JPS61138711A - Production of acrylic yarn having improved durability - Google Patents

Abstract

PURPOSE:To obtain the titled yarn useful as crapets, curatins, blankets, etc., by dissolving an acrylonitrile polymer in an aqueous solution of a rhodanide to form a dope, spinning and drawing it by the use of a specific coagulating bath and drawing bath. CONSTITUTION:An acrylonitrile polymer containing >=50wt% acrylonitrile is dissolved in 40-60wt% aqueous solution of a rhodanide to give a dope. Then, the dope is spun into a coagulating bath consisting of a solvent such as a rhodanide, dimethylformamide, etc. and a coagulating agent such as water, methanol, etc., set in a concentration range unable to form a skin layer, coagulated at >=5 spinning draft within <=60 seconds retention time of the coagulating bath, and the yarn is pulled up. Then, the yarn is drawn at >=5 times by a drawing bath consisting of a solvent and coagulating agent, set in a concentration range unable to form a skin layer, to give the aimed acrylic yarn.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for producing acrylic fibers having excellent durability and comprising an acrylonitrile summer polymer or an acrylonitrile copolymer.

<Conventional technology> Acrylic 4 fibers! The value is that the manufacturing methods are extremely diverse. The raw material polymer is not only a single component, but also acrylamide, acrylic acid, sodium acrylate,
Contains copolymerized components such as styrene, sulfonate, methyl acrylate, vinyl acetate, vinyl chloride, pyridine chloride, etc., and the solvent for dissolving the polymer is rhodan salt aqueous solution, zinc chloride bath solution, nitrate, etc. In addition, in the wet spinning method, there are many types of coagulants, both aqueous and non-aqueous. This is to do so.

In the normal wet spinning method, for industrial reasons, such as spinnability and productivity, the coagulation bath is heated so that the conditions are such that the spinning dope quickly coagulates into fibers. It is common for the composition to be set as follows. However, when fibers are obtained using a coagulation bath with such a composition, the coagulation force is strong, and a dense and hard skin layer with a thickness of about 0.1 to several μm is formed on the surface of the fiber, and an internal Iid is formed on the surface of the fiber. It is formed. It is thought that such a skin layer not only hinders the diffusion of dye during dyeing, but also causes a decrease in physical properties such as flexibility of the fiber. Nine, the existence of male ids also causes devitrification,
This often results in disadvantages in physical properties such as decreased color development and lack of flexibility. The appearance of this skin layer and voids also disappears by post-processing such as stretching and heat treatment.

On the other hand, acrylic fibers are dyed with cationic dyes and have excellent durability and vivid coloring properties, and are used in the interior fields such as curtains, cars, bedding fields such as blankets, and clothing fields such as knits and chassis. Widely used in the field.

<Problems to be Solved by the Invention> With the recent diversification of consumer needs, highly durable acrylic fibers have come to be required.

The inventors of the present inventors have been respectful of the current situation, and as a result of intensive study, they have essentially eliminated the skin layer fI which occurs during the coagulation process and formed continuous fibrils, thereby improving the ability of the skin. We succeeded in obtaining durable acrylic fibers.

Means for Solving the Problems> That is, the present invention provides a method for wet spinning an acrylonitrile polymer containing at least 50% acrylonitrile by weight, by dissolving the polymer in an aqueous solution of Rodan salt. , the fibers are spun into a coagulation bath consisting of a solvent and a coagulant set in a range in which skin layer formation is impossible, and the coagulated fibers are pulled up at a spinning draft of 5 or more and within 60 seconds of residence time in the coagulation bath, and then skin layer formation is impossible. The present invention provides a method for producing nine-acrylic fibers with excellent durability, which is characterized by stretching 5 times or more in a stretching bath consisting of a solvent and a coagulant whose concentrations are set within a range.

In the method of the present invention, an acrylonitrile polymer containing at least 50% by weight of acrylonitrile is dissolved in 40 to 60 g of a rhodan salt bath solution. Although the dissolution may be carried out at room temperature, a temperature range of -5°C to 10°C is usually used. A suitable spinning dope contains 10 to 40% by weight of acrylonitrile polymer to obtain the necessary spinnability for spinning.

Next, this dope is made into fibers by a wet spinning method. Dawg does not form a sun layer! The acrylonitrile polymer is spun into a coagulation bath set in the d degree range and taken from a coagulant and a solvent that dissolves the acrylonitrile polymer. The solvents used here have conventionally been inorganic solvents such as concentrated water bath solutions of inorganic salts such as rhodan salt, lithium bromide, subcomplex chloride, and aluminum perchlorate;
Concentrated aqueous solutions of inorganic acids such as nitric acid, sulfuric acid, and perchloric acid, organic solvents such as amide compounds such as dimethylformamide and dimethylacetamide, nitrile compounds, sulfone and sulfoxide compounds such as dimethyl sulfoxide, thiocyanate compounds, and nitro compounds. , amino compounds, phosphorus compounds, carnate compounds, and mixtures thereof.

In addition, coagulants include water, methanol, ethanol,
Known examples include proAl-nol, butanol, acetone, acetic acid, ethylene glycol, glycerin, carbon tetrachloride, xylene, benzene, chloroform, carbon tetrachloride, and ethyl acetate. The composition of coagulation baths used industrially is generally a combination of the above-mentioned solvent and water, and from the viewpoint of productivity such as recovery, the solvent in the coagulation bath and the solvent in Dogue are usually the same. used.

Conventionally, the concentration of the solvent in these coagulation baths is usually in a concentration range such that a skin layer is formed. This means that when considering industrial productivity,
This is because conditions are selected that provide excellent spinning stability and operability. In addition, within the concentration range in which the skin layer cannot be formed, the coagulated fibers meander in the coagulation bath, resulting in the resulting fibers becoming cloudy, losing their transparency, and requiring a long time for coagulation.

Here, the concentration range in which the skin layer cannot be formed can be determined by a scanning electron microscope. The dope used for fiber formation is applied to a thickness of several μ to 1 μm on a slide glass, and the slide glass is immersed in a coagulation bath prepared from a solvent and a coagulant used for fiber formation. The temperature of the coagulation bath is set to the temperature used for fiber formation. A necessary number of coagulation baths are prepared in which the concentration is varied so that the weight fraction of the solvent in the coagulation bath is at intervals of 1%. After completion of coagulation, the product is washed with water, methanol, and air-dried to obtain a film-like product.

The surface of this film-like material (the surface not in contact with the slide glass surface) was examined using a scanning electron microscope, for example, JEOL Ltd.
Observation is performed using a scanning electron microscope manufactured by Amadeus Co., Ltd. at an acceleration voltage of 5 to 15 kV and a magnification of 10,000 times. When observing, 50-5
Coat the surface with 00X thick Au. Based on this observation, if a skin layer is formed, 100
At 00x magnification, the surface of the film-like object is smooth;
Only some undulations and deposits are observed. When the concentration falls within the range where skin layer formation is impossible, the surface becomes 0.05 μm to several 1 μm.
At the zero end, particulate matter of about 0.05 to 0.5 μtIL is observed. By this method, it is possible to determine the lower limit concentration of the range in which it is impossible to form a skin layer.

The lower limit concentration is do! The inability to coagulate can be determined as #&degree.

The coagulation bath used in the method of the present invention most preferably uses an aqueous Rodan salt solution as a solvent and water as a coagulant. The weight fraction of the Rodan salt aqueous solution in the coagulation bath is set within the concentration range that does not allow skin layer formation, and is usually 25 to 40%.
Weight percentages are used, preferably a concentration range of 25 to 35 weight percent. The temperature of the coagulation bath is usually -5℃ to 80℃
The temperature range is preferably set at a temperature range of -5°C to 30°C.

In the method of the present invention, the dope is spun into the above-mentioned coagulation bath and then pulled up at a speed such that the spinning draft is 5 or more. Usually, the spinning draft is set between 5 and 100. The spinning draft at O is expressed by the following formula.

Spinning draft = (pulling roller speed) / (spinning talker specific wire speed at nozzle hole υ) If the spinning draft is less than 5, the fibers may sag or break in the coagulation bath, and the fibers may wrap around the rotating part. The resulting fibers become cloudy and lose their transparency.

Furthermore, in the method of the present invention, the residence time of the dope spun into the coagulation bath in the coagulation bath is also an important factor.

If the residence time is too short, coagulation will be incomplete and fiber breakage or adhesion will occur. If the length is too long, the fibers composed of coagulated glue will lack fluidity, and the arrangement of microfibrils and fibrils described below will be insufficient, making it impossible to obtain excellent durability.

A suitable coagulation bath residence time should be set depending on the coagulation bath concentration, dope concentration, and denier of the resulting fibers, but usually a residence time of 60 seconds or less, preferably 0.5 to 30 seconds is used. .

Next, the fibers made of fluid glue pulled up from the coagulation bath are stretched by at least 5 times in a drawing bath consisting of a solvent and a coagulant whose concentration is set to a concentration range that does not allow the formation of a skin layer, without going through a water washing process. be done.

In conventional wet spinning of acrylic fibers, the fibers are pulled up from the coagulation bath, subjected to a water washing process, and then drawn. However, in the method of the present invention, in order to impart excellent durability to the obtained fibers, it is essential that the fibers be drawn in a fluid state without passing through a water washing step. After passing through the water washing process, the fluidity of the fibers with a glue structure is lacking, similar to or even more so than when the residence time in the coagulation bath is too long, which is the characteristic of the acrylic fibers obtained by the method of the present invention. It becomes impossible to obtain the desired durability. Fibers with suitable durability are drawn in the range of 7 to 30 times.

The combination of the solvent and coagulation bath used in the drawing bath is not particularly limited as long as it is a combination of the above-mentioned acrylonitrile polymer solvent and coagulant, but it is suitable for industrial productivity and glue fluidity. When considering stability, it is preferable to select a combination of the solvent used for the dope and water. Further, the temperature of the stretching bath is in the range of 5 to 85°C. If the temperature is too low, the drawability will be reduced, and if the temperature is too high, fiber adhesion and deterioration will easily occur. Furthermore, in order to perform stretching efficiently, two or more stretching baths may be installed or multistage stretching may be performed.

The higher the stretching ratio in the stretching bath, the more durable and excellent acrylic fibers can be obtained.

Fibers produced within the scope of the present invention are subjected to conventional water washing treatments to remove solvent to less than 0.1%. The washing method may be any of the commonly used methods such as immersion AC washing, net washing, and vibro washing. The fibers from which the solvent has been removed may be redrawn in hot water or steam to impart more suitable physical properties.

Next, drying is performed to remove moisture contained in the fibers.

Drying may be performed using a commonly used drum dryer, cylinder dryer, net dryer, or other known device.

The fibers from which water has been removed are then subjected to a heat relaxation treatment.

Thermal relaxation can be carried out in a heated atmosphere such as in pressurized steam, hot air, hot water, or between hot plates.

Such water washing, re-stretching, drying and heat treatment do not reduce the excellent durability properties of the fibers obtained by the method of the present invention.

The surface structure of the fibers obtained by the method of the present invention was observed using a commercially available scanning electron microscope, such as JSM-35 manufactured by JEOL Ltd.
When observed using a CF scanning electron microscope at an accelerating voltage of 5 kV and a magnification of 3000 times, fibrillar structures with a width of 0.1 to 10 μm and a length of 50 μm or more were observed, arranged in parallel to the fiber axis direction.

When further observed at 10,000x magnification, the width was 0.0
The presence of microfibrillar structures of 5 to 0.3 μm and 0.5 to 10 μm in length was confirmed. Fibrillar structures are formed by the aggregation of these microfibrillar structures)
In conventional acrylic fibers, the presence of such fibrillar structures and microfibrillar structures could not be confirmed even when similar observations were made, and they were formed during the manufacturing process. Only wrinkles due to volume contraction or streaks caused by evaporation of the solvent are observed. The fibers obtained by the method of the present invention exhibit excellent durability due to the presence of fibrillar structures formed by aggregation of microfibrillar structures. Furthermore, the presence of microfibrillar structures was found to be effective in developing deep color development, as a result of dyeing fibers with cationic dyes and performing visual judgment.

<Effects of the Invention> As described above, the fibers obtained by the method of the present invention have excellent durability and can be used in interior fields such as carpets and curtains, bedding fields such as blankets, and clothing fields such as knits and jerseys. Effective for expansion. When used for carpets, it has excellent durability and good compression recovery rate, which is 1.5 to 2 times that of conventional products.

The durability of the fibers of the present invention can be determined by measuring the hook strength and elongation according to the fiber tensile test method shown in JIS L1069.
It can be expressed as E (%).

The fiber of the present invention has a hook strength and elongation product that is 1.5 to 3 times that of conventional products.

<Example> Hereinafter, the method of the present invention will be explained in more detail with reference to Examples.

Example 1 91.5% acrylonitrile, 8% methyl acrylate,
A copolymer consisting of 0.5% methallylsulfonate was dissolved in a 50% by weight aqueous sodium thiocyanate solution at 50°C to prepare a 12% by weight spinning stock solution.

Next, this stock solution was heated at 5°C with a pore diameter of 0.2 mm and a pore number of 1.
It was extruded into the coagulation bath using a No. 00 nozzle at a discharge linear velocity of 1 m/mln, and taken out from the coagulation bath at a winding speed of 1 Om/m S n. At this time, the residence time of the coagulated fibers in the coagulation bath was 22 seconds. The coagulation bath was composed of an aqueous solution of sodium thiothiocyanate, and the temperature was 10°C. Subsequently, the film was stretched 8 times in a stretching bath containing 34 sodium thiocyanate aqueous solution at a bath temperature of 75°C. The stretched fibers were washed with water, thoroughly dried in hot air at 130°C, and then subjected to a heat relaxation treatment in steam at 120°C. The hook strength elongation product (LSXLE) of this fiber was 251.

As a result of observing the obtained fibers with a scanning electron microscope, it was found that the surface of the fibers had a width of 0.1" 0.2 μm and a length of O15-3.
It was observed that microfibrillar structures of μm size were arranged in the fiber axis direction. In addition, the microfibril-like structures were aggregated to form a fibril-like structure having a width of 0.5 to 5 μm and a length of 50 μm to 400 μm in the fiber axis direction.

Example 2 91.5% acrylonitrile, 8% methyl acrylate,
A copolymer containing 0.5% of methallylsulfonic acid was dissolved in a 50% by weight aqueous solution of sodium thiocyanate at 50° C. to prepare a 12% by weight spinning stock solution.

Next, this stock solution was extruded into a coagulation bath using a nozzle with a hole diameter of 0.4 nun and a number of holes of 50 at a discharge linear velocity of l rrl/rni n, and was removed from the coagulation bath at a winding speed of 10 m/in l n. I took it out. At this time, the residence time of the coagulated fibers in the coagulation bath was 11 seconds. In addition, the coagulation bath is 32
It was composed of a wt % sodium thiocyanate aqueous solution, and the temperature was 25°C. Subsequently, the film was stretched 10 times in a stretching bath containing a 35% by weight aqueous sodium thiocyanate solution at a bath temperature of 80°C. After the stretched fibers were washed with water, they were thoroughly dried in hot air at 130°C and subjected to a thermal relaxation treatment in steam at 120°C. The hook strength elongation product (LSXLE) of this fiber was 281.

Comparative Example 1 91.5% acrylonitrile, 8% methyl acrylate,
A copolymer consisting of 0.5% methallylsulfonate was dissolved in a 50% by weight aqueous sodium thiocyanate solution at 50° C. to prepare a 10 weight i:h spinning stock solution.

Next, using a nozzle with a hole diameter of 0.2 mm and a number of holes of 100, this stock solution was extruded into a coagulation bath at a discharge linear velocity of l rrv/ml n, and an attempt was made to take it out at a winding speed of 10 rv/min. The fibers were frequently cut and could not be taken out. The winding speed was set to 21V″min (
I dropped it and took it out. The coagulation bath residence time at this time was 80 seconds. The coagulation bath was composed of a 20 liter aqueous solution of sodium thithiocyanate, and the temperature was 5°C. The taken out fibers were washed with water and then stretched 10 times in hot water at 90°C. The stretched fibers were sufficiently dried in hot air at 130° C. and subjected to thermal relaxation treatment in steam at 120″C.

Comparative Example 2 A copolymer consisting of 91.5% of acrylonitrile, 8% of methyl acrylate, and 0.5% of methyl sulfonate was dissolved in a 50% by weight aqueous sodium thiocyanate solution at 500°C, and spun at 12% by weight. A stock solution was prepared.

Next, this stock solution was extruded into a coagulation bath using a nozzle with a hole diameter of 0.4 mm and a number of holes of 50 at a discharge linear velocity of 1 m/rn, and was coagulated at a winding speed of 10 m/ml. I took it out of the bath. At this time, the residence time of the coagulated fibers in the coagulation bath was 11 seconds. In addition, the coagulation bath is 35% by weight.
It was composed of an aqueous solution of sodium thiocyanate, and the temperature was kept at 5°C. Subsequently, after washing the fibers thoroughly with water, 35% by weight
The film was stretched 10 times in a stretching bath containing an aqueous solution of sodium thiocyanate and having a bath temperature of 80°C.

The stretched fibers were washed with water, thoroughly dried in hot air at 130°C, and then subjected to a thermal relaxation treatment in steam at 120°C.

The obtained fiber was cloudy and could not be used as a product. The strength and elongation product (LSXLE) of this fiber was measured and was found to be 106.

Comparative Example 3 In Comparative Example 1, the fibers taken out from the coagulation bath were stretched 10 times in a stretching bath containing a 35% by weight aqueous sodium thiocyanate solution at a bath temperature of 80°C, without washing with water.

The results were washed with water and thoroughly dried in hot air at 130°C.
Thermal relaxation treatment was performed in steam at 0°C. This fiber had a hook strength elongation product (LSXLE) of 118.

Claims (1)

[Claims] When wet-spinning an acrylonitrile-based polymer containing at least 50% by weight of acrylonitrile, the dope obtained by dissolving the polymer in an aqueous Rodan salt solution is made of a solvent and a coagulant whose concentration is set to a range that does not allow the formation of a skin layer. The fibers are spun into a coagulation bath and coagulated at a spinning draft of 5 or higher and within 60 seconds of residence time in the coagulation bath. A method for producing highly durable acrylic fiber, which involves stretching.