US3558761A - Method for manufacturing acrylonitrile filaments - Google Patents

Abstract

AN IMPROVED METHOD FOR MANUFACTURING ACRYLONITRILE FILAMENTS CONTAINING AT LEAST 85% BY WEIGHT OF ACRYLONITRILE BY SPINNING FILAMENTS, APPLYING SECONDARY STRETCHING UPON THE PRIMARILY STRETCHED FILAMENTS WHILE HEATING, APPLYING PREHEATING UPON THE SECONDARY STRETCHED FILAMENTS AND FINALLY, APPLYING ADDITIONAL HEAT TREATMENT UPON THE FILAMENTS. THE HEATING TEMPERATURE IN ALL HEAT TREATMENTS SHOULD BE CONTROLLED TO A PREDETERMINED RELATION. THE FILAMENTS MANUFACTURED ARE PLROVIDED WITH LESS UNEVENNESS OF THICKNESS, UNIFORM DYEABILITY, EXCELLENT CONFORMITY TO DYEING, AND IMPROVED MECHANICAL PROPERTIES. SO-CALLED DRY-WET SPINNING METHOD IS PARTICULARLY FAVORABLE FOR OBTAINING THE FILAMENTS IN THE PRESENT INVENTION.

D R A W I N G

Description

9 7 YOSHIJIRO TABARA ETAL 3558576! METHCD FOR MANUFACTURING ACRYLONITRILE FILAMENTS Filed March 27. 1968 {Sheets-Sheet} 26, 1971 YOSHIJIRO TABARA ETAL 3,558,761

METHOD FOR MANUFACTURING ACRYLONITRILE FILAMENTS 3 Sheet s-Sheet 3 Filed March 27, 1968 0mm Z IOF m2; OZFQwI zoozo HEATING TEMPERATURE IN C United States Patent Olfic 3,558,761 Patented Jan. 26, 1971 3,558,761 METHOD FOR MANUFACTURING ACRYLONITRILE FILAMENTS Yoshi rro Tabara, Nobuhide Teranishi, Shigern Kikuchi, Kunito Ono, and Shoji Irnao, Otake-shi, Japan, as signers to Mitsubishi Rayon (10., Ltd. and Mitsubishi Vonnel (30., Ltd., both of Tokyo, Japan, both companies of Japan Filed Mar. 27, 1968, Ser. No. 716,382 Int. Cl. Dlllf 7/00 US. Cl. 264-182 6 Claims ABSTRACT OF THE DISCLOSURE An improved method for manufacturing acrylonitrile filaments containing at least 85% by weight of acrylonitrile by spinning filaments, applying secondary stretching upon the primarily stretched filaments while heating, applying preheating upon the secondary stretched filaments and, finally, applying additional heat treatment upon the filaments. The heating temperature in all heat treatments should be controlled to a predetermined relation.

The filaments manufactured are provided with less unevenness of thickness, uniform dyeability, excellent conformity to dyeing, and improved mechanical properties. So-called dry-wet spinning method is particularly favorable for obtaining the filaments in the present invention.

The present invention relates to an improved method for manufacturing acrylonitrile filaments having improved qualities, more particularly relates to an improved method for manufacturing acrylonitrile filaments having less unevenness of thickness, uniform dyeability and excellent dyeability by, spinning filaments by any one of the known spinning methods, primarily stretching the filaments at a stretching ratio of from 2.00 to 7.00 applying secondary stretching upon the primarily stretched filaments while heating, applying preheating treatment upon the secondarily stretched filaments, and finally, applying additional heat treatment upon the preheated filaments.

In the present invention, acrylonitrile polymer containing at least 85% by weight of acrylonitrile is used as the material of the filaments of the present invention.

The principal object of the present invention is to provide a novel method for manufacturing acrylonitrile filaments having less unevenness of thickness together with silk-like luster.

The other object of the present invention is to provide an improved method for manufacturing acrylonitrile filaments provided with uniform and excellent dyeability together with improved mechanical properties such as tenacity, anti-frictional property and resistance against impact loading.

A further object of the present invention is to provide an improved method for manufacturing acrylonitrile filaments which is provided with preferable functional features as a material of textile products with less troubles in textile processing such as filament or yarn breakage.

In order to attain the above-described objects of the invention, the method of the present invention comprises, spinning filaments by any one of the known spinning methods, primarily stretching the filaments applying secondary stretching upon the primarily stretched filaments while heating them at a temperature (T between 170 and 220 C., applying preheating treatment upon the secondarily stretched filaments at a temperature between 80 C. and C. above the heating temperature (T in the secondary stretching and, finally, applying additional heat treatment upon the preheated filaments at a temperature between 230 and 250 C. under such a tension that the filaments are not shrunk more than 35%.

Further features and advantages of the present invention will be apparent from the ensuing descriptions with reference to the accompanying drawings in which;

FIG. 1 is a schematic side view of a dry-wet spinning process favorably used for the purpose of the present invention,

FIG. 2 is a schematic side view of a process for carrying out the additional heating of filaments using a contacttype heating device,

FIG. 3 is a schematic side view of a process for carrying out the additional heating of filaments using an indirect-type heating device,

FIG. 4 is a graphical drawing for showing the relation between heating temperature in the secondary stretching and the maximum shrinkage of the filaments for various preheating temperatures,

FIG. 5 is a graphical drawing for showing the range of the combination of the preheating temperature with the heating temperature in the secondary stretching which is recommended for the purpose of the present invention,

FIG. 6 is a graphical drawing for showing the relation between the additional heating temperature and tenacity of the filaments obtained for various heat shrinkages,

FIG. 7 is a graphical drawing for showing the relation between the additional heating temperature and the saturated basic dye absorption for various heat shrinkages,

FIG. 8 is a graphical drawing for showing the relation between the temperature and the time in additional heat treatment.

In the spinning of the filaments used in the present invention, the spinning solution is prepared by dissolving the before-mentioned acrylonitrile polymer with solvent such as dimethylformamide, dimethylacetamide or dimethylsulfoxide. Spinning of the filaments from such a polymer solution can be carried out by any one of the known spinning methods such as dry-spinning process, wet-spinning process or dry-wet spinning process. Among these spinning methods, the dry-wet spinning process is preferably employed in the manufacture of filaments of the present invention in accordance with the beforementioned objects of the present invention. Filaments thus formed are subjected to primary stretching and aftertreatment by the conventional procedure.

Referring to FIG. 1, an embodiment of the dry-wet spinning process is shown. In the present embodiment, a coagulating bath 2 is positioned 5 to 15 mm. below the outlet of a spinning nozzle 1. The temperature of the coagulating bath 2 is maintained between 0 and 45 C. and the bath contains from 30 to by weight of the solvent which is the same as that used for dissolving the acrylonitrile polymer. It is recommended that a stretch from 1.03 to 4.80 be applied to the filaments within an area between the spinning nozzle 1 and the first godet roller 3 in order to provide the filaments having excellent luster and touch. Then the filaments are primarily stretched in'a boiling water bath 5 positioned between the first godet roller 3 and the second godet roller 4. While the stretching ratio of this primary stretching should be determined in accordance with that of the later-mentioned secondary stretching, it is recommended that the filaments be stretched in the boiling water at a stretching ratio from 2.00 to 7.00 in order not to cause unevenness of the filaments obtained. After the primary stretching, the filaments are washed in a washing bath 6, subjected to oiling treatment by an oiling device 7, dried by a drying roller 8 and taken up onto a package 9 by a package drive 10.

As for the dry-spinning process, no special limitation of the spinning conditions is necessary. However, it is desirable to make the content of the residual solvent within the filaments before secondary stretching lower than 2% by weight. In case this content of the residual solvent exceeds 2%, it is liable to cause undesirable troubles in the following heat treatments such as spot melting within the filaments or tinting of the filaments obtained.

Generally, the primarily stretched filaments obtained by the above-described method is provided with tenacity from 1.6 to 2.5 g./denier, elongation from 20 to 40% and shrinkage in boiling water from to 18%. However, such primarily stretched filaments are not suitable for textile products practically because of its poor antifrictional resistance and poor dyeing property. Consequently, it becomes necessary to apply a secondary stretching upon the primarily stretched filaments in order to make the filaments suitable for actual utilization by improving its fiber properties.

In the method of the present invention, a secondary stretching is applied to the primarily stretched filaments while heating the filaments using such heating members as a heated roller, a heated pin, a heated plate or a heated cylinder.

With respect to the heating temperature (T of the filaments in the secondary stretching, it should be within the range of 170 and 220 C. As an example of the effect of the heating temperature, the fiber properties of the filaments obtained by secondarily stretching the filaments, which are manufactured in such a manner as is detailly described later in Example 1, at a stretching ratio of 2.5 at 160 to 235 C., are illustrated in Table 1 for various secondarily stretching temperatures (T ranging between 160 and 235 C.

As is clearly shown in the table, a secondary stretching temperature below 170 C. results in lowering of the dry tenacity, the dry elongation and the dry knot tenacity of the filaments obtained. This is because of the fact that the fiber structure of the primarily stretched filaments is destroyed by secondary stretching them at such a low temperature. On the other hand, in case the secondary stretching temperature is higher than 220 C., lowering of the tenacity of the filaments obtained is also observed. This is due to the fact that the formation of fiber structure is difficultly occurred by secondarily stretching the filaments at such a high temperature and effective stretching can not be performed. However, the filaments obtained by secondary stretching of the primarily stretched filaments at the above defined temperature are high in boiling water shrinkage and insufiicient in dyeability and fiber properties.

against impact loading. When the filaments are not sufficiently provided with such properties, they often cause many processing troubles such as filament breakage during textile processing or yarn breakage during weaving, both resulting in remarkably lowered quality of the textile products obtained.

In order to effectively eliminate such troubles, it is recommended that an additional heat treatment be applied to the secondarily stretched filaments at a temperature between 230 and 250 C. in a tensioned or slack state.

Referring to FIG. 2, an embodiment of a continuous process for carrying out the method of the present invention is shown. This process is characterized by using a contact-type heating member such as a heated plate, a heated pin or a heated roller. This type of process is favorably used in case the additional heat treatment is applied to the filaments under a tension. In the present embodiment, primarily stretched filaments 11 are taken out from a supply package 12, secondarily stretched while being contacted to the surface of heated plate 13, preheated by a roller-type heating member 14, subjected to additional heat treatment while being contacted to the surface of a heated plate 15 positioned between the preheating member 14 and a take-up godet roller 16 and,

finally, taken up onto a take-up bobbin 17.

As is well-known acrylonitrile filaments are extremely sensitive to fluctuation of tension applied upon the filaments under a heated condition. A large fluctuation of the tension often causes unevenness of the thickness and dyeing afiinity of the filaments manufactured. Therefore, in case the acrylonitrile filaments are heated under a slacked condition, it is strongly recommended that the tension be controlled in such a manner that the fluctuation of the tension should be limited within a narrow range. When heating of the filaments under a slacked condition is carried out by the process shown in FIG. 2, a large disturbance of the tension by a frictional force due to contact between the heating member and the filaments passing at a high speed is unavoidable.

In order to avoid such defects due to frictional contact between the heating member and the filaments, another type of the process for carrying out the method of the present invention is shown in FIG. 3. The mechanical arrangement of the present embodiment is almost the same as that of the embodiment shown in FIG. 2 with the only exception that an indirect-type heating member 18 is used instead of the contact-type heating member 15 of the preceding embodiment. The indirect-type heating member 18 can be made both in the form of a heated cylinder or a pair of heated plates faced with a slight intervening distance as the filaments can be passed.

As an example of the effect of the additional heating of the secondarily stretched filaments manufactured in such a manner as is detailly stated later in Example 2, the unevenness of the thickness of the filaments, kind of heating member, heating temperatures, tension applied to the filaments and shrinkage of the filaments in the additional heat treatment are illustrated in Table 2.

TABLE 2 Heating Uneven tempera- Tension Shrinkage ness in Heating member ture in C in g. in percent U percent A heated cylinder of cm. dia. 280 14 0 1. 0 D 280 3 2.0 2. 3 260 10 0 2. 4 250 5 2.0 7. 3

Moreover, the above-described secondary stretching alone is not enough to provide the filaments with sufficient antifrictional resistance and strong resistance In the illustrated example, the unevenness of thickness in U percent of the filaments denier/40 filaments) before additional heat treatment was 1.8. The secondary stretching of the filament was performed at a temperature of 190 C. and at a stretching ratio of 3.50. After the secondary stretching, the filaments were continuously heated by a preheating roller maintained at 180 C. and fed to the additional heating process at a speed of 200 meters/ min.

In order to obtain good results by the method of the present invention, it is necessary to set suitably the relation among the temperatures of secondary stretching, preheating and additional heating.

In FIG. 4, the effect of the secondary stretching temperature T upon the maximum shrinkage of the filament during the additional heating for various preheating temperature T is shown. In the drawing, the maximum shrinkage of the filament is taken on the ordinate and the secondary stretching temperature T is taken on the abscissa while the curve designated with a corresponds to a preheating temperature T of 80 C., curve b to 100 C., curve to 150 C., curve d to 175 C. and curve e to 200 C. In the example shown, the primarily stretchedfilaments (560 d./40 ft.) were subjected to secondary stretching at a speed of 200 meters/min. and a stretching ratio of 3.50. After the secondary stretching, the filaments were heated with a preheating roller and further heated while passing through a dry heated cylinder of 100 cm. effective length maintained at 280 C.

As is clearly understood from the results shown in the drawing, little shrinkage of the filaments is observed in case the preheating temperature T is lower than 80 C. provided that the secondary stretching temperature T isdefined Within a range between 170 and 220 C. Consequently, the preheating temperature T is required to be higher than 80 C. in order to obtain an effective shrinkage of the filaments and, the higher the preheating temperature T the larger is the shrinkage of the filaments. Again, it can easily be estimated from the results shown in the drawing that the maximum value of the shrinkage of the filament for a certain preheating temperature can be obtained when the preheating temperature T falls within a range between T C. and T +10 C. From above-described discussions, it can be concluded that in order to perform additional heat treatment effectively, the preheating temperature T must be defined by the following equations in accordance with the secondary stretching temperature T The range of the combination of the preheating temperature T and the secondary heating temperature T defined by the above-described equations is shown by the hatched area in FIG. 5, wherein the former is taken on the ordinate and the atter is taken on the abscissa.

In order to provide the filaments obtained with preferable fiber properties as a material for actual textile products, it is generally required to shrink the secondarily stretched filaments lower than 35%, more preferably from 10 to 35 while heating them at a high temperature. As is well-known, acrylonitrile filaments have a tendency to be easily fibrillated resulting in whitening of the textile products made of them. In order to prevent such unfavorable fibrillation of filaments, the above-described heat shrinking treatment is especially required in case of acrylonitrile filaments. The shrinkage of the filaments by this treatment is generally required to be higher than 10% as already-described, however, it can also be lower than 10% in case no special heat shrinking treatment is necessary such as, for instance, in case of the manufacture of high bulky filament yarns.

Referring to FIG. 6, the relation of the heating temperature and tenacity of the filaments for various degrees of shrinkages is shown. In the drawing, tenacity of the filaments obtained is taken on the ordinate and the heating temperature is taken on the abscissa while the curve designated with :1 corresponds to 0% heat shrinkage, the

curve b to 10% and the curve 0 to 35 The numerals in parenthesis at the plotted points show the length of time in second required for sufficient shrinkage of the stretched filaments predetermined degree at the corresponding heating temperature. From this result, it is clearly shown that the heating temperature exceeding 250 C. causes deterioration of fiber structure of the filament resulting in lowering of tenacity of the filaments manufactured.

Referring to FIG. 7, the relation of the heating temperature and the saturated basic dye absorption of the filaments obtained for various degrees of shrinkages is shown. In the drawing, the saturated basic dye absorption of the filaments is taken on the ordinate and the heating temperature is taken on the abscissa while the curve designated by a corresponds to a heat shrinkage of 0%, the curve b to 10% and the curve 0 to 35 As is clearly shown in the drawing, a heating temperature lower than 230 C. results in poor degree of dye absorption of the filaments manufactured.

The combined discussion of the results shown in FIG. 6 and FIG. 7 leads us to the conclusion that the optimum heating temperature of the additional heating is in the range between 230 and 250 C.

With respect to the length of the heating time, sufiicient heating time is necessary in order to highly shrink the filaments as shown in FIG. 6. In order to cause a shrinkage of filaments from 10 to 35% at a heating temperature between 230 and 250 C., from 0.10 to 20.0 seconds of heating time is generally required. In case the heating time is not long enough to cause shrinkage of the filaments shaking of the filaments taken upon godet roller 16 in FIG. 2 is caused, resulting in unstable heat shrinking treatment leading to increased unevenness of the filaments manufactured. Moreover, when the filaments are passed through the process shown in FIG. 3, shaking of the filaments cause them to contact the inside wall of the heating member 18 and this often results in breakage of the filaments by melting by heat. Consequently, the length of the heating time must be determined within the above-described region in accordance with the required degree of shrinkage and the degree of the heating temperature. However, it should also be noted too that a too long heating time causes tinting and fragility of the filaments manufactured. The relation between the heating temperature and the corresponding heating time is graphically shown in FIG. 8, wherein the reation is presented by a hyperbola-shaped curve. In case the combination of the temperature and the time deviates too much from this curve, it results in fragility or tinting of the filaments obtained as above-described.

The following examples are illustrative of the present invention, but are not to be construed as limiting the same.

EXAMPLE 1 25% of spinning solution was prepared by dissolving an acrylonitrile copolymer composed of 91.3% by Weight of acrylonitrile and 8.7% by Weight of vinyl acetate with dimethylacetamide. Specific viscosity of the copolymer measured in dimethylfo rmamide at 25 C. was 0.15. The solution was extruded through a spinneret having 40 holes of 0.15 mm. dia. each into air and then directed into a coagulating bath containing dimethylacetamide and water to make filaments (500 denier/40 filaments).

After leaving the godet roller, the filaments were primarily stretched at a stretching ratio of 1.90. In the arrangement of the spinneret and the coagulating bath, an intervening distance of 5 mm. was formed between the face of the spinneret and surface of liquid of the coagu lating bath in order to make the filaments pass through the air just after being extruded from the spinneret.

Next the primarily stretched filaments were fed to a process shown in FIG. 2, wherein the filaments were secondarily stretched at a temperature of C. a stretching ratio of 2.50 and at a speed of 200 meters/ min., preheated at 200 C. for 13 seconds and finally heated by contacting with a heated plate which was maintained at 250 C. and has a length of 35 cm. While stretching in a tensioned state.

The unevenness of thickness of the filaments obtained (200 denier/40 filament) was 2.1, and the filaments were provided with tenacity of 3.53 g./d., elongation of 17.1% and shrinkage in boiling water of 3.1%.

Then a false-twisting treatment was applied to the filaments obtained under such conditions that the temperature was 180 C., the rotating speed of the falsetwist spindle was 110,000 rpm, the false twists number was 1650 turns/meter and the overfeeding ratio was 0. The treatment could be carried out smoothly without troubles such as yarn breakage or twist slacking, and the filaments obtained were provided with an excellent extensibility.

A knitted cloth made of the filament yarn thus obtained was dyed with basic dyes, and the resulting knitted cloth was provided with uniform color effect, beautiful luster and preferable bulkiness.

EXAMPLE 2 Filaments (560 denier/4O filaments) were obtained by the same method as Example 1 from the same spining solution as in Example 1. Then the filaments were fed to a process shown in FIG. 3, wherein the filaments were secondarily stretched at a temperature f 190 C., at a stretching ratio of 3.50 and at a speed of 200 meters/ min. preheated at 200 C. for 1.3 seconds and finally heated while passing through a heated cylinder of 100 cm. length heated at 280 C. while being shrunk 20%. The unevenness of thickness in U percent of the filaments (200 denier/40 filaments) obtained was 1.7, and the filaments were provided with tenacity of 3.13 g./d., elongation of 25.4% and shrinkage in boiling water of 1.2%.

Then a woven cloth of tufted weave having refined surface effect was made with the filaments thus manufactured. For the same of confirmation of the effect of the present invention, this Woven cloth was dyed with basic dyes and the resulting color of the cloth was preferably uniform.

EXAMPLE 3 Filaments obtained by the same method as Example 1 were secondarily stretched at a temperature of 205 C., at a stretching ratio of 2.50 and at a speed of 400 meters/ min., preheated at 210 C. for 0.65 seconds and finally heated by contacting with a heated plate of 35 cm. length and maintained at 250 C., in a tensioned state. The filaments of 200 denier obtained was composed of 40 filaments.

Then the filaments were subjected to a false-twisting treatment under the same conditions as those in Example 1. The treatment could be carried out smoothly without any troubles such as yarn breakage or twists slacking.

By dyeing a knitted cloth made of the filament yarns thus manufactured, almost the same effects a those in Example 1 was obtained.

EXAMPLE 4 25% spinning solution was prepared by dissolving an acrylonitrile copolymer composed of 91.3% by weight of acrylonitrile and 8.7% by weight of vinyl acetate with dimethylformamide. Specific viscosity of the copolymer was 0.15. Then the spinning solution was extruded through a spinneret having 40 holes of 0.15 mm. dia. each to form filaments by dry-spinning method. The unstretched filaments (500 denier/ 40 filaments) thus formed were stretched 3.78 times between the spinneret and the take-up roll. The content of the residual formamide within the filaments was lowered from 13% to 0.4% by washing the filaments with boiling water at 100 C. for about '60 seconds. After secondary stretching, preheating and additional heating in a tensioned state under the same conditions as'those in Example 1, the filaments obtained were provided with an unevenness of thickness in U-percent of 2.5.

Then the filaments were subjected to a false-twisting treatment in the same manner as in Example 1 without any troubles such as yarn breakage or twists slacking. By dyeing a knitted cloth made of the filament yarns thus obtained, the same results as in Example 1 Was obtained with the only exception that the hand feeling of the cloth obtained was slightly harder than that in Example 1.

While the invention has been described in conjunction with certain embodiments thereof, various modifications and changes may be made without departing from the spirit and scope of the invention.

What is claimed is:

1. A method of manufacturing acrylonitrile filaments comprising: providing primarily stretched acrylonitrile filaments composed of more than 85% by weight of acrylonitrile and the remainder a monomer copolymerizable therewith; secondarily stretching said primarily stretched filaments while maintaining same at a temperature T within a temperature range of from 170-220 C.; heat treating said secondarily stretched filaments within a temperature range of from C. to 10 C. above said temperature T and then further heat treating said secondarily stretched and heat-treated acrylonitrile filaments at a temperature between 230 C. and 250 C. while maintaining same under sufficient tension to prevent shrinkage of said filaments in excess of 35%.

2. A method according to claim 1; wherein said providing step comprises providing acrylonitrile filaments composed of more than by weight of acrylonitrile and the remainder a monomer copolymerizable therewith, and primarily stretching said acrylonitrile filaments in boiling water at a stretching ratio between 2.0 and 7.0.

3. A method according to claim 1; wherein said providing step comprises providing dry-Wet spun acrylonitrile filaments.

4. A method according to claim 1; wherein said providing step comprises providing Wet spun acrylonitrile filaments.

5. A method according to claim 1; wherein said providing step comprises providing dry spun acrylonitrile filaments having 'a residual solvent content less than 2% by weight.

6. A method according to claim 1; wherein said further heat treating step comprises heat treating said secondarily stretched and heat-treated acrylonitrile filaments for from 0.1 to 20.0 seconds.

References Cited UNITED STATES PATENTS 2,445,042 7/1948 Silverman 8--l30.1 2,558,733 7/1951 Cresswell et a1 264182 2,988,419 6/1961 Walter 264206X 3,052,512 9/1962 Kocay et al. 264210 3,088,793 5/1963 Kundsen et al. 264-206X 3,447,998 6/1969 Fitzgerald et al. 264210ZL FOREIGN PATENTS 1,017,855 1/1966 Great Britain 264182 41/7,898 4/1966 Japan 264206 JAY H. WOO, Primary Examiner US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Dated 26' lnventot-(s) YOShijiI'O et a1 It is certir'ied that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading of the patent, column 1, lines 6 and 7, delei "and Mitsubishi Vonnel Co. Ltd. both"; lines 7 and 8, del

"both companies" and insert "a company" Signed and sealed this 7th day of December 1 971 (SEAL) Attest:

EDWARD M.FLETCHER,JR. Attesting Officer ROBERT GOTTSCHALK Acting Commissioner of Pa

Images