JP2862745B2 - Method for producing polyalkylene naphthalate twisted cord - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyalkylene naphthalate twisted cord having high strength and high elastic modulus.

[0002]

BACKGROUND ART Polyalkylene naphthalate fibers powerful because inherently molecular skeleton is rigid, and combines the high modulus of elasticity, also excellent heat resistance and dimensional stability. Soshi
Te, fibers of this rope is widely applied to industrial and general purpose have been used such as fishing nets or protective clothing.

[0003] However, even fiber of this, elongation at break and there is a drawback to say that there is quite low handling is not always easy.

[0004] In particular, since elongation of the fatigue resistance is degraded less when using the fiber as a rubber reinforcement such as tire cords, belts usually improves the fatigue resistance is the figure as twisted cord. Therefore, the role of the twisted yarn is much more important than fibers made of other thermoplastic polymers. This is because such fibers have high rigidity , and thus have a problem that cord strength and cord elasticity after twisting are remarkably reduced. More particularly high twist number is, the ratio of decrease in strength and elastic modulus of the twisted cord size Kunar.

[0005] The cause of the drop in the strength and elastic modulus of this twisted cord is
The reason is that the rigidity of the polyalkylene naphthalate fiber itself is high.
For this reason, yarn or monofilament (constituent fiber)
(Irradiation) is difficult to be evenly distributed. I
The elongation of the polyalkylene naphthalate fiber is 5 to 1
Remarkably low of 2% makes it difficult to obtain an evenly uniform
It is difficult.

Conventionally, as means for improving the twist strength,
Improve the alignment of the single yarn of the yarn, or add polyethylene to the yarn.
Reduces friction between fibers by applying renwax oil
Or the twisting operation is divided into two and
We have devised so that uniform twisting can be performed.
Isn't the strength or modulus of the code satisfactory?
Was.

Further, the cord fabric is in JP-B-56-15321 that warps the twisted cord Ru polyethylene-2,6-naphthalate Tona, plus 8% -6%
Bond heat treatment at 150 to 240 ° C. under stretching up to 150 ° C. is described.

However, according to the study by the present inventors,
For example, the above elongation rate is increased for the woven fabric, especially
% Or more , the tension of the warp twisted cord becomes non-uniform due to the restraint by the weft, and as a result, the weft is not at right angles to the warp but inclined obliquely. Turned out to be a phenomenon
Was . Therefore, the strength of the twisted cord by heat treatment under tension
Further improvements in power and modulus have not been realized.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to obtain a twisted cord having a high strength or modulus which has never been obtained when a twisted cord is formed using a high-strength, high-modulus polyalkylene naphthalate fiber. It is an object of the present invention to provide a manufacturing method that can be used.

[0010]

Means for Solving the Problems The present inventors have made an effort to improve the strength of twisted cords of polyalkylene naphthalate fibers.
As a result of intensive studies, the twisting code prior to the cord fabric Te,
Tensile heat treatment with elongation of 10% or more in the cord state
High twist strength or high elastic modulus
Was found to be. This is the comparative example in Table 4 below.
As shown in the figure, tension heat treatment was performed in the state of the traditional blind fabric.
The product is compared to the product that has been subjected to tension heat treatment in the cord state.
Even at the same elongation rate, warp twisted yarn due to binding by weft
Non-uniform cord elongation, sufficient twist strength improvement
In light of the fact that it has no effect,
The condition of "state" and the requirement of "tensile heat treatment of 10% or more"
It can be said that it is organically bonded.

Thus, according to the present invention, the strength is 5 g / de.
In the method for manufacturing a twisted yarn cord formed from the above polyalkylene naphthalate fiber, 100 to the fiber 2 or more twist a twisting code obtained by twisting <br/> yarn coefficients, while coding state
There is provided a method for producing a polyalkylene naphthalate twisted cord, which is subjected to a tension heat treatment at a temperature of 350 ° C. at an elongation of 10 to 30% .

[0012] Such improvement in the strength of twisted yarn is achieved by using a rigid poly-
It is effective only for alkylene naphthalate fiber.
Conventional hot melt polymers such as polyethylene tereph
Not found on tarates, nylon 6 or nylon 66
No. Because polyethylene terephthalate and nylon 6
Alternatively, nylon 66 is twisted because its molecular skeleton is sufficiently flexible.
Even single yarns and yarns can be flexibly followed even when twisting with a high coefficient.
And the yarn elongation is as high as 10-20%, so when twisting
This is because it is not necessary to improve the strength of the twisted yarn after twisting.

Hereinafter, the present invention will be described in detail. The polyalkylene naphthalate fiber of the present invention comprises the following repeating unit (formula 2). Particularly preferably polyethylene-
2,6-naphthalate fiber. A copolymer containing less than 15 mol% of the third component may be used. The polyalkylene naphthalate may contain an inert matting agent in an amount of less than 3%.

[0014]

Embedded image

The alkyl group may be aliphatic or alicyclic, but is preferably a linear alkyl group having 2 to 4 carbon atoms. Particularly, polyethylene-2,6-naphthalate is preferred.

The strength of the raw yarn must be 5 g / de or more. If it is less than 5 g / de, the value as a high-strength fiber is reduced, and it is not much different from a normal hot-melt synthetic fiber. Preferably it is 7 g / de or more. The twist coefficient (TM) is 2 or more. Twist coefficient (TM) is defined by the following equation (1).

TM = 0.00323 × (denier of yarn) 1/2 × (number of twists / 10 cm) (1) Unless the twisting coefficient TM is 2 or more, the effect of the present invention is sufficient. I can't show it. Especially when TM becomes 3 or more , 10% or less
The effect of the present invention is remarkable by the combination with the above strain heat treatment.
Well expressed. Conventional knowledge that this is the degree of general twisting strength decrease as the number of twists increases is significantly
Can be said to be a contrasting event.

The total fineness of the yarn used is approximately 500 to
10,000 denier is preferred. A multifilament yarn of 500 to 3000 denier is generally used as the twist cord. The code created is 100
The range of 0 to 18000 denier is usual. The method for producing the twisted cord may be a single twist in which one yarn is twisted in only one direction or a twisting of two or more yarns like a rope, and any method may be used. When two or more yarns are twisted, each yarn is preliminarily twisted with the same number of twists, and then the yarns are aligned and the upper number of twists is almost equal to the number of twists in the reverse direction. This is the calculation of when the twist coefficient you calculated using many people the value of the twisted lower twisted or above as the number of twist using a total denier of the yarn that is plied as a total denier.

The heat treatment temperature for tensioning the twisted cord is 100 to 350 ° C. , preferably 150 to 300 ° C. This temperature is less than 100 ° C. rather small, strong increment of twisted cord, also fiber is deteriorated this temperature exceeds 350 ° C.. Heating heater you can use even in cylindrical or slit type heater of a non contact type in the hot plate of a contact type.

The elongation at the time of heat treatment is 10 to 30%.
This elongation rate is defined as follows. Assuming that the drawing speed at which the twisted cord is unwound from the bobbin is V0 and the speed of the roll at which the twisted cord is pulled out after completing the tension heat treatment is Vh, the elongation is calculated by the following equation (2). Elongation rate = (Vh−V0) / V0 × 100 (2)

[0021] The extension but it may also be carried out in two or more stages may be performed in a single stage. As for the mode of performing the tension heat treatment, there are a method of performing heat treatment after elongating the twisted cord and a method of performing heat treatment at the same time as substantially elongating the cord, but both may be used. However it preferred in the sense that the latter method is Ru can take a large elongation. The twisted cord that has been subjected to the tension heat treatment may be wound as it is while cooling naturally, or may be wound after being cooled by a cooling roll.

When the elongation is less than 10 % , the twist
The effect of the tension heat treatment in the cord state is insufficient, and the strength of the twisted cord is not significantly improved. On the other hand, if the elongation exceeds 30%, the polyalkylene naphthalate fiber will be overstrained, and problems such as breakage will occur. The optimization of the elongation rate is also affected by the twisting coefficient and the processing temperature, but when the twisting coefficient is high or the processing temperature is high, increasing the elongation rate tends to increase the strength and modulus of the twisted cord. The tension heat treatment of the present invention may be performed as an independent process, or may be performed continuously while performing a chemical treatment in another processing step.

[0023]

As described above, according to the present invention, a twisted cord obtained by twisting a polyalkylene naphthalate fiber is used as a core.
As it is (and therefore does not include the woven fabric)
By applying 10% or more tensioning heat treatment additively, follow
The elongation rate that could not be achieved by the occurrence of skew in the conventional woven fabric
High tension heat treatment of 10% or more becomes possible, and
The state or stress at the time of elongation of the twisted cord due to tension heat treatment
Also state when receiving a becomes uniform, that-out <br/> in that unprecedented strong and elastic modulus to obtain a twisted yarn cord was significantly improved.

Hereinafter, the present invention will be described with reference to examples.
In addition, each characteristic value in an Example was measured by the following method.

(1) Strength and elongation The fiber strength and elongation were based on JIS-L-1017.
Sample length 25 cm, elongation speed 30 cm / min. The strength and elongation of the twisted cord also conformed to JIS-L-1017.

(2) Initial elastic modulus The initial elastic modulus of the fiber was measured according to the initial tensile resistance of JIS-L-1017.

(3) Intrinsic Viscosity Chips or fibers are dissolved in a mixed solvent of phenol and 2,4,6-trichlorophenol (weight ratio 6: 4) and dissolved in a solvent.
Calculated from the flow time at ° C.

(4) Dry heat shrinkage rate According to JIS-L-1017B method (dry heat shrinkage rate), 18
The dry heat shrinkage after heat treatment at 0 ° C. for 30 minutes was determined. However, an initial load of 50 g was applied to the cord.

[0029]

Example 1 Polyethylene naphthalate was obtained by subjecting naphthalene-2,6-dicarboxylic acid and ethylene glycol to a polycondensation reaction. The intrinsic viscosity [η] of the polyethylene naphthalate was 0.6. The polyethylene naphthalate-cut chips were placed in a nitrogen atmosphere at 230 ° C. for 30 minutes.
Solid phase polymerization was performed for a period of time to obtain a polyethylene naphthalate having an intrinsic viscosity [η] of 0.9. The solid phase polymerization chip was melted at 300 ° C. and spun at 315 ° C. from a 320-hole spinneret. A heating area having an ambient temperature of 350 ° C. was provided 50 cm below the spinneret, and then cooled and solidified with a cooling air of 25 ° C. and wound at 500 m / min.

The wound undrawn yarn is drawn 6.5 times at 155 ° C. and further drawn 1.15 times on a hot plate at 220 ° C.
A constant-length heat treatment is performed on a heating roll at 00 ° C. to obtain a 1500 denier / 250 filament (hereinafter, 1500 de / 250 f).
) Was obtained.

The yarn had a strength of 10.8 g / de, a breaking elongation of 6.3% and an initial modulus of elasticity of 290 g / de.
Prepare two yarns and add 4 yarns per 10 cm to each yarn.
After 0 times of twisting, the two yarns were aligned and reverse twisted 40 times per 10 cm to give a twisted cord. This twisting operation is generally called twin twisting and can be carried out by a conventional twisting machine. Length of the obtained twisted cord is 3
The strain heat treatment was performed while passing through a 20 m / min cylindrical heater at a speed of 20 m / min. 85 internal temperature of cylindrical heater
Table 1 shows the results of heat treatment at a constant value of 10% with the elongation changed from 380C to 380C. Note that the twist coefficient of the twisted yarn cord is TM = 0.00323 × (300
0) 0.5 × 40 = 7.1.

[0032]

[Table 1]

As is clear from Table 1, the cord strength immediately after twisting was only 21.6 kg, but the temperature was 120 to 33.
When the tension heat treatment is performed in the range of 0 ° C., the cord strength is 23.1.
It is greatly improved to 24.1 kg . Meanwhile heat treatment temperature 80 ° C. At cord strength improvement is reduced. The strength of the twisted yarn cord temperature is 380 ° C. is had become worse.

[0034]

Example 2 The original twisted cord prepared in Example 1 (Experiment N
O1; blank) and passed through a 3 m long cylindrical heater at 20 m / min. Table 2 shows the result of fixing the heater temperature at 250 ° C. and changing the elongation rate variously. When the elongation is less than 10 % (Experiment NO8), the strength of the twisted cord is slightly improved as compared with the blank (Experiment NO1), but the effect is small. Yarn breakage during improved twisted cord strength is more than 2 4 kg treatment range stretch ratio of the 10 to 25% even without throat occurs N殆. However, when the elongation rate exceeded 30%, thread breakage frequently occurred .

[0035]

[Table 2]

[0036]

Example 3 Polyethylene naphthalate of [η] 0.6 polymerized in Example 1 was used (without solid-phase polymerization) of 30.
It was melt spun at 5 ° C. The spinneret has 320 holes, heats 20 cm below the spinneret to 350 ° C., then cools and solidifies the spun yarn with cooling air at 20 ° C., spins at 4500 m / min, and has a surface temperature of 15 ° C.
It is wound around the first roll at 0 ° C. for 15 turns, and then the stretching speed is 5
It was guided to a draw roll of 400 m / min and a temperature of 200 ° C., wound around the roll 15 times and heat-treated to obtain a 1500 filament / 320 f multifilament yarn, which was wound by a high-speed winder. The strength of the obtained yarn is 6.8 g / de,
The elongation was 9% and the initial elastic modulus was 220 g / de. Two yarns are prepared and each yarn has 40
After the first twist, two twisted cords were prepared by aligning the two and twisting them in the opposite direction for 40 twists per 10 cm. The twisted cord is immersed in a 13% strength aqueous solution of epoxy to improve rubber adhesion, and then immersed in a 25% strength solution of resorcinol-formalin latex (RFL). Dried. The weight ratio of resorcinol: formalin: latex is 5: 5: 9.
0 was set. During the drying, the strength of the dip cord obtained by tensioning the twisted cord at various elongation rates was measured. Table 3 shows the results.

[0037]

[Table 3]

The above yarn obtained by high-speed spinning and direct drawing has a lower absolute value of tenacity than that of the examples, but nevertheless, the tenacity is effectively increased by the heat treatment of the present invention. The dip cord of the present invention obtained by high-speed spinning (Experiment No. 1)
5 and 16) are 180 ° C. despite high elongation
, The dry heat shrinkage ratio was 2% or less, indicating excellent performance in thermal stability. When the elongation rate exceeded 30%, the cord was broken during processing, and a sample could not be collected.

[0039]

Embodiment 4 In this embodiment, the heat bonding treatment of the cord fabric and the heat bonding treatment of the twisted cord were compared. 100 twisted cords prepared in Example 1 (Experiment No. 1; blank test) were prepared, and the cords were used as warps to prepare a cord fabric. 1 for weft
It was driven at a density of 2 pieces per inch using 00 denier 24 filament drawn polyethylene terephthalate fiber. The obtained cord fabric was subjected to a heat bonding treatment in accordance with the method described in Example 3 . That is, it is immersed in a 13% aqueous solution of epoxy, then immersed in a mixture of 25% resorcinol / formalin / latex (RFL), and dried with a non-contact heater at 270 ° C. to obtain an elongation of 10%.
% Was subjected to a tension heat treatment. The weft was removed from the cord fabric after the treatment, and the strength of 100 warp twisted cords was measured, and the average value was obtained. On the other hand, 100 twisted cords prepared in Example 1 (experiment NO1; blank test) were directly aligned and subjected to the same heat bonding treatment, and the strength of the 100 heat-bonded twisted cords obtained was measured. The average was determined. The results are shown in Table 4 .

The weft removed from the cord fabric after the heat bonding treatment has a practically extremely undesirable phenomenon that the weft is not at a right angle to the warp but is obliquely inclined .
An inclination of about 10 degrees with respect to the normal weft direction was observed everywhere. In addition, tension heat treatment in the twisted cord state
In comparison with the woven fabric, the tension heat treatment in the state of the cord fabric
The power improvement effect is very small. These are woven into woven fabrics
The warp twisted cord is restrained by the weft,
The elongation of the yarn twisted cord becomes non-uniform, resulting in a high elongation
Even if stretch heat treatment is performed, it is not necessarily
It does not lead to improvement of physical properties.

[0041]

[Table 4]

Continuation of front page (56) References JP-A-4-352811 (JP, A) JP-A-3-292203 (JP, A) JP-A-50-50504 (JP, A) JP-A-48-77116 (JP) , A) (58) Fields investigated (Int. Cl. ⁶ , DB name) D02G 3/00-3/48 D01F 6/62

Claims (2)

(57) [Claims] 1. A method for manufacturing a twisted yarn cord formed from the intensity 5 g / de or more polyalkylene naphthalate fiber, twisted cord obtained by twisting the fibers in two or more twist coefficient
And the temperature of 100 to 350 ° C. while the Code State 1
A method for producing a polyalkylene naphthalate twisted cord, which is subjected to a tension heat treatment at an elongation of 0 to 30%. 2. The method for producing a polyalkylene naphthalate twisted cord according to claim 1, wherein 85 mol% or more of the repeating units of the polyalkylene naphthalate are composed of the following repeating units (formula 1). Embedded image