JP5029975B2 - Cross-linked acrylate fiber - Google Patents

Description

  The present invention relates to a crosslinked acrylate fiber and a method for producing the same. More specifically, the present invention relates to a crosslinked acrylate fiber having a color that does not cause discomfort in appearance even when used in combination with other fibers for industrial materials in the industrial material field.

  Cross-linked acrylate fibers are known to have various functions such as moisture absorption and desorption, moisture absorption exothermicity, deodorant properties, antibacterial properties, and flame retardancy, and are expected to expand into various fields. is there. However, since the color of the fiber is pink and the hue becomes deeper with post-processing and aging, there is a problem that application development is limited. Many studies have been conducted on this issue for the purpose of expanding into the clothing field.

  For example, Patent Documents 1 to 3 have been studied to improve whiteness, and crosslinked acrylate fibers having practical whiteness have been obtained. Patent Document 4 discloses black cross-linked acrylate-based fibers obtained using black original acrylic fibers as a raw material. Further, in Patent Documents 5 and 6, studies are made on various colors by dyeing crosslinked acrylate fibers. However, with respect to dyeing, further examination is necessary to make it practically sufficient in terms of hue stability, dyeing spots, dyeing fastness, and the like.

  As described above, in the prior art, various studies have been made on the color of the crosslinked acrylate fiber for the purpose of developing in the clothing field, but only a limited color is provided in practice.

  On the other hand, the restriction on the color of the crosslinked acrylate fiber cannot be ignored in the industrial material field. In the industrial material field, various types of industrial material fibers are often mixed and commercialized, and the color of such industrial material fibers is often similar to a gold color. For this reason, when the above-mentioned cross-linked acrylate fiber is used in combination, the appearance of the product is uncomfortable. White is less uncomfortable than pink or black, but is costly and difficult to adopt because it takes many steps to improve whiteness. Thus, the conventional cross-linked acrylate fiber is in a situation where it is difficult to develop in the industrial material field, despite having various functions as described above.

  In addition, as described above, the cross-linked acrylate fiber has flame retardancy. Especially, when the carboxyl group in the fiber is a magnesium salt type, the cross-linked acrylate fiber is extremely high that is not found in general organic fiber. It is known to have flame retardancy (Patent Document 7). Furthermore, the magnesium salt type crosslinked acrylate fiber has a feature of slow moisture absorption / release, that is, a low moisture absorption / release rate (Patent Document 8). For this reason, continuous heat generation by moisture absorption is possible, which is particularly useful in the clothing field.

  However, this indicates that, in the prior art, magnesium salt-type crosslinked acrylate fibers cannot achieve both high flame retardancy and high moisture absorption / release rate, and cannot be developed for applications requiring such characteristics.

Japanese Patent Laid-Open No. 9-158040 JP 2000-303353 A JP 2002-294556 A JP 2003-89971 A JP 2003-278079 A JP 2006-70421 A International Publication No. 2006/027911 Pamphlet International Publication No. 2006/027910 Pamphlet

  An object of the present invention is a cross-linked acrylate which has an unfavorable appearance in color even in combination with other industrial material fibers in the industrial material field, which has not been provided in the prior art, and is advantageous in terms of cost. It is to provide a system fiber. Another object of the present invention is to provide a cross-linked acrylate fiber having both high flame retardancy and high moisture absorption / release rate.

The above object of the present invention is achieved by the following means. That is,
[1] A cross-linked acrylate fiber used in combination with a fiber for industrial materials, and without being dyed, in the display method according to JIS-Z-8729, L ^* is 60 to 75 and a ^* is 5.0 to 14 .5, b ^* is a cross-linked acrylate fiber having a color of 23.0 to 30.0.
[ 2 ] The crosslinked acrylate fiber according to [1 ], wherein at least some of the carboxyl groups in the crosslinked acrylate fiber have magnesium and / or zinc ions as counter ions.
[ 3 ] At least some of the carboxyl groups in the crosslinked acrylate fiber have a magnesium ion as a counter ion, a limiting oxygen index of 30 to 50, and a saturated moisture absorption of 20 to 60% by weight. The crosslinked acrylate fiber according to [ 2 ].

  Since the cross-linked acrylate fiber of the present invention has a color similar to a gold color, there is no sense of incongruity even when mixed with a fiber for industrial materials, and the number of manufacturing steps is small, so the cost can be suppressed. It can be suitably used in the field. Further, in the crosslinked acrylate fiber of the present invention, even when the magnesium salt type is adopted, it is possible to express a high moisture absorption / release rate, and the high flame retardance that could not be realized by the conventional crosslinked acrylate fiber. Since it is possible to achieve both high performance and a high moisture absorption / release rate, it becomes possible to develop applications where such characteristics are required.

FIG. 1 shows the moisture absorption curves of the crosslinked acrylate fibers of Examples 1 and 2 and Comparative Examples 1 and 2.

The present invention is described in detail below.
The cross-linked acrylate fiber of the present invention has a color similar to a gold color not found in conventional cross-linked acrylate fibers, and does not cause a sense of incongruity even when mixed with fibers for industrial materials. Specifically, the color is such that, in the display method described in JIS-Z-8729, L ^* is 60 to 75, a ^* is 5.0 to 14.5, and b ^* is 23.0 to 30.0. It is a certain color, and it is preferable that L ^* is 65 to 75, a ^* is 7.0 to 13.0, and b ^* is 23.5 to 27.0.

  The crosslinked acrylate fiber of the present invention is obtained by subjecting the acrylonitrile fiber to (a) a crosslinking introduction treatment with a hydrazine compound, (b) a treatment with a peroxide, and (c) a hydrolysis treatment with an alkaline metal compound. Can be obtained in the order of (a), (b), (c), or (b) and (c) after applying (a).

  The acrylonitrile fiber employed in the present invention is produced from an acrylonitrile polymer according to a known method, and the composition of the polymer is preferably 40% by weight or more, more preferably Is 50% by weight or more, more preferably 80% by weight or more. In the present invention, as described later, a crosslinked structure is introduced into the fiber by reacting the nitrile group of the acrylonitrile copolymer that forms the acrylonitrile fiber with the hydrazine compound. The cross-linked structure greatly affects the fiber properties. If the copolymerization composition of acrylonitrile is too small, the cross-linked structure must be reduced, and the fiber properties may be insufficient. It becomes easy to obtain a favorable result by making a polymerization composition into the said range.

  As copolymerization components other than acrylonitrile in the acrylonitrile-based polymer, sulfonic acid group-containing monomers such as methallylsulfonic acid and p-styrenesulfonic acid and salts thereof, and carboxylic acid groups such as (meth) acrylic acid and itaconic acid Examples thereof include monomers such as a monomer and a salt thereof, styrene, vinyl acetate, (meth) acrylic acid ester, (meth) acrylamide and the like, and are not particularly limited as long as the monomer is copolymerizable with acrylonitrile.

  The form of the acrylonitrile fiber employed in the present invention may be any form such as short fiber, tow, yarn, knitted fabric, and non-woven fabric, and may be employed as an intermediate product in the manufacturing process, waste fiber, or the like.

  In the treatment (a), by treating the acrylonitrile fiber with a solution containing a hydrazine compound, the nitrile group of the acrylonitrile fiber and hydrazine react to form a crosslinked structure in the fiber. Examples of the hydrazine-based compound include hydrazine hydrate, hydrazine hydrochloride, hydrazine sulfate, neutral hydrazine sulfate, and hydrazine carbonate. The treatment conditions include a method in which the acrylonitrile fiber described above is immersed in an aqueous solution to which the hydrazine compound is added so that the hydrazine concentration is 3 to 40% by weight, and the treatment is performed at 50 to 120 ° C. within 5 hours. Can be mentioned.

  In the treatment (b), the fiber obtained by the treatment (a) is treated with a solution containing a peroxide. By performing such treatment, the color of the finally obtained crosslinked acrylate fiber can be made a color that approximates the gold color. Examples of the peroxide used for the treatment include hydrogen peroxide, ammonium persulfate, and potassium persulfate. Examples of treatment conditions include immersing the fiber in an aqueous solution having a peroxide concentration of 1 to 15% by weight, preferably 3 to 8% by weight, and treating at 50 to 120 ° C. for 0.5 to 20 hours. . Prior to this treatment, it is desirable to thoroughly wash the fibers with water and remove as much of the chemical remaining in the treatment (a) as possible.

  Treatment (c) is a hydrolysis treatment with an alkaline metal compound. By this treatment, the nitrile group or amide group present in the fiber is hydrolyzed to form a carboxyl group. The carboxyl group is a factor that develops characteristics such as moisture absorption / release properties, moisture absorption exothermic property, and deodorizing property in the crosslinked acrylate fiber. Generally, the total carboxyl group amount is 1 to 12 mmol / g, preferably 3 to 10 mmol / g, more preferably 3 to 8 mmol / g of carboxyl groups are formed. The amount of carboxyl groups formed can be adjusted depending on the processing conditions. In addition, an amide group is produced | generated from a part of nitrile group in the process (a).

  Examples of the alkaline metal compound used in the treatment (c) include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and alkali metal carbonates such as sodium carbonate. Examples of the treatment conditions include immersing the fiber in an aqueous solution having an alkaline metal compound concentration of 1 to 10% by weight, preferably 1 to 5% by weight, and treating at 50 to 120 ° C. for 1 to 10 hours. In addition, the counter ion of the formed carboxyl group is a metal ion corresponding to the used alkaline metal compound.

  The processes (b) and (c) described above can be performed simultaneously. In this case, what is necessary is just to immerse and process the fiber obtained by giving the process (a) to the solution containing both the peroxide mentioned above and an alkaline metal compound.

  As described above, by performing the treatments (a) to (c) on the acrylonitrile fiber, the crosslinked acrylate fiber of the present invention can be obtained. Further, nitrates, sulfates, hydrochlorides and the like can be obtained. Ion exchange treatment with metal salts, acid treatment with nitric acid, sulfuric acid, hydrochloric acid, formic acid, etc., or pH adjustment treatment with alkaline metal compounds, etc., to give the carboxyl group in the fiber a desired salt-type carboxyl group or H-type carboxyl It is also possible to adjust properties such as moisture absorption / release properties, moisture absorption exothermic properties, deodorizing properties, antibacterial properties, and flame retardancy by converting them into groups or mixing different types of salt-type carboxyl groups.

  Here, the kind of metal constituting the base carboxyl group is one kind from alkali metals such as lithium, sodium and potassium, alkaline earth metals such as magnesium and calcium, and other metals such as manganese, copper, zinc and silver. Alternatively, a plurality of types can be selected according to required characteristics.

  For example, regarding moisture absorption / release properties, salt-type carboxyl groups such as sodium, potassium, magnesium and calcium are suitable. However, in the crosslinked acrylate fiber of the present invention, a conventional crosslinked acrylate fiber which is not subjected to peroxide treatment. Compared to the above, even if the metal type of the salt-type carboxyl group is the same and the saturated moisture absorption rate is the same, it has the feature that the moisture absorption rate can be increased relatively, and it exhibits better moisture absorption and desorption it can.

  Further, in order to increase the flame retardancy that is important in the industrial material field, it is desirable to select a magnesium salt type carboxyl group or a zinc salt type carboxyl group as the salt type carboxyl group. The amount of these salt-type carboxyl groups is preferably 2 mmol / g or more as an absolute amount and 50% or more based on the total amount of carboxyl groups, and more preferably 2 mmol / g or more as an absolute amount and total amount. 60% or more with respect to the amount of carboxyl groups, or 3 mmol / g or more as an absolute amount and 50% or more with respect to the total amount of carboxyl groups, and most preferably 3 mmol / g or more as absolute amount and the total amount of carboxyl groups On the other hand, it is 60% or more. The method for obtaining such a salt-type carboxyl group will be described below by taking a magnesium salt-type carboxyl group as an example.

  A crosslinked acrylate fiber having a magnesium salt-type carboxyl group can be obtained by immersing the fiber after the treatment (c) in an aqueous solution containing magnesium ions such as an aqueous magnesium nitrate solution. Moreover, when it is desired to control the amount of the magnesium salt type carboxyl group more accurately, the following method can also be employed.

  First, the fiber after the treatment (c) is immersed in an acid aqueous solution such as nitric acid so that all the carboxyl groups in the fiber are H-type carboxyl groups. Next, the obtained fiber is immersed in an alkaline aqueous solution containing sodium ions such as an aqueous sodium hydroxide solution to convert the H-type carboxyl group into a sodium salt-type carboxyl group. At this time, the amount of carboxyl groups converted to the sodium salt type can be changed by adjusting the pH.

  Subsequently, it can be converted into a magnesium salt type carboxyl group by immersing in an aqueous solution containing magnesium ions such as an aqueous magnesium nitrate solution. Here, a sodium salt type carboxyl group is converted to a magnesium salt type carboxyl group, and an H type carboxyl group is hardly converted to a magnesium salt type carboxyl group. That is, it is possible to control the amount of magnesium salt type carboxyl groups by controlling the amount of sodium salt type carboxyl groups by adjusting the pH. In addition, since conversion of sodium salt type carboxyl group to magnesium salt type carboxyl group is a reversible reaction, the chemical equilibrium is shifted by the amount of magnesium ion in the aqueous solution containing magnesium ion to control the amount of magnesium salt type carboxyl group. It is also possible to do.

  The magnesium salt-type crosslinked acrylate fiber of the present invention obtained as described above has a flame retardancy equivalent to that of a conventionally known magnesium salt-type crosslinked acrylate fiber, and has a critical oxygen index of 30 to 50, Preferably 35-50 can be expressed. Further, the fiber has a saturated moisture absorption rate of 20 to 60% by weight, preferably 30 to 60% by weight, and the moisture absorption rate is a saturated moisture absorption rate of about the same for 5 minutes in a 20 ° C. and 65% RH atmosphere. Compared to the conventional magnesium salt-type crosslinked acrylate fiber having a high rate, it achieves both high flame retardancy and high moisture absorption rate, both of which have not been achieved before.

  Also, zinc salt-type crosslinked acrylate fibers can be obtained in the same manner as the magnesium salt-type crosslinked acrylate fibers described above. In this case, an aqueous solution containing zinc ions such as an aqueous zinc chloride solution, an aqueous zinc nitrate solution, or an aqueous zinc sulfate solution may be used in place of the aqueous solution containing magnesium ions such as the aqueous magnesium nitrate solution described above.

  In the present invention, the reason why a crosslinked acrylate fiber having a color similar to a gold color is obtained is not certain, but the pink color of the conventional crosslinked acrylate fiber is derived from a tetrazine ring structure formed by a crosslinking introduction treatment with a hydrazine compound. Therefore, it is presumed that the tetrazine ring structure was changed by the peroxide treatment in the present invention.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples. In addition, unless otherwise indicated, the part and percentage in an Example are shown on a weight basis. First, an evaluation method for each characteristic and a notation method for evaluation results will be described.

[Total amount of carboxyl groups]
About 1 g of a sufficiently dried sample is precisely weighed (W1 [g]), 200 ml of a 1 mol / l hydrochloric acid aqueous solution is added thereto, and the mixture is allowed to stand for 30 minutes, filtered through a glass filter, added with water, and washed. After repeating this treatment three times, the filtrate is sufficiently washed with water until the pH of the filtrate reaches 5 or more. Next, after putting this sample in 200 ml of water and adding 1 mol / l hydrochloric acid aqueous solution to pH 2, a titration curve is obtained with a 0.1 mol / l sodium hydroxide aqueous solution according to a conventional method. The consumption amount (V1 [ml]) of an aqueous sodium hydroxide solution consumed by carboxyl groups is determined from the titration curve, and the total carboxyl group amount is calculated by the following formula.
Total carboxyl group content [mmol / g] = (0.1 × V1) / W1

[Amount of salt-type carboxyl group]
A sufficiently dried sample is precisely weighed and acid-decomposed with a mixed solution of concentrated sulfuric acid and concentrated nitric acid according to a conventional method, and then a metal contained in the form of a salt of a carboxyl group is quantified by atomic absorption spectrophotometry according to a conventional method. The amount of salt-type carboxyl groups is calculated by dividing by the atomic weight of the metal.

[Saturated moisture absorption]
About 5.0 g of the sample is dried with a hot air dryer at 105 ° C. for 16 hours and weighed (W2 [g]). Next, the sample is placed in a thermo-hygrostat adjusted to a temperature of 20 ° C. and 65% RH for 24 hours. The weight of the sample thus absorbed is measured (W3 [g]). Based on the above measurement results, the calculation is performed by
Saturated moisture absorption [%] = {(W3-W2) / W2} × 100

[Hygroscopic curve]
About 2.5 g of the sample is dried with a hot air dryer at 105 ° C. for 16 hours and weighed (W4 [g]). Subsequently, the sample was placed in a cylindrical mesh basket (diameter 7.5 cm, height 9.8 cm) without being pressed so as to be quickly soft, and the entire temperature was adjusted to 20 ° C. × 65% RH immediately. Put in a humidifier. The time at which the sample is placed in a thermo-hygrostat is set as the start of moisture absorption, and the weight of the moisture-absorbed sample when 5 minutes, 10 minutes, 20 minutes, and 30 minutes have elapsed is measured (W5 [g]). From the above measurement results, the moisture absorption rate at each measurement point is calculated by the following equation to obtain a moisture absorption curve.
Moisture absorption [%] = {(W5−W4) / W4} × 100

[Limited oxygen index (LOI)]
A non-woven fabric having a basis weight of 180 g / m ² was prepared using the sample fiber, and LOI was measured for the non-woven fabric based on the JIS-K-7201-2 measurement method. A larger value means higher flame retardancy.

[Fiber color]
The defibrated sample was measured three times using a colorimeter CR300 (D65 light source) manufactured by Minolta Co., Ltd., and the average values of L ^* , a ^* , and b ^* by the display method described in JIS-Z-8729 Ask for.

[Example 1]
A spinning stock solution prepared by dissolving acrylonitrile-based polymer of 90% acrylonitrile and 10% methyl acrylate with 48% aqueous sodium thiocyanate solution was prepared, and spinning, washing, stretching, crimping, and heat treatment were carried out according to ordinary methods. 9 dtex, 70 mm raw fiber was obtained. This raw fiber was immersed in a 15% hydrazine aqueous solution at a bath ratio of 1:10 and treated under conditions of 120 ° C. and 1 hour. The obtained fiber was washed with water, immersed in a 4% ammonium persulfate aqueous solution at a bath ratio of 1:10, and peroxide-treated at 100 ° C. for 1 hour. Next, the obtained fiber is immersed in a 5% aqueous sodium hydroxide solution at a bath ratio of 1:10, hydrolyzed at 110 ° C. for 1 hour, and washed with water to obtain a sodium salt type crosslinked acrylate fiber. It was. The evaluation results of the properties of the obtained fiber are shown in Table 1 and FIG.

[Comparative Example 1]
In Example 1, a sodium salt type crosslinked acrylate fiber was obtained in the same manner except that the peroxide treatment was not performed. The evaluation results of the properties of the obtained fiber are shown in Table 1 and FIG.

[Example 2]
The crosslinked acrylate fiber obtained in Example 1 was treated with 1 mol / l nitric acid aqueous solution to convert the carboxyl group to H type, washed with water, adjusted to pH 12 with 1 mol / l sodium hydroxide, washed with water, sodium A fiber having a salt-type carboxyl group was obtained. By immersing the fiber in an aqueous solution containing magnesium nitrate in an amount equivalent to 1.2 times the amount of carboxyl groups of the fiber, converting to a magnesium salt type at 50 ° C. for 1 hour, and washing with water A magnesium salt type crosslinked acrylate fiber was obtained. The evaluation results of the properties of the obtained fiber are shown in Table 1 and FIG.

[Comparative Example 2]
In Example 2, a magnesium salt type crosslinked acrylate fiber was obtained in the same manner except that the crosslinked acrylate fiber obtained in Comparative Example 1 was used in place of the crosslinked acrylate fiber obtained in Example 1. The evaluation results of the properties of the obtained fiber are shown in Table 1 and FIG.

[Example 3]
In Example 1, sodium salt type crosslinked acrylate fiber was obtained in the same manner except that the peroxide treatment was performed with 3% hydrogen peroxide solution. Table 1 shows the evaluation results of the properties of the obtained fibers.

[Example 4]
The raw material fibers employed in Example 1 were immersed in a 15% hydrazine aqueous solution at a bath ratio of 1:10, treated at 120 ° C. for 1 hour, and washed with water. The obtained fiber was immersed in an aqueous solution containing 4% ammonium persulfate and 5% sodium hydroxide at a bath ratio of 1:10, and simultaneous treatment with peroxide treatment and hydrolysis treatment at 100 ° C. for 1 hour. And washed with water to obtain a sodium salt type crosslinked acrylate fiber. Table 1 shows the evaluation results of the properties of the obtained fibers.

[Example 5]
A spinning stock solution in which acrylonitrile-based polymer of 88% acrylonitrile and 12% vinyl acetate was dissolved in 48% sodium thiocyanate aqueous solution was prepared, and spinning, washing, stretching, crimping and heat treatment were carried out in accordance with a conventional method, and 0.9 dtex was obtained. , 70 mm raw fiber was obtained. This raw fiber was immersed in a 15% aqueous hydrazine solution at a bath ratio of 1:10 and treated under conditions of 120 ° C. and 1.5 hours. The obtained fiber was washed with water, immersed in a 3% aqueous potassium persulfate solution at a bath ratio of 1:10, and peroxide-treated at 60 ° C. for 30 minutes. Next, the obtained fiber is immersed in a 5% aqueous sodium hydroxide solution at a bath ratio of 1:10, hydrolyzed at 110 ° C. for 1 hour, and washed with water to obtain a sodium salt type crosslinked acrylate fiber. It was. Subsequently, the fiber is treated with a 1 mol / l nitric acid aqueous solution to convert the carboxyl group to H type, washed with water, adjusted to pH 12 with 1 mol / l sodium hydroxide, washed with water, and a fiber having a sodium salt type carboxyl group. Got. By immersing the fiber in an aqueous solution containing zinc sulfate equivalent to 1.3 times the amount of carboxyl groups of the fiber, converting to a zinc salt type at 50 ° C. for 1 hour, and washing with water A zinc salt type crosslinked acrylate fiber was obtained. Table 1 shows the evaluation results of the properties of the obtained fibers.

[Example 6]
The crosslinked acrylate fiber obtained in Example 1 was treated with 1 mol / l nitric acid aqueous solution to convert the carboxyl group to H type, washed with water, adjusted to pH 12 with 1 mol / l sodium hydroxide, washed with water, sodium A fiber having a salt-type carboxyl group was obtained. By immersing the fiber in an aqueous solution containing magnesium nitrate equivalent to 1.6 times the amount of carboxyl groups of the fiber, converting to a magnesium salt type at 50 ° C. for 1 hour, and washing with water A magnesium salt type crosslinked acrylate fiber was obtained. Table 1 shows the evaluation results of the properties of the obtained fibers.

  As can be seen from Table 1, the crosslinked acrylate fibers of Comparative Examples 1 and 2 have a pink color, but the crosslinked acrylate fibers of Examples 1 to 6 subjected to peroxide treatment have a gold color. is there. In addition, as can be seen from FIG. 1, the crosslinked acrylate fibers of Examples 1 and 2 have a lower amount of salt-type carboxyl groups than the crosslinked acrylate fibers of Comparative Examples 1 and 2, respectively, but 5 minutes from the start of moisture absorption. Looking at the moisture absorption rate later, in the case of the sodium salt type, it was 28% in Example 1 compared to 20% in Comparative Example 1, and in the case of the magnesium salt type, it was performed against 2% of Comparative Example 2. In Example 2, it is 6%, and the improvement in the moisture absorption rate is remarkable in the magnesium salt type.

Claims (3)

In the display method described in JIS-Z-8729, the cross-linked acrylate fiber is used in combination with the industrial material fiber, and in the display method described in JIS-Z-8729, L ^* is 60 to 75, a ^* is 5.0 to 14.5, A crosslinked acrylate fiber having a color with b ^* of 23.0 to 30.0. Cross-linking acrylate fiber of claim 1 wherein at least a portion of the carboxyl groups of the crosslinked acrylate-based fibers is characterized in that as the magnesium and / or zinc ions counterions. 3. At least a part of the carboxyl groups in the crosslinked acrylate fiber has a magnesium ion as a counter ion, a limiting oxygen index of 30 to 50, and a saturated moisture absorption of 20 to 60% by weight. cross-linking acrylate-based fiber according to.

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