JPH0830282B2 - High strength polyhexamethylene adipamide for tire cord - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polyhexamethylene adipamide fiber, and more specifically, a high strength for tire cord having a strength of 10 g / d or more and having a small strength change in a post-processing step, particularly a vulcanization step. Strong polyhexamethylene adipami
Do fiber .

[0002]

2. Description of the Related Art Polyhexamethylene adipamide fiber is
Because of its excellent strength, toughness, heat resistance, dyeability, and color development, it is widely used as a fiber for industrial materials, interior bedding, and clothing. In particular, it is excellent in strength, toughness, heat resistance, fatigue resistance, adhesion to rubber, etc.
Widely used as a fiber for tire cords.

In recent years, energy-saving technology has been required for tires, and tires with less fuel consumption have been demanded. To that end, tire manufacturers are seeking tires with lower rolling resistance and lighter weight. Accordingly, tire cords are required to have a higher modulus thread and a higher strength thread. In particular, polyamide tire cords are mainly used for large-sized tires with a large number of laminated layers such as light trucks, truck buses, construction vehicles, and aviation, and there is a problem that the amount of yarn used per tire is large. Reducing the number of laminated sheets and the number of woven fabrics not only achieves low fuel consumption associated with tire weight reduction, but also improves fatigue resistance associated with lower heat generation and increased heat radiation, and improves safety against separation due to improved adhesion. Higher strength polyamide tire cords are required to contribute to improvement and productivity in tire manufacturing processes. Fibers currently marketed as polyamide fibers have a strength of 9.0 to 9.5 g / d. Efforts are being made to improve this even further, but satisfactory fibers have not yet been obtained. Moreover, a method for producing such a fiber having a higher strength is not provided.

[0004]

Generally, in order to obtain a polyamide fiber or a polyester fiber having a high strength, it is necessary to spin a polyamide or a polyester having a high degree of polymerization and draw the spun yarn at a high ratio. . However, when the degree of polymerization of the polymer is increased, the melt viscosity of the discharged polymer is increased, so that the orientation degree of the obtained spun yarn is increased and the drawability is deteriorated. In particular, this tendency is remarkable in polyhexamethylene adipamide having a high crystallization rate.

In order to obtain a spun yarn with a low degree of orientation, there are methods such as a method of increasing the melting temperature, a method of decreasing the spinning draft, a method of decreasing the spinning speed, a method of increasing the cooling air volume, etc., but they are not sufficient. In order to improve this, a method of controlling the atmospheric temperature under the spinneret by providing a heating cylinder under the spinneret during melt spinning (Japanese Patent Publication Nos. 397251 and 43-898).
No. 5), a heating cylinder is provided under the spinneret to control not only the atmospheric temperature under the spinneret but also the cooling (Japanese Patent Publication Nos. 43-10176 and 50-16446).
No.) etc. have been proposed. By using such a method, the degree of orientation of the spun yarn is reduced, high-strength drawing becomes possible, and the strength of the obtained drawn yarn is improved. Thus, the relative viscosity of the polyhexamethylene adipamide used can be adjusted to 50 to 60 to 70, and as a result, the strength of the resulting tire cord is changed from 8 g / d to 9.0 to 9.
It has become possible to improve to 5 g / d. As a result of further studying to obtain a high-strength yarn by further increasing the degree of polymerization and drawing at a high ratio, we were able to obtain a yarn having a strength of 10 g / d or more. However, when this high-strength raw yarn was used, after undergoing a twisting process, a woven process, an adhesive heat treatment process, and a vulcanization process, a yarn was taken from rubber and the strength thereof was measured. As a result, a conventional commercially available yarn of 9.5 g / d was obtained. It was found that, using the polyhexamethylene adipamide tire cord of No. 3, after passing through the above steps, the strength of the yarn sampled from the rubber was about the same as 7 g / d. In particular, it was found that the decrease was remarkable in the vulcanization process, and the effect of increasing the strength of the raw yarn was not exhibited at all.

The present invention solves the problems of the conventionally known polyhexamethylene adipamide fiber and has a high strength which has not been obtained in the past, and is used for a tire cord having a small strength reduction in a post-processing step, particularly a vulcanization step. High strength polyhexa
It is intended to provide methylene adipamide fiber .

[0007]

The inventors of the present invention have earnestly studied about a method for producing polyhexamethylene adipamide fiber having a small strength reduction in a post-processing step, particularly a vulcanization step. We have found that it is important to improve the thermal stability of the elastic modulus of the yarn.

That is, the thermal stability of the fibrous material (retention of elastic modulus during high temperature treatment) depends on the viscosity in the temperature region closely related to the micro Brownian motion indicated by the polymer chain segment existing inside the amorphous region. It can be estimated from elastic mechanical dispersion and temperature change of storage elastic modulus E ′ after (αa absorption). That is, α
a Temperature after absorption, in the case of polyhexamethylene adipamide fiber, in the temperature range of 150 ° C or higher and 220 ° C or lower
A value obtained by multiplying the temperature gradient of logE 'by 62.5, that is, -6
2.5d (logE ') / dT (T = temperature) is 150 ° C
Shows stability of elastic modulus against thermal history in the range of ~ 220 ℃
However, irreversible microstructural changes in amorphous and crystalline regions
To reflect. The present inventors have found that in the temperature range after absorption of αa
The inventors have found that the value of −62.5d (logE ′) / dT affects the strength retention rate in the vulcanization step, which causes the largest strength reduction even in the post-processing step of the tire cord, and arrived at the present invention.

The high-strength polyhexamethylene chloride according to the present invention
One reliable method of dipamide fiber is as a polyhexamethylene adipamide pellet, which is obtained by once melt-polymerizing a polymer having a relative viscosity of formic acid of 70 or less into chips and then 180
After melt-spinning using a polymer solid-phase polymerized so that the relative viscosity of formic acid is 75 or more and 150 or less at ℃ to 240 ℃, after cooling and applying a spinning oil, immediately take it up to the first roll pair, and successively Polyhexamethylene adipate by guiding to a multi-stage roll pair rotating at a higher peripheral speed and performing multi-stage drawing heat setting under the following conditions
It is a method for producing a mid fiber . The roll surface temperature of at least one of the roll pair with the highest peripheral speed or the roll pair after that is 220 ° C.
As described above, set the temperature to 250 ° C. or lower, and set the winding speed to T. S. , The peripheral speed of the roll pair with the highest peripheral speed is G. S. Then, 0.92 ≧ T. S. / G. S.
Take up so that ≧ 0.86 is satisfied.

High strength hexa for tire cord according to the present invention
Methylene adipamide fiber has a formic acid relative viscosity of 70 to 15
0, strength 10 g / d or more, toughness 200 g / d ·% or more, tie molecule stability coefficient 0.20 or less, and 160 ° C.
Shrinkage when allowed to free shrink dry heat stroke 30 min 4% or less pressurized
This will meet the requirement that the strength of the vulcanized cord is 7.6 g / d or more .

The polyhexamethylene adipamide fiber referred to here is mainly composed of repeating units of the following formula.

Embedded image Polyhexamethylene adipamide fibers modified by adding 10% by weight or less of other amide-forming units can also be used in the method of the present invention. Examples of such a small amount of amide-forming unit include aliphatic dicarboxylic acids such as sebacic acid and dodecanoic acid; aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid; aliphatic diamines such as decamethylenediamine; and metaxylylenediamine. Aromatic diamines, ω-amino acids such as ε-aminocaproic acid, and lactams such as caprolactam and laurinlactam can be used. It is also possible to use a mixture of the above polyhexamethylene adipamide with 20% by weight or less of another type of polyamide such as polycapramide and polyhexamethylene sebacamide.

Further, the above-mentioned polyhexamethylene adipamide fiber is an additive usually used for polyamide, for example, a heat stabilizer such as copper acetate, copper chloride, copper iodide, mercaptobenzimidazole, manganese lactate, hypochlorous acid. Light stabilizers such as manganese phosphate, phosphoric acid, phenylphosphonic acid, thickeners such as sodium pyrophosphate, titanium dioxide,
It may contain a matting agent such as silicon dioxide and kaolin, a lubricant such as ethylene bisstearylamide and calcium stearate, and a plasticizer.

As used herein, the "relative viscosity of formic acid" is 90%.
It is the solution relative viscosity in 25 degreeC of the polymer concentration 8.4 weight% solution of formic acid. A high-strength yarn can be produced even if the relative viscosity of formic acid is less than 70, but it is not preferable because the high-stretching needs to be performed to that extent and the strength utilization factor in the post-processing step becomes low. When the relative viscosity of formic acid is increased, the melt viscosity of the discharged polymer is increased, and as a result, the orientation degree of the spun yarn obtained is increased and the drawability is deteriorated. This tendency is particularly remarkable in polyhexamethylene adipamide, which has a large crystallization rate. Therefore, it is necessary to lower the orientation degree of the spun yarn by raising the melting temperature, lowering the spinning speed, attaching a heating cylinder, controlling the cooling conditions, and high stretching, but the relative viscosity of formic acid is not so high. If it becomes too high, even if the orientation degree of the spun yarn is lowered by the above-mentioned means, the orientation degree is still high, the high draw ratio cannot be obtained, and the strength cannot be increased. Formic acid relative viscosity is 150
When such a phenomenon is exceeded, such a phenomenon is observed, but with the progress of the orientation relaxation technology for spun yarn, spun yarn on the high viscosity side can be used. Formic acid relative viscosity is 70 to 150, preferably 70 to 1
00.

High strength polyhexa for tire cord of the present invention
The methylene adipamide fiber needs to have a strength of 10 g / d or more. The strength of the commercially available polyhexamethylene adipamide fiber is around 9.5 g / d. To change the tire design and change the number of layers to be laminated and the number of woven fabrics, check the safety factor and Strength improvement of about 5% is required. Of course, even if the yarn having a strength of 10 g / d or less is provided with the tie molecule stability coefficient as shown in the present invention, the tenacity utilization factor in the post-processing step is improved, The effect is small as compared with the improvement with respect to the yarn of d or more.

However, if the elongation is low even if only the strength of the original yarn is increased (that is, if the toughness = the original yarn strength × the elongation) is low, the energy until the breaking of the original yarn becomes small, which is not preferable. High-strength polyhexame for tire cord of the present invention
Tylene adipamide fiber has a toughness of 200 g / d ·% or more, as will be seen in Examples described later.

The term "tie molecular stability coefficient" as used herein means
Toyo Baldwin's Vibron DDV-IIC
Using a mold, measuring frequency of 110Hz, heating rate 3 ℃ /
Min, E'-temperature characteristic was measured in dry air, and this was measured by JI
Copy it on S4 standard A4 size semi-logarithmic graph paper and keep it at 150 ℃
-62.5d (lo in the temperature range below 220 ° C)
gE ') / dT . It is desirable that the tie molecule stability coefficient is close to 0, but if the tie molecule stability coefficient is 0.20 or less, strength reduction can be tolerated. It is preferably 0.15 or less.

To reduce the Thai molecule stability coefficient,
An approach from both the polymer side and the spin draw side is needed. A polymer having a relative viscosity of formic acid of 70 or more was prepared by melt polymerization in the same manner as a conventional polymer for a yarn having a relative viscosity of formic acid of less than 70, and subsequently spun, stretched and heat set to obtain a strength of 1
Even if a raw yarn of 0 g / d or more is prepared, the tie molecule stability coefficient becomes 0.20 or more, and the strength reduction in the post-processing step is large. It is considered that this is because it is necessary to prolong the melting time in order to obtain a polymer having a high degree of polymerization, and during this period, part of polyhexamethylene adipamide, which is easily decomposed by heat, is decomposed and the stability of the tie molecule is lowered. . Therefore, in order to obtain a high degree of polymerization polyhexamethylene adipamide fiber having a tie molecular stability coefficient of 0.20 or less, 180 ° C. to 240 ° C. after chip formation of a polymer melt-polymerized to a formic acid relative viscosity of 70 or less, preferably 60 or less. It is preferable to carry out solid state polymerization at ° C.

The solid phase polymerization temperature may be less than 180 ° C., but the solid phase polymerization time becomes long, and the drawability of the spun yarn from the obtained polyhexamethylene adipamide pellets deteriorates. If it exceeds 240 ° C, fusion of pellets is observed during solid phase polymerization, which is not preferable. A more preferable solid phase polymerization temperature is 190 ° C or higher and 210 ° C or lower. The relative viscosity of formic acid of the polyhexamethylene adipamide pellets after the solid state polymerization is preferably 75 or more and 150 or less. If the relative viscosity of formic acid is less than 75, a high-strength yarn can be produced, but it is necessary to carry out high-stretching to that extent, and the strength utilization factor in the post-processing step becomes low, which is not preferable. If the relative viscosity of formic acid is increased too much, the melt viscosity of the extruded polymer will increase, and as a result, the orientation degree of the obtained spun yarn will be too large, the drawability will not increase, and a raw yarn having sufficient strength and elongation will be obtained. Can't get This phenomenon becomes remarkable when the relative viscosity of formic acid exceeds 150. Even if the polyhexamethylene adipamide pellets after solid-state polymerization are remelted and spun while suppressing the decrease in viscosity, the relative viscosity is reduced by about 5 due to molecular chain breakage in the stretching stage.

After concentrating a 50% aqueous solution of hexamethylene diammonium adipate to 70% in a concentrating tank, 220 ° C. to 25 ° C. while maintaining a pressure of 17.5 kg / cm ² in the first reactor.
The temperature is raised to 0 ° C. in 1.5 hours. Then, while raising the temperature to 280 ° C. in the second reactor, the pressure is returned to normal pressure in 20 minutes. After separating the water vapor in the gas-liquid separation tank, it was passed through a three-way valve, one side was made into a rope through the spinneret, and after water cooling it was cut into chips (I), and the other side was 350 mmHg, 280 in the post-polymerization vessel.
After polymerizing at 15 ° C. for 15 minutes, it was made into a rope through a spinneret, cooled with water, and cut into chips (II). After the melt polymerization step, the polymer was sampled from sampling nozzles before and after the polymerization vessel, and the [COOH] terminal group and [N
The H ₂ ] end group was measured and is shown in FIG. 1 (curve B). Chip (I) has a relative viscosity of formic acid of 29.7, [COOH] terminal group is 101.5 meq / kg, and [NH ₂ ] terminal group is 62.5.
It was meq / kg. 5000 parts of the chip (I) was placed in a tumbler type solid-state polymerization vessel at a jacket temperature of 200 ° C., 3 l / hr.
Polymerization was carried out under a nitrogen flow rate of / kg of polymer. During solid state polymerization,
The [COOH] terminal group and the [NH ₂ ] terminal group of the obtained chip were measured by sampling with time from a sampling nozzle and are shown in FIG. 1 (curve A). As shown in FIG. 1, in the solid-state polymerization (curve A), as the polymerization proceeds, the [COOH] terminal group and the [NH ₂ ] terminal group decrease in almost equimolar proportions. Little decrease in [NH ₂ ] terminal groups. This is due to polycondensation [COO
It is shown that the reaction of increasing [NH ₂ ] terminal groups due to thermal decomposition of polyhexamethylene adipate as shown below occurs with the decrease of both H] and [NH ₂ ] terminal groups.

Embedded image (Refer to "Procedures for Macromolecular Discussion 71'5A10 P123")

In the polymer thus pyrolyzed,
In addition to the above reaction, NH ₃ is eliminated by the reaction between the terminal amines to generate secondary amines and tertiary amines, and many crosslinked structures are formed. Therefore, it is considered that the polyhexamethylene adipamide fiber produced by using such a polymer has a low thermal stability of elastic modulus and a large decrease in strength in a post-processing step. Therefore, it is necessary to use a polymer which is less likely to undergo such thermal decomposition in order to obtain a polyhexamethylene adipamide fiber having a low tie molecule stability coefficient, and it is preferable to improve the degree of polymerization by solid phase polymerization. Is the way.

As a method for producing high-strength polyhexamethylene adipamide fiber, Japanese Examined Patent Publication No. 48-32616 is known. However, even if a polymer having a relative viscosity of formic acid of 70 or more is directly spun by the method disclosed in Japanese Patent Publication No. 48-32616, it is difficult to obtain a raw yarn having a low tie molecular stability coefficient. In order to obtain a yarn with a low coefficient of tie molecule stability, it is necessary to heat-set at high temperature to reduce the shrinkage rate of the yarn and stabilize the thermal structure. The permissible shrinkage rate of the raw yarn is 7% or less, preferably 4% or less when freely shrinking in dry heat at 160 ° C. for 30 minutes. When it is 7% or more, the tie molecule stability coefficient becomes 0.20 or more and the strength retention rate in the post-processing step becomes low even when a solid-phase polymerized polymer having a small thermal decomposition is used.

As a spinning method for obtaining a low shrinkage yarn, there are a method in which the spun yarn is once wound as an undrawn yarn and then drawn and heat set, and a method in which the spun yarn is directly drawn and heat set. In the production of a raw yarn having a large relative viscosity of formic acid as described above, the shrinkage rate becomes high, so that a higher temperature heat set, for example, a high temperature heat set of 220 ° C. or higher is required, and a relaxation rate also needs to be made high. High temperature heat setting is the preferred method.

In the direct spinning and drawing high temperature heat setting, the polyhexamethylene adipamide pellets are melt-spun and then cooled, and the spinning oil is added thereto, and immediately thereafter, the polyhexamethylene adipamide pellets are immediately taken up by the first roll pair and successively rotated at a higher peripheral speed. It is guided to a pair of multi-stage rolls and subjected to multi-stage drawing and heat setting.
As the roll pair, one in which both rolls are positively driven, and one in which one is actively driven and the other is negatively driven are used. The multi-stage stretching heat set performs stretching and heat setting in two or more stages among at least three sets of roll pairs having different peripheral speeds, but among the roll pairs having the fastest peripheral speed or the roll pairs thereafter. The surface temperature of at least one pair of rolls is preferably 220 ° C. or higher, 250
Set the winding speed to T.C. S. , The peripheral speed of the godet roll group with the fastest peripheral speed S. Then 0.92
≧ T. S. / G. S. By performing the winding so as to satisfy ≧ 0.86, it is possible to reduce the shrinkage ratio of the original yarn to 4% or less when freely shrinking in the dry heat of 160 ° C. for 30 minutes.

The polymer melt-polymerized to a relative viscosity of formic acid of 70 or less was once made into chips, and then melt-spun using a polymer which was solid-phase polymerized at 180 ° C. to 240 ° C. so that the relative viscosity of formic acid was 75 or more and 150 or less. After the post-cooling and application of the spinning oil, the roll was immediately taken up by the first roll pair, and then successively led to the multi-stage roll pair rotating at a higher peripheral speed, and even if multi-stage drawing heat setting was performed, the roll with the fastest peripheral speed was obtained. 220 for each pair or rolls thereafter
C. or less, or T.I. S. / G. S. When the ratio is 0.92 or more, the shrinkage ratio of the raw yarn is 4% or more and the tie molecule stability coefficient is 0.20 or more. Although the yarn obtained by the above-described manufacturing method has a high yarn strength of 10 g / d or more, when the yarn is used for a twisting process, a woven process, an adhesive heat treatment process, and a vulcanization process. The decrease in strength is small. Therefore,
It is useful for reinforcing products that require strength such as tire cords and belts. In particular, it is useful for reinforcing tires for construction vehicles, aircraft, and truck buses that have a large amount of yarn used and a large number of layers.

[0025]

EXAMPLES The method of the present invention will now be specifically described with reference to examples, but the present invention is not limited to these examples. In the examples, the relative viscosity of formic acid is the relative viscosity at 25 ° C. of a solution prepared by dissolving 90% formic acid in a polymer concentration of 8.4% by weight. What is an amino terminal group?
The neutralization point is a value obtained by dissolving 6.0 g of the polymer in 50 ml of a 90% by weight phenol aqueous solution and carrying out potential titration with 1/20 N hydrochloric acid. The carboxylic acid end group means that 4.0 g of the polymer is dissolved by heating in 50 ml of benzyl alcohol,
It is a value obtained by neutralization titration with 1/10 N sodium hydroxide using a phenolphthalein indicator. Toughness is
80 times / using Shimadzu Autograph S-100
25 cm length of yarn with m twist and descent speed of 30
cm / min, chart speed 60 cm / min, full scale 25 kg. Dry heat shrinkage is 80 times /
It is a value obtained by freely shrinking a 1.0 m raw yarn containing m twists in an air oven at 160 ° C. for 30 minutes. Thai molecular stability coefficient is Vibron manufactured by Toyo Baldwin
Using DDV-IIC type, measuring frequency of 110 Hz,
The E'-temperature characteristic was measured in dry air at a temperature rising rate of 3 ° C / min, and this was copied to a JIS standard A4 size semi- logarithmic graph paper.
-62.5d (log at 150 ° C to 220 ° C)
It is a value obtained by calculating E ′) / dT .

Example 1 A 50% aqueous solution of hexamethylene diammonium adipate was quantitatively supplied at a rate of 2000 parts / hour, and 70% in a concentrating tank.
After concentrating to%, the temperature in the first reactor was raised from 220 ° C. to 250 ° C. in 1.5 hours while maintaining a pressure of 17.5 kg / cm ² . Then, the temperature was raised to 280 ° C. in the second reactor and the pressure was returned to normal pressure in 20 minutes. After separating the water vapor in the gas-liquid separation tank, it was made into a rope through the spinneret, cooled with water, and cut into chips. The relative viscosity of formic acid of the chips is 29.7, [C
OOH] terminal group is 101.5 meq / kg, [NH ₂ ]
The end group was 62.5 meq / kg. The chip 50
00 parts were polymerized by a tumbler type solid-state polymerization machine at a jacket temperature of 210 ° C. and a nitrogen flow rate of 31 / hour / kg of polymer. After 7 hours and 15 minutes, it was cooled and discharged. Formic acid relative viscosity 9
0.0, [COOH] terminal group 62.7 meq / kg,
Chips with [NH ₂ ] end groups of 23.0 meq / kg were obtained. The chips were spun out from a spinneret having 312 holes of 0.27 mmφ at 303 ° C., passed through a 150 mm heating cylinder heated at 350 ° C., cooled, and a spinning oil agent was applied, and then immediately the first Nelson Pick it up on a roller,
Subsequently, the film was guided to the second to fourth Nelson rollers which successively rotate at a higher peripheral speed, and the drawing heat setting was performed in three stages, and the film was wound at a speed of 1500 m / min. Assuming that each godet roll group of four stages is G _{1 to} G ₄ , the temperature of each roll is G ₁ : 80 ° C., G ₂ : 210 ° C., G ₃ : 230 ° C.,
And G ₄ : 250 ° C. The peripheral speed ratio of each roll is G
₂ / G ₁ = 3.63, G ₃ / G ₂ = 1.67, G ₄ / G
₃ = 0.995, and was winding speed _/ G 4 = 0.890. The obtained yarn is 1890d / 312f,
Formic acid relative viscosity 83.0, strength 10.4 g / d, elongation 2
It was 1.0%, toughness 218.4 g / d ·%, dry heat shrinkage ratio 2.0%, and tie molecule stability coefficient 0.09.

The raw yarn was twisted at 32.0 × 32.0T / 10 cm to form a raw cord of 1890d / 2, and a computer treater manufactured by Ritztuler was used. The first zone had a temperature of 160 ° C. and a tension of 2.0 kg. / Code, time 140 seconds, second
Zone temperature 230 ℃, tension 3.8kg / cord, time 4
At 0 seconds, the third zone was subjected to a dip treatment with resorcin / formalin latex solution at a temperature of 230 ° C., a tension of 2.6 kg / cord, and a time of 40 seconds. The amount of dip liquid deposited is 4.
5%.

After embedding the dep cord in rubber for carcass and vulcanizing at a temperature of 190 ° C. for 30 minutes under free shrinkage,
The vulcanized rubber was destroyed, the vulcanized cord was taken out, and its strength was measured to be 7.9 g / d (vulcanized cord strength retention rate of 76.0).
%)Met.

Comparative Example 1 A 50% aqueous solution of hexamethylene diammonium adipate was quantitatively supplied at a rate of 2000 parts / hour, and 70% in a concentrating tank.
After concentrating to%, the temperature in the first reactor was raised from 220 ° C. to 250 ° C. in 1.5 hours while maintaining a pressure of 17.5 kg / cm ² . Then, the temperature was raised to 280 ° C. in the second reactor and the pressure was returned to normal pressure in 20 minutes. After separating the water vapor in the gas-liquid separation tank, polymerization was carried out in a post-polymerization vessel at 200 mmHg and 280 ° C. for 15 minutes to form a rope through the spinneret, followed by cooling with water and cutting into chips. The relative viscosity of formic acid of the chips is 78.7, [CO
The OH] end group was 58.6 meq / kg, and the [NH ₂ ] end group was 33.4 meq / kg.

0.27 mmφ at 298 ° C. using the chip
From a spinneret with 312 holes
Pass through a heated 150 mm heating cylinder, cool, and spin oil
Immediately after applying, take it to the first Nelson roller
2nd to 4th, which continuously rotate at a higher peripheral speed
Lead to a Nelson roller and set in 3 stages of stretching heat
And was wound at a speed of 1500 m / min. 4 steps
G for each godet roll group ₁~ G_FourAnd the temperature of each roll
The degree is G₁: 80 ° C, G₂: 210 ° C, G₃: 230 ℃,
G_Four: 230 ° C., and the peripheral speed ratio of each roll is G₂
/ G₁= 3.63, G₃/ G₂= 1.67, G_Four/ G₃
= 0.995, winding speed / G_Four= 0.890.
The obtained yarn has a relative viscosity of formic acid of 74.0 and strength of 10.3.
g / d, elongation 21.5%, toughness 221.5 g / d.
%, Dry heat shrinkage 2.7%, Thai molecular stability coefficient 0.21
Met.

The raw yarn was made into a raw cord and a dip cord as in Example 1, then vulcanized, the vulcanized cord was taken out, and its strength was measured to be 7.2 g / d (vulcanized cord strength retention). The rate was 69.9%).

[0032]Comparative example 2 Hexamethylene diammonium adipate 50% water soluble
A fixed amount of liquid is supplied at a rate of 2000 parts / hour and 70
% In the first reactor after concentration to 17.5 kg / cm²Keep the pressure of
While raising the temperature from 220 ℃ to 250 ℃ in 1.5 hours
I have The temperature is then raised to 280 ° C in the second reactor.
After 20 minutes, the pressure was returned to normal pressure. Water vapor in gas-liquid separation tank
After separating the mixture, place it in a polymerization vessel at 350 mmHg and 280 ° C for 15 minutes.
After combining, it is made into a rope through the spinneret, and after water cooling it is cut into chips.
did. Relative viscosity of formic acid of chips is 67.0, [COOH]
The end group is 65.9 meq / kg, [NH₂] The terminal group is 34.
It was 1 meq / kg. Using the chip, at 298 ° C.
Directly spun from a spinneret with 312 27 mmφ holes
Immediately after cooling and applying the spinning oil,
Controller, and continue to successively increase the peripheral speed.
Guide to rotating 2nd to 4th Nelson rollers in 3 stages
Stretching heat setting is performed separately and at a speed of 1900 m / min.
I wound up. G with 4 godet rolls₁~ G_FourWhen
Then the temperature of each roll is G₁: Room temperature, G₂: 70 ° C, G
₃: 215 ° C, G_Four: 215 ° C, peripheral speed of each roll
Ratio is G₂/ G₁= 1.05, G₃/ G₂= 3.24, G
_Four/ G ₃= 1.65, winding speed / G_Four= 0.91
Was. The obtained yarn has a relative viscosity of formic acid of 62.0 and strength of 9.4.
g / d, elongation 20.8%, toughness 195.5 g / d.
%, Dry heat shrinkage 3.5%, Thai molecular stability coefficient 0.15
Met.

The raw yarn was made into a raw cord and a dip cord as in Example 1 and then vulcanized, and the vulcanized cord was taken out.
The strength was measured and found to be 7.0 g / d (vulcanized cord strength retention rate 74.5%).

Example 2 Low-viscosity chips obtained in Example 1 (formic acid relative viscosity 29.
Using 7), solid phase polymerization was carried out for 6 hours and 30 minutes in the same manner as in Example 1 to obtain chips having a relative viscosity of formic acid of 79.0. Spin setting heat setting was performed in the same manner as in Comparative Example 1 using the chips. The obtained yarn has a relative viscosity of formic acid of 74.1 and a strength of 10.
3g / d, elongation 21.7%, toughness 223.5g / d
%, Dry heat shrinkage 2.6%, Thai molecular stability coefficient 0.1
It was 3. The raw yarn was made into a raw cord and a dip cord and then vulcanized in the same manner as in Example 1. The vulcanized cord was taken out and its strength was measured to be 7.6 g / d (vulcanized cord strength retention rate: 73.8%). )Met.

[0035]Example 3 Low-viscosity chips obtained in Example 1 (relative viscosity of formic acid 29.
Using 7), solid phase polymerization was conducted for 6 hours and 50 minutes in the same manner as in Example 1.
Then, chips having a relative viscosity of formic acid of 83.6 were obtained. The chip
Have 312 holes of 0.24 mmφ at 298 ° C.
200mm which was spun from the spinneret and heated to 320 ℃
After passing through the heating cylinder, cooling and applying the spinning oil, immediately
To the No. 1 Nelson Roller and continue
Guided to the 2nd-4th Nelson rollers that rotate at high peripheral speed
1800m by stretching heat setting in 3 steps
It was wound up at a speed of / minute. 4 stages of each godet roll set
G ₁~ G_FourThen, the temperature of each roll is G₁: 80 ° C, G
₂: 210 ° C, G₃: 230 ℃, G_Four: At 230 ° C
The peripheral speed ratio of each roll is G₂/ G₁= 3.50, G ₃
/ G₂= 1.70, G_Four/ G₃= 0.995, winding speed
/ G_Four= 0.890. The obtained thread is formic acid
Viscosity 78.4, strength 10.5 g / d, elongation 20.6%,
Toughness 216.3 g / d ·%, dry heat shrinkage rate 2.5%,
The Thai molecular stability coefficient was 0.12.

Similar to Example 1, the raw yarn was made into a raw cord and a dip cord and then vulcanized, and the vulcanized cord was taken out,
The strength was measured and found to be 7.9 g / d (vulcanized cord strength retention rate 75.2%).

Example 4 Using the chips obtained in Comparative Example 2 (relative viscosity of formic acid 67.0), solid phase polymerization was carried out for 4 hours and 30 minutes in the same manner as in Example 1 to obtain chips having relative viscosity of formic acid 85.7. Obtained. Using the chips, spinning and stretching heat setting were performed in the same manner as in Example 3.
The obtained yarn has a relative viscosity of formic acid of 80.2 and strength of 10.5 g.
/ D, elongation 20.5%, toughness 215.3 g / d.
%, Dry heat shrinkage rate 2.6%, Thai molecular stability coefficient 0.15
Met.

The raw yarn was made into a raw cord and a dip cord as in Example 1 and then vulcanized, and the vulcanized cord was taken out,
The strength was measured and found to be 7.6 g / d (vulcanized cord strength retention rate 72.4%).

Comparative Example 3 The solid-state polymerized chip obtained in Example 4 (formic acid relative viscosity 8
5.7) with a hole 312 of 0.27 mmφ at 298 ° C.
After spinning from a spinneret having a number of pieces, passing through a 200 mm heating cylinder heated to 320 ° C., cooling, applying a spinning oil, immediately taking it out to a first Nelson roller, and successively rotating at a higher peripheral speed. Lead to the 2nd-4th Nelson roller and perform stretching heat setting in 3 stages.
It was wound up at a speed of 1800 m / min. When the godet roll groups of four stages are G _{1 to} G ₄ , the temperature of each roll is G ₁ :
_{Rt, G 2: 70 ℃, G} 3: 215 ℃, G 4: 215 ℃
And the peripheral speed ratio of each roll is G ₂ / G ₁ = 1.05, G
_{3 / G 3 = 3.43, G} 4 / G 3 = 1.65, was winding speed _/ G 4 = 0.91. The obtained yarn has a relative viscosity of formic acid of 80.2, a strength of 10.5 g / d, an elongation of 18.9%,
Toughness 198.5 g / d ·%, dry heat shrinkage rate 4.7%,
The Thai molecule stability coefficient was 0.21.

The raw yarn was made into a raw cord and a dip cord as in Example 1 and then vulcanized, and the vulcanized cord was taken out.
When the strength was measured, it was 7.1 g / d (vulcanized cord strength retention rate 67.6%).

As shown in the above Examples and Comparative Examples, a raw yarn having a relative viscosity of formic acid of 70 or more and a strength of 10 g / d or more should not be directly spun and drawn by the method described in Japanese Patent Publication No. 48-32616. A raw yarn having a low Thai molecular stability coefficient cannot be obtained.
And, with the decrease of the shrinkage rate of the yarn due to high temperature heat setting and the improvement of the degree of polymerization of decomposition suppression type such as using solid phase polymerization, the yarn having a low tie molecular stability coefficient is obtained, and the yarn is used. For the first time, a cord having a high strength utilization rate, that is, a cord having a high strength after vulcanization can be obtained even after post-processing steps such as a twisting step, a dipping step, and a vulcanizing step. By using the raw yarn of the present invention, it is possible to reduce the number of laminated layers in the tire and the belt, and reduce the number of driving.

[0042]

According to the production method of the present invention, for the first time, the strength of the raw yarn is as high as 10 g / d or more, and the strength utilization factor is high even after the post-processing such as the twisting process, the dipping process, and the vulcanization process. After that, a high-strength cord is obtained. By using the raw yarn obtained by the production method of the present invention, it is possible to reduce the number of laminated layers in tires and belts, and reduce the number of driven yarns. Particularly, the amount of yarn used, the number of laminated layers is for construction vehicles, aircraft, truck buses. Useful for reinforcing tires for automobiles.

[Brief description of drawings]

FIG. 1 is a graph showing changes in end groups in melt polymerization (curve B) and solid phase polymerization (curve A) of polyhexamethylene adipamide.

FIG. 2 is a graph showing a storage elastic modulus E ′ and a tie molecule stability coefficient measured by Vibron.

Claims (1)

[Claims] (1) Relative viscosity of formic acid 70 to 150, (2) Strength of 10 g / d or more (3) Toughness of 200 g / d ·% or more (4) Tie molecule stability coefficient of 0.15 or less (5) 160 ° C dry Shrinkage after free shrinking for 30 minutes in heat
The ratio is 4% or less, (6) the requirement that the strength of the vulcanized cord is 7.6 g / d or more
High polyhexamethyylene adipa for tire cords
Mid fiber.