JPS60197407A - Tire - Google Patents

Abstract

PURPOSE:To secure high strength per area and a high modulus as well as to improve sizing stability and resistance to fatigue, by using a polyhexamethyleneazimide system dip cord having the specified characteristic for carcass plies. CONSTITUTION:A pneumatic tire is made up of disposing bead wires 2 at symmetrical both sides of a carcass ply layer 1 consisting of single or plural layers of plies weaving cords into tire-fabric form. As carcass plies used for a suchlike tire, they are composed of a hexamethyleneazimide system polymer whose repetitive structural unit of hexamethylene azimide is more than 95mol%. In addition, it has a high polymerization degree of more than 2.8 in sulfuric acid relative viscosity, and it consists of a polyhexamethylene azimide fabric containing an antioxidant of copper sulfate and/or other than this copper sulfate, using a polyhexamethyleneazimide system dip cord having upper twisting and lower twisting of 2,000-1,300 in a twist coefficient impregnated with a dip solution for improving its adhesiveness with rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tire using a cord made of polyhexamethylene adipamide fiber (hereinafter also referred to as nylon 66), which exhibits high strength and excellent fatigue resistance, as a carcass ply.

The carcass ply of a tire supports the tread, supports the load, and can be called a skeleton that can withstand external shocks and internal air pressure, so it has strict quality requirements for the cord used for car power splies. There is something. As such carcass ply cords, cords made of polyamide fibers have been used along with rayon cords, polyester cords, and the like.

Advantages of polyamide fibers include high strength, heat resistance, fatigue resistance, impact resistance, and good adhesion with rubber, and there is little loss of strength due to twisting, so it is used as a material for carcass ply cords. Although it is suitable for cording, it has the disadvantage of poor dimensional stability compared to other cord materials such as polyester, and in particular, it shrinks greatly due to moisture absorption and heat, so it encounters various inconveniences during the subsequent processing steps. , it is necessary to take measures to avoid this. For example, when applying nylon 6 cord to a tire, the tread of the tire is vulcanized with the dipped cord or dipped blind fabric embedded in the tread. When the nylon 6 is heated and vulcanized and then immediately removed from the vulcanizer and the tension is relaxed, remarkable strong deterioration (vulcanization deterioration) due to rapid thermal contraction of nylon 6 is observed.

On the other hand, there is a growing demand for lighter tires, and as driving speeds increase, there is an increasing demand for improving tire uniformity and fatigue resistance. This is an important drawback.

Such inconveniences are thought to be due to the occurrence of structural defects (for example, kink bands) in the polyamide fiber itself, and have been dealt with by devising vulcanization conditions. For example, instead of taking it out of the vulcanizing iron immediately after heating during vulcanization, it is held in the vulcanizing end until the humidity drops to a level where the amount of heat shrinkage is small, and then it is taken out after it has cooled to a certain extent. is one such method. However, if this method is adopted, the vulcanization reaction cycle becomes extremely long, which significantly reduces productivity, and the energy required to reheat the vulcanizing iron also increases, which does not meet the demands of the times for energy conservation. .

The present invention was made with attention to such circumstances,
The aim is to provide a tire using polyhexamethylene adipamide cord with little vulcanization deterioration and excellent fatigue resistance.

Therefore, if dimensional stability and high modulus were imparted to the nylon 66 dip cord, its uses would further expand, so improvements in the properties of the nylon 66 dip cord have been sought for a long time.

On the other hand, for the purpose of improving these characteristics,
As seen in No. 012, a nylon for rubber reinforcement with low shrinkage and improved dimensional stability is created by spinning at a spinning speed of 2000 m for 7 minutes or more to create a highly oriented undrawn yarn and then drawing it. 66 fibers have been proposed.

However, although these methods improve dimensional stability, they have the disadvantage of decreasing strength.

The inventors of the present invention have carried out intensive research with the aim of obtaining a tire that is made of nylon 66 dip cord that is highly strong, has high modulus, and has excellent dimensional stability, and has low vulcanization deterioration and excellent fatigue resistance. , real envy 5- reached the light.

That is, the above object is (1) consisting of a nylon 66 polymer containing 95 mol% or more of repeating structural units of hexamethylene adipamide, having a high polymerization degree of sulfuric acid relative viscosity of 2.8 or more, and one or two types of hexamethylene adipamide repeating structural units. Melt spinning a polyamide containing the above copper salts and/or an inorganic or organic antioxidant other than the copper salts; (2) The birefringence of the undrawn spun yarn is 25 x 10.
(3) The yarn passed through the σ1 roll is taken up continuously or once, and then hot-stretched so that the total stretching ratio is 4.0 times or more. (4) The quality of the drawn yarn satisfies the following conditions (a) D
T≧10 f/d preferably DT≧12 r/d (b)
20%≧DI≧8% (c) Is≧35 t/d) 8HD≦15% (51 drawn yarn (multifilament yarn) with twist coefficient 2
000-1300, preferably 1800-1400
6 - Creating a raw cord by performing first twisting and final twisting; (6) subjecting the raw cord or a blind fabric woven from the raw cord to a dip liquid treatment to improve adhesion with rubber 1 (7) The nylon 66 cord fabric (dipped fabric) obtained in the above manner was sandwiched between rubber sheets and calendered to create a carcass ply, and bead wire was then applied. This is achieved by combining it with rubber and rubber to form a tire.

According to this method, hexamethylene adipamide is composed of a nylon 66 polymer containing 95 mol% or more of repeating structural units, has a high polymerization degree of sulfuric acid relative viscosity of 2.8 or more, and has one or more types. Nylon 66 fiber containing a copper salt and/or an inorganic or organic antioxidant other than the copper salt, and has a twist coefficient of 2000 to 1300 and is coated with a dip liquid to improve adhesion to rubber.
Preferably, it is a polyhexamethylene adipamide dip cord having a twist and a twist of 1,800 to 1,400, which has the following characteristics at the same time: high strength, high modulus, and significantly improved dimensional stability and fatigue resistance. A tire made of a polyhexamethylene adipamide dipped cord with little vulcanization deterioration and excellent fatigue resistance can be obtained.

(a) Breaking strength of dip cord A≧8.5f/d preferably A≧9.0t/d (b) Intermediate elongation of dip cord B≦8.5% (c)
Dip cord dry heat shrinkage C≦6% preferably 05
5% (d) C≦-2B+19 This dipped cord is significantly different from conventional nylon 66 dipped cord in that it has a lower shrinkage rate, a higher modulus, and higher strength.

More specifically, the method of the present invention and the characteristics of the fibers obtained by the method will be described in detail.

The raw material polymer may contain polyhexamethylene adipamide in 95 mol % or more of the number of repeating units in the molecular chain and less than 5 mol % of a copolymer component. Examples of other polyamide components that can be copolymerized include poly-6-caproamide, polyhexamethylene sebamide, polyhexamethylene isophthalamide, polyhexamethylene terephthalamide, and polyxylylene phthalamide. If the copolymer component is contained in an amount of 5 mol % or more, crystallinity and dimensional stability are reduced, which is not preferable.

As the nylon 66-based polymer, a polymer with a high degree of polymerization having a sulfuric acid relative viscosity of 2.8 or more, particularly 3.0 or more is preferable for obtaining the high-strength yarn of the present invention. Furthermore, since the polyamide fiber of the present invention is mainly used for industrial purposes, an antioxidant is added to the polyamide for the purpose of imparting sufficient durability against heat, light, oxygen, etc. As the antioxidant, copper salts such as copper acetate, cuprous chloride, cupric chloride, cuprous bromide, cupric bromide,
Cuprous iodide, copper phthalate, copper stearate, and complex salts of various copper salts and organic compounds, such as 8-oxyquinoline steel, copper complex salts of 2-mercaptobenzimidazole, preferably cuprous iodide, acetic acid copper, cuprous iodide complex salts of 2-mercaptobenzimidazole, etc.; 9 - halides of alkali or alkaline earth metals such as potassium iodide, potassium bromide, potassium chloride, sodium iodide, sodium bromide, zinc chloride; Calcium chloride etc., organic halides such as pentaiodobenzene, hexabromobenzene, tetrayothothyleataric acid, methylene iodide, tributylethylammonium iodide etc., inorganic and organic phosphorus compounds such as sodium pyrophosphate, sodium phosphite, etc. triphenyl phosphite, 9゜10-sibidoro-1O-(3',5'-di[-butyl-4'-hydroxypencyl)-9-oxerphosphaphenanthrene-10-oxide, etc., and phenolic antiseptics. Oxidizing agents such as tetrakis-[methylene-a-(3,5-di-t-butyl-4-hydroxyphenyl)propionate-co-methane, 1,3.5-)
Dimethyl-2,4,6-)lis(3,5-di-t-butyl-4-hydroxybenzyl)benzene, n-octadecyl-a-(3,5-di-t-butyl-4-hydroxyphenyl) -propionate, 4-hydroxy-3
, 5-di to 10-butylbenzyl phosphate diethyl ester, etc. Yaamine antioxidants such as N,N'-di-β-naphthyl-p-phenylenediamine, 2-mercaptobenzimidazole,
Phenyl-β-naphthylamine, N,N'-diphenyl-p-phenylenediamine, condensation reaction product of diphenylamine and allyl ketone, preferably potassium iodide, 2
-Mercaptobenzimidazole, etc.

The antioxidant can be incorporated into the polyamide during the polymerization process or by sprinkling it on the chips after the polyamide is once made into chips.

The content of antioxidant is 10 to 300 p as copper for copper salt.
pm, preferably 50-200 ppm.

Other antioxidants are 0.01-1%, preferably 0.03%
~0.5% range. The antioxidant is preferably used in combination with one or more of copper salts and other antioxidants. Usually, the polyamide dried to a moisture content of 0.1% or less is spun using a melt spinning machine, preferably using an extruder type spinning machine.

The spinning take-off speed is such that the birefringence of the collected yarn is 25X1G.
It is set to be less than "10XIO", preferably less than 10XIO. The spinning conditions corresponding to the birefringence can be determined by optimizing many factors such as not only the spinning take-off speed but also the nozzle hole diameter, the nozzle-quench distance, the relative viscosity of the polymer, and the spinning temperature.

If the birefringence of the spun drawn yarn is 25×10” or more, a high-strength yarn with a cutting strength DT of 10 f/d or more cannot be stably obtained.

When the molecular weight of the polymer is constant, it is preferable to make the birefringence of the spun yarn as small as possible in order to obtain a high-strength yarn.

The stretching method is, for example, melt-spinning nylon 66 with RV = 3.0 to obtain a birefringence of 5 x 10''-a to 10XI.
When stretching the O-3 drawn yarn either continuously after spinning or once wound up, between the undrawn yarn first supply roller and the undrawn yarn second supply roller maintained at 100° C. or lower,
1. It is preferable to give a preliminary stretching of 10 times or less, and then perform a first stage stretching of 40% or more of the total stretching ratio with the first stretching roller, and if necessary, with the undrawn yarn second supply roller. A high-temperature pressurized steam jet nozzle is provided between the first stretching roller and the nozzle temperature.
70 to 350°C slit heater (a heating device that has a slit as a yarn running path, and heats the yarn while running through the slit in a non-contact state: Ambient temperature refers to the temperature inside the slit ) The thread inside is 0.3 ae
The film is allowed to pass through the film so that it can stay there for at least e, and then it is applied to the second stretching roller. At that time, a temperature gradient is provided in the slit heater, the atmospheric temperature at the yarn inlet is set to 160°C or higher, the exit atmospheric temperature is set to 350°C or lower, and
It is preferable that the yarn be passed through the slit heater so that the yarn can remain in the atmosphere at 0.3° C. for 0.3 seam or more, and then the yarn be drawn in substantially two stages. In addition, after the two-stage stretching is completed, the dimensional stability can be further improved by performing a 13-relaxation treatment of 10% or less at 210 to 150°C either continuously without winding or after winding. is also possible.

In order to obtain the high tenacity, low elongation yarn used in the present invention, it is drawn at a high draw ratio of 85% or more, preferably 90% or more of the maximum draw ratio, and the residual elongation is 8% to 20%. but,
The stretching ratio of each sample is basically determined by the degree of orientation of each drawn yarn.

Note that the maximum stretching ratio refers to the maximum stretching ratio that can be stretched.

The nylon 66 fiber thus obtained has the following properties.

(a) DT≧10f/d (b) 20%≧DE≧8% (c) Is≧35 f/d) SHD≦15% The nylon 66 multifilament yarn obtained above is prepared by a conventional method. Twist the yarn according to the instructions and make it into a raw cord.

Further, the raw cord or the blind fabric woven from the raw cord is treated with a dip liquid to improve its adhesion to rubber, followed by pot stretching.

The inventors of the present invention have carefully studied the process from making these raw cords to dipping treatment, and have been able to make the dip cords highly strong, have low intermediate elongation, and have a low shrinkage rate, which is superior to conventional nylon 66 dip cords. The present inventors have discovered that it is possible to achieve excellent performance that cannot be achieved with conventional methods.

That is, in the case of the high-strength, low-elongation nylon 66 fiber used in the present invention, the twist coefficient ('r
turn/10 cm), the tensile strength utilization rate of the raw cord decreases, but when the twist coefficient is set in the range of 1300 to 2000, preferably 1400 to 1800, the tensile strength utilization rate is very excellent, and hot stretching during the dipping process By setting the ratio as low as 0 to 5%, a dipped cord with low shrinkage rate and low intermediate elongation can be obtained.

The intermediate elongation is a measure corresponding to the modulus of the cord, and the fact that the intermediate elongation of the dip cord is low indicates that the modulus of the cord is high.

Normally, when manufacturing nylon 66 dip cord, the hot stretch ratio in the dipping process is set to 7% to 12% in order to increase the modulus of the cord. on the other hand,
Generally, when the hot stretch ratio in the dipping step is increased, the shrinkage rate of the dipped cord increases and the dimensional stability decreases.

Therefore, none of the conventional nylon 66 dipped cords has been able to satisfy both dimensional stability and high modulus.

The feature of the present invention is that the conventional nylon 66 is used at the high-strength yarn manufacturing stage.
By stretching the molecular chains more than in high-strength yarns, high-strength, high-modulus, low-elongation yarns are already created, and after twisting, the modulus of the dipped cord is increased by hot stretching in the dipping process. In other words, since there is no need to lower the intermediate elongation, the load on the cord during the dipping process is reduced, resulting in low shrinkage and low intermediate elongation (high modulus) that were previously unimaginable for nylon 66. The reason lies in the achievement of a high-strength dip cord.

None of the conventional nylon 66 dipped cords had a breaking strength A of 8.5 t/d or more, and an intermediate elongation B and a dry heat shrinkage C satisfying the following formulas. (See Figure 1) (b) B≦8.5% (c) C≦6% (d) C≦-2B+19 These dip cord characteristics have a twist coefficient of 2000 to 13
00, more preferably 1,800 to 1,400, and can only be achieved under low stretch conditions of a hot stretch ratio of 0 to 5% in the dipping step.

Reducing the number of twists has the advantage of increasing the twisting speed and reducing costs, but according to conventional knowledge, it has the disadvantage of decreasing fatigue resistance.

However, since the dipped cord of the present invention satisfies the formulas (a) to (d), even a low-twist cord has a fatigue resistance higher than that of a conventional cord with 17 twists. These properties are evident, for example, in the high residual strength after disk fatigue tests.

Bias tires using treated cords manufactured with a reduced number of twists were found to have improved flat spot properties and improved durability. In addition, when used as a V-belt cord, as an example of an application other than tire cord, the dimensional stability during rubber vulcanization is good, resulting in a significant improvement in yield and flex fatigue life. When used as a base fabric for resin-coated fabrics, it exhibited dimensional stability and was well received.

Hereinafter, the present invention will be explained in detail with reference to Examples, but characteristics and measurement methods not mentioned above are as follows.

<Method for measuring relative viscosity> 96, a A sample solution was prepared by dissolving the sample in ±0.1% by weight reagent special grade concentrated sulfuric acid so that the polymer concentration was 10% by weight, and the sample solution was heated at 20°C ±0. Ice falling seconds at a temperature of 05°C 6
Measure the solution relative viscosity using an Ostwald viscometer at ~7 seconds. For the measurement, use the same 18-degree viscosity liver, and use the same 20-degree sulfuric acid as when preparing the sample solution.
The relative viscosity RV is calculated from the ratio of the falling time To (seconds) of - and the falling time T1 (seconds) of sample solution 20- using the following formula.

RV = TI/T.

<Method for measuring birefringence (mu)> A Nikon polarizing microscope POH model Uin's Berek compensator was used, and a spectral light source activation device (Toshiba 5LS-8-B model) was used as the light source ( Na light source). 5
A sample cut at an angle of 45 degrees to the fiber axis with a length of ~6 frn is placed on a glass slide with the cut side facing up.

Place the sample slide glass on the rotating stage, adjust the rotating stage so that the sample is at a 45 degree angle to the polarizer, insert the analyzer to obtain a dark field, and then set the compensator to 30°. count the number of stripes (n pieces). Turn the compensator clockwise to measure the compensator scale a1 at the point where the sample first becomes darkest.Turn the compensator counterclockwise to measure the compensator scale at the point where the sample first becomes darkest. After that (read up to 1/10 scale in both cases), return the compensator to 30, remove the analyzer, measure the diameter d of the sample, and calculate the birefringence (△n) based on the following formula (number of measurements: 20). average value).

△n = r / d (rni retardation r−nλ0+6)λo=58
9.3mμ ξ: C/1 in Leitz compensator manual
0 (from 100 and 1.

1 = (a-b) (: Difference in compensator reading) <Method for measuring strength and elongation characteristics of fibers and cords> J I 5
- According to the definition of L1017. Take the sample in a skein shape and hold it for 20 minutes.
℃, 65% R1 (temperature and humidity controlled room) for 24 hours, using a 6 tensilon" UTM-4L type tensile tester [manufactured by Toyo Baldwin Co., Ltd.], test length 20 cm
It was measured at a % tensile rate of 2oan/min.

<Measurement method for dry heat shrinkage rate 8HD> Take the sample in a skein shape, leave it in a temperature and humidity controlled room at 20°C and 65% RH for more than 24 hours, and then measure by applying a load equivalent to 0.1 f/d of the sample. The sample of length Lo was left in an oven at 150°C for 30 minutes without tension, then taken out of the oven and left in the temperature and humidity control room for 4 hours, and then the load was applied again to measure the length. It was calculated from tl using the following formula.

<Formula for calculating twist coefficient> Twist coefficient plus number of twists x (denier) 2 Number of twists: turn / 10m <Method for measuring disk fatigue> Using a normal disk fatigue tester, embed a dip cord and vulcanize. Set the prepared test piece and set the compression ratio to 1.
After applying forced fatigue by rotating at a speed of 2500 ppm for 48 hours under an elongation ratio of 2.5% and an elongation ratio of 6.3%, the dipped cord was removed from the rubber and its residual strength was measured.

21- <Method for measuring intermediate elongation> According to the definition of JIS-L1017. Constant load W (Kp)
Measure the elongation rate at. The elongation measurement conditions are based on the measurement conditions for strength and elongation properties. The constant load W is defined by the following formula. □ d2: Sample denier, dl: Standard denier, which is 840 denier for raw yarn and 1680 denier for cord.

Method for measuring strength after vulcanization> After applying a tension of 153 t to each dip cord, the cords were fixed at a constant length and arranged in parallel. Sandwich this between 2m thick sheets of unvulcanized rubber, put it in a mold and make 160.17
The vulcanization layer was vulcanized for 20 minutes using a heat press maintained at 0.180°C. After vulcanization, the mold was removed from the heat press, the dip cord was immediately cut from its fixed end, allowed to shrink freely, and the specimen was removed from the mold and cooled.

After being left for 24 hours, the dipped cord was removed from the rubber and 22-residual strength was measured.

<Manufacturing example> Using nylon 66 having the relative viscosity shown in Table 1 as a raw material, spinning was carried out under the conditions shown in the same table, and the birefringence index m (20
An undrawn yarn with relative viscosity (measured after standing for 24 hours at 6a% RH) and relative viscosity was obtained.

In addition, during spinning, an appropriate amount of spinning oil was applied to the surface of the yarn before taking off the undrawn yarn.

The obtained undrawn yarn was drawn under the conditions shown in Table 2 to obtain drawn yarn having the quality shown in Table 3.

Table 3 shows the yarn quality of commercially available polyhexamethylene adipamide fiber for tire cord as Comparative Example 1.

Next, the drawn yarns of Example 1 and Comparative Example 1 were separately combined to obtain multifilament yarns of 840 denier.

Table 1 24- 23- 2 Table 25- Table 8 47 T/1 Gc+++ in each of the obtained yarns
, 42 'r,' 10 an, and 37T/10c
The rR was twisted and twisted to form a 2-strand cord of A4OA/2 ply.

The raw cord thus obtained was immersed in a nylon 66 dip solution consisting of a resorcinol-formalin-latex solution, and then dried with hot air at 120°C for 2 minutes under a 1.5% stretch.Subsequently, it was placed in a hot stretch zone. Introduced to 210℃
After hot stretching by 1%, 3%, and 7% in heated air at 210 DEG C., the cord was further heat-treated at 26 DEG C. for 36 seconds under a fixed length in heated air at 210 DEG C. to produce a dipped cord.

The properties of the raw cord and dipped cord according to this example were as shown in Table 4.

The dipped cord obtained in the present invention has significantly improved strength compared to the dipped cord obtained in the comparative example, and has low intermediate elongation and low dry heat shrinkage, which is a measure of dimensional stability, and can be used in low temperature regions. It also has excellent fatigue resistance.

The properties of the raw cord and dipped cord according to this production example were as shown in Table 4.

The dipped cord obtained in the present invention has significantly improved strength compared to the dipped cord obtained in the comparative example, and has low intermediate elongation and low dry heat shrinkage, which is a measure of dimensional stability, and can be used in low temperature regions. It also has excellent fatigue resistance.

27- <Example> Using the nylon 66 cord obtained in invention 1 in the production example,
A tire as shown in Figure 3 was manufactured. That is, the tire is made of plies woven from cords in the form of a blind, with bead wires 2 disposed on both left and right sides of a carcass ply layer 1 consisting of one or more plies, and a carcass ply layer J having a curved shape. do. The carcass ply layer 1 is reinforced by providing a belt layer 4 on its crown portion 3, and the circumferential recesses of these constituent layers are further covered with a rubber layer (tread) 5 to obtain the tire of the present invention. The material of the rubber layer is not particularly limited, and for example, natural rubber, butyl rubber, butadiene rubber, nitrile butadiene rubber, styrene butadiene rubber, isoprene rubber, and blend rubbers thereof in arbitrary proportions can be used.

As clarified by the comparative study of the above manufacturing example and comparative manufacturing example (using the ratio 7 cord in comparative example 1), the nylon 66 cord used in the tire of the present invention possesses the excellent strength of the yarn itself. As a result, the tires of the present invention as typified by the examples exhibit excellent performance such as high toughness and resistance to vulcanization deterioration, and are superior to conventional nylon 66.
It exhibits performance that cannot be obtained with tires using cords.

Figure 2 is a graph showing a comparison of raw cord strength, dipped cord strength, and post-vulcanization strength, and the strength of the former three is based on the values of Invention 1 and Comparative Example 7 shown in Table 4. The strength after vulcanization shows the decrease in strength when the dip cords in Table 4 were vulcanized under the conditions of iao°C, 170°C and 180°C, immediately removed from the mold, and rapidly relaxed.

The strength after vulcanization of the dipped cord of the present invention is far superior to that of the comparative example, and the strength decrease after vulcanization is also small.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the characteristics of the dip cord constituting the tire of the present invention, where the vertical axis shows the dry heat shrinkage rate, the horizontal axis shows the intermediate elongation, and the shaded area is the dip cord according to the present invention. This area shows the characteristics of the code. Moreover, FIG. 2 is a graph showing a comparison of raw cord strength, dip cord strength, and strength after vulcanization, in which (I) shows the dip cord according to the present invention, and (■) shows the dip cord of the comparative example. Moreover, FIG. 3 is a half-sectional view of the main part of the tire of the present invention. 1...Carcass ply layer 2...Bead wire 3...Crown part 4...Belt part 5...Tread patent applicant Toyobo Co., Ltd. 31- Haya l Figure--Bokun 4? Skin ('/=) Sheep 2 figure y! P8I! l et al.

Claims (1)

[Claims] 1. The repeating structural unit of hexamethylene adipamide is 9
Consisting of 5 mol% or more of polyhexamethylene adipamide-based polymer, having a high degree of polymerization with a sulfuric acid relative viscosity of 2.8 or more, and containing one or more copper salts and/or other than the above-mentioned copper ring. It is made of polyhexamethylene adipamide fiber containing an inorganic or organic antioxidant, and has a twist coefficient of 2,000 to 1,800, which is attached with a dip plate to improve adhesion to rubber. A polyhexamethylene adipamide-based dip cord having the properties (a) to (d) below, which has high strength and high modulus, and has significantly improved dimensional stability and fatigue resistance. A tire characterized by using pamid type dipped cord in the carcass ply. (a) Breaking strength of dip cord A≧s, st/a(
b) Intermediate elongation of dip cord B≦8.5% (c)
Dry heat shrinkage rate of dip cord C≦6% (d) C≦-2
B+19 2. In claim 1, a polyhexamethylene adipamide dip cord is used, which has a breaking strength of 9.0 f/d or more and a dry heat shrinkage rate of 5% or less. A tire characterized by: 3. A tire according to claim 1 or 2, characterized in that a polyhexamethylene adipamide dip cord having a twist coefficient of 1,800 to 1,400 is used.