JPS6234847B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing cellulose acetate fibers, and its main purpose is to improve dyeability by mixing and spinning cellulose acetate with a specific acrylonitrile polymer. Acetate fibers are dyed with disperse dyes, have relatively good clarity, and have a silky texture, and are widely used as clothing fibers. The fibers in this case are usually produced by a dry spinning method using acetone or methylene chloride as a solvent, and are mainly filaments. On the other hand, in order to expand the use of acetate fibers, there is a need to develop new materials such as tow or stable fibers, and materials with improved mechanical properties and easy dyeability. From the viewpoint of dyeability, cellulose acetate currently being developed has no choice but to dye with disperse dyes due to its chemical structure, but it is possible to use ionic dyes, i.e. cationic dyes, which have good color development and excellent fastness. If it can be dyed with dyes or acid dyes, it is expected that it will become a useful material because of the ease of dyeing operation. The present invention has been carried out with various studies aimed at imparting dyeability different from conventional cellulose acetate, and has developed a design for fibers that can be dyed with ionic dyes without losing the characteristics of acetate fibers. We found a manufacturing method and arrived at the present invention. The gist of the present invention is that 70 to 95 wt% of cellulose acetate with an oxidation degree of 54% or more, a monomer having an ionic group selected from the group of acidic groups and basic groups as a dyeing site, and acrylonitrile.
Copolymer with 50wt% or more and 100% ionic group
A method for producing cellulose acetate fibers, which comprises spinning a solution of a polymer mixture containing 30 to 5 wt% of an acrylonitrile polymer containing at least mmol/Kg in dimethylacetamide, removing the solvent, and then drying. The gist of the present invention is to first mix and spin a substance dyeable with ionic dyes using cellulose acetate as a matrix. It is essential that the substance has sufficient dyeing ability and does not fall off from the acetate thread even after fiber formation, and for this reason, a substance with a high molecular weight is preferred. On the other hand, it is important that it be mixed uniformly with cellulose acetate so that no staining spots occur. As a result of examining many polymers from these points, it has been found that an acrylonitrile (AN)-based polymer having a specific amount of ionic dye seat is preferable. Next, from the point of view of the fiber manufacturing process, it is relatively difficult to achieve a balance between the yarn-forming properties and the formed structures of the two polymers, since they are not necessarily similar. In particular, the progress of crystallization caused by the cellulose acetate side is important in balancing the fiber properties, and as described below, sufficient attention must be paid to the heat treatment after solvent removal, such as the drying process of wet yarn. Based on the above-mentioned gist, the present invention will be described below in accordance with its implementation. The starting material of the present invention is cellulose diacetate or cellulose triacetate for ordinary fiber forming with a degree of acetylation of 54% or more, and the degree of polymerization is generally
Approximately 150 to 400 will be selected. On the other hand, the AN polymer for mixing contains 100 mmol/Kg or more of ionic groups as a dyeing seat. Examples of the ionic group include sulfonic acids or sulfonic acid esters, acidic groups such as carboxyl groups, salts thereof, and basic groups in a broad sense such as amino groups and ammonium salts. ionic group
In order to introduce it into an AN-based polymer, it is usually sufficient to copolymerize a monomer mainly containing an ionic group with AN. Examples of such a copolymerizable monomer containing an ionic group include (meta) Acidic group-containing monomers such as allylsulfonic acid, (meth)acrylic acid or itaconic acid, styrenesulfonic acid or their salts, dialkylaminoalkyl (meth)acrylates, vinylpyridines and their quaternary ammonium salt derivatives, etc. Examples include basic group-containing monomers. On the other hand, when polymerization is carried out using a specific polymerization catalyst, a sulfonic acid or its ester group is introduced as a catalyst fragment at the end of the polymer, so such a polymer has a small amount of copolymerized monomer containing an acidic group. It can be effectively used for the purpose of the present invention. Specifically, such a catalyst includes a redox initiator made of persulfates or a combination thereof with a reducing sulfoxy compound. Of course, the number of these terminal acidic groups per unit weight of the polymer is influenced by the number of molecules of the polymer, in other words, the molecular weight. In the case of polymers, approximately 30~
Since it has a sulfonic acid group of 40 mmol/Kg, the effect of the sulfonic acid group is particularly significant in the present invention in terms of its utilization. In addition, the AN-based polymer
There is no specific limit to the AN content, but it is preferably approximately 50 wt% or more. The mixing ratio of the above two types of polymers is 70 to 95 wt% for cellulose acetate and 30 to 95 wt% for AN polymer.
It is assumed to be 5wt%. However, within this range, a small amount of other third polymer may also be added. For example, in order to improve the compatibility between the two, a so-called compatibilizer such as a graft or block polymer may be used together, or
It is possible to add substances that have functions other than staining. If the AN polymer exceeds 30 wt% of the above mixing ratio, the devitrification of the resulting fiber will be greatly increased and the unique feel of acetate will be lost. Also that is
If it is lower than 5wt%, an AN polymer containing an extremely large amount of ionic groups will be required in order to impart the desired dyeability, but it is generally difficult to produce such a polymer, so it is not preferable. . The general limit in terms of the productivity of AN-based polymers is the ionic group content of about 1000 mmol/Kg. Both polymers are preferably dissolved in a common solvent and mixed. As the solvent, a normal AN polymer solvent is used, but dimethylacetamide (DMAc), which has a slow diffusion rate in water, is preferably used to produce fibers with a homogeneous structure. The total polymer concentration in the solution is 8-35wt% suitable for spinning, preferably
The content should be in the range of 15-25wt%. For the purpose of the present invention, it is important to mix the two as uniformly as possible, but since they are different types of polymers, microscopic phase separation is inevitable, and when observing the phase state of the mixed solution, in both cases, Cellulose acetate forms a matrix, and the AN-based polymer is dispersed in particles to form a sea-island stock solution. Figure 1 is an optical micrograph (magnification: 100) of the solution showing the state.The cellulose acetate is cellulose triacetate with a degree of acetylation of 61.5%, and the AN polymer is AN-sodium methallylsulfonate (1-5wt). %) of the polymer. The particle size of the island component is 1/10 to several microns, and this state of dispersion is almost directly reflected in the state of mixing and dispersion in the fiber throughout the fiber formation process. In terms of the uniformity of staining, or in other words, the appearance of spots observed with the naked eye, the finer the particle size, the better.As a result of studying this method, we found that:
It has become clear that the polymer composition of the AN-based polymer contributes, and that it is better to include vinyl acetate (VAc) or methyl (meth)acrylate in addition to the ionic group-containing monomer. There is no special regulation on their content in AN polymer, but their effects and
5 to 15 wt% is appropriate due to problems in preparing the AN polymer. Although the reason for this is not certain, it is thought that it is because the acetate group of cellulose acetate has a high affinity with these monomer side chains. Figure 2 of the drawings shows cellulose triacetate and AN with the composition AN/VAc/sodium methallylsulfonate = 90/7/3 (wt%) as in Figure 1.
This figure shows the phase state of a mixed solution of polymers. It can be seen that the sea-island stock solution is more uniform than that shown in FIG.
Note that stirring and mixing accompanied by high mechanical shear is desirable as a premise for preparing such a homogeneous solution. The solution thus obtained is thoroughly filtered and degassed before being introduced into the spinning process. As for the spinning method, any of the usual dry, dry-wet, and wet spinning methods are possible, but when performing wet spinning, an aqueous solution of the above-mentioned solvent as a coagulant is industrially advantageous in terms of handling, etc. . Since the coagulation properties of the two polymers are different, it is important to reduce the temperature of the coagulation bath as low as possible to achieve mild coagulation in order to reduce the difference and obtain a yarn with as high transparency as possible. The spun yarn is then desolventized in hot water,
The residual solvent in the yarn should be approximately 1wt% or less. Although the yarn may be slightly stretched at the same time as this cleaning, excessive stretching or excessive stress may cause a peeling phenomenon at the interface of the mixed polymer, resulting in the formation of voids and devitrification. This is undesirable as it causes a decrease in color development. The stretching ratio is preferably 1 to 2 times at most. After applying a suitable oil to the washed yarn, it is then dried. At this time, the cellulose acetate of the matrix is easily crystallized by the tension heat treatment, and the crystallization hardly contributes to an improvement in strength, unilaterally causing a decrease in elongation and a decrease in knot toughness. Therefore, it is desirable to dry under virtually no tension, at a temperature of 100 to 180°C, usually 110 to 160°C.
Dry at ℃. From the viewpoint of productivity, it is preferable that this drying process be directly connected to the washing process and be continuous, and a preferred method for this is to overfeed the wet yarn onto an endless processing conveyor and introduce it into a heated atmosphere using hot air or the like. Strain to dry. In addition, during the main drying process, the threads are approximately 5 to 15 cm long in the length direction.
% shrinkage, it is desirable to set the overfeed rate to at least a level exceeding this value. . After drying, the fibers can be used as they are, or they can be crimped and, if necessary, heat treated to form filaments, tows, or cut into staples, either alone or blended with other synthetic fibers or natural fibers.
Useful products can be provided by inter-knitting and inter-weaving. In particular, since the fibers of the present invention can be easily dyed with cationic dyes or acidic dyes at relatively low temperatures, they can be mixed with other fibers that can be dyed with these dyes and can be dyed in one bath. Although the basic requirements of the present invention have been explained above, various modifications can be made by combining other known techniques. A more detailed explanation will be given below with reference to Examples. Example 1 An AN-based polymer shown in Table 1 prepared by an aqueous polymerization method using cellulose triacetate (abbreviated as CTA) with an acetylation degree of 61.5%, potassium persulfate, and an acidic sodium sulfite-based redox initiator was used. The following experiment was conducted.

[Table] CTA and AN-based polymers were weighed out at a ratio of 80/20 and dissolved in DMAc at 90°C using a kneader with stirring so that the total polymer concentration was 15 wt%. The obtained mixed polymer solution was filtered and defoamed to obtain a spinning stock solution. When these stock solutions were immediately observed under a microscope at room temperature, the results shown in Figure 1 (1-a, 1-b, and 1-c correspond to polymers (), (), and (), respectively) were obtained. . Although both cases involve phase separation, it can be seen that the higher the NaMS content, the finer the island component made of AN polymer becomes. On the other hand, the state of these stock solutions after being left for 24 hours is shown in Figure 2 (2-a,
As shown in 2-b and 2-c), both were relatively stable. Using each stock solution, fibers were produced by a wet spinning method as follows. Hole diameter 0.05mmφ, number of holes
40% kept at 10℃ from 1000 spinning nozzles
It was spun into an aqueous solution of DMAc, coagulated, and drawn off at a speed of 10 m/min. After washing in hot water at 98°C, the fibers were coated with an oil, overfed onto a net conveyor, and dried by running in hot air at 140°C to produce single fibers with a fineness of 3 denier. In all cases, the spinning operability was good. The properties of the obtained fibers are shown in Table 2. For comparison, fibers similarly obtained from CTA alone without mixing AN polymer are also shown.

【table】

[Table] As shown in Table 2, the fibers of the present invention are endowed with dyeability for cationic dyes without impairing mechanical properties and transparency, compared to fibers made from CTA alone. Furthermore, in order to fully satisfy the dyeability, a dyeing rate of approximately 50% is required, and for this purpose, the polymer () cannot be used as a starting material. Next, fibers were produced in the same manner using the above polymer (2) and varying the mixing ratio with CTA, and the results shown in Table 3 below were obtained.

[Table] As is clear, the dyeability improves as the mixing ratio of AN polymer increases, but when it exceeds 30%, the phase separation state worsens, resulting in a marked decrease in transparency and yarn damage. The quality, especially the knot strength and elongation, deteriorates significantly. Example 2 80 parts of CTA used in Example 1 and the composition are AN/
VAc/NaMS=90/7/3 (wt%) and its specific viscosity
Mix 20 parts of AN-based polymer that is 0.170 to 90% DMAc.
A solution with a concentration of 15 wt% was prepared by dissolving at ℃ and then stirring with a high speed mixer rotating at 3000 rpm. The results of optical microscopic observation of the solution are shown in Figure 3 (3-a
(immediately) and 3-b (after 24 hours). All of them had a uniform, fine sea-island shape and had good stability. The mixture was then filtered and defoamed to obtain a spinning dope, which was then subjected to wet spinning in the same manner as in Example 1, followed by washing and drying. After the washing, a method was also carried out in which the material was dried under a fixed length while running a hot roll having a predetermined surface temperature. The results are shown in Table 4.

[Table] From Table 4, the fiber of the present invention in Experiment No. 7 has a good yarn quality balance, whereas the tension-dried yarn has a large decrease in knot strength and elongation regardless of the drying temperature. Example 3 Cellulose diacetate (CA) with a degree of acetylation of 55%
The following study was conducted using an AN-based polymer containing 500 mmol/kg of amino groups dyeable with acid dyes. In other words, CA90 parts and the composition are AN/
VAc/dimethylaminoethyl methacrylate (DM) = 85/7/8 (wt%), its specific viscosity is 0.160.
A spinning stock solution having a concentration of 17.5 wt% was prepared from 10 parts of the AN-based polymer by dissolving it in DMF using a conventional method. This is the hole diameter
The fibers were spun into a 30% DMF aqueous solution maintained at 0° C. from a spinning nozzle with a diameter of 0.06 mm and 1000 holes, and drawn off at a speed of 10 m/min. Then, while removing the solvent in hot water at 80°C, a 1.2x stretching was applied to apply an oil agent, and the same as in Example 1 was dried under no tension to produce a single fiber with a fineness of 5 denier. . Table 5 shows the physical properties of the obtained fibers.

[Table] Note that the amino group content in the AN-based polymer described above was determined by dyeing the polymer powder in a large excess dye bath to determine the saturated dyeing amount, and the value was used as is. On the other hand, the CA fiber alone without the AN polymer was only stained by the acid dye.

[Brief explanation of the drawing]

Figures 1, 2, and 3 are all enlarged optical microscope photographs (100 magnification) showing the phase state of an organic solvent solution of cellulose acetate and AN polymer mixture.
It is.

Claims (1)

[Claims] 1. Cellulose acetate with a degree of acetylation of 54% or more 70~
Acrylonitrile which is a copolymer of 50 wt% or more of acrylonitrile and a monomer having 95 wt% and an ionic group selected from the group of acidic groups and basic groups as a dyeing seat, and containing 100 mmol/Kg or more of ionic groups. 1. A method for producing cellulose acetate fibers, which comprises spinning a solution of a polymer mixture consisting of 30 to 5 wt% of the polymer in dimethylacetamide, removing the solvent, and then drying. 2. The method according to claim 1, wherein the drying is carried out under substantially no tension. 3. The method according to claim 1, wherein a copolymer containing vinyl acetate or methyl (meth)acrylate as a copolymerization component in addition to the ionic group-containing monomer is used as the acrylonitrile polymer.