JPH01192816A - Production of acrylic fiber with improved whiteness - Google Patents

Abstract

PURPOSE:To obtain the title fiber useful for clothing use, etc., by dry spinning a spinning solution containing an acrylonitrile based polymer and a specified amount of triazole-coumarin derivative using DMF as a solvent and improving whiteness with a small amount of a whiteness modifier. CONSTITUTION:Dimethylformamide or dimethylacetoamide is used as a solvent and an acrylonitrile based polymer containing >=85.0wt.% acrylonitrile and a triazole-coumarin derivative expressed by the formula in an amount of 0.01-0.1wt.% based on the polymer as a whiteness modifier are added thereto and dissolved to prepare a spinning solution. The obtained spinning solution is then dry spun by discharging through a nozzle at 130 deg.C discharging temperature into hot air at 250 deg.C to form an undrawn fiber. Drawing, washing with water, drying and relaxation treatment thereof are subsequently carried out to provide the aimed fiber with improved whiteness.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a novel method for producing acrylic fibers with improved whiteness and suitable for clothing and interior uses.

It has a wide range of applications in the fields of textile products and other molded products, and is widely used in the clothing and interior fields5.

Acrylic fibers are usually obtained by solution spinning a polymer of 85% by weight or more of acrylonitrile (hereinafter referred to as AN) and one or more vinyl monomers copolymerizable with the same.

However, fibers obtained by spinning AN-based polymers tend to yellow when exposed to heat during the melting process, fiber drying process, etc., and the best way to prevent such yellowing is to The goal is to reduce the history as much as possible, but this method naturally has its limits. In particular, acrylic fibers obtained by dry spinning are brought into contact with high-temperature gas during spinning to promote desolvation and impart color stability to copolymerized components (for example, in JP-A No. 49
18938) or a method of adding a stabilizer to the spinning dope (for example, JP-A-55-14166).
A method using hydroxyurea and a sulfur compound as shown in the above publication has been proposed. In addition, in the method of adding an appropriate whiteness improver to the spinning dope to obtain a product with high commercial value, the whiteness improver used may not have good affinity or compatibility with the AN polymer. It is necessary that the material has a certain level of solubility in dimethylformamide, dimethylacetamide, etc., which are spinning solvents. That is, if the solubility is too low, it may precipitate in the spinning dope and be removed from the system by filtration or the like, making it impossible to obtain the desired whiteness. Conventionally, various whiteness improvers have been used to improve the whiteness of acrylic fibers, but none of them meet the above conditions or do not provide a sufficient whiteness improvement effect. ,
There was nothing that would satisfy me in practical terms.

<Problems to be Solved by the Invention> As a result of intensive studies aimed at improving the whiteness of acrylic fibers in dry spinning, the present inventors found that a specific triazole coumarin derivative is a whiteness improver for acrylic fibers. The present invention was achieved by discovering that this method is effective as a method.

Means for Solving Problems〉 The present invention involves the use of dimethylformamide or dimethylacetamide as a solvent to polymerize an AN-based polymer consisting of 85% by weight or more of AN and a triazole coumarin derivative represented by the following structural formula (1). A method for producing AN-based fibers with improved whiteness, characterized by dry spinning a spinning dope containing 0.01 to 0.0% of IN.

The AN-based polymer used in the present invention is composed of 85% by weight or more of AN, and may contain 15% by weight or more of two or more types of vinyl monomers copolymerizable with AN. Vinyl monomers copolymerizable with AN include (meth) acrylate, methyl methacrylate, etc.
These include acrylic esters, vinyl acetate, styrene, acrylamide, acrylic acid and its salts, methallylsulfonic acid and its salts, etc., which are generally used as copolymerization monomers for acrylic fibers. It is not limited.

The whiteness improver used in dry spinning has a solubility in dimethylformalamide or dimethylacetamide of 2.
5C is desirably 0.01% by weight or more, but the whiteness improver triazole coumarin derivative used in the present invention has a solubility of 0.12% in dimethylacetamide and dimethylacetamide at room temperature. ! Amount% and 0,
+5% by weight satisfies the above conditions.

The amount of the triazole coumarin derivative represented by the structural formula (]) used in the present invention is 0.01 based on the AN polymer.
~ DJ weight %. If the amount added is less than 0.0+i% by weight, a sufficient whiteness improvement effect cannot be obtained, and if it exceeds 0.1% by weight, the whiteness will be saturated, which is not only disadvantageous in terms of cost, but also The increase in dropout during the process causes many problems in manufacturing.

The present invention is preferably carried out as follows: a triazole coumarin derivative of the structural formula (υ) is dissolved in dimethylformamide or dimethylacetamide;
A solution of this and an AN-based polymer dissolved in dimethylformamide or dimethylacetamide was mixed to a polymer concentration of 25 to 3.
The mixture is mixed to give a spinning stock solution of 5% by weight.

Dry spinning for forming fibers is performed by a known method.

That is, a spinning stock solution of 100 to 150 C is extruded through a nozzle into air or inert gas heated to 160 to 280 C to form an undrawn yarn. This undrawn yarn is subjected to ordinary stretching, water washing, drying, and relaxation treatment. . The fibers obtained in this manner not only have significantly improved whiteness compared to fibers not containing the triazole coumarin derivative represented by structural formula (1), but also Compared to fibers containing known coumarin derivatives, the whiteness is much improved and the product has high commercial value.

<Examples> Hereinafter, the present invention will be specifically explained with reference to Examples, and all % in the text represents weight %. Further, the whiteness in each example was determined based on the Lb value. The equipment used was the Tokyo Chishoku TO-5D model, which measured the L value and b value, and calculated the Lb coordinate and the L value.
The b value was calculated.

The closer Li is to +00, the whiter it is; the closer to 0, blacker a;+
1lll indicates the degree of green on the red-side; yellow on the + side;
Assuming an Lb coordinate with L on the vertical axis indicating the degree of blue color on the − side and +b on the horizontal axis, measurement is performed using a colorimeter, or the value of b is calculated using an equation.

Therefore, the smaller the Lb value, the better the whiteness.

The structure of the whiteness improver used in the examples is shown below.

Triazole coumarin derivative used in the present invention.

A conventionally used coumarin derivative.

t Example 1 A polymer having a composition consisting of 93.5% AN, 6% methyl acrylate, and 0.5% sodium methallylsulfonate is dissolved in sidimethylformamide to a concentration of 50% by a conventional method. On the other hand, a triazole coumarin derivative represented by structural formula (1) is dissolved in 0.02% dimethylformamide based on the polymer, and this is added to the polymer solution to form a homogeneous solution. This solution was passed through a spinning nozzle with a hole diameter of 0.15 mm and a number of holes of 500 H in hot air of 250 C at a discharge temperature of 160 C to form an undrawn yarn, which was then subjected to stretching, water washing, drying, and relaxation treatment. For comparison, the conditions were exactly the same as above (Comparative Example 1) except that the coumarin derivative shown by the structural formula (2) was used as the base of the triazole coumarin derivative shown by the structural formula fi+, and no whiteness improver was added. Fibers were shaped under the respective conditions (Comparative Example 2).

Table 1 shows the whiteness of the obtained fibers.

Table 1 The products of the present invention exhibit extremely clear whiteness compared to products to which no whiteness improver is added.

Furthermore, coumarin derivatives conventionally used in acrylic fibers have not been able to provide fibers with sufficient whiteness when used in dimethylformamide.

Example 2 The whiteness (Lb
values) are shown in Table 2.

Table 2 The whiteness improves as the amount of the triazole coumarin derivative of the present invention increases, but the improvement in whiteness reaches saturation when the amount added is 0.1%, and when it exceeds 0.1%, it is stretched and washed. During this process, some of the particles fell off, and if it was less than 0.0+X, the improvement in whiteness was insufficient.

<Effect of the invention> Misfire F! According to 8JVc, it is possible to obtain an acrylic fiber with improved whiteness by dry spinning, and its whiteness improving effect is achieved by using a coumarin derivative x, which is known as a whiteness improver.
Even a small amount can have a remarkable effect.

Patent applicant: Mitsubishi Rayon Co., Ltd.

Claims (1)

[Scope of Claims] Using dimethylformamide or dimethylacetamide as a solvent, an acrylonitrile-based polymer consisting of 85.0% by weight or more of acrylonitrile and a triazole coumarin derivative represented by the following structural formula (1) at 0.01% by weight relative to the polymer.
A method for producing acrylic fibers with improved whiteness, characterized by dry spinning a spinning dope containing ~0.1% by weight ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (1)