JP4025742B2 - Polyvinyl alcohol crosslinked fiber and method for producing the same - Google Patents

Description

The present invention relates to a crosslinked polyvinyl alcohol fiber and a method for producing the same, and more specifically, polyvinyl chloride having a degree of polymerization of 1,000 or more and a degree of saponification of 97.0 mol% or more in dimethyl sulfoxide (hereinafter referred to as DMSO). Alcohol resin is dissolved, dry and wet gel spinning using methanol as a coagulation solvent, stretching and heat treatment to give a twisted 500-3,000 denier polyvinyl alcohol drawn yarn to produce a lower twisted yarn. After three or three yarns are combined and an upper twist is added to produce a raw cord and wound on a crosslinking reaction bobbin, the raw cord wound on the crosslinking reaction bobbin is mixed with an aromatic aldehyde compound and an acid catalyst. A cross-linking agent charging apparatus capable of effectively inducing a cross-linking reaction of a wound raw cord when the cross-linking reaction is proceeded with a cross-linking aqueous solution containing the same, and using the same It relates polyvinyl alcohol crosslinked fibers produced.

Polyvinyl alcohol ( also referred to as PVA) fiber has superior strength and elastic modulus compared to general-purpose fibers such as polyamide, polyester, and polyacrylonitrile fiber, and especially has excellent adhesion, water dispersibility, alkali resistance and chemical resistance. Because it is excellent, it is used as a variety of industrial materials.

  Recently, it has been used in various ways as a reinforcing material for concrete and cement and a reinforcing material such as rubber and plastic, and has been researched and developed as a material having high applicability to new fields.

To date, various methods for obtaining high strength polyvinyl alcohol fibers have been introduced.

In Patent Document 1, a gel spinning method (Patent Document 2) that uses high molecular weight polyethylene as a raw material to obtain high-strength fibers through a high-strength drawing step is used in a method for producing polyvinyl alcohol fibers. A method for producing high strength polyvinyl alcohol fibers is disclosed. In the gel spinning method, a polymer compound and a solvent are mixed to produce a uniform solution, and then high-strength fibers are drawn by stretching at a high magnification while appropriately adjusting the state separation and gelation speed that occur in the spinning process. It is a common method of manufacturing.

In addition, a technique related to a method for producing a polyvinyl alcohol fiber having superior mechanical properties by such a gel spinning method has been announced.

Patent Document 3 discloses a spinning hole having a spinning hole diameter (D) of 0.1 to 1 mm and a ratio of the spinning hole length (L) to the diameter of the spinning hole (L / D) of 3 to 20. using a spinneret having, by a dry-wet spinning, tensile strength 22 g / denier or more and an initial modulus 440 g / denier or more, polyvinyl single yarn fineness uniformity (CV) value of 5% or less A method for producing alcohol multifilament fibers is disclosed.

However, although the polyvinyl alcohol fiber manufactured by the above method has excellent mechanical properties, it is dissolved in high-temperature hot water at 100 ° C. or higher due to the hydrophilic property of the polyvinyl alcohol resin itself, or mechanical properties. Therefore, there are many restrictions on the use of tire cords and the like having the largest market among industrial fibers.

There is a very small amount of moisture inside the tire, but if the tire is damaged, there is a risk that excessive amount of water may flow in, and the moisture temperature is about 130 ° C. due to high-speed driving of the automobile. If it rises up, it will be hydrothermalized and damage the polyvinyl alcohol fiber, jeopardizing the stability of the car. As a result, ordinary polyvinyl alcohol fibers could not be easily used as a tire reinforcing material.

Further, when used as a tire cord, the fatigue resistance is remarkably lowered due to the high crystallinity of the polyvinyl alcohol fiber, so that the problem of being weak against fatigue must also be solved.

Therefore, as a conventional technique for improving hot water resistance and fatigue resistance, there are various methods such as spinning high-polymerization polyvinyl alcohol , high-strength heat drawing and heat treatment, acetalization, acid-catalyzed crosslinking reaction, etc. Although developed, it is difficult to apply industrially to filaments, and there are problems when using this technique with hot water above 130 ° C.

  In particular, in the conventionally proposed crosslinking technique, a crosslinking agent is mixed into the spinning dope before the drawing process, or a crosslinking agent is added in the extraction process or the oil process.

  In Patent Document 4, as a method for producing a polyvinyl alcohol fiber excellent in hot water resistance, a raw yarn containing an acetal compound of an aliphatic dialdehyde as a cross-linking agent is produced, and this is subjected to dry heat drawing, and then an acid is used. A method of crosslinking treatment was proposed.

  Patent Document 5 proposes a method for producing a polyvinyl alcohol fiber excellent in hot water resistance by subjecting a raw yarn containing ammonium sulfate as a crosslinking agent to dry heat drawing and then crosslinking treatment.

As described above, in the crosslinking technique proposed so far, a crosslinking agent is mixed into the spinning dope before the drawing process, or a crosslinking agent is added in the extraction process or the oil process. In such a conventional crosslinking treatment method, when the crosslinking agent contained in the unstretched polyvinyl alcohol yarn is thermally stretched at a high temperature of 200 ° C. or higher, a crosslinking reaction is caused to lower the stretchability or the boiling point is low. Since the crosslinking agent is volatilized and decreases the crosslinking efficiency, it is difficult to have hot water resistance of 130 ° C. or higher.

In addition, since the crosslinking treatment method as described above is simply performed by immersing the bobbin around which the undrawn yarn is wound into the crosslinking agent for crosslinking, the undrawn yarn wound inside the bobbin has a crosslinking agent. Since it cannot permeate, the unstretched yarn wound on the inside of the bobbin is not completely cross-linked, or there is a significant difference between the cross-linking treatment on the outside and inside of the unstretched yarn wound on the bobbin. There was a point.
US Pat. No. 4,440,711 US Pat. No. 4,698,194 JP 7-109616 A Korean Patent Publication No. 210727 Korean Published Patent Publication No. 96-41438

  In the present invention, a twisted 500-3,000 denier polyvinyl alcohol drawn yarn is twisted to produce a lower twisted yarn, and two or three lower twisted yarns are combined and an upper twist is added to produce a raw cord. After being wound on the crosslinking reaction bobbin, the raw cord wound on the crosslinking reaction bobbin is allowed to proceed with a crosslinking reaction with a crosslinking aqueous solution containing an aromatic aldehyde compound and an acid catalyst. The technical problem is placed on providing a cross-linking agent charging apparatus capable of exhibiting high-strength fiber properties and a polyvinyl alcohol cross-linked fiber manufactured using the same.

  According to the present invention described above, (A) after spinning polyvinyl alcohol having a polymerization degree of 1,000 to 7,000 by dry-wet or wet spinning, the undrawn yarn produced is drawn at a high magnification, A step of heat-treating, and (B) a step of producing a raw cord by applying twist to the drawn polyvinyl alcohol yarn to produce a lower twisted yarn, adding two or three lower twisted yarns and adding an upper twist. And (C) a raw material cord that has been subjected to a crosslinking treatment by immersing the raw cord in a crosslinking agent and subjecting it to a crosslinking reaction treatment.

Further, the present invention provides a cylindrical bobbin in which a medium hole is formed, a plurality of through holes are formed on a circumferential surface and a polyvinyl alcohol raw cord is wound, and the crosslinking agent is filled. There is provided a cross-linking agent charging device comprising a sealed container provided so that the cross-linking reaction bobbin is immersed therein.

  In the present invention, (A) Polyvinyl alcohol having a polymerization degree of 1,000 to 7,000 and a saponification degree of 97.0 mol% or more is dissolved in dimethyl sulfoxide and spun by dry wet or wet spinning. A step of heat-treating the produced undrawn yarn at a high magnification, and (B) twisting the polyvinyl alcohol drawn yarn to produce a lower twisted yarn. Two or three lower twisted yarns are produced. A step of producing a raw cord by adding main twist and adding an upper twist; and (C) a step of adding alcohol to a cross-linking aqueous solution containing an aromatic aldehyde compound and an acid catalyst and reacting the raw cord with the cross-linking device. A cross-linked raw cord produced by a method comprising:

  The alcohol added to the aqueous crosslinking solution in the step (C) is preferably methanol.

  Moreover, it is preferable that content of the alcohol added to bridge | crosslinking aqueous solution at the said (C) process is 1 to 30 weight%.

  The content of the aromatic aldehyde compound crosslinked in the raw cord in the step (C) is preferably 0.1 to 5.0% by weight.

  Moreover, it is preferable that the aromatic aldehyde compound crosslinked in the raw cord in the step (C) is terephthaldicarboxaldehyde (TDA).

  In addition, when the raw cord is subjected to a crosslinking treatment reaction in the step (C), it is preferable to use an acid catalyst.

  The acid catalyst in the step (C) is preferably acetic acid.

In addition, the present invention provides a dip cord for a tire cord having the following physical properties, which is produced by treating the crosslinked raw cord with an adhesive liquid (RFL).
(1) Cutting load 20.0 to 50.0 kg, (2) Fineness 1,000 to 6,000 denier, (3) Hot water resistance 130 ° C. or higher, (4) Fatigue resistance 80% or higher.

  According to the present invention, a twisted 500-3,000 denier polyvinyl alcohol drawn yarn is twisted to produce a lower twisted yarn, two or three lower twisted yarns are combined, and an upper twist is added to produce a raw cord. After the production and winding on the crosslinking reaction bobbin, the raw cord wound on the crosslinking reaction bobbin is subjected to a crosslinking reaction by adding alcohol to a crosslinking aqueous solution containing an aromatic aldehyde compound and an acid catalyst. A cross-linked raw cord to be produced is provided. The raw cord thus crosslinked is excellent in hot water resistance and can be used for tire cords.

As the crosslinking agent used in the present invention, an aldehyde compound capable of crosslinking reaction with the hydroxy group of polyvinyl alcohol is used, and a compound having two or more aldehyde groups is preferably used in order to increase the crosslinking efficiency. . As the aldehyde compound, an aromatic compound that penetrates only into the fiber non-crystalline region is more preferable.

  Examples of such aromatic aldehyde compounds include terephthaldicarboxaldehyde (TDA), isophthaldicarboxaldehyde (IDA), and naphthaldicarboxaldehyde (NDA). Two or more aldehyde compounds are used in combination. Also good.

  In the present invention, a preferred aromatic aldehyde compound is terephthaldicarboxaldehyde (TDA).

  The core technical matter of the present invention is the use of an aromatic aldehyde that can penetrate only into the amorphous region of the drawn yarn as a cross-linking agent. Since the aromatic aldehyde penetrates mainly only into the non-crystalline region, it is possible to prevent the strength of the drawn yarn from being lowered by the crosslinking agent.

  The most important feature of the present invention is the crosslinking process. In general crosslinking treatment, a method of dissolving the crosslinking agent in an organic solvent in the extraction process was used to infiltrate the crosslinking agent into the inside of the fiber. Thus, the crosslinking agent inside the unstretched fiber is 200 ° C. Since the stretching workability is lowered in the above high-temperature hot stretching process, it cannot have sufficient hot water resistance and fatigue resistance. The cross-linking agent used in the extraction process makes it difficult to recover the organic solvent, making the overall process difficult.

Therefore, in the present invention, in order to increase the crosslinking efficiency and prevent the fiber from being damaged, a cross-linking agent is infiltrated into the twisted polyvinyl alcohol raw cord and then subjected to a cross-linking reaction, whereby a hot water resistance of 130 ° C. or higher. And high strength polyvinyl alcohol fiber having high fatigue resistance of 80% or more.

  Another core technical matter of the present invention is to add a raw cord to a crosslinking aqueous solution containing an aromatic aldehyde compound and an acid catalyst by adding an alcohol. By adding alcohol to the cross-linking liquid, it is possible to prevent the strength reduction after the cross-linking reaction at a considerable level.

Below, the manufacturing method of the polyvinyl alcohol fiber of this invention is demonstrated concretely.

Polyvinyl alcohol having a polymerization degree of about 1,000 to 7,000 is used, and it is effective to use polyvinyl alcohol having a high polymerization degree of 1,500 to 4,000. If the degree of polymerization is 1,000 or less, it is difficult to form fibers, and if it is 7,000 or more, the viscosity is too high and the spinning process is reduced. Since the high strength polyvinyl alcohol fiber normally used in the industrial material field requires hot water resistance, polyvinyl alcohol having a saponification degree of 97.0 mol% or more is used. As the organic solvent, ethylene glycol, glycerin, and DMSO can be used, but it is appropriate to use DMSO, which has the highest solubility in polyvinyl alcohol . DMSO is preferably used after being purified to have a water content of several tens of ppm or less.

The concentration of the polyvinyl alcohol dope is preferably adjusted so that the viscosity is in the range of 50 to 4,000 poise. To obtain excellent physical properties, the viscosity is 500 to 3,000 poise. Is effective. If the viscosity is 50 or less, it is difficult to form the fiber, and if it is 4,000 or more, the spinnability of the fiber is lowered, which is not preferable.

The coagulation tank can be spun at a temperature of −30 to 30 ° C., but it is effective to set the temperature of the coagulation tank to −10 to 10 ° C. for uniform gel formation. If the temperature of the solidified layer is −30 ° C. or lower, the polyvinyl alcohol spinning dope may be frozen, which is not preferable. If the temperature of the coagulation tank is 30 ° C. or higher, gel formation becomes impossible and spinnability is lowered.

Polyvinyl alcohol fiber production methods include a dry method, a wet method, and a dry-wet method in which these two methods are mixed. In a high-strength polyvinyl alcohol fiber production method that requires a high-magnification drawing process, a dry-wet method is used. It is effective. For the production of polyvinyl alcohol filaments, the air gap in the dry / wet method can be 5 to 200 mm, but a narrow air gap of 5 to 50 mm is preferable for high-strength heat stretching. When the air gap is 5 mm or less, workability is lowered. On the other hand, if it is 200 mm or more, the degree of crystallinity is higher than that of gelation, so that high-magnification thermal drawing becomes impossible, and fusion between fibers occurs in the nozzle cross section, resulting in decreased productivity. To do.

The drawing process in the production method of high strength polyvinyl alcohol fiber is very important for improving high strength and hot water resistance. Heating method of drawing step is hot air heated and rollers heated, but since the fiber surface easily damaged filaments in contact with the roller surface in the roller heating, hot air heating type for high strength polyvinyl alcohol fiber produced More effective. Heating is possible at a temperature of 140 to 250 ° C, but 160 to 230 ° C is preferable. Since the molecular chain does not behave sufficiently at a heating temperature of 140 ° C. or lower, high-strength thermal stretching is impossible, and at 250 ° C. or higher, polyvinyl alcohol is easily decomposed, resulting in a decrease in physical properties.

Next, polyvinyl alcohol fibers used as tire cords among industrial materials are required to have high strength and fatigue resistance. For this purpose, polyvinyl alcohol drawn yarns are twisted to produce raw cords. When the number of twists is increased in a general synthetic fiber twisting process, the strength is reduced, but the fatigue resistance tends to be improved. Therefore, it is very important to select an appropriate number of twists depending on the purpose of use. For example, a tire cord used for a tire cacass part is used by giving a twist number of a lower twist and an upper twist with 1500 d / 2p as 300 to 500 TPM (twist number / M).

In order to improve hot water resistance and fatigue resistance, a twisted polyvinyl alcohol raw cord is reacted with a crosslinking agent.

In order to penetrate the cross-linking agent only into the amorphous region of the polyvinyl alcohol fibers twisted at high magnification, an aromatic aldehyde is used as the cross-linking agent as previously described.

  In the present invention, terephthaldicarboxaldehyde (TDA) can be mentioned as a preferred aromatic aldehyde compound. A crosslinking compound having a concentration of 0.1 to 5% by weight with respect to the fiber is used, but a compound having a range of 0.5 to 2.0% by weight is preferred. When the concentration of the crosslinking compound is 0.1% by weight or less, the hot water resistance is not sufficient at 130 ° C. or less. When the concentration of the cross-linking compound is 5.0% by weight or more, the strength reduction is large, and the use as a high-strength tire cord becomes difficult.

In order to react the crosslinking compound with the OH group of the polyvinyl alcohol , an acid catalyst is required in the aqueous solution of the crosslinking compound. An acid such as sulfuric acid or acetic acid can be used as the acid catalyst, but acetic acid is preferred in view of adjusting the reaction rate and stability. The concentration of the acid catalyst is preferably 5 to 30% by weight with respect to the aqueous solution of the crosslinking compound. If the concentration of the acid catalyst is less than 5% by weight, the speed of the crosslinking reaction proceeds too slowly, and if it exceeds 30% by weight, it is difficult to remove in the water washing step after the reaction.

  Another core technical matter of the present invention is that the raw cord is subjected to a crosslinking reaction by adding an alcohol to a crosslinking aqueous solution containing an aromatic aldehyde compound and an acid catalyst. By adding alcohol to the cross-linking liquid, it was possible to prevent the strength decrease after the cross-linking reaction to a considerable level.

  Preferred alcohols added to the aqueous crosslinking solution in the present invention include methanol, ethanol, propanol, butanol, etc. Among them, methanol is more preferable. The alcohol added is preferably in the range of 1 to 30% by weight with respect to the aqueous crosslinking solution. If the alcohol content is less than 1% by weight, the strength is greatly reduced during the cross-linking reaction, making it difficult to use as a high-strength tire cord. If the alcohol content exceeds 30% by weight, it is disadvantageous in terms of cost. Is not preferred because it proceeds too slowly.

  Another core technical matter of the present invention is that two or three polyvinyl alcohol drawn yarns are combined to produce a raw cord wound on a crosslinking reaction bobbin, and then wound on the crosslinking reaction bobbin. It is to immerse the obtained raw cord in a cross-linking solution to advance the cross-linking reaction.

In order to infiltrate the cross-linking compound into the amorphous region of the highly crystalline polyvinyl alcohol fiber, a method of increasing the activity of the cross-linking compound by increasing the temperature of the reaction solution to 50 ° C. or higher is used by pressurizing the reaction vessel. did. The time for the crosslinking reaction varies depending on the crosslinking compound and conditions, but 30 minutes or more is effective. However, when the crosslinking reaction is carried out for an excessively long time, the decrease in strength becomes large, which is not preferable.

The polyvinyl alcohol raw cord subjected to the cross-linking treatment is washed and dried, and an RFL solution is attached (hereinafter referred to as dipping) in order to improve the adhesion to rubber, followed by drying and heat treatment. The dipping process will be described in more detail. Dipping is achieved by impregnating a resin layer called RFL (Resorcinol-Formalin-Latex) on the surface of the fiber, which is originally a fiber for tire cords having poor adhesion to rubber. It is to be implemented to improve the disadvantages.

  In this invention, what was prepared using the following methods can be used as an adhesive liquid for adhesion | attachment with a PVA raw | natural cord and rubber | gum. The examples described below are provided for a clearer understanding of the present invention and are not intended to limit the scope of the present invention.

29.4% by weight Resorcinol 45.6 parts by weight Pure water 255.5 parts by weight 37% formalin 20 parts by weight 10% by weight sodium hydroxide 3.8 parts by weight

  After preparing the said liquid, after making it react with stirring at 25 degreeC for 5 hours, the following component is added.

40% by weight VP-latex 300 parts by weight Pure water 129 parts by weight 28% ammonia water 23.8 parts by weight

  After adding the above components, the mixture is aged at 25 ° C. for 20 hours to maintain a solid content concentration of 19.05%.

In order to prevent the RFL liquid from penetrating deeply into the interior when attaching the RFL liquid, a 0.5 to 3% stretch is applied when attaching the RFL liquid, and the adhesion rate of the RFL liquid ( (Hereinafter referred to as DPU) is 3.0 to 9.0% by weight. When the stretch is 0.5% or less, the DPU becomes excessively 9% by weight or more and penetrates deeply into the single fiber to reduce fatigue resistance. On the other hand, if the stretch is 3% or more, excessive tension is applied to the raw cord, causing damage to the raw cord. The heat treatment must be performed at 170 to 230 ° C., and is preferably performed at 200 to 220 ° C., in which the movement of the polyvinyl alcohol molecules in the amorphous portion is the best. At this time, it is possible to manufacture a high-strength polyvinyl alcohol dip cord by minimizing the tension applied to the fiber and maximizing the heat treatment effect by allowing the maximum molecular movement. In the heat treatment step performed after immersing the raw cord in the dipping solution, it is important to set the stretch rate to 0 to -5%. If the stretch is 0% or more in the heat treatment, the elongation of the dip cord is low, and therefore, when used for a tire cord that requires high fatigue resistance of 60% or less, a cord cut or detachment phenomenon occurs. On the other hand, if it is -5% or less, recrystallization occurs in the direction perpendicular to the fiber axis due to excessive molecular movement, resulting in a decrease in strength. If the cross-linking agent that has not been washed in the previous cross-linking treatment process remains inside the fiber, it acts as an impurity on the product in which the polyvinyl alcohol fiber is used. Reaction or volatilization can further improve the crosslinking efficiency.

  Here, a cross-linking reaction bobbin used in the above-described cross-linking treatment and a use state thereof will be briefly described.

  FIG. 1 is a perspective view showing a cross-linking reaction bobbin according to the present invention, and FIG. 2 is a use state diagram showing a use state of the cross-linking reaction bobbin according to the present invention.

In the cross-linking process described above, a cross-linking reaction bobbin 10 is provided, and the cross-linking reaction bobbin 10 is separated into a first bobbin 10a forming one side of the cross-linking reaction bobbin 10 and the first bobbin 10a. A second bobbin 10b is formed which can be coupled to form the other side of the bobbin 10 for cross-linking reaction, and the first and second bobbins 10a and 10b are formed with inner holes 16a and 16b, respectively, and a large number are provided on the circumferential surface. Cylindrical bobbin shafts 12a and 12b around which the polyvinyl alcohol raw cord 1 is wound are formed, and the first and second bobbins 10a and 10b are provided at the inner ends thereof. A corresponding coupling jaw 18a and a coupling groove 18b are formed for coupling the one bobbin 10a and the second bobbin 10b.

Here, the first bobbin boule 14a coupled to the first bobbin 10a is provided to seal one side of the inner hole 16a formed by the coupled cross-linking reaction bobbin 10, and The second bobbin boule wheel 14b coupled to the two bobbins 10b is formed of the inner holes 16a and 16b formed in the cross-linking reaction bobbin 10 by the supply device that supplies the cross-linking agent 2 at a predetermined pressure. A cross-linking agent supply line 30 for supplying the cross-linking agent 2 so that the cross-linking agent 2 is introduced into the inside of the polyvinyl alcohol raw cord 1 wound on the cross-linking reaction bobbin 10 by being pressurized or depressurized. Provided.

The cross-linking reaction bobbin 10 wound with the polyvinyl alcohol raw cord 1 is provided in a state where it is immersed in the cross-linking agent 2 in a closed container 40 filled with the cross-linking agent 2 during the cross-linking treatment. The cross-linking agent 2 is supplied by being pressurized or depressurized at a predetermined pressure through the conduit 30, and the supplied cross-linking agent 2 has a large number of through-holes formed in the bobbin shafts 12 a and 12 b of the cross-linking reaction bobbin 10. The polyvinyl alcohol raw cord 1 wound through 13a and 13b was moved from the inside to the outside, or moved from the outside to the inside of the polyvinyl alcohol raw cord 1, and wound on the cross-linking reaction bobbin 10. The inside and outside of the polyvinyl alcohol raw cord 1 can be uniformly cross-linked.

  Hereinafter, the configuration and effects of the present invention will be described in more detail with reference to specific examples and comparative examples. However, these examples are intended to make the present invention more clearly understood, and are within the scope of the present invention. It is not intended to limit. In Examples and Comparative Examples, the physical properties were evaluated by the following methods.

(A) Polyvinyl alcohol cord strong (kgf)
After drying at 107 ° C. for 2 hours, an 80 TPM (80 turns / m) twist is added using an Instron low-speed extension type tensile tester, and then the sample length is 250 mm and the tensile speed is 300 m / min.

(B) Hot water resistance (WTb, ° C)
A 3,000 denier one of the twisted raw cords is selected and cut to 4 cm, and the end load is adjusted to 3 g / piece. After this is deposited in a pressure glass container with water, the temperature at which the fiber is cut is measured while being heated at a rate of 2 ° C./min.

(C) Fatigue resistance After a fatigue test using a Goodrich Disc Fatigue Tester, which is commonly used for fatigue testing of tire cords, the residual strength is measured and the resistance to fatigue is measured. The degree of fatigue was compared. The fatigue test conditions were 120 ° C., 2500 RPM, compression 10% and 18%. After the fatigue test, the rubber and cord were separated after being immersed in a tetrachloroethylene solution for 24 hours, and the residual strength was measured. . The residual strength was measured after drying at 107 ° C. for 2 hours and using an ordinary tensile strength tester according to the method (a) described above.

Example 1
Polyvinyl alcohol was used in a powder form having a saponification degree and a polymerization degree of 99.9 mol% and 2,000, respectively. For methyl alcohol and DMSO, a purified solvent having a water content of 100 ppm or more was used. As the content of methyl alcohol in the solvent is 5 vol%, a mixture of DMSO and methyl alcohol to prepare a mixed solvent, so that a 22 wt% with respect to polyvinyl alcohol spinning dope, the polyvinyl alcohol Dissolved. Thereafter, the polyvinyl alcohol fiber was dissolved by a dry and wet spinning method using gel spinning. At this time, the number and diameter of the nozzles were 500 and 0.5 mm, respectively, and a circular nozzle having an L / D of 5 was used. The air gap was 50 mm, and methanol was used as the solvent in the coagulation bath. At this time, the coagulation bath has a solvent / methanol mixing ratio of 2
The conditions of 0/80, temperature 0 ° C. were maintained. After passing through the extraction tank, the polyvinyl alcohol fiber should not have DMSO as a solvent. If the solvent remains in the filament, it is discolored in a high-temperature hot drawing process, which is an important cause of deterioration of physical properties of the final filament. The hot drawing was performed using a two-stage hot air heating method, and the hot air heating temperature was adjusted to 200 ° C. in the first step and 220 ° C. in the second step so that the total draw ratio was 13.5 times. As a result, a high-strength polyvinyl alcohol fiber having a strength of 13.0 g / d and an elongation of 7.0% was produced. Such a drawn yarn is twisted so that the lower twist and the upper twist are 300/300 TPM, respectively, to produce a cord yarn. The produced raw cord has a strength of 34 kgf. The raw cord wound around the cross-linking reaction bobbin is immersed in terephthaldicarboxaldehyde (TDA), which is an aromatic aldehyde, by a cross-linking agent feeding apparatus capable of effectively inducing a cross-linking reaction and is subjected to a cross-linking treatment. The cross-linking treatment was carried out by preparing a cross-linking aqueous solution in which 2% by weight of terephthaldicarboxaldehyde and 10% by weight of acetic acid were dissolved in water, and then adding 10% by weight of methanol to the above cross-linking aqueous solution and winding it on a bobbin for cross-linking reaction. The raw raw cord was immersed at 70 ° C. for 1 hour and washed with water after the reaction. The strength of the raw cord after crosslinking is 33.6 kgf and is impregnated with an RFL solution to produce a polyvinyl alcohol dip cord. The results of physical property evaluation are shown in Table 1.

(Examples 2 and 3)
After adjusting the ratio of terephthaldicarboxaldehyde, acetic acid, and methanol at the ratio shown in Table 1, and crosslinking treatment, the strength and fatigue resistance were compared.

(Comparative Examples 1 and 2)
Comparative Example 1 is the case where the crosslinking treatment was not performed, and the results are shown in Table 1. Comparative Example 2 shows fiber properties when methanol in an aqueous solution was not used, and the results are shown in Table 1.

(Comparative Examples 3 and 4)
In Comparative Example 3, the crosslinking reaction was carried out for 6 hours, and the results are shown in Table 1. In Comparative Example 4, the reaction temperature was 30 ° C., and the results are shown in Table 1.

It is the perspective view which showed the bobbin for crosslinking reactions by this invention. 1 is a use state diagram illustrating a cross-linking agent charging apparatus using a cross-linking bobbin according to the present invention.

Explanation of symbols

  10: Crosslinking reaction bobbin, 12a, 12b: Bobbin shaft, 13a, 13b: Through hole, 30: Crosslinking agent supply conduit, 40: Airtight container.

Claims (8)

A cylindrical bobbin shaft is formed in which a medium hole is formed, a number of through holes are formed on the circumferential surface, and a polyvinyl alcohol raw cord is wound, and a coupling jaw is formed on the other side of the bobbin shaft. A bobbin shaft having one bobbin and a medium hole formed therein, a cylindrical bobbin shaft on which a plurality of through holes are formed on a circumferential surface and a polyvinyl alcohol raw cord is wound is provided, and the first bobbin shaft is provided on one side of the bobbin shaft. A cross-linking reaction bobbin composed of a second bobbin formed in a shape corresponding to the coupling jaw formed on the bobbin and formed with a coupling groove coupled to the coupling jaw;
A first bobbin hoyle that prevents the polyvinyl alcohol raw cord from being detached and joined to the other side of the first hole of the first bobbin and seals the hole of the cross-linking reaction bobbin;
While preventing the polyvinyl alcohol raw cord from being coupled and wound on one side of the second bobbin bore, the cross-linking agent is supplied to the inside of the bridging reaction bobbin under pressure or reduced pressure. A second bobbin hoile to which a crosslinker supply line is coupled;
A cross-linking agent charging apparatus, comprising: a closed container filled with the cross-linking agent and provided so that the cross-linking reaction bobbin is immersed in the cross-linking agent. (A) Polyvinyl alcohol having a polymerization degree of 1,000 to 7,000 and a saponification degree of 97.0 mol% or more is dissolved in dimethyl sulfoxide and spun by dry-wet or wet-spinning. A step of heat treatment after drawing the yarn;
(B) providing a twist to the drawn polyvinyl alcohol yarn to produce a lower twisted yarn, adding two or three lower twisted yarns and adding an upper twist to produce a raw cord;
(C) A crosslinking treatment produced by a method comprising a step of adding an alcohol to a crosslinking aqueous solution containing an aromatic aldehyde compound and an acid catalyst to cause the raw cord to undergo a crosslinking reaction using the crosslinking agent charging apparatus according to claim 1. Raw code. The crosslinked raw cord according to claim 2, wherein the alcohol added to the aqueous crosslinking solution in step (C) is methanol. The crosslinked raw cord according to claim 2, wherein the content of the alcohol added to the aqueous crosslinking solution in the step (C) is 1 to 30% by weight. The crosslinked raw material according to claim 2 , wherein the content of the aromatic aldehyde compound crosslinked in the raw cord in the step (C) is 0.1 to 5.0% by weight. code. The crosslinked raw cord according to claim 2, wherein the aromatic aldehyde compound crosslinked to the raw cord in the step (C) is terephthaldicarboxaldehyde (TDA). 3. The crosslinked raw cord according to claim 2, wherein the acid catalyst in the step (C) is acetic acid. A dip cord for tire cord having the following physical properties, produced by treating the raw cord subjected to crosslinking treatment according to claim 2 with an adhesive liquid (RFL).
(1) Cutting load 20.0 to 50.0 kg, (2) Fineness 1,000 to 6,000 denier, (3) Hot water resistance 130 ° C. or higher, (4) Fatigue resistance 80% or higher.