EP0661392A1 - Procédé de préparation d'une solution de filage d'alcool polyvinylique - Google Patents

Procédé de préparation d'une solution de filage d'alcool polyvinylique Download PDF

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Publication number
EP0661392A1
EP0661392A1 EP94203761A EP94203761A EP0661392A1 EP 0661392 A1 EP0661392 A1 EP 0661392A1 EP 94203761 A EP94203761 A EP 94203761A EP 94203761 A EP94203761 A EP 94203761A EP 0661392 A1 EP0661392 A1 EP 0661392A1
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Prior art keywords
pva
spinning solution
polyvinyl alcohol
solution
spinning
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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EP94203761A
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German (de)
English (en)
Inventor
Naohiko C/O Res. And Dev. Center Nagata
Shiro C/O Res. And Dev. Center Murakami
Kazunari C/O Res. And Dev. Center Nagadomi
Shinya C/O Res. And Dev. Center Takagi
Yoshihiro C/O Res. And Dev. Center Akiyama
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Unitika Ltd
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Unitika Ltd
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Priority claimed from JP35314693A external-priority patent/JPH07197315A/ja
Priority claimed from JP35315393A external-priority patent/JPH07197316A/ja
Application filed by Unitika Ltd filed Critical Unitika Ltd
Publication of EP0661392A1 publication Critical patent/EP0661392A1/fr
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    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
    • D01F6/02—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D01F6/14—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polymers of unsaturated alcohols, e.g. polyvinyl alcohol, or of their acetals or ketals

Definitions

  • the present invention relates to a method for preparing a polyvinyl alcohol-based spinning solution for use in producing polyvinyl alcohol (hereinafter referred to as PVA) fibers. More particularly, the invention relates to a method for the preparation of a polyvinyl alcohol-based spinning solution which makes it possible to obtain in a simple and efficient manner a PVA spinning solution having a high saponification degree effective to provide improved hot water resistance from commercially available PVA's having a commercial saponification degree.
  • PVA fibers are mainly used in the area of industrial materials in which fiber materials are generally required to have a low boil-off shrinkage ratio.
  • vinyl acetate is polymerized in a methanol solvent into a methanol solution of polyvinyl acetate, which in turn is saponified through catalytic action of acid or alkali, being thereby converted into PVA.
  • this saponification reaction is an ester exchange reaction. If the degree of saponification is more than 99 mol %, the reaction is reversible and it is impossible to obtain the degree of saponification more than 99 mol %. Therefore, the degree of saponification of commercially available PVA is about 99 mol %. When the degree of saponification is required more than 99 mol %, resaponification reaction is needed.
  • PVA fibers have hitherto been produced under general name of vinylon, and in the process of producing vinylon there is employed a coagulating bath containing alkaline ingredients of high concentration. Therefore, even where the material PVA is not so highly saponified, a saponification reaction progresses in the coagulating bath so that the final product has a high degree of saponification on the order of 99.9 mol % or more. For this reason, in any known process for producing PVA fibers, no special care has been taken with respect to the saponification degree of the material PVA. No particular problem has been posed as long as the material PVA has a saponification degree of a commercially acceptable level, i. e., 99 mol % or more.
  • USP 4,599,267 discloses a spinning method wherein a glycerin solution of a PVA with a weight-average molecular weight of 500,000 or more is spun into a methanol bath.
  • USP 4,603,083 and USP 4,698,194 disclose a spinning method wherein a dimethyl sulfoxide solution of PVA is spun into a methanol bath. According to these spinning methods, all steps involved in the process of spinning, such as preparation of spinning solution, coagulating, and washing, are carried out using organic solvents. Therefore, no saponification reaction will progress in the spinning process as in the earlier mentioned process for vinylon production.
  • one method comprises dispersing a powdery or granular mass of PVA in water to prepare a suspension, adding to the suspension an alkaline ingredient in such an amount as is more than required for effecting a saponification reaction, and, if necessary, effecting heating for a saponification reaction.
  • a similar process is carried out using alcohol.
  • PVA polymers are commercially available in the form of dry polymer. Such a polymer must be first suspended in water or alcohol. Then, an excessive amount of an alkaline ingredient is added to the suspension for saponification reaction, and thereafter the excess alkaline ingredient must be neutralized with acid. Subsequently, the liquid and the polymer therein are separated from each other by dehydration or otherwise. This separating step must be followed by washing, and after the washing step a drying step is required for restoring the polymer to its original state of dry polymer.
  • the PVA in order that the saponification degree of PVA may be rendered higher at the stage of material polymer, the PVA must be passed through a number of processing stages, which will naturally result in an increase in the material cost.
  • the present inventors have made an extensive research in order to solve the above discussed problem and, as a result, the present invention has been developed.
  • a first method for the preparation of a polyvinyl alcohol-based spinning solution comprises dissolving polyvinyl alcohol in a solvent, and adding an alkaline ingredient to, and causing the same to be dissolved in the solvent and/or polyvinyl alcohol.
  • a method of spinning a polyvinyl alcohol fiber comprises dissolving polyvinyl alcohol in a solvent thereby to prepare a spinning solution, adding an alkali solution to the spinning solution, and spinning fibers from the alkali-mixed spinning solution.
  • a second method for the preparation of a polyvinyl alcohol-based spinning solution comprises dissolving polyvinyl alcohol under heating in a solvent, adding an alkaline ingredient to the solvent and/or polyvinyl alcohol to form a polyvinyl alcohol / solvent / alkali mixture, thereby saponifying a residual acetyl group of the polyvinyl alcohol, then adding an acid ingredient to the mixture, and effecting heating.
  • measurements for polymerization degree and for saponification degree are in accordance with JIS K 6726.
  • the PVA's useful for the purpose of the invention are not particularly limited, but in order to insure production of a final fiber product having high strength and high modulus, the PVA should preferably have a polymerization degree of 1500 or higher, more preferably a polymerization degree of 3000 or higher.
  • the saponification degree of the PVA may be of a commercially acceptable level, because the PVA is brought in contact with an alkaline ingredient for improvement in the saponification degree thereof prior to the stage of PVA dissolution.
  • the saponification degree is preferably 99 mol % or higher.
  • such PVA is dissolved in a solvent to provide a spinning solution.
  • solvents include, for example, water, ethylene glycol, dimethyl sulfoxide, glycerin, and mixtures of these. Above all, dimethyl sulfoxide is most preferred.
  • the concentration of PVA in the preparation of a spinning solution is preferably determined within a concentration range of from 3 to 35 wt. % in order to ensure production of a final fiber product having good physical properties. If the concentration is less than 3 wt. %, the spinnability of the PVA is bad. If the concentration is more than 35 wt. %, the viscosity of the PVA is excessively high so that the drawability of the resulting fiber tends to be lower.
  • the PVA is dissolved in a solvent to provide a spinning solution.
  • an alkaline ingredient be added to the solvent and/or PVA before the PVA is dissolved.
  • the hot water resistance of a PVA fiber is substantially influenced by the saponification degree of a fiber. If the saponification degree is relatively low or, more specifically, 99.4 mol % or lower, the PVA fiber will be dissolved in boiling water at 100°C.
  • an alkaline ingredient is added to the solvent and/or PVA in conjunction with the dissolving of the PVA. Therefore, a saponification reaction proceeds simultaneously with the dissolving of the PVA or step by step as the PVA is dissolved, and this enables saponification degree to be enhanced to 99.8 mol % or more.
  • the manner of adding the alkaline ingredient to the solvent and/or PVA is not particularly limited.
  • the alkaline ingredient may be added directly to the solvent; or the alkaline ingredient as prepared in the form of a solution may be added to the solvent; or such a solution of alkaline ingredient may be added by being impregnated into a powdery or granular mass of the PVA.
  • these methods may be used in combination.
  • the one in which a solution of the alkaline ingredient is added to the solvent, or the one in which addition is made by impregnating the PVA with such a solution is easy in operation and is most preferred.
  • the amount of the alkaline ingredient added is preferably at least 0.1 equivalent but at most 2.0 equivalents of the amount of a residual acetyl group of the PVA. If the addition of the alkaline ingredient is less than 0.1 equivalent, the saponification degree can not be higher. If the addition is more than 2.0 equivalents, a residual alkaline ingredient is present in an excessive amount in the spinning solution. In particular, it is more preferable that the amount of the alkaline ingredient added is at least 0.8 and at most 1.3 equivalents, in which case the saponification degree can be sufficiently enhanced and, in addition, the residual amount of alkaline ingredient can be minimized.
  • the solvent used in preparing the solution may be one having good capability of dissolving the alkaline ingredient used.
  • the amount of water and/or alcohol is regulated so as to be at least 0.1 wt. % but at most 10 wt. % relative to the total weight of the spinning solution, whereby the alkaline ingredient can be sufficiently dissolved and there is no problem of the spinnability of the spinning solution.
  • Alkaline ingredients useful for the purpose of the invention are not particularly limited insofar as they are effective to permit smooth progressing of a saponification reaction. Specifically, alkaline ingredients, such as sodium hydroxide, potassium hydroxide, and lithium hydroxide, are preferred because they are inexpensive and easily available. These ingredients may be used alone or in combination.
  • additives such as heat resisting agents, crosslinking agents, pigments, and other additives, may be added as far as the saponiation reaction is not hindered.
  • a spinning solution comprised of a PVA having increased saponification degree can be obtained.
  • the increase in the saponification degree of the PVA can be determined by measuring the saponification degree of an undrawn fiber as spun from the spinning solution.
  • the hot water resistance of PVA fibers is substantially influenced by the saponification degree of a final fiber product; if the saponification degree is relatively low, or more specifically lower than 99.4 mol %, the PVA fiber will be dissolved in boiling water at 100°C.
  • the alkaline ingredient added to the solvent and/or PVA is brought into contact with the PVA before the dissolution of the PVA takes place.
  • a saponification reaction is enhanced by the alkaline ingredient so that the saponification degree can be increased to the order of 99.8 % or more.
  • the addition of the acid ingredient is important. Without such addition, the presence of an alkaline residue results in the formation of other chemical bond in PVA molecular chains. This in turn may result in some coloration and, in some extreme case, a molecular chain breakage, thus resulting in a lower polymerization degree, which would not be preferable to the objective of the invention.
  • a mixture comprising such alkaline add acid additions is heated and dissolved, whereby a spinning solution is prepared.
  • the temperature for the process of heating and dissolving is not particularly limited. However, a temperature of 80°C or more is preferred, since heating and dissolving at such temperature will result in uniform dissolution.
  • the amount of the alkaline addition is preferably at least 0.3 equivalent but at most 5.0 equivalents of the amount of a residual acetyl group of the PVA. If the amount of the alkaline addition is less than 0.3 equivalent, it is difficult to obtain a reasonably high saponification degree. If the amount is greater than 5.0 equivalents, the alkaline concentration of the mixture is excessively high, which may easily lead to decreased polymerization degree, other chemical bond formation, and/or coloration. In particular, an alkaline addition of at least 0.8 equivalent but at most 1.3 equivalents is more preferable, because such troubles as above noted can be made more unlikely to occur.
  • the condition for adding the acid ingredient is preferably such that the mixture of the PVA and the solvent with the alkaline ingredient has been kept at a temperature of 40°C or more but less than 80°C for at least 5 minutes but at most 4 hours. If the temperature is less than 40°C and the time period for holding the mixture as such is less than 5 minutes, an insufficient saponification reaction will take place. If the temperature is more than 80°C. and the holding time is more than 4 hours, there will occur formation of other chemical bonds and molecular chain breakage.
  • the amount of acid ingredient addition is not particularly limited. However, if the amount of acid addition is greater than the amount of alkaline addition, the resulting spinning solution may be unstable, or there may occur some coloration. Therefore, it is preferable that the amount of acid addition be less than the number of equivalents of the alkaline addition.
  • Useful acids for such addition include inorganic acids, such as hydrochloric acid, sulfuric acid, and phosphoric acid; organic acids, such as acetic acid, paratoluene, sulfonic acid; and mixtures of these.
  • a number of spinning processes are applicable to the spinning method of the invention, including the dry/wet spinning process wherein a spinning solution using an organic solvent as such is discharged through an inert atmosphere zone into a coagulating bath comprised of an organic solvent or a cooling bath; the wet spinning process wherein a spinning solution in which water is used as the solvent is discharged into a coagulating bath; and the dry spinning process wherein a spinning solution is discharged into a heated air.
  • the dry/wet spinning method in which an organic solvent is used is preferred.
  • the period for addition of the alkaline solution to the spinning solution is not particularly limited.
  • the alkaline solution may be introduced into the tank after the PVA has been dissolved.
  • the alkaline solution may be added at a location adjacent an outlet port of the dissolver. More preferably, such addition is made in a pipe line provided for transferring the spinning solution to a spinneret, which provides greater simplicity.
  • a static agitator is provided on the pipeline at a location downward of a position set for such addition, because the alkaline solution added is allowed to be more uniformly mixed throughout the entire spinning solution.
  • additives such as heat resisting agent, crosslinking agent, pigment, and other additives, may be added to the spinning solution simultaneously upon addition of the alkaline solution.
  • an alkaline ingredient is added to the solvent and/or PVA for dissolving the PVA, so that the alkaline ingredient reacts with a residual acetyl group of the PVA.
  • an alkaline ingredient is added to the solvent and/or PVA and then an acid ingredient is added, the PVA being then heated and dissolved.
  • the alkaline ingredient is caused to react with a residual acetyl group of the PVA thereby to improve the saponification degree of the PVA.
  • dissolution of the PVA takes place when a residual alkaline ingredient has reacted with the acid ingredient to form a salt. Therefore, in this case, too, it is possible to obtain a spinning solution for producing a PVA fiber having a high saponification degree, from a commercially available PVA having a commercial saponification degree.
  • Fig. 1 is a graph showing by way of example the relationship between the amount of addition of an alkaline ingredient and the saponification degree of an undrawn fiber obtained as a final product.
  • Example 1 a PVA having a polymerization degree of 4000 and a saponification degree of 99.45 mol % (with a residual acetyl group of 0.55 mol %) was dissolved in dimethyl sulfoxide to a concentration of 15 wt %.
  • a solution prepared by dissolving in water 1.0 equivalent of sodium hydroxide relative to the weight of the residual acetyl group was added to the dimethyl sulfoxide, and the PVA was introduced into the mixed solution, which was heated up to 115°C with stirring so that the PVA was dissolved therein, a spinning solution being thus prepared.
  • the quantity of water was so adjusted as to be 4 wt. % relative to the total quantity of the spinning solution.
  • a spinning solution was prepared in the same way as Example 1, except that no addition was made of sodium hydroxide. In this case, too, the quantity of water was so adjusted as to be 4 wt. % relative to the total quantity of the spinning solution.
  • Each of these spinning solutions was discharged at 100°C through a spinneret having 300 holes of 0.3 mm each in hole diameter into a methanol coagulating bath at room temperature according to the dry/wet spinning process. Then, coagulated filaments were washed with methanol while being taken up, the dimethyl sulfoxide present in the filaments being thus removed. Subsequently, a lubricant was applied and drying was effected. Thus, an undrawn fiber was obtained.
  • the undrawn fiber of Example 1 had a saponification degree of 99.97 mol % and a polymerization degree of 3970, whereas the undrawn fiber of Comparative Example 1 had a saponification degree of 99.45 mol % and a polymerization degree of 3980. This witnessed that the undrawn fiber of Example 1 had a sufficiently high saponification degree in contrast to the undrawn fiber of Comparative Example 1.
  • the PVA fiber of Example 1 as obtained from the spinning solution incorporating sodium hydroxide, exhibited good hot water resistance, with a boil-off shrinkage ratio registered at 1.42 %.
  • the PVA fiber of Comparative Example 1 as obtained from the spinning solution prepared without addition of sodium hydroxide, was found very unsatisfactory in hot water resistance, with a boil-off shrinkage ratio registered only at 68.2 %.
  • Example 2 a PVA having a polymerization degree of 3300 and a saponification degree of 99.21 mol % (with a residual acetyl group of 0.79 mol %) was dissolved in dimethyl sulfoxide to a concentration of 17 wt %.
  • a solution prepared by dissolving in methanol 1.25 equivalents of potassium hydroxide relative to the weight of the residual acetyl group was added to the dimethyl sulfoxide, and the PVA was introduced into the mixed solution, which was heated up to 115°C with stirring so that the PVA was dissolved therein, a spinning solution being thus prepared.
  • the quantity of methanol was so adjusted as to be 2 wt. % relative to the total quantity of the spinning solution.
  • a spinning solution was prepared in the same way as Example 2, except that no addition was made of potassium hydroxide. In this case, too, the quantity of methanol was so adjusted as to be 2 wt. % relative to the total quantity of the spinning solution.
  • the undrawn fiber of Example 2 had a saponification degree of 99.98 mol % and a polymerization degree of 3280, whereas the undrawn fiber of Comparative Example 2 had a saponification degree of 99.20 mol % and a polymerisation degree of 3270. This witnessed that the undrawn fiber of Example 2 had a sufficiently high saponification degree in contrast to the undrawn fiber of Comparative Example 1.
  • the PVA fiber of Example 2 as obtained from the spinning solution incorporating potassium hydroxide, exhibited good hot water resistance, with a boil-off shrinkage ratio of 1.22 %. Whilst, with the PVA fiber of Comparative Example 2, as obtained from the spinning solution prepared without addition of potassium hydroxide, measurement of its boil-off shrinkage ratio was tried, but fiber fusion occurred and the measurement could not be made.
  • the PVA was introduced into respective mixed solution, which was heated up to 115°C with stirring so that the PVA was dissolved therein, a spinning solution being thus prepared.
  • the quantity of water was so adjusted as to be 5 wt. % relative to the total quantity of the spinning solution.
  • the respective spinning solution so prepared was dry/wet spun into an undrawn fiber in the same way as in Example 1. Then, the fiber was drawn in the same way as in Example 1.
  • Table 1 are shown saponification and polymerization degrees of the undrawn fibers obtained, as well as boil-off shrinkage and thermal shrinkage ratios of the drawn fibers. The relationships between alkaline additions and saponification degrees with respect to undrawn fibers are shown in Fig. 1 wherein the measurement results of Example 1 are also covered.
  • PVA fibers obtained in Examples 3 to 7 exhibited good hot water resistance without exception.
  • PVA fibers obtained in Examples 4 to 7, wherein the amount of sodium hydroxide was at least 0.5 equivalent showed very good heat resistance, with a boil-off shrinkage ratio of less than 2 %.
  • a PVA having a polymerization degree of 3300 and a saponification degree of 99.64 mol % (with 0.36 mol % of a residual acetyl group) was impregnated by spraying with an aqueous solution in which was dissolved 1.1 equivalents of sodium hydroxide relative to the quantity of the residual acetyl group.
  • the PVA was dissolved in dimethyl sulfoxide to a concentration of 17 wt. %, a spinning solution being thereby prepared. In this case, the quantity of water was so adjusted as to be 7 wt. % relative to the total weight of the spinning solution.
  • the spinning solution was dry/wet spun through a spinneret having 100 holes of 0.5 mm diameter each into a methanol coagulating bath, and thus an undrawn fiber was obtained.
  • the undrawn fiber was drawn into a PVA fiber.
  • the undrawn fiber obtained had a saponification degree of as high as 99.99 mol %, and the drawn fiber had good boil-off shrinkage ratio or 1.12 %.
  • a PVA having a polymerization degree of 4000 and a saponification degree of 99.45 mol % (with 0.55 mol % of residual acetyl group) was dissolved in dimethyl sulfoxide to a concentration of 15 wt. %, a spinning solution being thereby prepared.
  • the spinning solution was spun into an undrawn fiber according to the dry/wet spinning process.
  • spinning was carried out while an aqueous solution of sodium hydroxide as adjusted to a concentration of 2.4 wt. % was loaded into a transfer pipe for the spinning solution at the rate of 4.9 g/minute against the discharge rate of 160 g/minute of the spinning solution.
  • the coagulated filaments were washed with methanol while being taken up, whereby the dimethyl sulfoxide present in the filaments was removed. Subsequently, a lubricant was applied and drying was effected. Thus, an undrawn fiber was obtained.
  • the amount of sodium hydroxide was 1.0 equivalent relative to weight of the residual acetyl group of the PVA, and the quantity of water was 3 wt. % relative to the quantity of the spinning solution.
  • the undrawn fiber of Example 9 had a saponification degree of 99.91 mol % and a polymerization degree of 3990, whereas the undrawn fiber of Comparative Example 3 had a saponification degree of 99.45 mol % and a polymerization degree of 3980. This witnessed that the undrawn fiber of Example 9 had a sufficiently high saponification degree in contrast to the undrawn fiber of Comparative Example 3.
  • the PVA fiber of Example 9 as obtained from the spinning solution incorporating sodium hydroxide, exhibited good hot water resistance, with a boil-off shrinkage ratio registered at 1.49 %.
  • the PVA fiber of Comparative Example 3 as obtained from the spinning solution while water only was added thereto, was found very unsatisfactory with a boil-off shrinkage ratio of 68.2 % only.
  • a PVA having a polymerization degree of 3300 and a saponification degree of 99.21 mol % (with 0.79 mol % of residual acetyl group) was dissolved in dimethyl sulfoxide to a concentration of 17 wt. %, a spinning solution being thereby prepared.
  • the spinning solution was spun into an undrawn fiber according to the dry/wet spinning process.
  • spinning was carried out while a methanol solution of potassium hydroxide as adjusted to a concentration of 3.0 wt. % was loaded into a transfer pipe for the spinning solution at the rate of 6.8 g/minute against the discharge rate of 120 g/minute of the spinning solution.
  • the coagulated fiber was washed with methanol while being taken up, whereby the dimethyl sulfoxide present in the thread was removed. Subsequently, a lubricant was applied and drying was effected. Thus, an undrawn fiber was obtained.
  • the amount of potassium hydroxide was 1.0 equivalent relative to the weight of the residual acetyl group of the PVA, and the quantity of methanol was 5.5 wt. % relative to the quantity of the spinning solution.
  • the undrawn fiber of Example 10 had a saponification degree of 99.96 mol % and a polymerization degree of 3270, whereas the undrawn fiber of Comparative Example 4 had a saponification degree of 99.20 mol % and a polymerization degree of 3270. This witnessed that the undrawn fiber of Example 10 had a sufficiently high saponification degree in contrast to the undrawn fiber of Comparative Example 4.
  • the PVA fiber of Example 10 as obtained from the spinning solution while a methanol solution of potassium hydroxide was added thereto, exhibited good hot water resistance, with a boil-off shrinkage ratio of 1.29 %. Whilst, with the PVA fiber of Comparative Example 4, as obtained from the spinning solution while only methanol was added thereto, measurement of its boil-off shrinkage ratio was tried, but fiber fusion occurred and the measurement could not be made.
  • Example 11 The same PVA as used in Example 9 was dissolved in dimethyl sulfoxide to a concentration of 15 wt. % in a tank, whereby a spinning solution was prepared. Subsequently, a solution prepared by dissolving in water 0.2 equivalent (Example 11); 0.6 equivalent (Example 12); 0.9 equivalent (Example 13); 1.1 equivalents (Example 14); 1.9 equivalents (Example 15) of sodium hydroxide, relative to the weight of the residual acetyl group of the PVA within the tank, was respectively added to the spinning solution, followed by stirring. In that case, the quantity of water was so adjusted as to be 5 wt. % relative to the quantity of the spinning solution.
  • the respective spinning solution was dry/wet spun into an undrawn fiber in the same way as in Example 9. Then, the fiber was drawn in the same way as in Example 9.
  • Table 2 are shown saponification and polymerization degrees of the undrawn fibers obtained, as well as boil-off shrinkage and thermal shrinkage ratios of the drawn fibers.
  • PVA fibers obtained in Examples 11 to 15 exhibited good hot water resistance without exception.
  • PVA fibers obtained in Examples 12 to 15, wherein the amount of sodium hydroxide was not less than 0.8 equivalent showed very good heat resistance, with a boil-off shrinkage ratio as low as less than 2 %.
  • a spinning solution was prepared by dissolving a PVA having a polymerization degree of 4000 and a saponification degree of 99.45 mol % (with 0.55 mol % of residual acetyl group) in dimethyl sulfoxide to a concentration of 15 wt. %.
  • a solution prepared by dissolving in water 2.0 equivalents of sodium hydroxide relative to the weight of the residual acetyl group was added to the dimethyl sulfoxide, and the PVA was introduced into the mixed solution, which was heated up to 60°C under agitation.
  • the PVA-introduced solution was kept intact for one hour, to which was then added 1.0 equivalent of acetic acid relative to the weight of the residual acetyl group of the PVA. This solution was again heated up to 115°C, at which the PVA was dissolved, a spinning solution being thus prepared.
  • This spinning solution was discharged at 100°C through a spinneret having 172 holes of 0.4 mm each in hole diameter into a methanol coagulating bath at room temperature according to the dry/wet spinning process. Then, coagulated filaments were washed with methanol while being taken up, the dimethyl sulfoxide present in the filaments being thus removed. Subsequently, a lubricant was applied and drying was effected. Thus, an undrawn fiber of Example 16 was obtained.
  • the undrawn fiber of Example 16 had a saponification degree of 99.96 mol % and a polymerization degree of 4000, showing good improvement in saponification degree.
  • the undrawn fiber of Comparative Example 5 had a saponification degree of 99.45 mol % and a polymerization degree of 3990, showing that the saponification degree remained low.
  • the undrawn fiber of Comparative Example 6 had a saponification degree of 99.97 mol % and a polymerization degree of 3560, showing good improvement in saponification degree but considerable decrease in polymerization degree. It was also observed that the undrawn fiber of Comparative Example 6 was colored dark brown.
  • the PVA fiber of Example 16 as obtained from the spinning solution incorporating sodium hydroxide and acetic acid, exhibited good hot water resistance, with a boil-off shrinkage ratio registered at 1.45 %. Whilst, the PVA fiber of Comparative Example 5, as obtained from the spinning solution prepared without addition of sodium hydroxide and acetic acid, was found very unsatisfactory, with a boil-off shrinkage ratio of 51.7 %. The PVA fiber of Comparative Example 6, as obtained from the spinning solution prepared with addition of sodium hydroxide only, had good heat resistance, with a boil-off shrinkage ratio of 1.42 %, but was found as having become colored.
  • a spinning solution was prepared by dissolving a PVA having a polymerization degree of 3300 and a saponification degree of 99.21 mol % (with 0.79 mol % of residual acetyl group) in dimethyl sulfoxide to a concentration of 17 wt. %.
  • a solution prepared by dissolving in methanol 3.0 equivalents of potassium hydroxide relative to the weight of the residual acetyl group of the PVA was added to the dimethyl sulfoxide, and the PVA was introduced into the mixed solution, which was heated up to 70°C under agitation.
  • Example 17 The PVA-introduced solution was kept intact for 40 minutes, to which was then added 2.9 equivalents of hydrochloric acid relative to the weight of the initial residual acetyl group of the PVA. This solution was again heated up to 105°C to allow the PVA to be dissolved therein, whereby a spinning solution of Example 17 was prepared.
  • Example 18 potassium hydroxide was added in the same quantity as in Example 17 and the solution was kept intact at 30°C for 3 minutes. Then, hydrochloric acid of the same quantity as in Example 17 was added, which solution was heated up to allow the PVA to be dissolved therein. Thus, a spinning solution was prepared.
  • Example 19 potassium hydroxide was added in the same quantity as in Example 17, which was kept intact at 90°C for 5 hours. Then, hydrochloric acid of the same quantity as in Example 17 was added, which solution was heated up to allow the PVA to be dissolved therein. A spinning solution was thus prepared.
  • Each of these spinning solutions was discharged at 105°C through a spinneret having 300 holes of 0.3 mm each in hole diameter into a methanol coagulating bath at room temperature according to the dry/wet spinning process. Then, coagulated filaments were washed with methanol while being taken up, the dimethyl sulfoxide present in the filaments being thus removed. Subsequently, a lubricant was applied and drying was effected. Thus, an undrawn fiber was obtained.
  • the undrawn fiber of Example 17 had a saponification degree of 99.99 mol % and a polymerization degree of 3280, showing good improvement in saponification degree and virtually no decrease in polymerization degree.
  • the undrawn fiber of Example 18 had a saponification degree of 99.54 mol % and a polymerization degree of 3290, showing only slight improvement in saponification degree.
  • the undrawn fiber of Example 19 had a saponification degree of 99.99 mol %, showing good improvement, but showed a decrease in polymerization degree to 2940. It was also observed that this undrawn fiber of Example 19 had become slightly colored brown.
  • the PVA fiber obtained from the spinning solution of Example 17 exhibited good hot water resistance, with a boil-off shrinkage ratio registered at 1.48 %.
  • the PVA fiber obtained from the spinning solution of Example 18 showed a boil-off shrinkage ratio of 9.85 % or a somewhat high value.
  • the PVA fiber obtained from the spinning solution of Example 19 exhibited good boil-off shrinkage ratio of 1.44 %, but was found as having become slightly colored.
  • a PVA having a polymerization degree of 3300 and a saponification degree of 99.64 mol % (with 0.36 mol % of the weight of a residual acetyl group) was impregnated by spraying with an aqueous solution in which was dissolved 1.5 equivalents of sodium hydroxide relative to the weight of the residual acetyl group.
  • the PVA was introduced into dimethyl sulfoxide to a concentration of 17 wt. %, which was heated up to 50°C under agitation and was then kept intact for 40 minutes.
  • the spinning solution was discharged into a methanol coagulating bath through a spinneret having 100 holes of 0.5 mm hole diameter each, whereby an undrawn fiber was obtained. This undrawn fiber was then hot drawn to produce a PVA fiber.
  • the undrawn fiber obtained had a saponification degree of 99.99 mol %.
  • the stretched fiber exhibited good hot water resistance, with a boil-off shrinkage ratio of 1.12 %.
  • Example 21 For the preparation of a spinning solution by dissolving the PVA as used in Example 16, in dimethyl sulfoxide to a concentration of 15 wt. %, a solution prepared by dissolving in water 1.2 equivalents (Example 21); 2.5 equivalents (Example 22); 4.5 equivalents (Example 23); 6.0 equivalents (Example 24) of sodium hydroxide relative to the weight of the residual acetyl group of the PVA, was respectively added to the dimethyl sulfoxide. The PVA was introduced into respective mixed solution, followed by heating up to 60°C with stirring.
  • Example 21 The respective PVA-introduced solution was kept intact for 1.5 hours, and then to the solution was added 0.2 equivalent (Example 21); 1.5 equivalents (Example 22); 3.5 equivalents (Example 23); 5.0 equivalents (Example 24) of acetic acid relative to the initial weight of the residual acetyl group of the PVA. Subsequently, the acetic acid-added solution was heated up to 120°C. to allow the PVA to be dissolved therein. The spinning solution was thus prepared.
  • the respective spinning solution so prepared was dry/wet spun into an undrawn fiber in the same way as in Example 16. Further, the undrawn fiber was hot-drawn in the same way as in Example 16.
  • Table 3 are shown saponification and polymerization degrees of the respective undrawn fibers obtained, as well as boil-off shrinkage and thermal shrinkage ratios of the respective drawn fibers.

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  • Chemical Kinetics & Catalysis (AREA)
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  • Artificial Filaments (AREA)
EP94203761A 1993-12-28 1994-12-27 Procédé de préparation d'une solution de filage d'alcool polyvinylique Withdrawn EP0661392A1 (fr)

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JP35314693A JPH07197315A (ja) 1993-12-28 1993-12-28 ポリビニルアルコール系紡糸原液の調製方法及び紡糸方法
JP353153/93 1993-12-28
JP353146/93 1993-12-28
JP35315393A JPH07197316A (ja) 1993-12-28 1993-12-28 ポリビニルアルコール系紡糸原液の調製方法

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Cited By (1)

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EP1059371A1 (fr) * 1999-06-09 2000-12-13 Kuraray Co., Ltd. Procédé pour la fabrication de polymères d'alcool polyvinylique et polymères d'alcool polyvinylique

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Publication number Priority date Publication date Assignee Title
EP0105169A2 (fr) * 1982-09-30 1984-04-11 Allied Corporation Fibres d'alcool polyvinylique à haute résistance et à haut module et méthode pour leur préparation
EP0146084A2 (fr) * 1983-12-12 1985-06-26 Toray Industries, Inc. Fibre d'alcool polyvinylique à ténacité ultra élevée et procédé pour sa fabrication
US4599267A (en) * 1982-09-30 1986-07-08 Allied Corporation High strength and modulus polyvinyl alcohol fibers and method of their preparation
EP0338534A2 (fr) * 1988-04-21 1989-10-25 Kuraray Co., Ltd. Fibre d'alcool polyvinylique ayant une excellente résistance à l'eau chaude et procédé pour sa fabrication
JPH0340808A (ja) * 1989-07-03 1991-02-21 Kuraray Co Ltd 高強力ポリビニルアルコール繊維の製法
JPH0340807A (ja) * 1989-07-03 1991-02-21 Kuraray Co Ltd 高強力ポリビニルアルコール繊維の製造方法
EP0496376A2 (fr) * 1991-01-22 1992-07-29 Unitika Ltd. Fibres d'alcool polyvinylique et leur procédé de préparation

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EP0105169A2 (fr) * 1982-09-30 1984-04-11 Allied Corporation Fibres d'alcool polyvinylique à haute résistance et à haut module et méthode pour leur préparation
US4599267A (en) * 1982-09-30 1986-07-08 Allied Corporation High strength and modulus polyvinyl alcohol fibers and method of their preparation
EP0146084A2 (fr) * 1983-12-12 1985-06-26 Toray Industries, Inc. Fibre d'alcool polyvinylique à ténacité ultra élevée et procédé pour sa fabrication
US4603083A (en) * 1983-12-12 1986-07-29 Toray Industries, Inc. Ultra-high-tenacity polyvinyl alcohol fiber and process for producing same
US4698194A (en) * 1983-12-12 1987-10-06 Toray Industries, Inc. Process for producing ultra-high-tenacity polyvinyl alcohol fiber
EP0338534A2 (fr) * 1988-04-21 1989-10-25 Kuraray Co., Ltd. Fibre d'alcool polyvinylique ayant une excellente résistance à l'eau chaude et procédé pour sa fabrication
JPH0340808A (ja) * 1989-07-03 1991-02-21 Kuraray Co Ltd 高強力ポリビニルアルコール繊維の製法
JPH0340807A (ja) * 1989-07-03 1991-02-21 Kuraray Co Ltd 高強力ポリビニルアルコール繊維の製造方法
EP0496376A2 (fr) * 1991-01-22 1992-07-29 Unitika Ltd. Fibres d'alcool polyvinylique et leur procédé de préparation

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PATENT ABSTRACTS OF JAPAN vol. 015, no. 173 (C - 0828) 2 May 1991 (1991-05-02) *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1059371A1 (fr) * 1999-06-09 2000-12-13 Kuraray Co., Ltd. Procédé pour la fabrication de polymères d'alcool polyvinylique et polymères d'alcool polyvinylique
US6743859B2 (en) 1999-06-09 2004-06-01 Kuraray Co., Ltd. Polyvinyl alcohol polymer production method and polyvinyl alcohol polymer
KR100666889B1 (ko) * 1999-06-09 2007-01-10 가부시키가이샤 구라레 폴리비닐 알코올계 중합체의 제조방법 및 폴리비닐알코올계 중합체

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