JP2009091681A - Polyester fiber cord and power transmission belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester fiber cord for a belt core wire which has excellent fatigue resistance, hardly causes tension reduction even after driving a belt for a long period, and hardly causes slip between the belt and a pulley. <P>SOLUTION: The polyester fiber cord is obtained by mixing a polyethylene terephthalate fiber in an amount of 10-70 wt.% with a polyethylene naphthalate fiber based on the polyethylene terephthalate, and has a tensile force and a dry heat shrinkage of the cord simultaneously satisfying the following formulas (I) and (II): (I) A≥0.050; and (II) A-B≤0.010 (wherein, A and B are each tensile forces (N/dtex) after holding the cord under an initial tension of 0.1 N/tex at 100°C for 2 and 48 hr respectively). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polyester fiber cord and a power transmission belt using the same, and more specifically, the present invention is used as a core of a friction transmission belt such as a V belt, a V-ribbed belt, and a flat belt. Thus, the present invention relates to a polyester fiber cord that can reduce the elongation during belt running as much as possible, maintain a high belt tension, and increase power transmission efficiency.

  In general, a belt by winding transmission such as a V-belt, a V-ribbed belt, a flat belt, etc., transmits power by the frictional force of the belt, and therefore the belt during traveling requires a certain tension according to driving conditions. . If the belt tension during running decreases, the gripping force with the pulley will decrease, and slip will easily occur and power cannot be transmitted sufficiently.

  Such a decrease in belt tension is strongly influenced by the stress relaxation characteristics of the core wire and the heat shrinkage characteristics caused by the friction between the belt and the pulley during running. Therefore, conventionally, as the core wire of such a belt, a cord in which several multifilaments are twisted down and several of them are collected and twisted up is used, and an adhesive is provided for bonding to the rubber layer, and high elasticity After a small stress relaxation and a heat stretching and fixing treatment for imparting a high heat shrinkage stress, the rubber layer is disposed and integrated with a constant tension and vulcanized.

  In order to improve the transmission capability of such a belt, for example, Patent Document 1 discloses that the initial tensile resistance is 58 g / de or more, the thermal stress when heated at 150 ° C. for 8 minutes is 0.5 g / de or more, and the stress A cord made of a polyester fiber cord having a ratio of 0.928 or more and a power transmission belt using the cord are disclosed.

Patent Document 2 discloses a power transmission belt core wire in which an adhesive is applied to a polyester cord obtained by twisting high toughness polyester multifilaments and further subjected to a stretching heat fixing treatment, and a transmission belt using these. Yes.
Further, Patent Document 3 discloses a power transmission belt using a core wire in which the ratio of the dry heat shrinkage rate to the dry heat shrinkage stress is 12% / g / de or less.

  However, in these belts, although the initial core contraction stress is constant, it is not possible to prevent a decrease in tension when the belt is operated for a long period of time. The grip force is reduced, slipping is likely to occur, and the power cannot be sufficiently transmitted.

JP-A-62-255637 Japanese Patent Publication No. 5-22091 JP-A-3-163241

  The object of the present invention is to solve the above-mentioned problems of the prior art, have excellent fatigue resistance, do not cause a decrease in tension even when the belt is operated for a long period of time, and hardly cause slippage between the belt and the pulley. It is to provide a polyester fiber cord for a core wire.

  As a result of intensive studies to achieve the above object, the inventors of the present invention have found that the desired polyester fiber cord can be obtained when reducing the tension drop of the cord after being held at 100 ° C. for 2 hours as much as possible. I have found out that it can be obtained.

Thus, according to the present invention, a polyethylene terephthalate fiber and a cord in which 10 to 70% by weight of polyethylene naphthalate fiber is mixed with the polyethylene terephthalate fiber, and the tension and dry heat shrinkage of the cord are A polyester fiber cord characterized by simultaneously satisfying the following formulas (I) and (II) is provided.
(I) A ≧ 0.050
(II) AB ≦ 0.010
Here, A and B represent the tension (N / tex) after holding at 100 ° C. for 2 hours and at 100 ° C. for 48 hours under an initial tension of 0.1 N / tex, respectively.

  According to the present invention, there is also provided a power transmission belt characterized in that the polyester fiber cord is arranged as a core wire.

  According to the present invention, since a polyester fiber cord for a belt core wire is provided that is less likely to cause a decrease in tension even when the belt is operated for a long period of time, it is possible to obtain a power transmission belt in which the slip between the belt and the pulley hardly occurs. it can.

The polyethylene terephthalate fiber used in the present invention is a fiber obtained by spinning and stretching a polymer comprising polyethylene terephthalate by a conventional method.
The polyethylene terephthalate fiber is not particularly limited in terms of the single fiber fineness, the number of filaments, the cross-sectional shape, the fiber physical properties, the fine structure, etc., and may be appropriately selected and set according to the purpose. The polyethylene terephthalate fiber may be twisted.

  Further, the polyethylene naphthalate fiber used in the present invention is a fiber obtained by subjecting a polyethylene naphthalate polymer represented by polyethylene-2,6-naphthalate (PEN) to a usual spinning drawing method, Polyethylene naphthalate may contain 90% by mole or more of ethylene-2,6-naphthalate units, and may be a polymer containing an appropriate third component in a proportion of 10% by mole or less.

  In general, polyethylene-2,6-naphthalate can be synthesized by polycondensation of naphthalene-2,6-dicarboxylic acid or an ester-forming derivative thereof with ethylene glycol in the presence of a catalyst under appropriate reaction conditions. . At this time, if one or more third components are added before the completion of the polymerization of polyethylene-2,6-naphthalate, a copolymer is synthesized.

Suitable third components include: (a) compounds having two ester-forming functional groups; for example, aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid and dimer acid; and alicyclic rings such as hexahydroterephthalic acid Aromatic dicarboxylic acids; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, naphthalene-2,7-dicarboxylic acid, diphenyldicarboxylic acid; diphenyl ether dicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenoxyethanedicarboxylic acid, 3,5-dicarboxyl Dicarboxylic acids such as sodium benzenesulfonate; oxycarboxylic acids such as glycolic acid, p-oxybenzoic acid p-oxyethoxybenzoic acid; trimethylene glycol, diethylene glycol, tetramethylene glycol, hexamethylene glycol, neopentylene glycol P-xylylene glycol, 1,4-cyclohexanedimethanol, bisphenol A, p, p'-dihydroxydiphenylsulfone, 1,4-bis (β-hydroxyethoxy) benzene, 2,2-bis (p- β-hydroxyethoxyphenyl) propane and the like.
Needless to say, the polyethylene naphthalate may contain a matting agent such as titanium dioxide and a stabilizer such as phosphoric acid, phosphorous acid and esters thereof.

  The intrinsic viscosity of polyethylene naphthalate is preferably 0.65 or more, particularly preferably in the range of 0.7 to 1.0. The intrinsic viscosity here is a value obtained from the viscosity measured at 35 ° C. by dissolving the polymer or undrawn yarn before drawing in a mixed solvent of phenol and orthodichlorobenzene (volume ratio 6: 4). When the intrinsic viscosity is less than 0.65, it is difficult to obtain high-strength, high-toughness fibers required as reinforcing fibers. On the other hand, if it exceeds 1.0, the spinning process tends to be defective, which is not practically desirable.

The polyethylene naphthalate fiber is not particularly limited in terms of the single fiber fineness, the number of filaments, the cross-sectional shape, the fiber physical properties, the fine structure, etc., and may be appropriately selected and set according to the purpose. The polyethylene naphthalate fiber may be twisted.
In the present invention, 10 to 70% by weight of polyethylene naphthalate fiber is mixed with the polyethylene terephthalate fiber to form a cord, and the tension and dry heat shrinkage of the cord are expressed by the following formulas (I) and (II). ) Is important at the same time.
(I) A ≧ 0.050
(II) AB ≦ 0.010
Here, A and B represent the tension (N / tex) after holding at 100 ° C. for 2 hours and at 100 ° C. for 48 hours under an initial tension of 0.1 N / tex, respectively.

  When A in the above formula (I) is less than 0.050, when the cord is used as a core wire, a rapid drop in tension is initially observed, and the belt tension is reduced in a short time after the start of operation. As for A, 0.060-0.090 is more preferable, and 0.06-0.08 is still more preferable.

  In addition, when А-B in the above formula (II) exceeds 0.010, it becomes impossible to operate for a long time due to a drop in tension during operation. Necessary. AB2 is preferably 0.002 to 0.005, more preferably 0.002 to 0.004.

Furthermore, in the present invention, dry heat shrinkage (%) when held at 150 ° C. for 30 minutes. When C exceeds 3.5, there is a tendency for the dimensional change of the belt to increase, which is not preferable.
Further, it is preferable to set the 1% modulus D of the cord length to 90 to 150 cN / dtex because the belt dimensional change during running tends to be small.

  In the present invention, the cord is obtained by twisting a polyethylene naphthalate fiber and a polyethylene terephthalate fiber, and a cord obtained by combining a plurality of these yarns and twisting the upper cord separately from the polyethylene terephthalate fiber and the polyethylene naphthalate fiber. It is easier to disperse the stress than the cord in which one or a plurality of these are twisted together and twisted together, and the shrinkage rate of the cord length after dipping can be suppressed low. In addition, belt dimensional changes tend to be kept low.

  In order to produce such a polyester fiber cord, a polyethylene terephthalate fiber and a cord in which 10 to 70% by weight, preferably 20 to 50% by weight of polyethylene naphthalate fiber are mixed and twisted with respect to the polyethylene terephthalate fiber are used. is required. When the blending ratio of the polyethylene naphthalate fiber is less than 10% by weight, a decrease in tension is likely to occur when the belt is operated for a long time, whereas when the blending ratio exceeds 70% by weight, the fatigue resistance of the belt It will be inferior.

Further, a cord in which polyethylene terephthalate fiber and 10 to 70% by weight of polyethylene naphthalate fiber are mixed and twisted with respect to the polyethylene terephthalate fiber can suppress the shrinkage rate of the cord length after dipping. Therefore, the belt using the cord as the belt core wire can suppress the contraction of the belt that occurs immediately after the belt is formed until the belt is mounted.
The cord can be twisted by a known method, and a cord can be formed by aligning a plurality of lower twisted yarns or a plurality of them. At that time, a ring twisting machine or the like can be used.

The cord is used as a core wire of a power transmission belt such as a V belt. 1 and 2
Is a representative example. FIG. 1 shows a longitudinal cross-sectional view of the obtained V-belt 1, which is a type of belt in which a rubber cloth 2 woven with natural fibers or synthetic fibers is present only on the upper and lower surfaces of the belt. is there. The cord 3 made of the cord is embedded in the adhesive rubber layer 4 adjacent to the compressed rubber layer 5. Short fibers 6 are mixed in the compressed rubber layer 5 in the belt width direction.

  The cord is not limited to the type of V-belt as shown in FIG. 1, and the cloth 2 with rubber may be used as the core of a wrapped type V-belt covering the entire circumference of the belt. 2, it may be used as a core of a V-ribbed belt 8 in the compressed rubber layer 5 and having a plurality of ribs 7 in the belt longitudinal direction.

  Hereinafter, an example is given and the composition and effect of the present invention are explained in detail. In addition, each physical property in an Example is calculated | required with the following method.

(1) Belt tension maintenance rate As shown in FIG. 3, a belt is installed on pulleys 9 and 10 having a diameter of 100 mm, the initial mounting tension is 900 N, and the pulley rotation speed during traveling is 3600 r. p. m. As a result, a running test was performed at room temperature. The belt tension after stopping for 4 hours and then allowing to cool for 24 hours was measured, and the tension maintenance ratio relative to the initial mounting tension was measured.

(2) Belt dimensional change rate The belt dimensional change rate was calculated by dividing the difference between the belt outer peripheral length immediately after vulcanization and the belt outer peripheral length after 30 days by the belt outer peripheral length immediately after vulcanization.

(3) Fatigue resistance The core wire was taken out from the belt after the belt running test in (1), and its strength was measured to calculate the strength maintenance ratio with respect to the strength of the cord taken out from the belt before the belt running test.

(4) Cord tension A creep heat shrink tester (Yasuda Seiki Seisakusho) was used to measure the change in cord tension with time in an atmosphere of 100 ° C. The initial tension was 0.1 N / tex.

(5) Shrinkage rate of cord length Using a creep thermal shrinkage tester (Yasuda Seiki Seisakusho), measure the change in cord length over time in an atmosphere of 40 ° C, and obtain the shrinkage rate of the cord length using the following formula. It was.
Shrinkage rate of cord length (%) = (Cord length after 100 hours−Initial trial length) / Initial trial length × 100
This measurement started within 24 hours after dipping, and when measuring the initial test length, a load of fineness (dtex) × 0.91 / 20 was applied.

(6) 1% modulus of cord Measured based on JIS L 1017.

(7) Belt tension maintenance rate As shown in FIG. 3, the belt is installed on pulleys 9 and 10 having a diameter of 100 mm, the initial mounting tension is 900 N, and the pulley rotation speed during traveling is 3600 rpm. A running test was performed at room temperature. The belt tension after stopping for 4 hours and then allowing to cool for 24 hours was measured, and the tension maintenance ratio relative to the initial mounting tension was measured.

(8) Belt dimensional change rate The belt dimensional change rate was calculated by dividing the difference between the belt outer peripheral length immediately after vulcanization and the belt outer peripheral length after 30 days by the belt outer peripheral length immediately after vulcanization.

(9) Fatigue resistance The core wire was taken out from the belt after the belt running test of (7), the strength was measured, and the strength maintenance ratio with respect to the strength of the cord taken out from the belt before the belt running test was calculated.

[Example 1]
Two polyethylene terephthalate fibers (PET) having a total fineness of 1100 dtex (P952NL, manufactured by Teijin Fibers Limited) were combined and twisted at a lower twist number of 220 T / m. Similarly, two polyethylene naphthalate fibers (PEN) (manufactured by Teijin Fibers Ltd., Q904M) having a total fineness of 1100 dtex were combined and twisted at a lower twist number of 220 T / m. Two former twisted cords and one latter twisted cord were twisted at an upper twist number of 95 T / m to obtain a cord of 1100/2/3.
After attaching epoxy / isocyanate as an adhesive treatment agent to the cord, heat treatment was carried out at 150 ° C. for 120 seconds and 240 ° C. for 60 seconds, and RFL (resorcin-formalin-latex) was further attached. Heat treatment was performed at 120 ° C. for 120 seconds and at 240 ° C. for 60 seconds.

The tension (N / tex) A after holding the obtained cord at 100 ° C. for 2 hours under an initial tension (66 N) of 0.1 N / tex was 0.072, and after holding at 100 ° C. for 48 hours The value A−B (N / tex) obtained by subtracting the tension after holding for 2 hours from the tension is 0.003, and the dry heat shrinkage (%) C is 2.3% when held at 150 ° C. for 30 minutes. The shrinkage ratio of the cord length after 100 hours in an atmosphere at 0 ° C. was 0.8%.
A V-belt 1 shown in FIG. 1 was manufactured using the obtained cord as a core wire. Table 1 shows the belt tension maintenance rate, belt dimensional change rate, and fatigue resistance of the obtained V-belt.

[Examples 2-3, Comparative Examples 1-2]
The same operation as in Example 1 was performed except that the same polyethylene terephthalate fiber and polyethylene naphthalate fiber as in Example 1 were used and the configuration of the cord was changed as shown in Table 1.
Belt tension maintenance factor of the obtained V belt when the V belt 1 shown in FIG. 1 was manufactured using the values of A, B, C and D of the obtained cord and the obtained cord as a core wire. Table 1 shows the belt dimensional change rate and fatigue resistance.

  ADVANTAGE OF THE INVENTION According to this invention, even when a belt is drive | operated for a long period of time, the tension fiber polyester fiber cord for a belt core wire which does not generate | occur | produce easily is provided. Further, since the fiber cord can be used as a core wire to obtain a power transmission belt in which the slip between the belt and the pulley hardly occurs, the present invention has a very high industrial utility value.

Sectional drawing which shows one embodiment of the belt which used the cord of this invention as a core wire. Sectional drawing which shows the other example of the belt which used the code | cord | chord of this invention as a core wire. The schematic diagram which shows the measuring method of a belt tension maintenance factor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 V belt 2 Cloth with rubber 3 Core wire 4 Adhesive rubber layer 5 Compression rubber layer 6 Short fiber 7 Rib 8 V ribbed belt 9, 10 Pulley

Claims (5)

A polyethylene terephthalate fiber and a cord obtained by blending 10 to 70% by weight of polyethylene naphthalate fiber with respect to the polyethylene terephthalate fiber, wherein the tension and dry heat shrinkage of the cord are represented by the following formulas (I) and ( A polyester fiber cord characterized by satisfying II) at the same time.
(I) A ≧ 0.050
(II) AB ≦ 0.010
Here, A and B represent the tension (N / tex) after holding at 100 ° C. for 2 hours and at 100 ° C. for 48 hours under an initial tension of 0.1 N / tex, respectively.   The polyester fiber cord according to claim 1, wherein the dry heat shrinkage of the fiber cord held at 150 ° C for 30 minutes is 3.5% or less.   The polyester fiber cord according to claim 1, wherein 1% modulus of the fiber cord is 90 to 150 cN / dtex.   The polyester fiber cord according to claim 1, wherein the fiber cord is a fiber cord obtained by blending and twisting a polyethylene terephthalate fiber and a polyethylene naphthalate fiber, and further arranging a plurality of them to give an upper twist.   A power transmission belt comprising the polyester fiber cord according to any one of claims 1 to 4 as a core wire.

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