KR100595841B1 - Process for preparing high-tenacity polyvinyl alcohol fiber having excellent hot water resistance - Google Patents

Abstract

In the present invention, polyvinyl alcohol having a degree of polymerization of 1,500 to 7,000 and saponification degree of 99.9 mol% or more is dissolved in dimethyl sulfoxide, spun by dry or wet spinning, and then the polyvinyl alcohol unstretched yarn is stretched at high magnification and then heat-treated. A stretched yarn of 1000 to 2000 denier is manufactured through. After twisting the polyvinyl alcohol stretched yarn to produce a lower twisted yarn, the lower twisted yarn is spliced into two or three yarns and added to the upper edge to make a raw cord, wound on the bobbin, and the raw cord wound on the bobbin It provides a cross-linked raw cord prepared by a method comprising the step of immersing in an aliphatic aldehyde or acetal compound to crosslinking treatment. The cross-linked raw cord has hot water resistance and high fatigue resistance of 80% or higher at 180 ° C or higher.

Polyvinyl alcohol fiber, raw cord, crosslinking agent, aliphatic aldehyde, acetal compound, butanedial, crosslinking reaction

Description

Process for preparing high-tenacity polyvinyl alcohol fiber having excellent hot water resistance

The present invention relates to a polyvinyl alcohol (hereinafter, abbreviated as PVA) fiber having excellent hot water resistance and high strength fiber property, and a method of manufacturing the same, and more particularly, to dimethyl sulfoxide containing methanol. Is dissolved in PVA resin of 98% or more of saponification degree, and methanol is used as a coagulation solvent to give wet and dry gel spinning, twisting and applying heat treated fibers to produce twisted yarn. After plying three or three and adding the upper edge to make a raw cord, and after the crosslinking reaction treatment using an aromatic dialdehyde to the conjugated raw cord for tire reinforcement to exhibit excellent heat-resistant water resistance and high strength fiber properties It relates to a PVA fiber and a method for producing the same.

PVA fiber has higher strength and elastic modulus than polyamide, polyester, and polyacrylonitrile fiber, which are general-purpose fibers. Especially, PVA fiber is used as various industrial materials because of its excellent adhesion, water dispersibility, alkali resistance and chemical resistance. .

Recently, it has been used in various ways as reinforcing materials such as concrete and cement reinforcing materials and rubber and plastics, and has been researched and developed as a material having high application potential in new fields.

To date, several methods for obtaining high strength PVA fibers have been introduced.

In US Pat. No. 4,440,711, a high-strength PVA fiber is produced by using a gel spinning method (US Pat. No. 4,698,194) which can obtain a high strength fiber through a high magnification stretching process using a high molecular weight polyethylene as a raw material. Announced how. Gel spinning is a general method for preparing high strength fibers by mixing polymer compounds and solvents to produce a uniform solution and stretching at high magnification while appropriately controlling phase separation and gelation rates in the spinning process.

In addition, a technique for spinning wet and dry spinneret has been published to facilitate the gel spinning method.

Japanese Laid-Open Patent Publication No. 7-109616 has a spinneret having a spinneret diameter (D) of 0.1-1 mm and a spinneret length (L) and a ratio (L / D) of spinneret diameter of 3-20. A method of producing PVA multifilament fibers having a spinneret, wet and dry spinning having a tensile strength of 22 g / denier or more, an initial modulus of 440 g / denier or more, and a single yarn fineness uniformity (CV) value of 5% or less has been disclosed.

However, although the PVA fiber produced by the above method has excellent mechanical properties, the hydrophilic property of the PVA resin itself dissolves in high temperature hot water of 100 ° C. or higher and degrades the mechanical properties. There was this.

Although a very small amount of water is present inside the tire, excess water may be introduced when the tire is damaged, and the water may be thermally hydrated when the temperature of the tire rises to about 130 ° C according to high-speed driving. This impairs the stability of the vehicle as it damages the PVA fibers. As a result, ordinary PVA fibers could not be used as a reinforcing material for tires.

In addition, the high crystallinity of PVA fibers reduces fatigue resistance required for tire cords, automobile brake hoses, etc., and therefore, problems must be solved through crosslinking treatment.

Therefore, as a conventional technique for improving the heat and humidity resistance, various methods such as high magnification thermal stretching and heat treatment, acetalization, and crosslinking reaction by acid catalyst have been developed by spinning PVA of high polymerization degree, but problems occur when used at a high temperature of 130 ° C. or higher. .

In particular, the cross-linking technique proposed in the prior art mixed the cross-linking agent in the spinning Dope before the stretching process, or added the cross-linking agent in the extraction process or the emulsion process.

Republic of Korea Patent Publication No. 210727 is a method for producing a polyvinyl alcohol-based fiber having excellent hot water resistance to prepare a yarn containing an acetal compound of aliphatic dialdehyde as a crosslinking agent, and then dry heat-stretched and crosslinked using an acid Proposed method.

Korean Unexamined Patent Publication No. 96-41438 proposes a method of preparing polyvinyl alcohol-based fiber having excellent hot water resistance, followed by dry-heat stretching of a yarn containing ammonium sulfate crosslinking agent, followed by crosslinking treatment.

As described above, the crosslinking technique proposed so far has mixed the crosslinking agent in the spinning Dope before the stretching process or injecting the crosslinking agent in the extraction process or the emulsion process. These conventional cross-linking treatment methods, the cross-linking agent contained in the PVA unstretched yarn causes cross-linking reaction when the heat stretching at a high temperature of 200 ℃ or more to lower the elongation or lower the cross-linking agent having a lower boiling point to reduce the cross-linking efficiency to 130 ℃ or more It is difficult to have hot water resistance.

The present invention relates to a polyvinyl alcohol (hereinafter, abbreviated as PVA) fiber having excellent hot water resistance and high strength fiber property, and a method of manufacturing the same, and more particularly, to dimethyl sulfoxide containing methanol. Is dissolved in PVA resin of 98% or more of saponification degree, and methanol is used as a coagulation solvent to give wet and dry gel spinning, twisting and applying heat treated fibers to produce twisted yarn. Plywood the yarn or three and add the staging to wind the bobbin with a raw cord, and cross-linking reaction treatment using aliphatic aldehyde or acetal to the raw cord wound on the bobbin so that excellent hot water resistance and high strength fiber properties can be exhibited. It is a technical problem to provide a tire reinforcement PVA fiber and its manufacturing method.

Accordingly, the present invention,

A) dissolving polyvinyl alcohol having a degree of polymerization of 1,500 to 7,000 and a saponification degree of 99.9 mol% or more in dimethyl sulfoxide and spinning according to dry or wet spinning, followed by stretching and then heat-treating the prepared non-stretched yarn at high magnification;

B) imparting twist to the polyvinyl alcohol stretched yarn to produce a lower twisted yarn, and adding the upper twisted yarn by adding two or three lower twisted yarns to prepare a raw cord and winding the bobbin;

C) provides a cross-linked raw cord prepared by the method comprising the step of immersing the raw cord wound on the bobbin in an aliphatic aldehyde or acetal compound to cross-link the reaction.

In addition, it is preferable that the twist number of the lower or upper edge in step B) is 300 to 500 TPM.

In addition, the aliphatic aldehyde crosslinked to the raw cord is preferably one or two selected from propanedial, butanedial, pentanedial, or heptanedial.

In addition, it is more preferable that the aliphatic aldehyde crosslinked to the raw cord in step C) is butanedial.

In addition, the content of the aliphatic aldehyde compound crosslinked to the raw cord in step C) is preferably 0.5 to 2.0wt% by weight.

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

In addition, the acid catalyst in step C) is preferably acetic acid.

In addition, there is provided a deep cord for a tire cord having the following physical properties, manufactured by treating the cross-linked raw cord with an adhesive liquid (RFL).

(1) cutting load 20.0 to 50.0 kg, (3) fineness 2,000 to 6,000 denier, (4) fatigue resistance more than 80%

The crosslinking agent used in the present invention may be an aldehyde compound capable of crosslinking with a hydroxyl group of PVA, but a compound having two or more aldehyde groups is preferred to increase crosslinking efficiency. As the aldehyde compound, an aliphatic aldehyde compound, an aromatic aldehyde compound and the like can be used, but in order to penetrate the crosslinking agent to the inside of the fiber, an aliphatic compound is preferred. Such aliphatic aldehyde compounds include propanedial, butanedial, pentanedial, heptanedial and the like, and may be used by mixing two or more aldehyde compounds. In addition, a compound obtained by reacting an aliphatic aldehyde compound with an alcohol such as methanol, ethanol, propanol, butanol and the like to be acetalized can also be used.

The most important feature of the present invention is the crosslinking process. In general, the cross-linking treatment uses a method of dissolving the cross-linking agent in an organic solvent in the extraction process in order to penetrate the cross-linking agent to the inside of the fiber. It does not have sufficient hot water resistance and fatigue resistance. The crosslinking agent used in the extraction process makes it difficult to recover the organic solvent, making the overall process difficult. Therefore, in the present invention, a high-strength PVA fiber having a hot water resistance of 130 ° C. or higher and high fatigue resistance of 80% or more is prepared by injecting a crosslinking agent after infiltrating the crosslinking agent into the PVA raw cord twisted to increase the crosslinking efficiency and preventing fiber damage. Such a crosslinking treatment method also serves to improve the workability and productivity by simplifying the overall process.

Hereinafter, the PVA fiber manufacturing method of the present invention was described in detail. PVA polymerization degree is about 1,500 to 7,000 is used, preferably high polymerization degree PVA of 1,700 to 3,000 is effective. When the degree of polymerization is less than 1,500, fiber formation is difficult, and when the degree of polymerization is 7,000 or more, the viscosity is so high that spinning processability is poor. High-strength PVA fiber, which is mostly used in the industrial material field, needs hot water resistance, so the saponification degree is higher than 99.9 mol%. Ethylene glycol, glycerin and DMSO may be used as the organic solvent, but DMSO having the best solubility in PVA is suitable. Such DMSO is preferably used to purify the water content to several tens ppm or less.

As for methyl alcohol mixed in DMSO, about 5-40 volume% is used, Preferably it is 10-20 volume%. If the content of methyl alcohol in the solvent is less than 5% by volume, the PVA spinning dope coagulates at 0 ℃ or less, and the gel spinning is impossible. If the volume is above 40%, the spinning dope coagulates, but the entire gel forms a turbidity, forming a uniform gel. I can't. It is preferable to adjust the concentration of PVA Dope so that the viscosity is in the range of 50 to 4,000 Poise, but 500 to 3,000 Poise is effective to obtain excellent physical properties. If the viscosity is 50 or less, it is difficult to form fibers, and at 4,000 or more, the fiber spinning property is poor.

The coagulation bath can spin at a temperature of -30 to 30 ° C, but -10 to 10 ° C is effective for uniform gel formation. If the coagulation bath temperature is -30 ℃ or less, the methyl alcohol content of the solvent should be mixed with 30%, so the PVA dissolving power is lowered, making it impossible to produce a uniform PVA spinning Dope. If the coagulation bath temperature is above 30 ° C, gel formation is impossible and radioactivity is poor.

PVA fiber manufacturing methods include a dry method, a wet method, and a dry and wet method in which the two methods are mixed. However, the wet and dry method is effective in the high strength PVA fiber manufacturing method requiring a high magnification stretching process. Air-gap can be 10 ~ 300mm in wet and dry method for manufacturing PVA filament, but narrow air-gap of 20 ~ 100mm is preferable for high magnification of thermal stretching. Air-gap is less than 10mm workability. On the other hand, higher than 300 mm thermal crystallization is impossible because the degree of crystallinity is larger than gelation, and the productivity decreases because fusion between fibers occurs at the nozzle cross section.

In the high-strength PVA fiber manufacturing process, the stretching process is very important for improving the high strength and hot water resistance. The heating method of the stretching process includes hot air heating and roller heating, but hot air heating is more effective for producing high strength PVA fibers because the filament is in contact with the roller surface and the fiber surface is easily damaged. Although heating is possible at the temperature of 140-250 degreeC, 160-230 degreeC is preferable. When the heating temperature is below 140 ° C, the molecular chain does not behave sufficiently, so high magnification thermal stretching is impossible, and above 250 ° C, PVA is easily decomposed, resulting in deterioration of physical properties.

Next, high strength and fatigue resistance are required for PVA fibers used as tire cords among industrial materials. For this purpose, raw cords are manufactured by twisting PVA drawn yarns. In the general synthetic fiber twisting process, increasing the number of softening decreases the strength but tends to improve fatigue resistance. Therefore, it is very important to select the appropriate training according to the purpose of use. For example, the tire cord used for the liar tire carcass part is used by giving the number of years of lower and upper edges to 1500d / 2p with 300-500 TPM (twist / M).

In order to improve the hot water resistance and the fatigue resistance, the PVA raw cords are twisted and reacted with a crosslinking agent. PVA fibers drawn at high magnification have high crystallinity and are difficult to penetrate the crosslinking agent, and therefore, as described above, an aliphatic aldehyde or acetal compound is used as the crosslinking agent. The crosslinking compound is used in a concentration of 0.1 to 5 wt% with respect to the fiber, but a range of 0.5 to 2.0 wt% is preferred. If it is less than 0.1wt%, the fatigue resistance is improved, but if the hot water resistance is less than 130 ° C and not more than 5.0wt%, the strong drop is large, making it difficult to use a high strength tire cord.

In order to react the crosslinking compound with the OH group of PVA, an acid catalyst is required in the crosslinked load aqueous solution. Acids such as sulfuric acid or acetic acid may be used as the acid catalyst, but acetic acid is preferred in view of reaction rate control and stability. The acid catalyst concentration is preferably 5wt% or more with respect to the aqueous solution of the crosslinking compound, but if an appropriate amount is used, it is important to use an appropriate amount because it is difficult to remove in the washing step after the reaction. In order to infiltrate the crosslinking compound to the inside of the PVA fiber having high crystallinity, a method of increasing the activity of the crosslinking compound by using the temperature of the reaction solution at 50 ° C. or higher was used. In addition, the crosslinking reaction time is different depending on the crosslinking compound and conditions, but more than 30 minutes is effective, but if the crosslinking reaction is performed for too much time, a strong decrease in strength.

The core technical matters in the present invention are polyvinyl alcohol stretched yarns, which are spliced into two or three pieces to prepare a raw cord wound in bobbins, and then the cross-linking reaction is performed by immersing the raw cord wound in the bobbin in a crosslinking solution. It is to proceed.

The crosslinked PVA raw cord is dried and heat treated by attaching RFL liquid (hereinafter referred to as "dipping") to clean and dry to improve adhesion to rubber. In more detail, the dipping process is achieved by impregnating the surface of the fiber with a resin layer called Resorcinol- Formaline-Latex (RFL) to improve the disadvantages of fibers for tire cords that are inherently less adhesive with rubber. Is carried out.

In the present invention, as an example of the adhesive liquid for the adhesion of the PVA raw cord and rubber can be prepared and used using the following method. The examples described below are only intended to more clearly understand the present invention and are not intended to limit the scope of the present invention.

29.4 wt% Resorcinol 45.6

Pure 255.5

37% formalin 20

10wt% sodium hydroxide 3.8

After preparing the reaction, the reaction was stirred at 25 ° C for 5 hours, and then the following components were added.

40wt% VP-Latex 300                     

Pure 129

28% ammonia water 23.8

After the ingredient is added, the mixture is aged at 25 degrees for 20 hours to maintain a solid concentration of 19.05%.

In order to prevent the RFL solution from penetrating deeply to the inside of the RFL attachment, a stretch of 0.5 to 3% is given when the RFL solution is attached, and the RFL solution adhesion rate (hereinafter referred to as DPU) is 3.0 to 9.0 wt%. At 0.5% or less stretch, the DPU becomes over 9wt% and penetrates deep into the short fiber to reduce fatigue resistance. In addition, over 3% of the live cord may be over-tensioned, causing damage to the live cord. The heat treatment should be carried out at 170 to 230 ° C., in particular at 200 to 220 ° C. which is the best in PVA molecular motion of the amorphous portion. As a result, high strength PVA deep cords can be manufactured by maximizing the heat treatment effect by minimizing the tension imparted to the fiber to maximize molecular movement. It is important to set the stretch ratio to 0 to -5% in the heat treatment step after immersing the raw cord in the dipping liquid. If the stretch is more than 0% in heat treatment, the deep cord elongation is low, so when used for tire cords requiring high fatigue resistance with less than 60% fatigue resistance, cord breakage or breakage occurs. On the other hand, in the case of -5% or less, recrystallization occurs in a direction perpendicular to the fiber axis due to excessive molecular movement, causing strong degradation. If the crosslinking agent that has not been washed in the previous crosslinking step remains inside the fiber, the PVA fiber acts as an impurity in the available product, and thus the crosslinking efficiency can be further improved by reacting or volatilizing the remaining crosslinking agent by heat treatment at 200 ° C or higher. .

Hereinafter, the structure and effects of the present invention will be described in more detail with specific examples and comparative examples, but these examples are only intended to more clearly understand the present invention and are not intended to limit the scope of the present invention. Properties in Examples and Comparatives were evaluated for physical properties in the following manner.

(a) PVA code strong (kgf)

After drying at 107 ° C. for 2 hours, an Instron low speed tensile tester was used. After twisting 80 TPM (80 twist / m), the sample was measured at 250 mm and a tensile rate of 300 m / min.

(b) Hot water resistance (WTb, ℃)

Select the stranded raw cord as 3,000 denier, cut it to 4cm and make the load 3g / bone at the end. This is immersed in a pressurized glass container with water, and the temperature at which the fiber is cut is measured while raising the temperature at a rate of 2 ° C / min.

(c) even with fatigue

The fatigue strength of the tire cord was measured using the Goodrich Disc Fatigue Tester, which is commonly used for fatigue testing of tire cords. Fatigue test conditions were 120 ℃, 2500RPM, compression 10% and 18% conditions, and after the fatigue test immersion in Tetra chloro ethylene solution for 24 hours to swell the rubber and to separate the rubber and cord to measure the residual strength. The residual strength was measured according to the method (a) using a conventional tensile strength tester after drying for 2 hours at 107 ° C.

Example 1

PVA used 99.9 mol% and 2,000 respectively in saponification degree and polymerization degree, and methyl alcohol and DMSO used a purified solvent having water content of 100 ppm or less. A mixed solvent was prepared by mixing DMSO and methyl alcohol so that the content of methyl alcohol in the solvent was 5% by volume, and PVA was dissolved to 22wt% with respect to PVA spinning Dope. Thereafter, PVA fibers were prepared by wet and dry spinning using gel spinning. At this time, the number of nozzle odds and hole diameters were 500 and 0.5 mm, respectively, and a circular nozzle having an L / D of 5 was used. Air-gap was 50 mm and methanol was used as a solvent in the coagulation bath. At this time, the coagulation bath was maintained at a solvent / methanol mixing ratio of 20/80 and a temperature of 0 ° C. After passing through the extraction bath, the PVA fibers should be free of solvent, DMSO. If the solvent remains in the filament is discolored in the hot stretching process is a major cause of the degradation of the physical properties of the final filament. Two stage hot air heating was used for hot drawing. The hot air heating temperature was 200 ℃ for first stage and 220 ℃ for two stages. The draw ratio of each stage was 9.0 times -1.5 times, and the total draw ratio was 13.5 times. As a result, high-strength PVA fibers having a strength of 13.5 g / d and elongation of 8.0% are produced. The twisted yarn is twisted to be 360 / 360TMP in each of the lower and upper edges, thereby producing the twisted yarn. The raw cord strength manufactured has 35 kgf. Subsequently, the crosslinking treatment is carried out using butanedial, an aldehyde compound. The cross-linking treatment prepared an aqueous solution in which 3 wt% butanedial and 6 wt% acetic acid were dissolved in water, followed by washing the raw cord at 70 ° C. for 1 hour, followed by washing with water. After crosslinking, strong cord of 33kgf of raw cord was impregnated in RFL solution to prepare PVA deep cord. The results are shown in Table 1.

[Examples 2 and 3]

Butanedial and acetic acid ratio was adjusted to the ratio as shown in Table 1 to compare the strength and fatigue resistance after crosslinking treatment.

[Comparative Examples 1 and 2]

In Comparative Example 1, the crosslinking treatment was not performed, and the results are shown in Table 1, and Comparative Example 2 compared the fiber properties when the concentration of butanediol in the aqueous solution was 10 wt%.

[Comparative Examples 3 and 4]

Comparative Example 3 is shown in Table 1 when the crosslinking reaction was performed for 3 hours. Comparative Example 4 is a case where the reaction temperature is 30 ℃, the results are shown in Table 1.

Table 1

division Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Cross-link Butanedial concentration (wt% / aqueous solution) 3 5 7 1700 10 7 7 Acetic acid concentration (wt% / aqueous solution) 6 10 14 - 20 14 14 Reaction temperature (℃) 70 70 70 - 70 70 30 Response time (minutes) 60 60 60 - 60 180 60 Island peculiarity Drawn yarn tensile strength (g / d) 13.5 13.5 13.5 13.5 13.5 13.5 13.5 Raw code strong (kgf) 35 34 33 36 28 25 35 Deep Code Strong (kgf) 36 35 34 37 28.5 25 36 Fatigue Resistance (%) 87 89 90 60 70 65 65 Hot water resistance (℃) 140 150 155 121 135 130 130

In the present invention, in order to increase crosslinking efficiency and prevent fiber damage, twisted polyvinyl alcohol stretched yarn is produced to produce lower twisted yarn, and the lower twisted yarn is spliced into two or three yarns and added to the upper twisted yarn to produce a raw cord. Thereafter, the raw cord surface is cross-linked raw cord prepared by a method comprising the step of cross-linking the PVA fibers using an aliphatic aldehyde or acetal compound. Such cross-linked raw cords can be suitably used for tire cords.

Claims (9)

A) dissolving polyvinyl alcohol having a degree of polymerization of 1,500 to 7,000 and a saponification degree of 99.9 mol% or more in dimethyl sulfoxide and spinning according to dry or wet spinning, followed by stretching and then heat-treating the prepared non-stretched yarn at high magnification; B) imparting twist to the polyvinyl alcohol stretched yarn to prepare a lower twisted yarn, and adding the upper twisted yarn to two or three yarns to produce a raw cord; C) A cross-linked raw cord prepared by the method comprising the step of crosslinking treatment using an aliphatic aldehyde or acetal compound in the raw cord. The method of claim 1, The cross-linking reaction of step C) is cross-linked raw cord, characterized in that the cross-linking reaction by immersing the raw cord in the cross-linking solution in a state wound in the bobbin. The method of claim 1, Cross-linked raw cord, characterized in that the twist of the lower or upper edge in step B) is 300 ~ 500TPM. The method of claim 1, The cross-linked raw cord, characterized in that the content of the aliphatic aldehyde or acetal compound cross-linked to the raw cord in step C) is 0.5 to 2.0wt% by weight. The method of claim 1, The aliphatic aldehyde crosslinked to the raw cord in step C) is one or two selected from propanedial, butanedial, pentanedial, or heptanedial. The method according to claim 1 or 5, Cross-linked raw cord, characterized in that the aliphatic aldehyde cross-linked to the raw cord in step C) is butanedial. The method of claim 1, Cross-linked raw cord, characterized in that to use the acid catalyst during the cross-linking treatment reaction to the raw cord in step C). The method of claim 7, wherein Cross-linked raw cord, characterized in that the acid catalyst in step C). A cord for a tire cord having the following physical properties, prepared by treating the cross-linked raw cord of claim 1 to an adhesive liquid (RFL). (1) cutting load 20.0 to 50.0 kg, (3) fineness 2,000 to 6,000 denier, (4) fatigue resistance more than 80%