer inner layer by applying an alkaline aqueous solution to the NAH-based woven fiber, the final The volume ratio and/or salt type force/levoxyl group (-COOX) of the outer layer of the hydrogel has a particularly close relationship with the water swelling degree and physical properties of the resulting fiber.
It is important to control Means for controlling the volume ratio and/or salt type carboxy tI/am of the outer layer of the hydrogel include the composition, crystallinity, single fiber fineness, etc. of the AM-based woven fiber to be treated, or the hydrolysis treatment conditions; That is, it can be varied in various ways depending on the concentration of the alkali metal hydroxide and/or electrolyte salts, the temperature during hydrolysis, the amount of alkaline aqueous solution applied to the fibers to be treated, the treatment time, etc. Although it is difficult to achieve this, the object of the present invention can be easily achieved by adjusting the hydrolysis treatment conditions, particularly the treatment time, within the range of approximately 40 minutes or less, preferably 2 to 30 minutes.

When hydrolyzing a fiber made of a single component of hxp polymer for a long period of time exceeding the recommended range of the present invention, the inner layer of the A M polymer may be completely eliminated, but some of the inner layer may remain. Even if the amount is small, or the boundary between the outer layer and the inner layer becomes unclear, water-swellable fibers with satisfactory physical properties cannot be obtained, which is undesirable.

The resulting water-swellable fibers are washed with water to remove residual alkali metal hydroxides, and after 7e, the salt-type carboxy/I/groups are treated with alkali by a known method if necessary. The hydrogel outer layer and the hwfi
It is possible to obtain water-swellable fibers composed of + polymer and/or other polymer inner layers, and surprisingly, the fibers have a content of 3 to 300 cc/7g, preferably 5 to 200 cc/
It has a water swelling degree of g, as well as dry strength, wet and dry elongation,
Regarding ta fiber properties such as knot strength, the performance is almost comparable to that of ordinary AN-based clothing fibers (for example, dry strength 2.0
g/d or higher and wet strength of 1.5 g/d or higher). In addition, since the fiber has an inner layer of ANix coalescence, etc., it also has the unique property that no dimensional change occurs in the length direction even in the ri1 wet state: thus, crosslinking is formed as a copolymer component. Uses normal AM-based woven fibers or waste fibers discharged from the AMM fiber manufacturing process as a starting material, without requiring the use of fibers made of a single amalgamation with a special composition containing monomers, etc. death,
Through a one-step treatment process with an aqueous alkaline solution, fibers with high water swelling performance and eroded physical properties can be obtained, and the degree of water swelling and physical properties of the resulting fibers can be easily controlled by adjusting the hydrolysis treatment conditions. This is a notable advantage of the present invention. Another advantage of the present invention is that the water-swellable fiber from Ka1 has excellent physical properties such as strength, elongation, flexibility, and elasticity, and can be handled in exactly the same way as existing clothing fibers. This is a major feature.

The water-swellable fiber of the present invention, which has such high water-swellability and abrasive physical properties, can be used alone or by blending with existing natural, biosynthetic, or synthetic fibers.
In addition to the new GI fiber material or fiber thion exchange fiber, A, etc., which has outstanding moisture absorption, water absorption, and water retention properties, it can also be used as instant sandbags, artificial soil, water drainage, heat preservation and cold preservation, as well as existing dry gel powder. It can be applied to materials, etc.

In order to further facilitate understanding of the present invention, examples are described below, but the gist of the present invention is not limited in any way by the description of these examples. Incidentally, all amounts and parts of b described in the examples are based on MW standards unless otherwise specified.

In addition, the degree of water swelling, salt type monomer/L/boxyl group (-coox)@, and volume ratio of the outer layer of the drogel described in the following examples were measured or calculated by the following methods.

(υ Degree of water swelling (CC/g) Approximately 0.1 g of sample fiber was immersed in pure water and kept at 25°C.
After 4 hours, wrap it in a nylon filter cloth (200 mesh) and remove the water between the fibers using a centrifugal dehydrator (3G x 3° minutes, where G is gravitational acceleration).Measure the weight of the sample in this way. (Wag).Next, the sample is dried in a vacuum dryer at 80°C until it reaches a constant weight, and Mm is measured (W2g).From the above measurement results, it was calculated by the following formula.Therefore, the water swelling The degree of water absorption is a numerical value that indicates how many times the fiber's own weight of water can be absorbed and retained.

W - W2 (degree of water swelling) = □ (2) -〇〇〇
1 of water was added) while heating to 50° C., a 1N aqueous hydrochloric acid solution was added to adjust the pH to 2', and then a titration curve was determined using a 0.1N aqueous sodium hydroxide solution according to a conventional method. From the titration curve, the consumption of caustic soda aqueous solution consumed by carboxylic acid V/L/group fit (from the measurement results of 0 or more,
It was calculated using the following formula.

0, 1 Y (-COOX group 4)= If polyvalent cations are included, it is necessary to determine the amount of these cations by a conventional method and correct the above formula.

(6) Volume ratio of the outer layer part (v2%) of Hydroge I. Twenty samples swollen by water absorption were magnified 100 to 1000 times (2 times), a photograph was taken, and the core part (A
N-based polymers and/or other polymers.

The average value of the diameter of the inner layer of the coalescence
It was calculated using the following formula.

However, J. Diameter of AN-based fiber to be treated (/j) Example 1 90% AN and 10% methyl acrylate (MA)
AN yarn fiber (single fiber fineness: 3d, ffl fiber length;
Intrinsic viscosity in dimethylformamide (DMF) solution at 30° C.
moJ/1000 g solution) Water-swellable fibers immersed in 96 parts of a caustic soda aqueous solution and boiled for 10 minutes while stirring, then washed with water to remove residual alkali in the fibers, and dried to produce a water-swellable fiber that exhibits a white to slightly yellow color. (1).

The obtained fiber (1) does not dissolve in water and has a thickness of 2.8 mm01
Contains 7 g of -C0ON& groups and also 174 c
It was confirmed that it had a water swelling degree of c/g. In addition, the results of measuring the various physical properties of the fiber (1) and the volume ratio ffJ of the hydrogel outer layer are listed in Table 1 together with the physical property values of the AN-based fiber to be treated.

As is clear from the results in Table 1, the water-swellable fiber according to the present invention maintains reference values for both strength and elongation (a level that is almost comparable to the treated AM-based wire fibers). will be understood.

On the other hand, as a comparative example, 10% (2,5mo171000
The treatment was carried out according to the above recipe except that a 23% (5.75 mol/1000 g solution) caustic soda aqueous solution was used. When such a low concentration aqueous solution of caustic soda alone was used, it was not possible to form water-swellable fibers as the object of the present invention.

In addition, 35% (6%) of caustic potash can be used instead of the above-mentioned caustic soda.
, 25 mojl/1000 g solution) When the treatment was performed according to the above recipe except that an aqueous solution was used, fibers that were white to slightly yellow in color, were substantially water-insoluble, and had water W5 repellency were obtained.

Example 2 AN7A gi consisting of 90% AN and 10% MA
fiber (single fiber fineness; 6d1 fiber length; s5mmq30℃D
Intrinsic viscosity in MFM liquid i 1.3) 5 parts to 20% (
The water-swellable fiber (II) was soaked in 95 parts of a 10%<2.5moJ/1000g10 caustic soda aqueous solution containing 3,45rnol/1000g solution] of common salt, and prepared according to the recipe described in Example 1. was formed. Obtained fiber (1)
is not dissolved in water, and the volume ratio of the outer layer of the hydrogel (V)
It was found to contain 25% and 1.9 mmol of -G OON, groups and to have a water swelling degree of 150 ca/g.

In addition, in the above, when only the hydrolysis treatment time was extended to 1 hour, the obtained fiber (III) was 8.6 m
Contains mojl/g of -COONa groups, 618 c
Although it has an extremely high degree of water swelling of c/g, it is extremely brittle, and when the fiber was squeezed in the water-swollen state, it was confirmed that no AN-based polymer core remained at all.

Example 3 In the formulation described in Example 2, 7 liters of nitric acid was used instead of 20% common salt, and the concentrations of the raw salt and caustic soda were varied as shown in the second notation to produce the AM system described in Example 2. Woven fiber treated.

Water swelling degree of the obtained 10 kinds of water-swellable fibers (I-■),
-cooM, base weight and volume ratio of the outer layer of the hydrogel (V
The results of measuring J are also listed in 1%2 Table ◎ From the results in Table 2 Table 2, when the concentration of salt coexisting in the alkaline aqueous solution is less than the range 1'14 recommended for the present invention (Sample A ), only fibers with a low degree of water swelling were obtained (1) and the yield of the desired water-swellable fibers was as low as about 40%, since the amount of water-soluble polymer formation matrix increased significantly. In addition, when the sample size (1), that is, the concentration of alkali was extremely low, fibers having the desired degree of water swelling could not be obtained. Furthermore, sample A
It is also clear from II, IV, W, and () that even if the alkali concentration is constant, fibers with various degrees of water swelling can be produced by changing the salt concentration.

Example 4 AI fiber consisting of 80% AM and 20% vinyl acetate (single fiber fineness; 15as fiber length; 50 mm, D at 60°C
Intrinsic viscosity in MFM liquid: 1.5) was treated according to the recipe described in Example 1 (however, treatment time: 6 minutes),
White to slightly yellow 'i = ML, -c of 1.6 mmol/g
Contains ooNa group and has a water swelling degree of 143 cc/g
Water-swellable fibers (cut 1) were obtained.

[Brief explanation of the drawing]

・Hgi iij pa..., °・ ・':',,,,,+
Translated by N.R.11η Procedural Amendment August 1986

Claims (1)

[Claims] 1. The fiber made of acrylonitrile polymer has 6.0
The outer layer of the fiber is treated with a high concentration alkali metal hydroxide aqueous solution having a concentration of mol/1000 g or more, or a low concentration alkali metal hydroxide aqueous solution coexisting with electrolyte salts having a concentration of 0.5 mol/1000 g or more. By hydrophilically crosslinking the salt-type carboxyl group represented by -COOX (X: alkali metal or NH_4),
4.0 mmol/g is introduced to form a fiber consisting of an outer layer made of a hydrophilic crosslinked polymer and an inner layer made of an acrylonitrile polymer and/or other polymers. A method for producing a novel water-swellable fiber having a degree of water swelling of g and high physical properties. 2. As a low concentration alkali metal hydroxide aqueous solution, 0.
The manufacturing method according to claim 1, wherein an aqueous alkali metal hydroxide solution having a concentration of 0.25 to 6.0 mol/1000 g solution is used in which an electrolyte salt having a concentration of 5 mol/1000 g solution or more is coexisting. 3. The manufacturing method according to claim 1, wherein 55% or less of the outer layer of the fiber is hydrophilically crosslinked based on the total volume of the fiber.