JPS61245303A - Acrylic yarn and production thereof - Google Patents

Abstract

PURPOSE:To obtain acrylic yarn having high strength and high modulus of elasticity and improved high-temperature wet heat characteristics, by subjecting a solution of acrylic polymer to spinning. drawing, washing with water, drawing further in boiling water, etc., and followed by drying, drawing and heat treatment under specific conditions, respectively. CONSTITUTION:A solution of an acrylic polymer consisting of 90-100wt% acrylonitrile and 0-10wt% vinyl monomer [e.g., (meth)acrylic acid methyl, etc.] is used as a spinning stock solution and it is subjected to wet spinning, dry and wet spinning or dry spinning. Then, the yarn is drawn, washed with water, drawn in boiling water or in steam and dried until the drawn yarn has 5-60wt% water content. The yarn is then drawn at 1:1-1:3.0 draw ratio at 120-200 deg.C, further heat-treated at 180-300 deg.C under tension to give the aimed yarn having >=6g/d strength, >=80g/d initial modulus of elasticity and >=60% strength retention ratio and >=60% retention ratio of modulus of elasticity after wet treatment in an alkali aqueous solution at 9-13pH at 180 deg.C for 8hr.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an acrylic fiber having high strength, high modulus of elasticity, and excellent high-temperature, wet-heat characteristics, and a method for producing the same.

More specifically, the present invention has a strength of 697 d or more, an initial elastic modulus of 80 g'/d or more, and a PM (9 to 1
The present invention relates to an acrylic fiber whose strength and initial elastic modulus retention rate after wet treatment at 180° C. for 8 hours in an alkaline aqueous solution of No. 3 is 60 degrees or more, and a technology for manufacturing such fiber industrially and at low cost.

[Conventional technology]

Conventionally, acrylic fibers have been used mainly in the fields of clothing, interior decoration, bedding, and miscellaneous goods due to their characteristics such as soft texture, bulkiness, and vivid color development. However, as a disadvantage of acrylic fibers, other synthetic fibers (polyester, nylon, polypropylene, vinylon, etc.)
Because it does not have physical properties such as high modulus of elasticity and high strength as seen in There was. Furthermore, the fiber performance required in the field of industrial material applications, such as industrial filter cloth, is not only strength and elastic modulus, but also chemical resistance and heat resistance (dry heat, wet heat). The use of the above-mentioned synthetic fibers is extremely limited, and it is necessary to use very expensive materials such as aramid fibers and Kagen fibers in this field. Also,
In the field of civil engineering and construction materials, in recent years, due to the global wave of asbestos regulations, research has begun on cheap synthetic fibers such as acrylic and vinylon as substitute materials for asbestos as cement reinforcement materials.

However, a rational method for improving the stability of cement compacts is often to go through a curing process using high-pressure steam. It becomes necessary to withstand humidity conditions. Under these conditions, the range of use of reinforcing fibers is more limited than in the field of temporary fabrics, and vinylon in particular cannot be used under moist heat treatment conditions of 110° C. or higher.

In addition, various proposals have been made to increase the strength and modulus of acrylic fibers, and the manufacturing method is to perform wet stretching after spinning, dry densification, and then use pressurized steam or dry heat conditions. A method of re-stretching is used. In particular, JP-A-58-120811 discloses wet spinning, stretching, washing,
After drying, the drawn yarn is subjected to secondary stretching in pressurized steam at at least 105° C. without causing shrinkage relaxation (15
It has been disclosed that acrylic fibers for cement reinforcement can be obtained by heat-setting under tension in a heated atmosphere of 0 to 250°C, and subsequently cooling the yarn while keeping it under tension. When the fiber was treated with hot water at 80°C for 30 minutes, its initial elastic modulus rapidly decreased from 14211/d to 909/d, and the retention rate of the initial elastic modulus was 63° C. In this case, the curing temperature of fiber-reinforced cement using such fibers has been limited to a narrow range from room temperature to 90°C or less, because the initial elastic modulus decreases and fibers deteriorate due to alkali at high temperatures. However, in recent years, curing methods for cement compacts have focused mainly on high-temperature steam curing in terms of product stability and process rationality, and concrete reinforcing fibers also have strength even during high-temperature steam curing. , small changes in initial elastic modulus and excellent alkali resistance are now required.

[Problem that the invention seeks to solve]

However, as a result of studies conducted by the present inventors, the strength and initial strength of acrylic fibers after processing under high temperature and high humidity conditions depend on the drawing method used to manufacture the fibers and the subsequent structural fixation method. The modulus of elasticity changes greatly, the fiber performance is unstable, and the alkali resistance changes depending on the valve type of the acrylonitrile copolymer that makes up the fiber, the type and proportion of the gold component, and under high temperature and high humidity conditions. It was discovered that there were many problems such as dissolution, swelling, and deterioration. That is, under high temperature and high humidity conditions, especially for cement reinforcing fibers, the temperature is 180°C in an alkaline aqueous solution (pH 9 to 13).

Developed acrylic fibers that maintain a high level of strength and initial elastic modulus during high-temperature steam curing for about 8 hours, and which can exert a reinforcing effect on cement, and established an industrial manufacturing method for the fibers. Therefore, the present invention aims to solve these problems.

Therefore, the object of the present invention is to improve the strength and initial elastic modulus, which are the weak points of acrylic fibers, and to improve the strength and initial elastic modulus in an alkaline aqueous solution (pH 9 to 13) at 180°C.

Retention rate of strength and initial elastic modulus is 60% even after 8 hours of treatment
The object of the present invention is to provide an acrylic fiber having a high degree of moisture heat resistance and alkali resistance of 1.0% or more, as well as to develop and provide a technology for industrially manufacturing the fiber.

[Means for solving problems]

The present invention consists of the following configuration.

1. An acrylic polymer fiber consisting of 90 to 100% by weight of acrylonitrile and 0 to 10% by weight of a vinyl monomer copolymerizable with acrylonitrile, and has a strength of 6.
g/d or more, the initial elastic modulus is 80 p/d or more,
and 8 at 180°C in an alkaline aqueous solution with a pH of 9 to 13.
Retention rate of strength and initial elastic modulus after humid treatment for 60 hours
An acrylic fiber characterized by having a resistance of more than 100%.

2. An acrylic polymer solution consisting of 90 to 100% by weight of acrylic a2) and 0 to 10% by weight of a vinyl monomer copolymerizable with acrylonitrile is used as a spinning stock solution, and this is used in wet, wet-dry or wet spinning. After dry spinning, stretching,
The drawn yarn is washed with water, further stretched in boiling water or steam, and then dried until the water content of the drawn yarn becomes 5 to 60% by weight.
1.0 to 1:3.0 stretching treatment and further iso℃
A method for producing acrylic fibers, which comprises heat-treating the fibers under tension at a temperature of ~300°C.

The present invention will be explained in detail below.

First, in the acrylic fiber of the present invention, 90 to 100% of the components forming the fiber are acrylonitrile),
10 to 0% by weight of the vinyl monomer copolymerizable with acrylonitrile, such as methyl acrylate, methyl methacrylate, methacrylonitrile, acrylamide, methacrylamide, N-methylacrylamide, N-ethylacrylamide, acrylic acid, Methacrylic acid, itaconic acid, acrylic acid dimethylamide, vinyl acetate, vinyl chloride, vinylidene chloride, allyl alcohol,
It is necessary to be composed of methacrylic alcohol, sodium allylsulfonate, sodium methallylsulfonate, etc.

In other words, the composition of the acrylic polymer constituting the fiber is related to the spinnability, drawability, heat treatability, etc. of the fiber, as well as its high temperature, moist heat, and alkali resistance. If it is outside the above range, even if temporary LK fibers with excellent physical properties are obtained, the fibers will dissolve, swell, or swell under wet treatment at 180°C for 8 hours in an alkaline aqueous solution (pH 9 to 13). The fibers become resinized, the physical properties of the fibers are extremely reduced, or the fibers no longer retain their shape. From this point of view, the copolymerization ratio of the vinyl monomer as a copolymerization component varies depending on the type of copolymerization component, but in @shi that satisfies spinnability, stretchability, heat treatability, etc. during production,
It is better to have as little as possible, and the proportion of the copolymerized component is preferably 10% by weight or less, preferably 5% by weight or less in Asahi.

In addition, the fiber of the present invention has a strength of 6
g/d or more and the initial elastic modulus is 80 g/d or more, and these should be as high as possible, and it may be 7 A/d. It is necessary that the retention rate of the strength and initial elastic modulus of the fiber after this is 60% or more.

That is, in the field of industrial materials, especially when using the fibers as cement reinforcing fibers as an alternative to asbestos, there are cases where the fibers are mixed into cement slurry and cured naturally or with moist heat at 90°C or less; °C~1
High temperature steam curing may be carried out for 8 to 10 hours at 80°C and 2.0 to 10.0°C, but especially during high temperature steam curing, the strength and initial elastic modulus of the fibers may be lower than the initial 60°C. % or more, and only by maintaining this highly maintained strength and initial elastic modulus can a reinforcing effect on cement be exhibited to a degree that has not been previously found. What is the retention rate of strength and initial elastic modulus?
Based on the strength and initial elastic modulus of the fiber before treatment, the following formula was calculated as an index for grasping the state of change in each value after treatment.

In addition, the strength and initial elastic modulus referred to here are lo.

Each value for the elongation of chi was determined from the chart.

The method for producing the acrylic fiber of the present invention, which has high strength, high elastic modulus, and has excellent high-temperature and moist heat properties, uses fibers with high strength and initial elastic modulus that are different from general clothing fibers. Furthermore, since it is necessary to maintain the fiber properties to a high degree even when subjected to high-temperature and humid treatment in an alkaline aqueous solution, it is necessary to use acrylonitrile alone or an acrylic polymer having the above-mentioned specific copolymer composition. Since it needs to be used as a fiber-forming polymer, conventional methods for producing acrylic fibers cannot be applied arbitrarily.

That is, the method for producing the acrylic fiber of the present invention is as follows:
An aqueous polymer in which 90 to 100% by weight of the fiber-forming components is acrylonitrile and 10 to 0% by weight is the vinyl monomer copolymerizable with acrylonitrile is mixed with nitric acid, zinc chloride, rhodan soda, and dimethylformamide. (DMF), dimethyl sulfoxide (D
MSO'), dimethylacetamide (DMAC), and other various solvents, and the resulting spinning stock solution is discharged from a spinneret, introduced into a coagulation bath, solidified, stretched, washed with water, and further coagulated in boiling water or steam. A method is used in which the drawn yarn is stretched 6 to 20 times, preferably 8 to 15 times, based on the bath winding speed, and then dried until the water content of the drawn yarn becomes 5 to 60% by weight. . Although there are no particular restrictions on this drying process, it is preferable that the drying process be performed at a drying temperature of 0.9 to 1.
．． It is best to hold it under tension at a ratio of about 1:1. At this time, the drying device is one that applies heat to the drawn yarn in a non-contact or contact manner, and the moisture content is 5 to 60% by weight.
, preferably 10 to 50% by weight, and there are no particular restrictions on the temperature of the drying device. However, in order to carry out the drying process industrially and stably, it is preferable to carry out the drying process for several seconds at a temperature of about 100 to 130° C. using a hot air circulation type hot drum type drying device, a heated cylinder type drying device, or the like. Next, the surface temperature of the filament having a water content of 5 to 60% by weight obtained in this way is set to 120 to 200°C, preferably 130 to 18°C.
Apply 1:1 to cough threads while heating to 0°C. O~1:3.0
By carrying out the drawing treatment, it is possible to improve the drawability of the fiber filament, and also to cause high orientation and high crystallization.

In other words, when the water content of the filament is greater than 60% by weight, the heat is absorbed by the evaporation of the water present inside the filament, and the surface temperature of the filament increases only to about 98°C. Even if the filament is stretched at this stage, sufficient stretchability cannot be ensured, and the degree of crystallinity and orientation of the fibers is low relative to the stretching ratio, and the physical properties of the fibers are only close to those of conventional acrylic fibers. I can't get it. Furthermore, when the water content is as low as 5% by weight, the stretching stress during stretching is high, and fiber yarns with high crystallinity and orientation can be obtained, as seen in the aforementioned patent publication regarding acrylic fibers. However, the drawability is poor, and the internal strain during drawing remains largely within the fiber yarn, so if the product is subjected to moist heat treatment at 180°C or lower, the internal strain will be exposed, and the retention rate of strength and initial elastic modulus will be 60. % cannot be maintained. That is, looking at the temperature, stretchability, and fiber physical properties (particularly the degree of crystallinity and orientation) with respect to the water content, the water content is 10 to 60% by weight, preferably 20 to 50% by weight.
There is a region where the weight% and stretchability are in the range of 1:1.0 to 1:3.0 and where the degree of crystallinity and degree of orientation show peak values. A fiber that best enhances fiber crystallization and orientation while reducing stress, and has low internal strain during stretching, so it retains its physical properties to a high degree even when subjected to moist heat treatment at an extremely high temperature of 180°C. That's what you get.

However, the stretching ratio is 1:1. If it is smaller than O, only heat shrinkage of the filament will occur, and the strength and initial elastic modulus of the obtained fiber will be low, which is not preferable. Moreover, the stretching ratio is 1:3. If it is larger than O, the stretching stress during stretching will be too large, resulting in stretch breakage or non-uniform stretching conditions, which may cause conditions for stable industrial operation. is undesirable because it cannot be achieved.

Further, the method of heating the surface temperature of the filament having a water content of 5 to 60% by weight to 120 to 200°C, preferably 130 to 180°C is not particularly limited, but cylinder roll type A method using a heating device or a contact hot plate type heating device is an industrially preferable method because it can effectively raise the temperature of the filament body, and it is also easy to draw at the same time. It is. Further, the drawing ratio here varies depending on the drawing ratio of the filament, but it is preferably set in a range where the total drawing ratio of the fiber is 10 to 30 times, preferably 13 to 25 times, and 5 to 60 times. The stretching ratio of the filament having a water content of % by weight is 1:1. O~1:
By setting it within the range of 3.0), the performance of the fiber of the present invention can be fully exhibited.

Furthermore, the above-mentioned fiber thread body is continued to be 180 to 300
The fibers of the present invention can be obtained by heat-treating the fibers at a temperature of .degree. C. while keeping the fibers under tension. That is, as a heat treatment method for the above-mentioned fiber thread, it is necessary to heat-treat the fiber thread in a tension state in the sense of removing internal strain caused by stretching while maintaining a high degree of orientation and crystallinity of the fiber thread. However, the degree of tension is 1:0.
The ratio is preferably 9 to 1:1.0, and there is no particular restriction as long as it is within this range. In addition, the heat treatment temperature is 180 to 300
There is no limit to - as long as the temperature is within the range of °C, but the treatment time is preferably in the range of 5 to 30 seconds under a temperature condition of 180 °C, and in the range of 1 to 10 seconds under a temperature condition of 300 °C. is preferred.

That is, the heat treatment conditions that ultimately determine the strength and initial elastic modulus of the fiber are uniquely determined by the heat treatment temperature and treatment time. A simple method for determining the degree of retention of strength and initial elastic modulus during high-temperature steam treatment of fibers is to measure the shrinkage rate of the fibers in water.The fibers of the present invention are treated in boiling water for at least 24 hours. It is necessary that the subsequent shrinkage rate is 3 ts or less, preferably 1 ts or less. The shrinkage rate in boiling water is one measure of the high-temperature wet characteristics of the fiber, and if the boiling water shrinkage rate is 3 or more, the shrinkage rate in boiling water is 180℃, 8
This was adopted based on the empirical knowledge that if the retention rate of the strength and initial elastic modulus of the fiber is lower than 60% during high-temperature steam treatment, the performance as a reinforcing fiber is unreliable.

As mentioned above, the fibers obtained in this way have high strength and initial elastic modulus different from those of general clothing, and they can be heated at 180°C.
If the retention rate of the strength and initial elastic modulus of the fiber after 8 hours of high temperature humid treatment is 60% or more, it can be used in the industrial material field, especially as fiber for reinforcing cement for high temperature steam and curing. .

〔Example〕

The present invention will be further explained below with reference to Examples.

Below is a blank space Example 1 A 70% by weight nitric acid solution (polymer concentration:
．． 0% by weight) was used as a spinning dope, and introduced into a 35% by weight nitric acid aqueous solution at ~0°C through a spinneret with 20,000 holes and a pore diameter of 0.12mm at a take-up speed of 5 m/min for wet coagulation. Subsequently, the film was stretched twice in a 40% by weight nitric acid aqueous solution at 60°C, and then washed with water to remove nitric acid residue. Subsequently, it was stretched 4 times in a hot water bath, and further stretched 1.5 times under saturated steam pressure at 115°C, so that the stretching ratio from the time of taking up the coagulation bath was 12.
A drawn yarn of twice the size was obtained. The water content of the drawn yarn at this time was 118% by weight. This drawn yarn was dried using a hot air circulation type heated drum dryer so that the moisture content became the value shown in Table 1.
Next, using a cylinder roll type heated stretching device, set the device temperature to 160°C, and set the stretching ratio to 1:1.2 to 1:2.
．． It was set to 5.

Furthermore, the ratio of 1:1 to the obtained fiber yarn was increased. Heat treatment was performed on a cylinder roll at 240° C. for 10 seconds while maintaining the O tension state. Table IK shows the physical properties of the obtained fiber. Furthermore, the fibers shown in Table IK were heated at 180°C for 8 hours in an alkaline aqueous solution (4 Rutland cement p water pH 12,
5), and the physical properties of the obtained fibers were measured, and the results are shown in Table 2.

Comparative Example 1 The drawn yarn obtained in Example 1 was dried and densified until the water content reached Ots, and then stretched at 160° C. in a ratio of 1:1.5 using a cylinder roll heating stretching device. After the same heat treatment as above, high temperature steam treatment was performed and the fibers were measured. Further, the same heat treatment system was treated in boiling water for 24 hours, and the physical properties of the fibers were measured. The results are shown in Table 12 and Table 2.

Comparative Example 2 The water content of the drawn yarn obtained in Example 1 was set to 118% by weight and 80% by weight, and the fibers were otherwise treated in the same manner as in Comparative Example 1. The obtained fiber physical properties are shown in Tables 1 and 2. It was shown to.

Example 2 Acrylonitrile homopolymers and acrylic copolymers whose polymerization compositions were changed as shown in Table 3 were obtained using an aqueous suspension polymerization method using ammonium persulfate and acidic sodium sulfite as polymerization catalysts. Using this polymer, fibers were obtained in the same manner as in Experiment No. 1-2 (Table 1) shown in Example IK, and each of the obtained fibers was subjected to the high temperature steam treatment as in Example 1. The physical properties of the fibers were compared. The results are shown in Table 3.

Example 3 180011, a suspension-precipitation polymer with an intrinsic viscosity of 1.82, consisting of 95% by weight acrylonitrile and 5% by weight methacryloethrile, was suspended in 8200f9 dimethylformamide at -20°C and A homogeneous spinning IIK solution was prepared by dissolving the mixture at °C with stirring. This stock solution was passed through a spinneret with 300 holes and a 0.10-pore diameter into a coagulation bath consisting of 55% dimethylformamide and 45% water and having a temperature of 40°C at a drawing speed of 5 m/min. introduced and wet coagulated, followed by a temperature 90% solution of 60% dimethylformamide and 40% water.
Stretched at 35 m/min in a drawing bath at ℃, and further stretched at 4 m/min in boiling water
It was stretched at 5 m/min. The moisture content of the obtained drawn yarn was 185
The weight was -. This drawn yarn was dried to a moisture content of 15% KPL using the same drying method as shown in Example 11C, and heated and stretched at a ratio of 1:2 in the same manner as in Experiment No. 1-2 (Table 1) of Example 1.
．． 0, and then the same heat treatment was performed. For comparison, the water content was 0.11%, and after drying and densification, the heating and stretching ratio was 1:2. After that, the same heat treatment was performed.

The obtained fibers were subjected to high-temperature steam treatment in an alkaline aqueous solution (Portland Cement F water-12.5) at 180° C. for 8 hours, and the physical properties of the obtained fibers were measured. The results are shown in Table 4.

Below margin

Claims (1)

[Scope of Claims] 1. Acrylic polymer fiber consisting of 90 to 100% by weight of acrylonitrile and 0 to 10% by weight of a vinyl monomer copolymerizable with acrylonitrile and having a strength of 6 g.
/d or more, the initial elastic modulus is 80 g/d or more, and the retention rate of the strength and initial elastic modulus after wet treatment at 180 ° C. for 8 hours in an alkaline aqueous solution of pH 9 to 13 is 60% or more. Characteristic acrylic fiber. 2. An acrylic polymer solution consisting of 90 to 100% by weight of acrylonitrile and 0 to 10% by weight of a vinyl monomer copolymerizable with acrylonitrile is used as a spinning stock solution, and after wet, dry-wet or dry spinning, The drawn yarn is drawn, washed with water, further drawn in boiling water or steam, and then dried until the water content of the drawn yarn becomes 5 to 60% by weight. :1
．． 0 to 1:3.0 stretching treatment and further 180°C to
A method for producing acrylic fibers, which comprises heat-treating the yarn under tension at a temperature of 300°C.