JPH04240207A - Polyvinyl alcoholic fiber and its production - Google Patents

Abstract

PURPOSE:To obtain polyvinyl alcoholic fiber having a high strength, initial elastic modulus, resistance to hot water and abrasion and suitable as fishing nets, ropes, etc. CONSTITUTION:PVA fiber is obtained by passing a solution of PVA having 3900 polymerization degree in DMSO through an air gap of 10 mm distance into a coagulation bath, carrying out dry jet-wet spinning, then extracting the DMSO, subsequently applying a catalyst solution prepared by mixing phosphoric acid in an oiling agent, drying the prepared fiber, providing undrawn yarn, hot-drawing the undrawn yarn at 20m/min speed under dry heat conditions and forming an intermolecularly crosslinked structure on the fiber surface. Thereby, the objective PVA fiber, excellent in abrasion resistance and having >=15g/d tensile strength, >=250g/d initial elastic modulus and >=140 deg.C resistance to hot water is obtained.

Description

Detailed Description of the Invention [0001] [Industrial Application Field] The present invention is made of a polyvinyl alcohol (hereinafter abbreviated as PVA) type polymer, which has excellent abrasion resistance and hot water resistance, and has high The present invention relates to fibers with high strength and high initial elastic modulus, and a method for producing the same. [Prior Art] PVA fibers have the highest strength and highest initial elastic modulus among general-purpose fibers, and are used in rubber hoses, conveyor belts, fibers for reinforcing cement, sewing threads for materials, tatami threads, fishing nets, and land nets. It is widely used as a fiber for industrial materials such as , heavy fabrics and ropes. [0003]In recent years, in response to the demands of the increasingly sophisticated market, PV
Various attempts have been made to further increase the strength and initial elastic modulus of A-based fibers.
No. 14 discloses a method in which a glycerin solution of PVA having a weight average molecular weight of 500,000 or more is gel-spun in a cooling bath, and after removing the glycerin from the solidified yarn, the yarn is hot-stretched. In addition, JP-A-60-126312 discloses dimethyl sulfoxide (DMS) of PVA with a degree of polymerization of 1800 or more.
O) A method is disclosed in which a solution is subjected to dry/wet spinning in a methanol bath and the resulting undrawn yarn is hot drawn. [0004] In these methods, the spinning and stretching conditions are devised and the molecular chains are highly oriented in the fiber axis direction by stretching at a high magnification. For this reason, although the fibers obtained by these methods do have improved strength and initial elastic modulus, they have the drawbacks of being weak in the direction perpendicular to the fiber axis, easily fibrillating, and having poor abrasion resistance. Improvements were particularly desired in applications such as fishing nets, land nets, and ropes. [0005] For this reason, JP-A-2-127568 and JP-A-2-210072 disclose a method of improving wear resistance by attaching organopolysiloxane and fluororesin to fibers and subjecting them to dry heat treatment. has been done. However, this method is disadvantageous because it requires chemical application and dry heat treatment after forming the fibers, which increases production costs and increases the number of steps.Furthermore, PVA fibers have poor resistance to hot water. It was not possible to improve the characteristics of [0006] It is known that the higher the degree of polymerization of PVA as a raw material and the higher the syndiotacticity, the higher the hot water resistance of the resulting fiber. Therefore, PVA with a high degree of polymerization or PVA with high syndiotact
It is obvious that PVA fibers with excellent hot water resistance can be obtained by using PVA fibers, but in order to obtain high hot water resistance of 140°C or higher, which enables wide application to industrial material applications, the degree of polymerization must be 10,000. It was necessary to use the above-mentioned ultra-high polymerization degree PVA and PVA with syndiotacticity (Diad) of 50% or more. However, such ultra-high polymerization degree PVA is not only difficult to obtain commercially, but also has problems in that it is difficult to spin due to its poor solubility in solvents. For this reason, JP-A-61-108713 discloses a method using highly syndiotact PVA made from vinyl trifluoroacetate. However, such PVA is also difficult to obtain commercially and is expensive. In addition, high syndiotact PV
In the method using A, it was not possible to obtain the abrasion resistance targeted by the present invention. On the other hand, as a method for obtaining PVA fibers with excellent hot water resistance from commercially available PVA, Japanese Patent Laid-Open No. 63
JP-A-120107, JP-A-1-156517, JP-A-2-133605, etc., disclose a method of treatment with a boric acid aqueous solution, a method of dry heat stretching after adhering a crosslinking agent, and a method of dry heat stretching after adhering a crosslinking agent. A method of blending coalescence, etc. is disclosed. However, these methods have problems in that not only the abrasion resistance is not improved at all, but also the hot water resistance is unsatisfactory, and the manufacturing cost increases, making it difficult to implement industrially. [0008] In order to solve the above-mentioned drawbacks, the present inventors proposed in Japanese Patent Application No. 2-90997 a hot-stretched PV
Hot water resistant P, in which a catalyst solution for promoting dehydration reaction mixed with a surfactant is applied to the A fibers, then dried, and then heat treated at a temperature of 150°C or higher to reduce the hydroxyl groups in the amorphous part.
We proposed a method for producing VA fibers. However, when the present inventors conducted a detailed study on the fibers obtained by this method, the surface layer of the fibers did indeed have improved hot water resistance, with hot water resistance of 180°C or higher. However, since this layer exists in a range of only a few microns, the hot water resistance inside the fiber has not been improved, nor has the abrasion resistance. It has become clear that this tends to decrease. Furthermore, since a drying step is required, there is a drawback that the operation is complicated. As mentioned above, PVA fiber has the highest strength and highest initial elastic modulus among general-purpose fibers, so PV
It is clear that if A-type fibers can be imparted with abrasion resistance and high hot water resistance, they will be extremely useful as fibers for industrial materials. Problem to be Solved by the Invention As mentioned above, PV
Various attempts have been made to impart high strength and high initial modulus of elasticity to A fibers, as well as attempts to impart hot water resistance, but the reality is that none of them have achieved improvement in abrasion resistance. Furthermore, PVA fibers that have high strength, high initial elastic modulus, abrasion resistance, and hot water resistance at the same time have not been known. [0011] Accordingly, the first object of the present invention is to provide a PVA fiber having excellent abrasion resistance and hot water resistance, as well as high strength and high initial modulus of elasticity. A second object of the present invention is to provide a method for producing PVA-based fibers having the above-mentioned physical properties with good productivity from commercially available PVA. [Means for Solving the Problems] As a result of intensive studies to solve the above problems, the present inventors surprisingly found that after adding a catalyst for promoting the dehydration reaction to PVA fibers, 1
The present invention was achieved based on the finding that not only hot water resistance but also abrasion resistance can be imparted by hot stretching at a speed of 0 m/min or more. That is, the present invention has the following configuration. (1) It is made of PVA with a degree of polymerization of 1500 or more and 7000 or less, has a tensile strength of 15 g/d or more, an initial elastic modulus of 250 g/d or more, and a hot water resistance of 140°C or more,
A PVA fiber having an abrasion resistance of 200 or more. (2) After applying a catalyst for promoting dehydration reaction to fibers made of PVA with a degree of polymerization of 1,500 or more and 7,000 or less,
PVA characterized by hot stretching at a speed of m/min or higher
A method for producing fibers. [0014] The tensile strength and initial elastic modulus in the present invention are determined according to JIS L-1013 at a grip interval of 25
cm, and the tensile speed is 30 cm/min. Moreover, hot water resistance and abrasion resistance are measured by the following methods. Hot water resistance device: PerkinElmer DSC-2C differential scanning calorimeter Temperature increase rate: 10°C/min Sample cell: High pressure (50 atm) cell Sample preparation method: 5 m fiber sample cut to approximately 5 mm length
g is sealed in a sample cell with 10 mg of water. Hot water resistance: The peak temperature of the melting curve obtained by the above method is defined as hot water resistance. Wear resistance In Figure 1, one end is fixed to a fixed wall with a hook 6, and the other end is applied with a load 4 of 1/50 g/d via a load pulley 5.
A wedge-shaped edge 3 with a tip angle of 60 degrees is applied to the sample (fiber) 1 supported by a pair of pulleys 2 and 2' with a tension of The edge 3 is stroked left and right at a stroke length of 6 cm and a stroke number of 36 times/minute, and the number of strokes until breakage is measured. Repeat the above measurement 10 times for the same sample,
The average value N(S) of eight measured values is obtained by removing the maximum value and the minimum value from the measured values. Additionally, commercially available PVA fibers:
A similar measurement was performed using HM-1 Vinylon (1800d/750f) (manufactured by Unitika Co., Ltd.), and the average value N (0)
The wear resistance (N) in the present invention is obtained by dividing N(S) by N(0) and multiplying it by 100. N=[N(S)/N(0)]×100 [0015] The present invention will be explained in more detail below. PVA with high strength, high initial elastic modulus, and excellent abrasion resistance and hot water resistance
Although the PVA fiber that serves as the precursor of the PVA fiber is not particularly limited, for example, the optimum conditions thereof may be determined according to the dry/wet spinning method described in Japanese Patent Application No. 1-122030 previously proposed by the present inventors. Can be manufactured below. That is, PVA with a degree of polymerization of 1500 or more and 7000 or less
A spinning stock solution prepared by dissolving DMSO in a solvent containing DMSO as a main component is dry/wet-spun using a spinneret having a discharge hole protruding from the spinning stock solution outlet side, and then DM with methanol.
It can be manufactured by removing SO, applying an oil agent, and drying. In this case, patent application No. 2-2123
It is preferable to add phosphoric acid or a phosphate salt to the spinning dope as described in No. 48, because it further increases the abrasion resistance of the resulting PVA-based fiber and makes it difficult to dissolve in DMSO. [0016] It can also be produced by a conventional spinning method, for example, a spinning method (wet spinning) in which a PVA aqueous solution containing boric acid or a boric acid salt is used as a spinning stock solution and an alkali hydroxide, sodium sulfate, etc. are used as a coagulation bath. It is possible to do so. As described above, PVA fibers applicable to the production method of the present invention can be produced by various methods, but
The degree of polymerization of the PVA used needs to be 1500 or more. If the degree of polymerization is less than 1500, it is unsuitable because the tensile strength of the final product will be lower than the desired value. Further, the degree of polymerization is 7000 or less from the viewpoint of polymer cost. In the present invention, a catalyst for accelerating the dehydration reaction is added to the PVA fiber obtained above before hot drawing. That is, as described above, in the method of applying a catalyst to the fibers after hot drawing, the strength tends to decrease, and in particular, the improvement in abrasion resistance becomes unsatisfactory. On the other hand, in the method of the present invention, a catalyst is added to the fiber before hot drawing, and the dehydration reaction proceeds all at once in the hot drawing and heat treatment steps, so the strength does not decrease, but rather tends to be improved. . Furthermore, the fibers undergo oriented crystallization due to hot drawing, resulting in a dense structure, so even if a catalyst is applied to the fibers after hot drawing, it is difficult for the catalyst to penetrate into the fibers, whereas the fibers before hot drawing is the spinning solvent (e.g. DMSO
) is removed, and the structure is rough, so the catalyst penetrates well into the fibers, resulting in a thick surface layer with improved hot water resistance and abrasion resistance. therefore,
The PVA fiber to which the catalyst for promoting the dehydration reaction is applied may be cold-stretched as long as it has not been hot-stretched, but orientation and crystallization will progress and the structure will become too dense, resulting in poor penetration of the catalyst. Therefore, the cold stretching is preferably 8 times or less, more preferably 6 times or less. Catalysts for promoting the dehydration reaction that can be used in the present invention include inorganic acids such as phosphoric acid and hydrochloric acid, and organic acids such as p-toluenesulfonic acid and terephthalic acid.
In particular, phosphoric acid and para-toluenesulfonic acid are preferably used. In the present invention, the method of applying these catalyst solutions to the fibers is not particularly limited, and methods such as immersion in the solution, application using a so-called oiling roller, and spraying the solution may be used. Among them, a method of mixing the catalyst with a spinning oil and applying the catalyst oil solution to the undrawn yarn using an oiling roller is preferred because it is simple. [0021] In the present invention, the amount of catalyst applied is not particularly limited;
It is preferable to apply the catalyst in an amount of 0.01 to 5 equivalents per m2. For example, when mixed with a spinning oil and applied together with the oil, the catalyst is added so that the acid concentration is 0.01 to 5N. is mixed with the oil agent, and the amount of oil agent adhesion is 0.1 to 2.
What is necessary is just to give so that it may become weight%. In the present invention, the fiber to which the catalyst for promoting the dehydration reaction has been applied is once wound up or continuously supplied to a hot drawing process to be hot drawn, and at that time, the hot drawing speed is adjusted. It is extremely important that the speed be 10 m/min or more. If the drawing speed is slower than 10 m/min, the dehydration reaction will proceed before the fibers are hot drawn, making it impossible to increase the drawing ratio, which will not only lower the strength of the fibers but also reduce the Since the crosslinked structure is destroyed while being stretched, the abrasion resistance and hot water resistance are also reduced, making it impossible to achieve the object of the present invention. [0023] Various methods can be applied as the hot stretching method, such as a method in which the undrawn yarn is stretched while being in contact with a heating body such as a heat plate, a method in which the yarn is stretched in a heating medium, and a method in which the yarn is stretched in a hot air heating bath. Examples include a method of stretching in a medium, a method of stretching using a dielectric heating method, and a hot air heating bath is preferably used. Length of these stretching machines (length of heating zone)
is set in conjunction with the stretching speed, but when the stretching speed is set to 10 m
/min or more, the length is preferably 3 m or more, and it is better to increase the length as the stretching speed increases. Also,
The temperature during hot stretching is not particularly limited, but for example, when stretching in a hot air heating bath, the inlet temperature is set to 200°C.
℃ or more, and the outlet temperature is preferably 260℃ or less. When the fibers to which a catalyst for promoting the dehydration reaction has been applied are hot-stretched at a speed of 10 m/min or more, the hot-stretching and dehydration reactions proceed simultaneously, but in order to allow the dehydration reaction to proceed sufficiently, further heat treatment is required after the hot-stretching. You may do so. The heat treatment is performed at a temperature 5 to 10°C higher than the maximum temperature of hot stretching, for 1/2 to 1/3 of the hot stretching time, for a constant length (relaxation rate 0%).
Alternatively, it is preferable to carry out under a relaxation rate of 10% or less. In the present invention, the total stretching ratio is preferably 10 times or more, more preferably 15 times or more. The total stretching ratio here is obtained by multiplying all the cold stretching ratios applied before hot stretching by the hot stretching ratio and (1-relaxation ratio during heat treatment/100). According to the present invention, PVA with a commercially available degree of polymerization is used to achieve excellent abrasion resistance (particularly wet abrasion resistance) and hot water resistance, as well as high strength and high initial modulus of elasticity. It is possible to manufacture PVA-based fibers with high productivity at low cost. Furthermore, the PVA fiber of the present invention obtained in this manner has a tensile strength of 15 g/d or more and a tensile strength of 25 g/d or more.
It has an initial elastic modulus of 0 g/d or more and has hot water resistance.
It has previously unknown properties such as a temperature of 140℃ or higher and an abrasion resistance of 200 or higher, and is used not only in fishing nets and ropes, which are typical uses for PVA fibers, but also in cement and concrete produced by autoclave curing. It can also be used to reinforce manufactured building materials. [Function] In the present invention, PVA fibers with excellent abrasion resistance and hot water resistance, high strength, and high initial elastic modulus can be obtained because they have a low degree of orientation, low crystallinity, and low porosity. Since a catalyst for promoting dehydration reaction is added to the unheated drawn yarn, the catalyst penetrates well into the fiber and no adhesion spots occur;
By hot stretching at a speed of 0 m/min or more, the dehydration reaction and stretching proceed simultaneously, so the strength does not decrease. Furthermore, the dehydration reaction occurs between the hydroxyl groups between the molecules, creating ether bonds between the molecules, and the molecular chain It is recognized that this is to increase the cohesive force between the two. [Example] Next, the present invention will be specifically explained with reference to Examples. Examples 1 to 3, Comparative Example 1 As shown in Table 1, the degree of polymerization was 1700, 3900, and 700.
A DMSO solution of PVA of
After dry/wet spinning through an air gap of 10 mm in a methanol coagulation bath at 1/2 min., DMSO was extracted with methanol, and the concentration was adjusted to 0.5 normal in an oil solution mainly composed of polyoxyethylene sorbitan trioleate. A catalyst solution containing phosphoric acid was added in an amount of 0.9% by weight, and the fiber was further dried at 95° C. to obtain an undrawn yarn. The syndiotacticity of these PVAs is 48.
%, and in Examples 1 to 3, spinnerets in which the inner diameters of stainless steel cylindrical tubes were 0.6, 0.7, and 0.9 mm were used, respectively. Next, these undrawn yarns were stretched to length 4 with an inlet temperature of 205°C and an outlet temperature of 260°C.
17.5 m at a stretching speed of 20 m/min using a hot air heating bath.
The fibers were stretched twice and then continuously heat-treated for a fixed length of 6 seconds in a heat treatment machine with an internal temperature set at 265°C to obtain fibers with a nominal fineness of 1500d/300f. The manufacturing conditions and the performance of the obtained fibers are shown in Table 1, and the fibers obtained in Examples 1 to 3 were excellent in both tensile strength, initial modulus, abrasion resistance, and hot water resistance. In addition, as Comparative Example 1, as shown in Table 1, a material with an inner diameter of 0.5 mm was made from PVA with a polymerization degree of 1300.
PVA-based fibers were produced in the same manner using a spinneret embedded with stainless steel cylindrical tubes, but the resulting fibers were inferior in both tensile strength and hot water resistance. Comparative Example 2 An undrawn yarn collected in the same manner as in Example 2 except that phosphoric acid was not mixed in the oil agent was hot-stretched in the same manner as in Example 2.
A methanol/water mixed solution of 0.1N phosphoric acid was applied and dried at 120°C, and then continued until the internal temperature reached 26°C.
The relaxation rate is 2.5% in a heat treatment machine set at 5℃.
It was heat treated as The abrasion resistance of the obtained fiber is 188
Moreover, both tensile strength and initial elastic modulus were inferior to the fiber obtained in Example 2. Comparative Example 3 The undrawn yarn obtained in Example 2 was heated at an inlet temperature of 205°C.
Using a 4 m long hot air heating bath with an outlet temperature of 260°C and a stretching speed of 8 m/min, the maximum stretching ratio was determined to be only 14.5 times. Therefore, hot stretching was performed to 13.1 times, which corresponds to 90% of the maximum stretching ratio, and heat treatment was performed in the same manner as in Example 2 to obtain a PVA-based fiber. The performance of this fiber is shown in Table 1, and it was found to be inferior to the fiber obtained in Example 2 in terms of tensile strength, initial elastic modulus, and hot water resistance. Example 4 A 12% by weight DMSO solution of PVA with a polymerization degree of 5100 was prepared by adding 0.24% by weight of phosphoric acid to PVA.
This spinning dope was discharged at a linear speed of 8 m/min using a spinneret in which 232 stainless steel cylindrical thin tubes with an inner diameter of 0.5 mm were embedded so as to protrude 3 mm from the spinning dope exit side.
Dry and wet spinning was carried out through a 10 mm air gap in a methanol coagulation bath at a spinning draft of 2.0, and D
After removing MSO, 0.5% by weight of a catalyst solution in which para-toluenesulfonic acid was mixed to a concentration of 0.02N was added to an oil agent mainly composed of polyoxyethylene oleyl ether, and then 90% by weight of a catalyst solution was added. It was dried at ℃ to obtain an undrawn yarn. This undrawn yarn was drawn 17.8 times at a drawing speed of 30 m/min using a 4 m long hot air heating bath with an inlet temperature of 205°C and an outlet temperature of 255°C, and was further continuously drawn at an internal temperature of 255°C. was heat treated for 5 seconds at a relaxation rate of 3.5% in a heat treatment machine set at 260°C to obtain fibers with a nominal fineness of 1500d/232f. This fiber had excellent properties such as tensile strength of 18.7 g/d, initial modulus of elasticity of 370 g/d, hot water resistance of 157° C., and abrasion resistance of 375. Furthermore, when the solubility of this fiber in DMSO at 120°C was determined, only 15.7% was dissolved in 2 hours, indicating that it had excellent DMSO resistance. Example 5 Using PVA with a degree of polymerization of 5100, an aqueous solution prepared by adding 2.1% by weight of boric acid and adjusting the pH to 4.2 was used as a spinning stock solution, and a spinneret with 500 holes was used. At a spinning draft of 0.25, wet spinning was performed in a coagulation bath containing 350 g/l of sodium sulfate and 40 g/l of caustic soda, followed by 250 g/l of sodium sulfate and 30 g/l of sulfuric acid.
After spinning and drawing 4.5 times while neutralizing in a neutralizing bath, washing with water, and applying an oil agent containing 1 N of phosphoric acid and mainly composed of polyoxyethylene lauryl amino ether. , and dried to obtain an undrawn yarn. This undrawn yarn was hot-stretched four times at a drawing speed of 60 m/min in a 5 m long hot air oven with an internal temperature set to 245°C, and then continuously drawn in a heat treatment machine with an internal temperature set to 250°C. It was heat treated for a fixed length. Table 1 shows the performance of the obtained fibers. [Table 1] Example 6 A 15% by weight DMSO solution of PVA with a degree of polymerization of 3900 was prepared by adding 0.16% by weight of phosphoric acid to PVA.
This spinning stock solution was dried through a 30 mm air gap in a methanol coagulation bath at a linear discharge speed of 6 m/min and a spinning draft of 1.5 using a spinneret embedded with 150 stainless steel cylindrical tubes with an inner diameter of 0.35 mm. Wet spinning,
DMSO with methanol using a countercurrent catalytic solvent extraction device
After removing the phosphoric acid, 1.1% by weight of a catalyst solution mixed with phosphoric acid to a concentration of 0.4N was added to an oil agent mainly composed of polyoxyethylene oleyl ether, and then dried at 85°C. An undrawn yarn was obtained. This undrawn yarn was drawn 17.2 times at a drawing speed of 60 m/min using a 6 m long hot air heating furnace with an inlet temperature of 220°C and an outlet temperature of 260°C, without subsequent heat treatment. The fiber was wound to obtain a fiber with a nominal fineness of 1200d/150f. This fiber has a tensile strength of 18.8 g/d and an initial elastic modulus of 330.
g/d, hot water resistance of 155° C., and excellent abrasion resistance of 370. Effect of the invention: The PVA fiber of the present invention not only has excellent strength and initial elastic modulus, but also has better abrasion resistance and hot water resistance than conventional PVA fibers. network,
It can be applied not only to the field of ropes, but also to rubber reinforcement applications such as rubber hoses and conveyor belts. Further, according to the production method of the present invention, PVA with a commercially available polymerization degree
Therefore, it is possible to produce PVA-based fibers with excellent abrasion resistance and hot water resistance, high strength, and high initial elastic modulus at low cost and with good productivity.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an example of a device used for measuring wear resistance in the present invention.

[Explanation of symbols]

1 Sample 2, 2' Pulley supporting the sample 3 Edge 4 Load 5 Load pulley 6 Hook for fixing the sample

Claims (2)

[Claims] Claim 1: Made of polyvinyl alcohol with a degree of polymerization of 1,500 or more and 7,000 or less, and has a tensile strength of 15 g/
A polyvinyl alcohol fiber having an initial elastic modulus of 250 g/d or more, hot water resistance of 140° C. or more, and abrasion resistance of 200 or more. 2. A polyvinyl alcohol fiber comprising polyvinyl alcohol having a polymerization degree of 1,500 or more and 7,000 or less, which is hot-stretched at a speed of 10 m/min or more after being provided with a catalyst for promoting a dehydration reaction. Manufacturing method.