JPH11229234A - Polyester yarn for thread used for producing tatami and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject yarn for providing a sewing thread used for producing a Tatami mat (rush mat), in which the yarn in positioned at the core part of a vinylon staple yarn-containing composite yarn, with high tenacity, by setting an elongation at break and a strength of a polymer yarn at specific values, respectively, by adjusting spinning, drawing and heat-treating conditions. SOLUTION: A polyester having a high polymerization degree comprising a polyethylene terephthalate as a main component is spun in a molten state from a spinneret 1, passed through heating columns 3a and 3b, cooled and solidified by a yarn cooling apparatus 5 and an undrawn yarn Y having 0.0005-0.0030 double refractive index is taken off by a take-off roller 7. Successively, the undrawn yarn is drawn between rollers 8 and rollers 10 at a draw ratio of 90-95% as the maximum draw ratio while being heated by a superheated steam spraying apparatus 9, heat-treated by the hot rollers 10 and rollers 11 at 130-180 deg.C and <=120 deg.C, respectively to give a polyester yarn having 0.8-1.1 intrinsic viscosity, <=13% elongation at break and >=9.7 g/d strength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester fiber used for a core of a core-sheath composite type tatami thread used for sewing a tatami floor and a method for producing the same.

[0002]

2. Description of the Related Art A sewing machine is used for sewing a tatami floor, but the sewing machine has a high impact force on a thread because of its high efficiency. )
And low elongation and low creep properties are required. Therefore,
A yarn obtained by twisting a plurality of spun yarns using vinylon staple fiber or a tatami yarn obtained by twisting a polypropylene split yarn with paraffin or a silicone-based smoothing agent has been used.

[0003] Tatami yarns made of spun yarns using vinylon staple fiber are excellent in strength, elongation, creep characteristics, etc., and are suitable for sewing on tatami floors, but in addition to the high price of vinylon material, In addition, since the spinning and twisting steps are required, there is a problem that processing costs are increased and products are expensive. Therefore, a conjugate fiber using a polyester filament or a nylon filament for the core and a spun yarn made of vinylon staple fiber for the sheath has been proposed. (Japanese Patent Application Laid-Open No. 9-291689)

[0004] The tatami floor sewing thread requires a small number of manufacturing steps, can be obtained at low cost, and has a good sewing state. However, there is a difference between the yarn quality performance such as the strength and elongation of the filament of the core and the yarn quality of the vinylon staple fiber of the sheath, and the core yarn and the sheath yarn are easily cut in stages, In particular, when used for applications requiring high strength, there is a problem that strength is not sufficient.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, and the performance such as strength and elongation is close to the performance of vinylon staple, which is used for the core portion and vinylon staple fiber is provided for the sheath portion. It is a technical object of the present invention to provide a polyester fiber which is hard to be cut when it is made into a conjugate fiber and can be used as a high-strength sewing thread for tatami floors, and a method for producing the same.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and have reached the present invention.
That is, the present invention provides the following (1) and (2). (1) Polyester fibers mainly composed of polyethylene terephthalate, having a limiting viscosity of 0.8 to 1.1, a breaking elongation of 13% or less, and a strength of 9.7 g / d or more, for a tatami yarn. fiber. (2) After spinning out from a spinneret, passing through a heating cylinder, cooling and solidifying with a cooling device, the birefringence of an undrawn yarn when taken up by a take-off roller is 0.0005 to 0.0030, and subsequently undrawn. The yarn is stretched at a draw ratio of 90 to 95% of the maximum draw ratio, and is subjected to a two-stage heat treatment until winding, and the first-stage heat treatment is performed at a temperature of 130 to 180 ° C and the second-stage heat treatment is performed at 120 ° C. 2. The method according to claim 1, wherein:
A method for producing the polyester fiber for a tatami thread according to the above.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The polyester fiber of the present invention is used for the core of a conjugate fiber using vinylon staple fiber for the sheath, and the strength, elongation, etc., are close to those of vinylon staple, so that the conjugate fiber has high strength. And can be suitably used as a sewing thread for tatami floors.

[0008] The polyester fiber of the present invention contains polyethylene terephthalate (PET) as a main component. As long as the effects of the present invention are not impaired, other copolymerization components may be contained, but the repeating unit of ethylene terephthalate should be contained in the molecular chain in an amount of 90 mol% or more, and more preferably 95 mol% or more. Is preferred. As copolymerization components, isophthalic acid, naphthalenedicarboxylic acid, 4-
Oxybenzoic acid, propylene glycol, 1,6-hexanediol and the like can be mentioned. Further, these polyesters may contain additives such as matting agents, stabilizers, coloring agents, and flame retardants.

The intrinsic viscosity of the polyester fiber of the present invention is:
It needs to be 0.8 to 1.1. If the intrinsic viscosity is less than 0.8, the fiber does not have the target strength (9.7 g / d or more). When the intrinsic viscosity exceeds 1.1, the elongation at break cannot be suppressed low, and the fiber does not have the target elongation at break (13% or less).

The polyester fiber of the present invention has a breaking elongation of 13% or less, preferably 11.5% or less. In order for a sewing machine used for sewing a tatami floor to withstand the impact force applied to the yarn, low elongation and low creep properties are required. In consideration of this, since the vinylon staple used for the sheath portion usually has a cut elongation of 9 to 11%, the cut elongation of the polyester fiber of the present invention used for the core portion needs to be 13% or less. There is. When the cutting elongation exceeds 13%, when a load is applied to the composite fiber using the polyester fiber of the present invention as the core and the sheath using vinylon staple, a large load is applied to the vinylon staple having a low cutting elongation. In this case, the fiber is easily cut and cannot be made into a composite fiber having high strength.

Further, the strength of the polyester fiber of the present invention is at least 9.7 g / d, preferably at least 9.9 g / d. If the strength is lower than 9.7 g / d, the strength of the composite fiber using the vinylon staple fiber in the sheath decreases, and if the distribution of the vinylon staple in the sheath increases to increase the strength, the cost increases In addition, if the fineness of the polyester fiber is increased to increase the strength, the composite fiber itself becomes thicker, and when used for mating the tatami floor, irregularities appear on the surface of the tatami mat, or the yarn is turned upside down Traces remain.

In the present invention, the strength and elongation are JIS-L
It was measured based on -1017. Then, it is preferable that the variation in strength be 0.22 or less. If the variation in the strength is large, even if the strength as a whole is high, the fiber is weak against impact force and easily breaks. In addition, the variation of the strength is measured by measuring the strength of the test yarn 10 times,
It is shown by the standard deviation.

The second invention is a method for producing a polyester fiber having the above-mentioned physical properties by a direct spin drawing method. First, spinning is performed from a spinneret, passed through a heating tube, cooled and solidified by a cooling device, taken up by a take-up roller, and subsequently subjected to a two-stage heat treatment until the undrawn yarn is drawn and wound.

[0014] The melt-spun yarn is cooled and solidified, and the birefringence of the undrawn yarn when taken up by a take-off roller is 0.0005 to 0.0005.
0.0030. If the birefringence is to be made lower than 0.0005, it is necessary to lower the tension of the spun yarn, so that the take-up speed is lowered and the productivity is reduced. On the other hand, if the birefringence is larger than 0.0030, it is necessary to increase the draw ratio in order to obtain a fiber having the desired high elongation, and the yarn is cut. Further, when the stretching is performed at a draw ratio capable of avoiding the cutting of the yarn, the cutting elongation increases.

Subsequently, the undrawn yarn is moved to the maximum draw ratio of 9%.
The film is stretched at a stretching ratio of 0 to 95%. If the stretching ratio is less than 90% of the maximum stretching ratio, it is not possible to obtain a fiber having high strength and low elongation. If the draw ratio exceeds 95% of the maximum draw ratio, yarn breakage increases and operability deteriorates.

The stretching is preferably performed between rollers, and is performed using a heating roller (about 70 to 230 ° C.) for 2 to 3 times.
The method may be carried out in stages, but a method in which high-pressure superheated steam is sprayed on the yarn to perform stretching in one stage is preferable because the elongation at break can be suppressed low.

Next, a two-stage heat treatment is performed until the stretched yarn is wound. This heat treatment is performed for imparting a certain shrinkage ratio or facilitating winding, and it is preferable to perform the heat treatment using a heating roller. The first heat treatment is performed at a temperature of 130 to 180 ° C., more preferably 140 to 170 ° C., and the second heat treatment is performed at 120 to 180 ° C.
C. or lower, more preferably at 40 to 110C.

If the temperature of the first heat treatment is lower than 130 ° C., the package lacks thermal stability and shrinks during winding, so that the winding shape of the package wound by the winder becomes poor. On the other hand, if the temperature exceeds 180 ° C., the elongation at break becomes 1 due to spontaneous elongation.
It cannot be less than 3%.

When the heat treatment temperature of the second stage is higher than 120 ° C., the wound shape of the wound package becomes poor. If the relaxation rate between the final roller and the winder is reduced to prevent this, the resulting fiber cannot be kept at a low cutting elongation.

In this heat treatment, relaxation may be performed between the first stage and the second stage.
It is preferably set to about 3.0%.

Furthermore, in the production method of the present invention, it is preferable that the conditions of the heating cylinder installed immediately below the spinneret be specified. That is, the total length of the temperature control range of the heating cylinder is 30 to 50 cm, the temperature control range is divided into two, and the upper stage has a length of 15 to 25 cm and a temperature of 4
00 to 500 ° C, the lower stage is 80
It is assumed that the temperature is set to be lower than or equal to ° C and higher than 300 ° C.

The heating cylinder used in the present invention is preferably one in which a sheath heater is cast from various types of highly conductive metals, such as a heater in which a linear sheath heater is wound around the outer surface of a heating wall, or a plate heater. Those provided with, etc. can also be used. It is a tube having a cross-sectional area larger than that of the spinneret and usually having a circular inner cross-section, and is connected directly below the spin block or via a suitable heat insulating material.

If the total length of the temperature control range of the heating cylinder is shorter than 30 cm, it is necessary to reduce the take-up speed in order to lower the birefringence of the spun yarn, and the productivity is reduced. Or 5
The temperature needs to be higher than 00 ° C., and heat resistance and heat retention must be imparted to the apparatus itself, which causes an increase in cost. If the length is longer than 50 cm, the spun yarn becomes large in the heating cylinder or in a cooling device provided immediately below the spun yarn, so that the yarn spots become large, and the fiber tends to have a large variation in strength.

Further, the heat treatment in the heating cylinder is performed by dividing the temperature control range into two parts, the length of the upper stage is set to 15 to 25 cm, the temperature is set to 400 to 500 ° C.
Set the temperature lower than 0 ° C or higher and higher than 300 ° C. As a result, a product having a sufficiently low birefringence, less yarn sway in the heating cylinder and the cooling zone, less unevenness in strength and elongation, and excellent quality can be obtained.

Therefore, if the temperature control range of the heating cylinder is not divided into two, even when the temperature is set to 400 to 500 ° C., the yarn sway is large and the yarn spots are likely to be large. When the temperature of the upper stage is lower than 400 ° C. or when the length of the upper stage is 15 c
If it is less than m, the birefringence of the undrawn yarn and the elongation of the resulting fiber tend to be high. When the temperature of the upper stage is higher than 500 ° C. or the length exceeds 25 cm, the yarn sway in the heating cylinder tends to increase.

Further, the temperature in the lower stage is 8
When the temperature is lower than 0 ° C., the effect of providing the above-described temperature difference is small, and the yarn sway in the heating cylinder tends to increase.

Next, an example of the manufacturing method of the present invention will be described with reference to the drawings. FIG. 1 is a process chart showing one embodiment of the production method of the present invention. The undrawn yarn Y spun from the spinneret 1 passes through the heating cylinder 3 and is cooled and solidified by the cooling device 5. At this time, the heating cylinder 3 is divided into two upper and lower stages, and between the upper heating cylinder 3a and the lower heating cylinder 3b, a heat insulating material 2b is provided between the upper heating cylinder 3a and the upper spin block. In between, a heat insulating material 2a is provided, and temperature sensors 4a and 4b are provided in the heating cylinders 3a and 3b, respectively. The oil solidified by the cooling and solidification is applied with an oil agent by the oiling roller 6 and taken up by the take-up roller 7. The birefringence of the undrawn yarn Y at the time of being taken up by the take-up roller 7 is set to 0.1.
0005 to 0.0030. Subsequently, the first roller 8
The stretching is performed between the first and second rollers 10, while the high-pressure superheated steam is blown by the superheated steam injection device 9 provided between the rollers. And the second roller 1
The 0 and third rollers 11 are used as heating rollers, and a two-stage heat treatment is performed.

[0028]

Next, the present invention will be specifically described with reference to examples. Various measurements and evaluations in the examples were performed as follows. [Intrinsic viscosity] Measured at 20 ° C using an equal weight mixture of phenol and ethane tetrachloride as a solvent. [Strength and breaking elongation] Measured by the method described in JIS-L-1017. [Dispersion in Strength] The strength of each test yarn was measured 10 times and expressed as the standard deviation. (Birefringence) The undrawn yarn taken by the take-up roller is
It was determined by a normal compensator method using a D-line as a light source using a deflection microscope. [Maximum stretch ratio] The stretch ratio is gradually increased, and the stretch ratio at the time of cutting the yarn is measured, and the average value is measured three times. [Operability] The following evaluation was made based on the number of yarn breaks per spindle per day. 0 to 1 time ○ 2 to 3 times △ 4 times or more ×

Examples 1 to 3 Comparative Examples 1 to 8 A PET chip with an intrinsic viscosity of 0.99 (Comparative Example 5 is a PET with an intrinsic viscosity of 0.78, and Comparative Example 6 is a PET with an intrinsic viscosity of 1.25.
ET) was supplied to an ordinary melt spinning apparatus, and melt spinning, stretching, and winding were performed according to the steps shown in FIG. The spinneret 1 has a hole diameter of 0.55 mm and 96 discharge holes, and the heating cylinder 3 is divided into two upper and lower parts.
a, the length and the temperature of the lower stage 3b as shown in Table 1 were used. Then, the speed of the take-up roller, the stretching ratio, and the temperatures of the second and third rollers (the temperatures of the first and second stages) were variously changed as shown in Table 1. The stretching is performed in two stages. The first stage is preliminarily stretched at a draw ratio of 1.01 between the take-up roller 7 and the first roller 8, and the second stage is formed by the superheated steam injection device 9 on the yarn. The process was performed between the first roller 8 and the second roller 10 while blowing superheated steam of 350 ° C. Further, the first stage heat treatment by the second roller 10 and the third roller 11
, The second stage heat treatment was performed, and the relaxation was performed between the second roller 10 and the third roller 11 at a relaxation rate of 1%. Table 1 shows the evaluation of the birefringence of the undrawn yarn, the maximum draw ratio, the strength of the obtained fiber, the elongation at break, the intrinsic viscosity, the variation in strength, and the operability when the yarn is drawn by the take-off roller.

[0030]

[Table 1]

Further, among the fibers obtained in Examples 1 to 3 and Comparative Example, Comparative Example 1 which could be obtained with good operability,
The above-mentioned polyester filament was used as a staple fiber in a core part by a spinning machine using perlock cut vinylon staple (strength 9.8 g / d, elongation 9.0%) having a single yarn fineness of 1 denier. Then, a composite fiber was formed so that the sheath portion became vinylon staple. The weight ratio of the filament yarn to the staple fiber is 48/52,
A core yarn having a total fineness of 1760 denier and a twist number of 5 t / in was added with 8% by weight of paraffin as a smoothing agent to obtain a sewing thread for a tatami floor. Table 2 shows the physical property values of the obtained sewing thread.

[0032]

[Table 2]

As is clear from Table 1, the fibers obtained in Examples 1 to 3 satisfy the physical properties such as the intrinsic viscosity, strength, and elongation at break specified in the present invention, and have a small variation in strength. there were. And, as shown in Table 2, the sewing thread using these fibers for the core had a sufficiently high strength and a good sewing state. On the other hand, in Comparative Example 1, since the stretching ratio was too low, the obtained fiber had low strength and high breaking elongation. In Comparative Example 2, since the draw ratio was too high, the yarn breakage increased, the operability deteriorated, and the obtained fibers had large variations in strength. In Comparative Example 3, since the first heat treatment temperature was too high, the obtained fiber had a high elongation at break. In Comparative Example 4, since the heat treatment temperature in the second stage was too high, the obtained fiber had a high elongation at break and a large variation in strength. In Comparative Example 5, since a polymer having a low intrinsic viscosity was used, the obtained fiber had an intrinsic viscosity that was too low and had a low strength. In Comparative Example 6, since a polymer having a high intrinsic viscosity was used, the resulting fiber had an excessively high intrinsic viscosity and a high breaking elongation. In both Comparative Examples 5 and 6, the operability was poor. In Comparative Example 7, since the entire length of the heating cylinder was short and the birefringence of the undrawn yarn was also high, Comparative Example 8 was too low in the temperature of the upper stage of the heating cylinder, and the birefringence of the undrawn yarn was also high. The obtained fiber had high elongation at break and poor operability. Since the fibers of Comparative Examples 1, 3, and 4 did not satisfy physical properties such as strength and elongation at break, composite fibers with vinylon staple using this fiber as a core were as shown in Table 2. In addition, the strength was low.

[0034]

When the polyester fiber of the present invention is used for the core of the composite fiber and the sheath is made of vinylon staple, it becomes a sewing thread for tatami floors having high strength,
An inexpensive and excellent strong sewing thread can be obtained.

[Brief description of the drawings]

FIG. 1 is a process chart showing one embodiment of a method for producing a polyester fiber of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Spinneret 3a, b Heating cylinder 5 Yarn cooling device 7 Take-up roller 8 First roller 10 Second roller 11 Third roller 12 Winder Y Yarn

Claims (3)

[Claims] 1. A polyester fiber comprising polyethylene terephthalate as a main component, having an intrinsic viscosity of 0.8 to
1.1. Polyester fibers for tatami yarn having a cut elongation of 13% or less and a strength of 9.7 g / d or more. 2. The birefringence of an undrawn yarn when spinning out from a spinneret, passing through a heating cylinder, cooling and solidifying by a cooling device, and then being taken up by a take-up roller is 0.0005 to 0.0030.
Subsequently, the undrawn yarn is subjected to the maximum draw ratio of 90 to 95.
% At a stretch ratio of 2%, and subjected to a two-stage heat treatment until winding, and the first-stage heat treatment is performed at a temperature of 130 to 180 ° C.
The method according to claim 1, wherein the second heat treatment is performed at a temperature of 120 ° C or lower. 3. The heating cylinder satisfies the following condition.
A method for producing the polyester fiber for a tatami thread according to the above. (A) The total length of the temperature control range is 30 to 50 cm, and (b) the temperature control range is divided into upper and lower halves. (C) The length of the upper stage is 15 to 25 cm, and (d) the temperature of the upper stage is 400 to 5
The temperature in the lower stage is set at 80 ° C. or lower than the temperature in the upper stage and higher than 300 ° C.