JPS61138710A - Production of acrylic yarn having improved durability - Google Patents

Abstract

PURPOSE:To eliminate a skin layer and void occurring in a coagulation process, to form a continuous fibril, and to obtain the titled yarn, by dissolving an acrylonitrile polymer in dimethylacetamide, subjecting the prepared dope to wet spinning and drawing the yarn under specific conditions. CONSTITUTION:An acrylonitrile polymer containing at least <=50wt% acrylonitrile is dissolved in dimethylacetamide. The prepared dope is subjected to wet spinning in a coagulating bath consisting of a solvent and a coagulating agent, set in a concentration range unable to form a skin layer, and the yarn which is coagulated at >=5 spinning draft within <=60 seconds retention time of the coagulating bath is pulled up. Then, the yarn is drawn at >=5 times in spinning bath consisting of a solvent and a coagulating agent, set in a concentration range unable to form a skin layer, to give the aimed 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 made of an acrylonitrile polymer or an acrylonitrile copolymer.

<Prior Art> Acrylic fibers are characterized by a wide variety of manufacturing methods. The raw material polymer is not only a single component, but also acrylamide, acrylic acid, sodium acrylate,
It may contain copolymerized components such as styrene, sulfonate, methyl acrylate, vinyl acetate, vinyl chloride, vinyl chloride, etc., and the solvent for dissolving Tellimer may be inorganic, such as Rodan salt solution, zinc chloride solution, nitric acid, etc. There are many types of solvents, such as organic solvents such as trimethylformamide, trimethylacedoamide, and trimethylsulfoxide;
This is because in the wet spinning method, there are many types of coagulants, both aqueous and non-aqueous.

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. Generally, the composition is set as follows. However, when obtaining fibers using a coagulation bath of such composition,
It has a strong coagulating force and has a thickness of 0.1 to several microns on the surface of the fiber. A dense and hard skin layer and an inner layer are formed. Such a skin layer is not only a hindrance to the diffusion of dye during dyeing, but also a cause of deterioration of physical properties such as flexibility of the fiber. In addition, the presence of Ioid often causes defects in physical properties such as devitrification, decreased color development, and lack of flexibility. This skin layer? Gey also loses its appearance through post-treatments such as stretching and heat treatment.

On the other hand, acrylic fibers are dyed with cationic dyes, and take advantage of their excellent durability and bright color development, and are used in interior applications such as curtains and carpets, bedding applications such as blankets, etc. Widely used in the clothing field.

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

In view of the current situation, the inventors of the present invention have made extensive studies and have found that by essentially eliminating the skin layer and voids that occur during the coagulation process and forming continuous fibrils, the inventors have developed a method that improves the durability of the soaked material. We succeeded in obtaining acrylic fibers that have the following properties.

Means for Solving the Problems> That is, the present invention provides an aqueous compound containing at least 50% by weight of an aqueous IJ C2 nido-IJ2)! J
When wet-spinning a base polymer, the dope obtained by dissolving the polymer in dimethylacetamide is spun into a coagulation bath consisting of a solvent and a coagulant whose concentration is set at a concentration range that does not allow skin layer formation. That’s all! I! A durable fiber that is characterized by pulling up the coagulated fiber within a solid bath residence time of 60 seconds, and then stretching it five times or more in a drawing bath consisting of a solvent and a coagulant whose concentration is set to a range that does not allow the formation of a skin layer. The present invention provides an excellent method for producing acrylic fibers.

In the method of the present invention, an acrylonitrile polymer containing at least 50% by weight of acrylonitrile is dissolved in dimethylacetamide.Dissolution may be done at room temperature, but in order to improve solubility, the acrylonitrile polymer is dissolved at a temperature in the range of room temperature to 90°C. May be heated.

If the temperature is too low, the solubility will decrease and it will not be possible to obtain a dope that can be used for spinning. If it is too high, the polymer will be colored and deteriorated. A suitable spinning dope contains 10 to 40% acrylonitrile polymer to obtain the spinnability necessary for spinning.

Next, it is made into fibers by this dope wet spinning method. The dope is spun into a coagulation bath consisting of a coagulant and a solvent that dissolves the acrylonitrile polymer at a concentration range that does not allow the formation of a skin layer. Conventionally, the bath additives used here include concentrated water bath solutions of inorganic salts such as rhodan salt, lyticum bromide, zinc chloride, perchlorinated Saka aluminum, etc.
Concentrated aqueous solutions of inorganic acids such as nitric acid, sulfuric acid, and perchloric acid, organic solvents such as amide compounds such as trimethylformamide and dimethylacetamide, nitrile compounds, sulfone and sulfogide compounds such as dimethyl sulfoxide, thiocyanate compounds, and nitro compounds. Compounds, amino compounds, phosphorus compounds, carfnate compounds, and mixtures thereof are used.

In addition, coagulants include water, methanol, ethanol,
Known examples include pronobase alcohol, butanol, acetone, acetic acid, ethylene glycol, glycerin, carbon tetrachloride, xylene, benzene, chloroform, carbon tetrachloride, and ethyl acetate. The composition of the coagulation bath 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 the dope are usually the same. Also 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 m+++ 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 solid bath temperature is
Set to the temperature used for fiber formation. A necessary number of coagulation baths are prepared with varying concentrations so that the weight fraction of the solvent in the coagulation bath is 1 inch apart. 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 direct contact with the slide glass) was examined using a scanning electron microscope, such as a scanning electron microscope manufactured by JEOL Ltd., at an accelerating voltage of 5 to 15%.
Observe at kV and 10,000x magnification. For observation, the surface is coated with Au with a thickness of 50 to 500×. According to this observation, when a skin layer is formed, the surface of the film-like material is smooth at a magnification of 10,000 times, and only some undulations and deposits are observed. If it falls into the gap / non-layerable debt range, 0.05 will appear on the surface.
Pores of micrometers to several tens of micrometers and particulate matter of about 0.05 to 0.5 micrometers are observed. By this method,
The lower limit concentration of the concentration range in which skin layer formation is impossible can be determined. The upper concentration limit can be determined as the uncoagulable concentration of the dope.

The coagulation bath used in the method of the present invention most preferably uses dimethylacetamide as a solvent and water as a coagulant. The weight fraction of dimethyl acedoate in the coagulation bath is set within a concentration range that does not allow the formation of a free layer,
Usually 70 to 90% by weight is used, preferably 75 to 89% by weight.
A concentration range of % by weight is used. #The temperature of the bath is usually set in the temperature range of -5°C to 80°C, preferably 20 to 80°C.
A temperature range of 60°C is used.

In the method of the present invention, the dope is spun into the aforementioned 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 1000. Here, the spinning draft is expressed by the following formula.

If the spinning ratio is less than 5, the fibers will sag or break in the coagulation bath, and the fibers will wind around the rotating parts, reducing operability, and the resulting fibers will become cloudy and transparent. Lose the feeling.

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 fluidity of the fibers composed of coagulated glue will be lacking, and the arrangement of microfibrils and fibrils, which will be described later, will be insufficient, making it impossible to obtain excellent durability.

Suitable coagulation bath residence times should be set by the coagulation bath concentration, dope concentration, and the resulting fiber properties, but typically less than 60 seconds, preferably residence times of 0.5 to 30 seconds are used. Ru.

Next, the fibers made of fluidized glue pulled up from the coagulation bath are stretched five times or more 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. .

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 prolonged, which is a characteristic of the acrylic fibers obtained by the method of the present invention. It becomes impossible to obtain a certain level of excellent 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 solvent and coagulant for the acrylonitrile polymer described above, 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 10 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 to perform multi-stage stretching.

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 to remove solvent to less than 0.14%. The washing method may be any of the commonly used methods such as immersion AC washing, net washing, and Pytro 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 water contained in the raw 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 characteristic 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 is observed using a commercially available scanning electron microscope, for example, JS
Accelerated voltage 5k by M-35CF scanning electron microscope
When observed at a magnification of 3,000 times, fibrillar structures having a width of 0.1 to 10 μm and a length of 50 or more were observed, arranged parallel to the fiber axis direction.

When further observed at 10,000x magnification, the width was 0.0
The presence of microfibrillar structures with a size of 5 to 0.3 μm and a length of 0.5 to 10 μm was confirmed. It has become clear that the fibrillar structure is composed of aggregation of these microfibrillar structures.

In conventional acrylic fibers, even if similar observations were made, the existence of such fibrillar structures or microfibrillar structures could not be confirmed, and the presence of wrinkles due to volume shrinkage thought to have been formed during the manufacturing process, or Only 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 the interior field such as carpets and curtains, the bedding field such as blankets, and the clothing field such as knitwear. Effective for expansion. When used for carpets, it has excellent durability and compression recovery rate, which is 1.5 to 2 times that of conventional products.

The durability of the fiber of the present invention is JIf9. The product of strength and elongation at break (L S (g/a)
A ζ table is created by x LE (>).

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 A copolymer consisting of acrylonitrile 9i, 5% methyl acrylate, 8% methyl sulfonic acid, and SS was dissolved in commercially available 1001 dimethylacetamide at 50°C to make a 20% spinning dope. was prepared.

Next, this stock solution was heated at 25°C with a pore diameter of 0.2 m and a pore number of 100.
The sample was extruded into the coagulation bath using a nozzle at a linear discharge speed of 1 @/min, and taken out from the coagulation bath at a winding speed of 12 @/min. At this time, the residence time of the coagulated fibers in the coagulation bath was 9 seconds. Further, the coagulation bath was composed of a 75% by weight dimethylacetamide aqueous solution, and the temperature was 25°C. Subsequently, the film was stretched 8 times in a stretching bath containing a 78% by weight dimethylacetamide aqueous solution and having 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 hooked strength and elongation product (LSXLK) of this fiber was 240.

Observation of the obtained fibers with a scanning electron microscope revealed that the fibers had a width of 0.1 to 0.2 im and a length of 0.5 to 3 μm directly on the surface.
It was observed that the microfibrillar structures of the tow were arranged in the fiber axis direction. Further, these microfibrillar structures were aggregated to form a fibrillar structure with a length of 50 .mu.m to 450 .mu.m in the fiber axis direction.

Example 2 A copolymer consisting of 91.5fi acrylonitrile, 8th methyl acrylate, and sodium methallylsulfonate O,SS was dissolved in commercially available 1001 dimethylacetamide at 50°C, and a 20% by weight spinning stock solution was added. Prepared.

Next, this stock solution was extruded into the same bath at a linear discharge speed of IVmin using a nozzle with a hole diameter of 0.4 and a number of holes of 50, and was taken up at a winding speed of 10Vmln for 1. It was taken out from the solid bath. At this time, the residence time of the coagulated fibers in the coagulation bath was 6 seconds. The coagulation bath was composed of an 80% by weight dimethylacetamide aqueous solution, and the temperature was 25°C. Continuing, 8
The film was stretched 10 times in a stretching bath containing a 0% by weight dimethylacetamide aqueous solution and having a bath temperature of 80°C. The fibers that have been stretched are thoroughly dried in hot air at 130°C after being washed with water.
Thermal relaxation treatment was performed in steam at ℃. The hook strength and elongation product (Li9XIJ) of this fiber was 263.

Comparative Example 1 Acrylonitrile 91.51, methyl acrylate 8%,
A copolymer consisting of methallylsul≠sodium phosphate 0.51 was dissolved in commercially available 1001 dimethylacetamide at 50°C to prepare a 201-Jt% spinning stock solution.

Next, using a nozzle with a hole diameter of 0.2 mm and 100 holes, this undiluted solution was extruded into a coagulation bath at a discharge linear velocity of IM%ADin, and an attempt was made to take it out at a winding speed of 10 Vmln, but the fibers were cut. Nakatsumaru occurs frequently and cannot be taken out. The winding speed was lowered by 2 to 10 mmK and the sample was taken out. The coagulation bath residence time at this time was 80 seconds. In addition, the coagulation bath is composed of a 55% by weight dimethylacetamide aqueous solution,
The temperature was 30°C. After washing the removed fibers with water,
It was stretched 10 times in hot water at ℃. The fibers that had been stretched were sufficiently dried in hot air at 130°C and subjected to thermal relaxation treatment in steam at 120°C. This fiber's hook strength and elongation product (L
fJXLE) was 10'Jl'6.

Comparative Example 2 91.5% acrylonitrile, 8% methyl acrylate,
A copolymer consisting of 0.5% sodium methallylsulfate was dissolved in commercially available 100% dimethylacetamide at 50°C to prepare a spinning stock solution with a concentration of 20%.

Then, this stock solution was extruded into a coagulation bath at a discharge linear velocity of IVmln using a nozzle with a hole diameter of 0.4mm and a number of holes of 50, and taken out from the coagulation bath at a winding speed of 10Vmln. At this time, the residence time of the coagulated fibers in the coagulation bath was 11 seconds. The coagulation bath is composed of an aqueous solution, and the temperature is 25
It was ℃. Subsequently, after washing the fibers thoroughly with water, 75
After the stretching was completed, the nine fibers were thoroughly dried in hot air at 130°C, after washing with water, the nine fibers were stretched 10 times in a drawing bath with a bath temperature of 80°C.
Thermal relaxation treatment was performed in steam. The obtained fiber was cloudy and could not be used as a product. The hook of this fiber was determined by measuring the strength and elongation product (LSXIJ) and found that it was 9
It was 4.

Comparative Example 3 In Ratio Softening Example 1, the NA fibers taken out from the coagulation bath were stretched 10 times in a stretching bath containing a 75% by weight dimethylacetamide aqueous solution at a bath temperature of 80°C, without washing with water. After washing the fibers with water, they were thoroughly dried in hot air at 130°C and subjected to heat relaxation treatment in steam at 120°C. The strength and elongation product (t, gxt, I) of this fiber is 106 and h
It was.

Claims (1)

[Claims] 1. When wet-spinning an acrylonitrile-based polymer containing at least 50% by weight of acrylonitrile, the dope obtained by dissolving the polymer in dimethylacetamide is mixed with a solvent and a coagulant set in a concentration range that does not allow the formation of a skin layer. The fibers are spun into a coagulation bath consisting of a spinning draft of 5 or more and the coagulation bath residence time is 60 seconds or less, and the fibers are pulled up, and then the fibers are spun into a drawing bath consisting of a solvent and a coagulant whose concentration is set at a concentration range that does not allow skin layer formation. A method for producing acrylic fiber with excellent durability, which is characterized by stretching more than twice as much.