JP3423814B2 - A method for producing a high-strength, high-modulus polyvinyl alcohol-based monofilament yarn having excellent hot water resistance. - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyvinyl alcohol having a high strength, a high initial elastic modulus, a fineness of 100 denier or more, and an excellent hot water resistance. Hereinafter, PVA
Abbreviated as) -based monofilament yarn. 2. Description of the Related Art PVA-based fibers have high strength and high initial elastic modulus among general-purpose fibers, and have been used in rubber hoses, conveyor belts, and the like.
It is used in various industrial material fields such as fiber for cement reinforcement, substitute fiber for asbestos, sewing thread for material, tatami thread, fishing net, heavy cloth, rope and the like. [0003] In recent years, various proposals have been made to further enhance the mechanical properties of PVA-based fibers in order to meet the needs of increasingly sophisticated markets. For example,
No. 61-215711 discloses that a spinning solution obtained by dissolving PVA having a degree of polymerization of 1500 or more in dimethyl sulfoxide (hereinafter abbreviated as DMSO) is subjected to dry-wet spinning or gel spinning, and the obtained undrawn yarn is dried in a dry heat tube. A method of producing a PVA-based fiber having a strength of 15 g / d or more and an initial elastic modulus of 250 g / d or more by hot stretching to 19 times or more using the above method is disclosed. Also,
JP-A-62-162010 discloses PVA having a degree of polymerization of 1500 or more.
The gel fibers obtained by wet-spinning or dry-wet spinning the DMSO solution of the above into a coagulation bath at 25 ° C or less are drawn to obtain a P fiber having a strength of 16 g / d or more and an initial elastic modulus of 400 g / d or more.
A method for producing a VA-based fiber is disclosed. However, the single fiber fineness of the PVA-based fibers obtained by these methods is 20 denier or less, and a high strength and high initial modulus PVA-based monofilament yarn of 100 denier or more is not disclosed. On the other hand, the present inventors have proposed in JP-A-3-807 a PVA-based monofilament yarn having a strength of 10 g / d or more, an initial elastic modulus of 200 g / d or more, and a fineness of 100 denier or more. Although this monofilament yarn has a large fineness, a high strength and a high initial elastic modulus, it still has the problem of low resistance to hot water which is characteristic of PVA-based fibers. At present, the expansion to material use is hampered. SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and has high strength, initial elastic modulus, and excellent hot water resistance while having a fineness of 100 denier or more. An object of the present invention is to provide a method capable of stably producing a PVA-based monofilament yarn having high strength and a high initial elastic modulus with high productivity. Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have reached the present invention. That is, the present invention has the following configuration. The spinning solution obtained by dissolving PVA in a solvent is coagulated.
Use, or in an organic solvent to have a gelling effect wet if
Or dry-wet spinning, and then extract the solvent from the spun yarn,
The obtained undrawn monofilament yarn (hereinafter referred to as undrawn yarn)
Name. ) Is dried and then hot-stretched for PVA monofilament.
(1) When the degree of polymerization is 1700-7000
To prepare a spinning solution using PVA, (2) spinning
Yarn is added with a catalyst for promoting dehydration (hereinafter referred to as catalyst)
Into the extracted extraction bath to extract the solvent and attach the catalyst.
And then re-catalyze the spun yarn leaving the extraction bath.
And then dried to produce undrawn yarn. (3) Acceleration of dehydration
The total amount of catalyst for application is 0.01 to 5.0% by weight based on PVA
(4) The undrawn yarn obtained by drying
Hot stretching so that the rate becomes 13 times or more.
Strength, high initial modulus PV with excellent hot water resistance
A method for producing an A-based monofilament yarn. Hereinafter, the present invention will be described in detail. In the present invention, the raw material PVA used
Requires a degree of polymerization of 1700 to 7000. If the degree of polymerization is lower than 1700, the number of molecular chain ends which are liable to be defective increases, and it is difficult to obtain a fiber having high strength and high initial modulus. The upper limit of the degree of polymerization is 7,000 from the viewpoint of manufacturing cost. Further, the degree of saponification of PVA is preferably at least 99 mol%. As a solvent for PVA, there are DMSO, ethylene glycol, water and the like. However, the state of spreading of molecular chains when PVA is dissolved in the solvent, the degree of entanglement of molecular chains, the stability as a solvent, and the problem of gelation. Considering the amorphous state of the compound, the degree of entanglement of the molecules at that time, and the operational problems, DMSO
Is preferred. The concentration of PVA in preparing a spinning solution is preferably 3 to 35% by weight in order to obtain fibers having good physical properties. In addition, an antioxidant for PVA, a heat-resistant agent, a crosslinking agent and the like may be added to the spinning solution. As a method for spinning the spinning dope obtained above, an organic solvent is used as a solvent for the spinning dope, and a coagulation of the organic solvent or a dry-wet spinning method is performed by discharging the solution through an inert atmosphere layer into a cooling bath. A wet spinning method of preparing a spinning solution using water as a solvent and discharging the solution into a coagulation bath can be employed, but a dry-wet spinning method using an organic solvent is preferred. The spinning hole diameter of the spinneret used for spinning is 0.7 to 5.0.
mm, more preferably 1.0 to 3.0 mm.
If the pore size is less than 0.7 mm, the fineness of the undrawn yarn becomes small, and it is difficult to obtain a monofilament yarn having a fineness of 100 denier or more, which is the object of the present invention. On the other hand, if the pore diameter exceeds 5.0 mm, even if the spinning draft is increased, the thread becomes thick, so that the solvent cannot be sufficiently extracted and the thread is easily cut in the drawing step. Therefore, in order to prevent the yarn from being cut in the drawing step, it is preferable that the target fineness of the drawn monofilament yarn be 400 denier or less. Further, as proposed in Japanese Patent Application Laid-Open No. 3-807, when a plurality of yarns are closely adhered and integrated in an inert atmosphere layer immediately after being discharged from a spinneret to form a monofilament yarn. , Spinning hole diameter 0.7m
m. The filament discharged from the spinneret is extruded into a coagulation bath through an air layer or an inert gas layer in the case of the dry-wet spinning method, or directly into the coagulation bath in the case of the wet spinning method. After that, it is sent to the extraction bath. As the coagulating liquid, lower alcohols having a coagulating action such as methanol, ethanol, propanol, etc., alkaline aqueous solutions of sodium nitrate, acetones, ethers, and a mixed solution of these with a PVA solvent are used. However, particularly from the viewpoint of the coagulation rate, an alkaline aqueous solution of methanol or silica gel is preferable. In addition, the filament discharged from the spinneret may be solidified in a cooling bath using decalin, paraffin oil or the like instead of the coagulation bath. [0015] The spun yarn obtained above is sent to an extraction bath to extract a solvent. As the extract, the same as the coagulation solution can be used. In the present invention, the most important point is to improve the hot water resistance by forming a polyene structure in the inner and outer layers of the fiber. Of these, it is necessary to apply a catalyst to the outer layer, and then to heat draw the undrawn yarn to which the catalyst has been applied. In order to apply a catalyst to the outer and inner layers of the spun yarn, it is necessary to perform the following two steps. First, the first stage is
The spun yarn is introduced into the extraction bath to which the catalyst has been added to extract the solvent in the fiber, and at the same time, the catalyst penetrates into the fiber, so that the catalyst is uniformly dispersed in the spun yarn. Next, in a second step, an oil agent mixed with a catalyst is applied to the spun yarn from the extraction bath before drying by an oiling roller or the like. In the above two steps,
The catalyst is uniformly dispersed in the outer and inner layers of the spun yarn. The amount of the catalyst to be applied to the spun yarn is preferably 0.01 to 5.0% by weight based on the PVA, of which 20 to 30% of the total amount of the catalyst applied in the first stage and the remainder in the second stage. Is preferred. If the amount of the catalyst is less than 0.01% by weight, even when heat-treated, dehydration does not occur uniformly on the fiber surface, and the effect of improving hot water resistance cannot be obtained. Also, 5.0
If the content is more than 10% by weight, the strength is extremely reduced due to the dehydration, which is not preferable. In order to apply the above range of catalyst to the spun yarn, it is necessary to apply the catalyst in two stages. If the catalyst is applied in one of the stages, it becomes difficult to apply a predetermined amount of the catalyst. , Monofilament yarn with excellent hot water resistance cannot be obtained. The catalyst that can be used in the present invention is not particularly limited as long as PVA causes a dehydration reaction by heat treatment. Examples of the catalyst include inorganic acids such as sulfuric acid, hydrochloric acid, phosphoric acid, and polyphosphoric acid, acetic acid, and the like. Examples include itaconic acid, alkylsulfonic acid, monoalkyl phosphate, monodialkyl phosphate, polyacrylic acid, and the like. Of these, phosphoric acid is preferred in terms of the thermal decomposition reaction and dehydration reaction for PVA. In the present invention, in the second stage of applying a catalyst to the spun yarn, it is preferable to apply an oil agent mixed with the catalyst by an oiling roller. The oil agent used here is not particularly limited, but a so-called straight oil containing polyoxyethylene sorbitan trioleate, polyoxyethylene oleyl ether, polyoxyethylene lauryl amino ether as a main component, and mineral oil as a diluent, is used. Oils are preferred. In the present invention, the spun yarn provided with the catalyst in two stages is dried to obtain an undrawn yarn. Note that drawing during the spinning process
During (spin drawing), the film is drawn in a bath during or after extraction of the solvent, and then dried to obtain an undrawn yarn. In the present invention, the undrawn yarn thus obtained is once wound up or continuously supplied to a hot drawing step to perform hot drawing. The draw ratio must be set so that the total draw ratio from spinning to hot drawing (spin draw ratio × hot draw ratio) is at least 13 times. If the total draw ratio is lower than 13 times, the target is set. Tensile strength and initial elastic modulus cannot be obtained. As a heat treatment method at the time of hot stretching, there is a method using a heating roller, a hot blast stove, a hot plate or the like, but is not particularly limited. The heat treatment is preferably performed at a temperature of 150 ° C. or higher and lower than the melting point of the fiber, preferably at a temperature of 180 ° C. to 260 ° C. for 1 to 60 seconds. If the heat treatment temperature is lower than 150 ° C. and the treatment time is shorter than 1 second, the dehydration reaction tends to be insufficient, and it becomes difficult to obtain the desired hot water resistance. On the other hand, if the heat treatment temperature is higher than 260 ° C. and the heat treatment time is longer than 60 seconds, the yarn strength tends to decrease, which is not preferable. In the present invention, the heat treatment may be performed subsequent to the hot stretching. In this case, it is preferable that the overfeed rate during the heat treatment is set to be -10 to 10%. As described above, by employing the production method of the present invention, a PVA having high strength, high initial elastic modulus and excellent hot water resistance can be obtained by using commercially available PVA having a polymerization degree.
The A type monofilament yarn can be manufactured with high productivity. The PVA monofilament thus obtained by the production method of the present invention has a single fiber fineness of 100 denier or more, a tensile strength of 12 g / d or more, an initial elastic modulus of 350 g / d or more, and a hot water temperature of not less than 100 g / d. Fiber with extremely high mechanical properties of 120 ° C or higher.
Not only can PVA fibers be used as fishing nets and ropes, which are typical applications, but they can also be used as an alternative reinforcing material for asbestos such as cement and plastic, making them suitable for various industrial materials. Things. According to the present invention, while the single yarn fineness is 100 denier or more, the tensile strength of 12 g / d or more and 350 g / d
The reason for obtaining a PVA-based monofilament yarn having the above initial elastic modulus and excellent hot water resistance with a hot water temperature of 120 ° C. or higher is not clear, but is presumed as follows. That is, in the first step, the spun yarn is introduced into an extraction bath containing a catalyst to extract the solvent in the fiber and simultaneously impregnate the catalyst into the fiber. It becomes possible to disperse evenly. Also, the second
In the stage, the catalyst is applied to the spun yarn that has exited the extraction bath, so that the catalyst is uniformly applied to the outer layer of the spun yarn, and then the drawn undried yarn to which the catalyst has been applied is subjected to hot drawing. Therefore, it is recognized that a polyene structure is formed in the inner and outer layers of the fiber, and the hot water resistance is improved. Next, the present invention will be described in detail with reference to examples. The tensile strength (hereinafter abbreviated as “strength”) and the initial elastic modulus (hereinafter abbreviated as “elastic modulus”) in the examples are as follows.
Measured at a sample length of 20 cm and a pulling speed of 20 cm / min according to JIS-L-1013. The hot water resistance was evaluated at the hot water temperature obtained by the following method. Apparatus: Perkin-Elmer DSC-2C type differential scanning calorimeter Heating rate: 10 ° C./min Sample cell: High pressure (50 atm) cell Sample preparation method: Fiber sample about 5 m cut into a length of about 50 mm
g together with 10 mg of water in a sample cell. Hot water temperature: The peak temperature of the melting (dissolution) curve obtained by the above method is defined as the hot water temperature. Examples 1 to 5 and Comparative Examples 1 to 2 PVA having a degree of polymerization of 1300, 1700, 3300, 4000 and 7000 was dissolved in DMSO as a solvent, and the PVA concentrations were 24, 21 and 21, respectively.
17, 16, and 10% by weight of the spinning dope were prepared. The spinning dope was fed from a spinneret having a spinning hole of 2 mm in diameter and 3 holes at 100 ° C. into a coagulation bath made of methanol.
0, dry-wet spinning with an air gap of 30 mm. Next, D was added to an extraction bath consisting of methanol containing 0.3% by weight of phosphoric acid.
The MSO was extracted and removed, and then an oil agent containing polyoxyethylene oleyl ether as a main component and 4.0% by weight of phosphoric acid was applied, followed by drying to obtain an undrawn yarn. The undrawn yarn was subjected to hot drawing using a drawing device having a hot-air drawing furnace placed between heating rollers at the final roller speed of 40 m / min under the conditions shown in Tables 1 and 2.
A VA monofilament yarn was obtained. Tables 1 and 2 show the spinning and hot drawing conditions and the yarn quality performance of the obtained PVA-based monofilament yarn. In the table, the final roller temperature is the temperature of the exit roller of the final hot stretching. Comparative Example 3 A PVA monofilament yarn was obtained in the same manner as in Example 3, except that the total draw ratio was changed to 10. Table 2 shows the yarn quality performance of the obtained PVA-based monofilament yarn. Comparative Examples 4 and 5 The amount of phosphoric acid was 0.001% by weight (Comparative Example 4), or the amount of phosphoric acid was 7.0% by weight (Comparative Example 5).
A PVA-based monofilament yarn was obtained in the same manner as in Example 3 except for the above. Table 2 shows the yarn quality performance of the obtained PVA-based monofilament yarn. [Table 1] [Table 2] As is clear from Table 1, the PVA-based monofilament yarns obtained in Examples 1 to 5 all have strength.
It had high strength and a high elastic modulus of 12 g / d or more and an elastic modulus of 360 g / d or more, and had excellent hot water resistance with a hot water temperature of 130 ° C or more. On the other hand, in Comparative Example 1 in which the degree of polymerization of PVA was less than 1700, Comparative Example 3 in which the total stretching ratio was less than 13 times, and Comparative Examples 2, 4 and 5 in which the amount of the catalyst applied was outside the range specified in the present invention. The obtained PVA monofilament yarn has high strength and high elasticity.
None of them satisfied the rate and the high temperature water temperature at the same time. Comparative Examples 6 and 7 Phosphoric acid was applied only with an extraction bath to which 10% by weight of phosphoric acid was added (Comparative Example 6), or phosphoric acid was applied only to an oil agent to which 10% by weight of phosphoric acid was added (Comparative Example) A PVA-based monofilament yarn was obtained in the same manner as in Example 3 except for Example 7). Table 3 shows the yarn quality performance of the obtained PVA-based monofilament yarn. [Table 3] As is clear from Table 3, the PVA monofilament yarns obtained in Comparative Examples 6 and 7 have high strength and high elasticity.
None of them satisfied the three factors of the modulus and the high temperature water temperature . According to the present invention, the polyvinyl alcohol-based monof
According to the manufacturing method of the filament yarn, it is an unprecedented high-strength, high-modulus monofilament yarn with excellent hot water resistance, and it can only be used as a fishing net or rope, which is a typical application of PVA fiber. Instead, it can be used as a substitute for asbestos such as cement and plastic, and it is possible to produce fibers suitable for various industrial materials with good productivity and at low cost.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-100912 (JP, A) JP-A-3-146704 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) D01F 6/14

Claims (1)

(57) [Claim 1] Polyvinyl alcohol is dissolved in a solvent
The obtained spinning dope has a coagulating action or a gelling action.
Wet or dry wet spinning in an organic solvent
The solvent is extracted from the spun yarn and the obtained unstretched monofilament is obtained.
After the yarn has been dried, it is stretched with heat and polyvinyl alcohol
When producing monofilament yarn, (1) the degree of polymerization is 17
Spinning stock solution using polyvinyl alcohol of 00-7000
(2) The spun yarn is added with a catalyst for promoting dehydration.
To extract solvent and promote dehydration by introducing into the extracted bath
Add a catalyst, and then dehydrate the spun yarn from the extraction bath again.
After applying the catalyst for promotion, dry and unstretched monofilament
(3) Total amount of dehydration promoting catalyst
To 0.01 to 5.0% by weight of PVA, (4)
Undrawn monofilament yarn obtained by drying is fully drawn
Hot stretching so that the draw ratio is 13 times or more.
High strength, high initial modulus poly vinyl with excellent hot water resistance
A method for producing a nyl alcohol-based monofilament yarn.