JP2012219399A - Polyester monofilament for hose reinforcing material and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester monofilament for a hose reinforcing material having a high Young's modulus, heat shrinkage resistance, bending fatigue resistance, and a sufficient physical property.SOLUTION: There is provided a polyester monofilament for hose reinforcing material, comprising a resin composition including 30 to 70 wt% of polyethylene naphthalate and 30 to 70 wt% of polyester other than polyethylene naphthalate. The polyester monofilament has a cross sectional shape of a split leaf A, in which a Young's modulus, a dry heat shrinkage ratio at 140°C, and the number of MIT bending times required for breaking in a bending fatigue test of the polyester monofilament each satisfy a specific number.

Description

  The present invention relates to a polyester monofilament for hose reinforcement and a method for producing the same. More specifically, the present invention relates to a polyester monofilament for a hose reinforcing material that maintains high Young's modulus, heat shrinkage resistance, and bending fatigue resistance and has sufficient characteristics for internal reinforcement of a hose, and a method for producing the same.

  Conventional hose reinforcements are used for reinforcement to withstand the internal pressure of the hose and maintain a tubular shape. For this reason, the hose reinforcements are strong enough to withstand high pressures and have a good pressure response. The characteristics of high Young's modulus and low creep are required.

  Conventionally, vinylon fibers have been mainly used for such applications, but hose reinforcements made of vinylon fibers have not been sufficiently durable for long-term use. The use of polyethylene terephthalate fibers, which are advantageous in particular, is increasing, especially high modulus polyethylene terephthalate fibers.

  However, in the process of manufacturing the hose, since heat treatment such as vulcanization and molding is performed, the reinforcing material to be used is impaired in the uniformity of the hose shape due to the shrinkage rate at the time of heating. The performance is required to have not only high modulus characteristics but also low shrinkage.

  As a solution for this, a technique for suppressing the dry heat shrinkage of the fiber cord during rubber vulcanization (for example, see Patent Document 1) has been proposed. However, this method reduces the elastic modulus of the hose reinforcement. Therefore, it has been desired to develop a reinforcing material having a higher elastic modulus and lower shrinkage.

JP 2005-54304 A

  The present invention has been achieved as a result of studying the above-described problems in the prior art as problems. That is, an object of the present invention is to provide a polyester monofilament for hose reinforcement having an unprecedented high Young's modulus, heat shrinkage resistance, and bending fatigue resistance, and sufficient characteristics as a reinforcement used for internal reinforcement of a hose. And providing a manufacturing method thereof.

In order to achieve the above object, according to the present invention, there is provided a polyester monofilament comprising a resin composition containing 30 to 70% by weight of polyethylene naphthalate and 30 to 70% by weight of polyester other than polyethylene naphthalate, There is provided a polyester monofilament for a hose reinforcing material which satisfies the requirements (A) to (C) at the same time.
(A) Young's modulus measured in accordance with JIS L1013-1999 8.10 is 12,000 N / mm ² or more, 27,000 N / mm ² or less,
(B) The dry heat shrinkage at 140 ° C. measured in accordance with B method of 8.18.2 of JIS L1013-1999 is 7.0% or less,
(C) The number of times of MIT bending required for cutting in the bending fatigue characteristic test measured according to JIS P-8115 is 200 times or more.

In the polyester monofilament for hose reinforcement of the present invention,
The polyester other than the polyethylene naphthalate is at least one selected from polyethylene terephthalate, polybutylene terephthalate, polybutylene naphthalate, polytrimethylene terephthalate, and the cross-sectional shape of the monofilament is in the fiber axis direction at the peripheral edge of the cross-section A preferable condition is that the shape of the leaf has one or more dents extending to the left.

  Further, the method for producing a polyester monofilament for hose reinforcing material of the present invention, when melt spinning and stretching a resin composition containing 30 to 70% by weight of polyethylene naphthalate and 30 to 70% by weight of polyester other than polyethylene naphthalate, A draft ratio formula (Q / R) represented by the ratio of the take-off speed Q (unit: m / min) of the melt discharged from the die to the discharge linear speed R (unit: m / min) is in the range of 6 to 12. And stretching at a total stretching ratio of 7.0 to 9.5 times in a temperature range of 120 to 160 ° C., and then relaxing the stretched monofilament to 200 to 270 ° C. and 0.90 to 1.00 times A heat treatment is performed.

  According to the present invention, a monofilament for a hose reinforcing material having a high Young's modulus, heat shrinkage resistance, and bending fatigue resistance can be obtained. Therefore, the polyester monofilament for hose reinforcement of the present invention is extremely effective for a hose having required characteristics such as pressure resistance, dimensional stability during manufacture of the hose, fatigue resistance, and adhesiveness with a resin.

(A)-(f) is sectional drawing which shows the cross-sectional shape of the polyester monofilament for hose reinforcement materials of this invention.

  Hereinafter, the present invention will be specifically described.

  The polyester monofilament for hose reinforcement of the present invention is characterized in that it is composed of a resin composition containing 30 to 70% by weight of polyethylene naphthalate and 30 to 70% by weight of polyester other than polyethylene naphthalate. is there.

  Examples of polyester resins other than polyethylene naphthalate in the present invention include polyethylene terephthalate (PET), polybutylene naphthalate (PBN), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), or a combination of two or more thereof. Examples thereof include polyester such as polymerization or blending.

  The resin composition constituting the polyester monofilament is preferably composed of 30 to 70% by weight of polyethylene naphthalate and 30 to 70% by weight of polyester other than polyethylene naphthalate, and the polyethylene naphthalate exceeds the above range, and the polyester other than polyethylene naphthalate. Is below the above range, a monofilament with a high Young's modulus and low shrinkage can be obtained, but the bending fatigue characteristics are reduced, so the hose used as a hose reinforcement is a hose lacking in bending resistance. It is not preferable.

  In addition, when the polyethylene naphthalate component is below the above range and the polyester other than polyethylene naphthalate is above the above range, the monofilament has a high heat shrinkage rate, and the heat applied during molding during the production of the hose increases the monofilament. This is not preferable because the hose which shrinks and tends to obtain a hose lacking in dimensional stability.

  The fineness of the polyester monofilament for hose reinforcement of the present invention can be appropriately selected depending on the size and application of the hose, but it is usually preferably in the range of 2,000 to 100,000 dtex.

  The polyester monofilament for hose reinforcing material of the present invention is a continuous yarn composed of one single yarn, and its cross-sectional shape is in the fiber axis direction at the periphery of the cross section in order to enhance the adhesion with rubber or resin as a hose material. Preferably, it is in the form of a cleft with one or more indentations extending to

  1 (a) to 1 (f) are cross-sectional views showing a cross-sectional shape of a polyester monofilament for hose reinforcing material of the present invention, and dents such as (a), (b), (c) and (d) are shown. It is preferable to have one or more.

  However, when the cross-sectional shape is round, the adhesion with the hose resin is lowered, which is not preferable.

  In addition to polygonal shapes such as triangles, squares (e), hexagons (heights), or shapes having protrusions on these shapes, the cross-sectional shape may be of a different shape such as a star shape, a ten-y-h shape, etc. However, it is particularly preferable to have a leaf crack shape such as (c) and (d).

Further, the polyester monofilament hose reinforcement member of the present invention, the Young's modulus of 12,000N / mm ² or more, preferably 30,000 N / mm ² or less, more 16,000N / mm ² or more, 28, More preferably, it is 000 N / mm ² or less.

  The Young's modulus is in accordance with JIS L1013-1999, 8.10, using “Tensilon” UTM-4-100 type tensile tester manufactured by Orientec Co., Ltd., to obtain a load-elongation curve of the monofilament, It is a value obtained from the obtained load-elongation curve. The tensile speed is 300 mm / min, and the average value is evaluated five times. If the average value is below the above range, the polyester monofilament for hose reinforcement lacking strength is obtained, and the hose cannot withstand the internal pressure. Since it becomes easy to break, it is not preferable. On the other hand, when the above range is exceeded, polyester monofilament lacks flexibility, and when used as a hose reinforcement, it becomes unpreferable because it becomes a hose lacking flexibility.

  Further, the polyester monofilament for hose reinforcement of the present invention preferably has a dry heat shrinkage at 140 ° C. of 7.0% or less, more preferably 5.0% or less.

  The dry heat shrinkage rate is in accordance with JIS L1013-1999 8.18.2. After cutting the monofilament to 500 mm and leaving it in a gear oven at 140 ° C. for 30 minutes, the length of the monofilament is measured again, and the shrinkage rate (%) Is a calculated value. The measurement was performed five times, and the average value was evaluated. When the average value exceeded the above range, the polyester monofilament for hose reinforcement increased in heat shrinkage, and the polyester monofilament was heated by vulcanization molding heat. Is reduced, and it tends to be easy to obtain a hose lacking dimensional stability.

  The polyester monofilament for hose reinforcing material of the present invention preferably has a MIT bending number of 200 or more required for cutting in the bending fatigue characteristic test.

  MIT flex number was manufactured by Toyo Seiki Co., Ltd .; according to JIS P-8115, load 2.2 cN / dtex, number of folds 175 times / minute, fold angle 270 degrees (each about right and left) 135 degrees) and the average value of the number of reciprocal bendings until 10 monofilaments were cut for each sample under the conditions of a curvature radius of 0.38 ± 0.02 mm for each of the left and right bending surfaces in the folding frame sandwiching the monofilaments When the average value falls below the above range, even if this monofilament is processed as a hose reinforcing material, only a hose lacking in bending resistance can be obtained.

  In addition, when the polyester monofilament for hose reinforcing material of the present invention is used as a constituent material that may be used in a hot and humid atmosphere such as an automotive application, various kinds are used for the purpose of suppressing the hydrolysis of the polyester. Carbodiimide compounds, epoxy compounds and oxazoline compounds can also be added as constituents of the polyester monofilament, and particularly those containing unreacted carbodiimide compounds have high hydrolysis resistance.

  Next, the manufacturing method of the polyester monofilament for hose reinforcement of the present invention will be described in detail.

  In the production method of the present invention, when a resin composition containing 30 to 70% by weight of polyethylene naphthalate and 30 to 70% by weight of polyester other than polyethylene naphthalate is melt-spun and stretched, the melt discharged from the die is taken up. The draft ratio formula (Q / R) represented by the ratio of the speed Q (unit: m / min) and the discharge linear speed R (unit: m / min) is in the range of 6 to 12, and is 120 to 160 ° C. Stretching is performed at a total stretching ratio of 7.0 to 9.5 times in a temperature range, and then the relaxation treatment is performed on the monofilament after stretching at 200 to 270 ° C. and 0.90 to 1.00 times.

  Polyethylene naphthalate, polyethylene terephthalate, polybutylene naphthalate, polybutylene terephthalate, polytrimethylene terephthalate and the like constituting the resin composition can be produced by a general polymerization method, for example, an antimony compound, a titanium compound, germanium, and the like. It can be produced by synthesizing from a dicarboxylic acid and / or an ester-forming derivative thereof and a diol and / or an ester-forming derivative thereof by an esterification reaction using a compound and an aluminum compound as a main catalyst.

  First, after drying a polyester resin pellet having an intrinsic viscosity of 0.5 or more composed of a dicarboxylic acid component and a glycol component, the polyester resin pellet is supplied to a spinning machine, measured by a gear pump, and melt-extruded from a nozzle nozzle. The draft ratio (Q / R) represented by the ratio of the take-off speed Q (unit: m / min) of the melt discharged from the die at this time and the discharge linear speed R (unit: m / min) is 6 to 6 12 and preferably a ratio of 8-10.

  When the draft ratio is below the above range, the take-off speed becomes slower than the discharge linear speed, and in this case, the stability when discharged from the die discharge hole is lowered, the undrawn yarn snakes, and the wire diameter varies. It is not preferable because it tends to deteriorate. When the above range is exceeded, the shape of the undrawn yarn cannot be maintained, and it tends to be difficult to obtain a monofilament with a uniform wire diameter.

  Next, the melt-extruded undrawn yarn is introduced into a cooling bath of 40 ° C. or higher and 90 ° C. or lower, preferably 50 ° C. or higher and 80 ° C. or lower, and rapidly cooled.

  If the temperature of the cooling bath is less than the above range, the undrawn yarn will meander and tend to deteriorate the wire diameter variation. On the other hand, if the temperature of the cooling bath exceeds the above range, the shape of the undrawn yarn can be maintained. However, it tends to be difficult to obtain a monofilament having a uniform wire diameter.

  The cooling bath refrigerant used here is a substance that can be easily removed from the surface of the undrawn yarn and does not give any physical or chemical change to the polymer. In the method, there is no particular limitation as long as it can maintain a liquid state, and examples thereof include water, paraffin, ethylene glycol, glycerin, amyl alcohol, and xylene.

  The undrawn yarn obtained in this way is subsequently drawn in order to obtain a very high tensile strength as a hose reinforcement.

  That is, in the temperature range of 120 to 160 ° C., one-stage or multi-stage stretching is performed under stretching conditions having a total stretching ratio of 7.0 to 9.5 times.

  When the drawing temperature is lower than the above range, the amount of heat given to the monofilament is insufficient, so that yarn breakage occurs at the time of drawing and the spinnability deteriorates, which is not preferable.

  In addition, when the temperature range of the heat medium exceeds the above range, the Young's modulus decreases, and the target physical properties cannot be obtained, which is not preferable.

  The heat medium used for stretching is preferably a liquid heat medium having a specific heat of 0 ° C. of 0.5 cal / g · ° C. or more, and examples of the heat medium include ethylene glycol and glycerin.

  When the total draw ratio is less than the above range, the target physical properties cannot be obtained, which is not preferable. When the total draw ratio is exceeded, the yarn breakage occurs at the time of drawing, and the spinnability deteriorates.

  The drawn monofilament is then preferably subjected to relaxation heat treatment at a relaxation heat treatment temperature of 200 to 270 ° C. and a relaxation heat treatment magnification of 0.90 to 1.00 times in a dry heat furnace.

  When the relaxation heat treatment temperature of the relaxation heat treatment is lower than the above range, the heat shrinkage rate of the polyester monofilament is increased, and when used as a hose reinforcement, the reinforcement shrinks due to the vulcanization molding heat at the time of hose manufacture, This is not preferable because a hose lacking in dimensional stability tends to be obtained.

  When the relaxation heat treatment temperature of the relaxation heat treatment exceeds the above range, or when the relaxation heat treatment magnification of the relaxation heat treatment is less than the above range, the monofilament tends to come into contact with the furnace and melt, and spinnability is deteriorated. Absent.

  When the relaxation heat treatment magnification of the relaxation heat treatment exceeds the above range, the heat shrinkage rate of the polyester monofilament is increased, and when used as a hose reinforcement, the reinforcement shrinks due to the vulcanization molding heat at the time of hose manufacture, This is not preferable because a hose lacking in dimensional stability tends to be obtained.

  The polyester monofilament for hose reinforcement of the present invention thus obtained has a high Young's modulus, heat shrinkage resistance and bending fatigue resistance, and has stable quality not found in conventional hose reinforcements. ing.

  EXAMPLES Hereinafter, although the polyester monofilament for hose reinforcements of this invention is demonstrated in more detail by an Example, this invention is not limited to a following example at all unless the main point is exceeded. In addition, the various characteristic values of the polyester monofilament described above and below are measured according to the following methods.

[Young's modulus]
In accordance with JIS L1013-1999, 8.10, a “Tensilon” UTM-4-100 type tensile tester manufactured by Orientec Co., Ltd. was used to obtain a load-elongation curve of the monofilament. Thereafter, the Young's modulus (N / mm ² ) was determined from the obtained load-elongation curve. The tensile speed was 300 mm / min, and the average value of 5 times was evaluated.

[Dry heat shrinkage at 140 ° C.]
In accordance with 8.18.2 of JIS L1013-1999, the monofilament was cut to 500 mm and left in a gear oven at 140 ° C. for 30 minutes. Thereafter, the length of the monofilament was measured again, and the shrinkage rate (%) was calculated. In addition, the measurement was performed 5 times and the average value was evaluated.

[Number of MIT flexing times required to cut]
Manufactured by Toyo Seiki Co., Ltd .; according to JIS P-8115, load 2.2 cN / dtex, number of bendings 175 times / minute, bending angle 270 degrees (about 135 degrees on each side) and The average value was obtained by measuring the number of reciprocal bendings until 10 monofilaments were cut per sample under the condition that the curvature radii of the left and right bending surfaces of the folding frame sandwiching the monofilaments were each 0.38 ± 0.02 mm. .

[Spinnability]
The thread breakage and the wire diameter unevenness after the process of drawing from the discharge from the die and stretching and relaxation treatment were visually evaluated.
○ No yarn breakage during spinning and no wire diameter irregularities.
Δ: No yarn breakage during spinning, but there is uneven diameter.
× The thread cannot be taken up.

[Adhesion with resin]
The surface of the obtained monofilament sample was melt-coated with a polyethylene resin (manufactured by Unitika, 9739) to a thickness of 2 mm, the sheath on one side was removed, and the monofilament was pulled out of the sheath. The strength (N) that acts at the time of drawing was measured with tensilon, converted per unit length (cm), and the value was evaluated as the evaluation value (N / cm) of adhesion in the following three stages.
○ ・ ・ ・ Adhesion good △ ・ ・ ・ Adhesion slightly good X ・ ・ ・ Adhesion poor

[Raw material of polyester monofilament]
PEN: Polyethylene naphthalate resin (Toyobo PN640)
PET: Polyethylene terephthalate resin (T701T manufactured by Toray Industries, Inc.)
PBN: Polybutylene naphthalate resin (AE-500, manufactured by Toyobo)
PBT: Polybutylene terephthalate resin (Toray 1500S)
PTT ・ ・ ・ Polytrimethylene terephthalate resin (ML-126 manufactured by DuPont)

[Examples 1-6, Comparative Examples 1-2]
PEN and other polyesters were blended in the proportions shown in Table 1, melted at 290 ° C. with an extruder-type spinning machine, the gear pump rotation speed was adjusted to a fineness of about 10,000 dtex, and then passed through the gear pump. The draft ratio (Q / R) expressed by the ratio between the take-off speed Q (unit: m / min) of the melt discharged from the spinneret hole and the discharge linear speed R (unit: m / min) is 8. The melted resin composition blended from the eight-leaf type spinneret hole was spun, led to a water cooling bath at a temperature of 70 ° C., and cooled and solidified.

  Thereafter, the cooled and solidified undrawn yarn was heated and drawn 7.5 times in a polyethylene glycol solvent bath at a temperature of 150 ° C. and in a polyethylene glycol solvent bath at a temperature of 160 ° C., and then in a dry hot air bath at a temperature of 245 ° C. Table 1 shows the results of measurement of the properties of the synthetic resin monofilament having an eight-leaf cross-sectional shape obtained by performing relaxation heat treatment.

  In Examples 2 to 6 and Comparative Examples 1 and 2, spinning, stretching, and relaxation heat treatment were performed under the same conditions as in Example 1 except that the raw material composition was changed as shown in Table 1, and physical properties of the obtained monofilaments were measured.

  As can be seen from Table 1, in Examples 1 to 6, there is no problem in spinnability, and the physical properties satisfy the target Young's modulus, dry heat shrinkage, and bending fatigue properties, whereas Comparative Example 1 has Young's modulus, Although the thermal shrinkage rate was satisfied, the bending fatigue characteristics were lowered and the target physical properties could not be obtained. In Comparative Example 2, thread breakage occurred, and the film could not be taken out with the draw ratio under the above conditions.

[Examples 7 to 12, Comparative Examples 3 to 11]
A monofilament obtained with the same blending raw material, die, target fineness and conditions as in Example 1 was obtained except that the draft ratio, draw ratio, draw temperature and ratio, and relaxation heat treatment were changed as shown in Table 2, and spinning was performed. The results of measuring each characteristic are shown in Table 2.

  As can be seen from Table 2, Examples 7 to 12 can be used as a hose reinforcing material without any problem in spinnability and physical properties.

  On the other hand, in Comparative Examples 3 and 4, the draft ratio was changed, and when the draft was set to 4 as in Comparative Example 3, the discharge linear speed was increased and the undrawn yarn could not be taken in time, so that the drawing was performed. I ca n’t pick up. When the draft is set to 15 as in Comparative Example 4, the yarn can be taken up, but the wire diameter unevenness is so severe that it cannot be used as a hose reinforcing material.

  In Comparative Examples 5 and 6, the drawing temperature was changed. When the drawing temperature was 100 ° C. as in Comparative Example 5, yarn breakage occurred in the drawing bath, and the yarn could not be taken up. As described above, when the stretching temperature is 180 ° C., the Young's modulus decreases, so that the target physical properties cannot be obtained.

  In Comparative Examples 7 and 8, the total draw ratio is changed. When the total draw ratio is 5.0 times as in Comparative Example 7, the yarn can be picked up, but there are some irregularities in the diameter, and Since the Young's modulus is lowered, the target physical properties cannot be obtained. When the total draw ratio is 10.0 times as in Comparative Example 8, yarn breakage occurs during drawing, and the yarn cannot be taken up.

  In Comparative Example 9, the relaxation heat treatment temperature is changed. When the relaxation heat treatment temperature is 300 ° C., the yarn is melted and cannot be taken up.

  In Comparative Examples 10 and 11, the relaxation heat treatment magnification is changed. When the relaxation heat draw ratio is 0.80 times as in Comparative Example 10, the yarn contacts and melts in the dry heat furnace, so that the yarn can be taken up. Can not.

  Further, when the draw ratio is 1.1 times as in Comparative Example 11, Young's modulus and flexural fatigue characteristics can be obtained as desired, but the dry heat shrinkage ratio is increased, so that the desired physical properties are obtained. Absent.

  The polyester monofilament for hose reinforcement of the present invention has excellent high Young's modulus, heat shrinkage, and bending fatigue resistance, and has stable quality not found in conventional hose reinforcement.

  Therefore, the hose reinforcing material of the present invention has an unprecedented high Young's modulus, heat shrinkage rate, and bending fatigue resistance, and also has improved adhesion to the hose material resin during hose processing. It exhibits extremely excellent effects as a material.

Claims (4)

A polyester monofilament comprising a resin composition containing 30 to 70% by weight of polyethylene naphthalate and 30 to 70% by weight of polyester other than polyethylene naphthalate, which simultaneously satisfies the following requirements (A) to (C): Characteristic polyester monofilament for hose reinforcement.
(A) Young's modulus measured in accordance with JIS L1013-1999 8.10 is 12,000 N / mm ² or more, 27,000 N / mm ² or less,
(B) The dry heat shrinkage at 140 ° C. measured in accordance with B method of 8.18.2 of JIS L1013-1999 is 7.0% or less,
(C) The number of times of MIT bending required for cutting in the bending fatigue characteristic test measured according to JIS P-8115 is 200 times or more. The polyester for hose reinforcement according to claim 1, wherein the polyester other than the polyethylene naphthalate is at least one selected from polyethylene terephthalate, polybutylene terephthalate, polybutylene naphthalate, and polytrimethylene terephthalate. Monofilament. 3. The polyester monofilament for hose reinforcement according to claim 1, wherein the cross-sectional shape of the monofilament is a leaf crack shape having one or more dents extending in the fiber axis direction on a peripheral edge of the cross-section. When melt spinning and stretching a resin composition containing 30 to 70% by weight of polyethylene naphthalate and 30 to 70% by weight of polyester other than polyethylene naphthalate, the take-up speed Q (unit: m / m) of the melt discharged from the die Min) and the ratio of discharge linear velocity R (unit: m / min), the draft ratio formula (Q / R) is in the range of 6-12, and the total draw ratio in the temperature range of 120-160 ° C. The film is stretched 7.0 to 9.5 times, and then subjected to relaxation heat treatment at 200 to 270 ° C. and 0.90 to 1.00 times on the monofilament after stretching. The manufacturing method of the polyester monofilament for hose reinforcement materials of 1 item | term.

Images