JPS60154901A - Tire - Google Patents

Abstract

PURPOSE:To decrease deterioration due to vulcanization and improve fatigue resistance by forming a carcass with nylon 6 system dip cord which comprises specific polycaproamid system polymer and includes specific antioxident and which is of high strength, with high modulous and with good size stability. CONSTITUTION:The captioned commodity is constructed by nylon 6 system fiber which comprises nylon 6 polymer in which repeated constitution unit of epsilon-caproamid is more than 95mol% and which has high polymerization more than 3.0 of sulfuric acid relative viscosity, and which includes one kind or more than two kinds of cuprous salt or inorganic or organic antioxident other than cuprous salt. And a carcass ply is constructed by a polycaproamid system dip cord which has an upper twisting and a lower twisting whose twisting coefficient is 2,000-1,300 and in which adhesion characteristics with rubber is improved by applying dip liquid, and in which a break strength (a) intermediate extension (b) and dry heating contraction rate (c) and formula of relation among (a)-(c) are specified. Thus deterioration due to vulcanization can be decreased and fatigue resistance can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tire in which a cord made of polyamide fiber having high strength and excellent fatigue resistance is used as a carcass buoy.

The carcass ply of a tire supports the tread, supports the load, and is an integral part of the skeleton that can withstand external shocks and internal air pressure. There are some tough ones. Cords made of polyamide fibers have traditionally been used as cords for carcass bridging, 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, 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 processing after twisting.
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. After heating and vulcanizing with
When the nylon 6 is immediately removed from the vulcanizer and the tension is relaxed, significant strength 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.

These inconveniences are thought to be due to the occurrence of structural defects (for example, king bands) in the polyamide fiber itself, and have been dealt with by devising vulcanization conditions. For example, one method is to take it out after it has cooled down to some extent at the stage where the heating during vulcanization has finished. However, when this method is adopted, the vulcanization reaction cycle becomes extremely long, which significantly reduces productivity, and the energy required to reheat the vulcanization can also increases, making it incompatible with the current demands for energy conservation. do not.

The present invention was made with attention to such circumstances,
The purpose of this invention is to provide a next-generation tire using a polyamide cord with little vulcanization deterioration and excellent fatigue resistance.

On the other hand, for the purpose of improving these characteristics, Japanese Patent Application Laid-Open No. 57-191
As seen in No. 337 and JP-A No. 58-54018, high-speed spinning at a spinning speed of 2,000 ff/min or higher is used to obtain undrawn yarn with a high degree of orientation, which is then drawn, resulting in low shrinkage and improved dimensional stability. A method for manufacturing nylon 6 cord for rubber reinforcement has been proposed.

However, although these methods improve dimensional stability, they have the drawback of decreasing tenacity.

The present invention was achieved as a result of intensive research aimed at obtaining a tire with excellent fatigue resistance and less vulcanization deterioration, which is made of nylon 6-based dipped cord with excellent dimensional stability.

That is, the above objects are (1) made of a nylon 6 polymer having a repeating structural unit of ξ-caproamide of 95 moles or more, and having a sulfuric acid relative viscosity of 3.
Melt spinning a polyamide having a high degree of polymerization of 0 or more and containing one or more copper salts and/or an inorganic or existing antioxidant other than the copper salts.

(2) The birefringence of the undrawn spun yarn is 25 x 1
Acceptance will be made under the condition that the score is less than 0-3.

(3) After the yarn that has passed through the take-up roll is wound up continuously or once, it is hot-stretched so that the total stretching ratio becomes 4.0 times or more.

(4) The quality of the drawn yarn satisfies the following conditions.

(b) DT≧10 f/d preferably DT≧12 f/
d(CI) 20%≧DE≧8% (c) IS≧35 f/d (d) SHD≦15% (5) [Twisting coefficient for drawing (multifilament yarn) 2000 to 1 aoo, preferably 1800 to 1400 To create raw cord by applying first twist and final twist.

(6) The raw cord or the blind fabric knitted from the raw cord is treated with a dip liquid to improve its adhesion to rubber, followed by 0 to 5% hot stretching.

(7) This is achieved by sandwiching the polyamide cord fabric (dipped fabric) obtained as described above between rubber sheets and calendering it to create a carcass ply, which is then combined with bead wire and rubber to form a tire. Ru.

According to this method, the repeating structural unit of ε-caproamide is made of a nylon 6 polymer having 95 moles or more,
Made of nylon 6-based fibers that have a high degree of polymerization with a relative viscosity of sulfuric acid of 3.0 or more and contain one or more copper salts and/or an inorganic or organic antioxidant other than the copper salts, and are rubber. The twist coefficient is 2000 to 1300. Preferably 1
A polycapramide dip cord having a twist of 800 to 1400 and a twist of 1,400, which is high strength, high modulus, and has significantly improved dimensional stability and fatigue resistance. A tire with low sulfur deterioration and excellent fatigue resistance can be obtained.

(a) Breaking strength of dipped cord A≧8.59/d Preferably A≧9. Or/d (b) Intermediate elongation of the dip cord B≦9% (C) Dry heat shrinkage rate of the dip cord C≦7% Preferably C≦59
1+ (d) C≦-4B+39 More specifically, the method of the present invention and f obtained by the method
C-woven fiber properties will be explained in detail.

The raw material polymer may contain e-caproamide in 95 mo/L'% or more of the repeating units in the molecular chain and less than 5 mole of a copolymer component. Examples of other polyamide components that can be copolymerized include polyhexamethylene adipamide, polyhexamethylene sebacamide, polyhexamethylene isophthalamide, polyhexamethylene terephthalamide, and polykylylene phthalamide. If the copolymer component is contained in an amount of 5 mo/L'% or more, the crystallinity and dimensional stability will decrease, which is not preferable.

As the nylon 6-based polymer, a polymer with a high degree of polymerization having a sulfuric acid relative viscosity of 3.0 or more, particularly 3.2 or more is preferable for obtaining the high strength yarn of the present invention. In addition, since the polyamide of the present invention is mainly used for industrial purposes, it is susceptible to heat.

Antioxidants are added to polyamide to provide sufficient durability against light, oxygen, etc. As the antioxidant, copper salts 1 such as steel acetate, cuprous chloride, cupric chloride, cuprous bromide, cupric bromide, cuprous iodide are used.

Copper phthalate, copper stearate, and complex salts of various copper salts and organic compounds, such as copper complex salts of 8-oxyquinoline copper and 2-mercaptobenzimidazole.

Preferably, cuprous iodide, copper acetate, cuprous iodide complex salts of 2-mercaptobenzimidazole, etc., and 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, hexaglombenzene, tetraiodoterephthalic acid, methylene iodide, tributylethylammonium iodide, etc., and inorganic and organic phosphorus compounds such as sodium pyrophosphate. , phosphite sorta, triphenylphosphite, 9.10-Sibidro-10-(3',5'-di-t-butyl-4'-hydroxybenzyl)-9-oxerphosphaphenanthrene-10-oxide etc., and phenolic antioxidants such as tetrakis-[methylene-3-(3,5
-di-t-butyne l/-4-hydroxybendi/L/)
Propionate-co-methane t LL5 - ) Li
- Mechi /L' -21416-) Squirrel (3
゜5-di-t-guchi) L/-4-hydroxybenzi/I
/) Benzene, n-oftade V/I/-3-(3+5-
di-t-butyA/-4-hydroxyphenyl)-propionate, 4-hydroxy-3,5-di-t-butylbenzyl phosphate diethyl ester, etc., and amine antioxidants such as N,N'-di-β- naphthiμmp-phenylenediamine, 2-mercaptobenzimidazo-/I/, phenyl-β-naphthylamine, N,N'-diphenyl-p
- Phenyl diamine, a condensation reaction product of diphenylamine and allyl ketone, preferably potassium iodide, 2-mercaptobenzimidazole, etc.

The antioxidant can be incorporated in the polyamide polymerization process or once formed into chips and then sprinkled on the chips.

The content of antioxidant is 10 to 300 p as copper for copper salt.
pm, preferably from 50 to 200 ppm, and other antioxidants range from 0.01 to 1%, preferably from 0.03 to 0.5%. The antioxidant is preferably used in combination with one or more of copper salts and other antioxidants.

The polyamide dried to a moisture content of 0.03% 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 25 x
10-3, preferably 10 x 10-" or less. The spinning conditions corresponding to the birefringence include not only the spinning take-off speed but also the nozzle hole diameter, the distance between the nozzle and the quench, the polymer It can be determined by optimizing a number of factors such as the relative viscosity of , spinning temperature, etc.

If the birefringence of the spun drawn yarn is 25 x 10-3 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 polyamide with RV = 3.2 to obtain a birefringence of 5 x 10 = ~ 10 x
When the drawn yarn of 10-3 is drawn continuously after spinning or once wound up, between the undrawn yarn first supply row and the undrawn yarn second supply port maintained at 100°C or less. It is preferable to apply a preliminary stretching of 1.10 times or less, and then perform a first-stage stretching of 40% or more of the total stretching ratio between the first stretching roller and, if necessary, a second supply of unstretched yarn. A high-temperature pressurized steam jet nozzle is provided between the row and the first stretching roller, and the nozzle temperature is set to 200° C. or higher to jet high-temperature steam.

The stretching point is fixed near the hot pressurized steam jet nozzle. Furthermore, when performing the second stage drawing, a slit heater (a heating device provided with a slit as a yarn running path) with an ambient temperature of 170 to 350°C is provided between the first drawing roller and the second drawing roller. The yarn is heated while running through the slit in a non-contact state (atmospheric temperature refers to the temperature inside the slit). 2. Subjected to stretching rollers.

At that time, a temperature gradient is created in the slit heater, and the atmospheric temperature at the yarn entrance is set at 160°C or higher, and the exit atmospheric temperature is set at 35°C.
It is preferable that the temperature is 0° C. or lower, and the yarn is passed through the slit heater so that the yarn can stay in an atmosphere of 170 to 350° C. for 0.3 seconds or more, and the yarn is drawn in substantially two stages in this slit heater. In addition, after the completion of the two-stage stretching, it can be carried out continuously without winding, or after winding once, 210
By performing a relaxation treatment of 10% or less at ~150°C.

It is also possible to further improve the dimensional stability.

In order to obtain the high strength, low elongation yarn used in the present invention, the maximum
Stretch at a high draw ratio of 85 inches or more, preferably 90% or more of the E draw ratio, so that the residual elongation is 8% to 20%, but the stretching ratio of each sample depends on the orientation degree of each drawn yarn. Basically determined by

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

The nylon 6 fiber thus obtained has the following properties.

(a) DT≧10 f/d [Lon 20%≧DE≧8% (c) IS≧35 f/d (d) SHD≦15% The nylon 6 multifilament yarn obtained above is Twisting according to the law.

Use raw code.

Further, the raw cord or the blind fabric woven from the raw cord is subjected to a dip liquid treatment to improve its adhesion to rubber, followed by hot stretching.

The inventors of the present invention have carefully studied the process from these raw cord preparation examples to the dip treatment, and have succeeded in making the dip cord highly strong, having a low intermediate elongation, and a low shrinkage rate. Excellent fc that cannot be expressed by code! 1
1. The present invention was discovered based on the discovery that this function can be realized.

Specifically, in the case of the high-strength, low-elongation nylon 6 fiber used in the present invention, the twist coefficient (T
0 to 2200 (for example, 47 for 840 d/2 twist
turn/10 on), the strength utilization rate of the raw cord will decrease, but if the twist coefficient is set to 1300-2000. Preferably, setting it in the range of 1400 to 1800 gives a very good strength utilization rate, and by lowering the hot stretch ratio in the dipping process to 0 to 5%, a dipped cord with a low shrinkage rate and low intermediate elongation can be obtained. is 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 6 dip cord, the hot stretch ratio in the dipping process is set to 7 chill 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, the conventional nylon 6 dipped cord can satisfy both dimensional stability and high modulus, and by elongating the molecular chain more than the nylon 6 high-strength yarn, it already has high strength, high modulus, and low elongation. Yarn is prepared in advance, and after twisting, the modulus of the Guitube 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 a low shrinkage rate that was previously unimaginable for nylon 6.

The goal is to achieve a high-strength dip cord with low intermediate elongation (high modulus).

None of the conventional nylon 6 dipped cords had a breaking strength A of 8.59/d or more, and an intermediate elongation B and a dry heat shrinkage C satisfying the following formulas. (Refer to Figure 1) (b) B≦9chi (c) C57% (d) C≦-4B+39 These dip cord characteristics have a twist coefficient of 2000 to 13
00. More preferably, it is in a low twist number region of 1800 to 1400, 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 a twist number. These properties are f
This is evident from the high residual strength after the disk fatigue test.

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, as an example of applications other than tire cords, (1) When used as a belt cord, the dimensional stability during rubber vulcanization greatly improved the per-step loss and the bending fatigue life increased by a large 1J. When used as a base width for resin-coated fabrics, its dimensional stability is enhanced.

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

<Method for measuring relative viscosity> A sample solution was prepared by dissolving the sample in 96.3±0.1% by weight reagent special grade concentrated sulfuric acid so that the polymer concentration was 10mg/*J, and the solution was heated at 20°C±0. The relative viscosity of the solution is measured using an Ostwald viscometer at a temperature of 0.05°C and an ice fall time of 6 to 7 seconds. During the measurement, the same viscometer was used, and the falling time T of 20 tsl of sulfuric acid was the same as when preparing the sample solution.
o @) and the falling time T1 (seconds) of 20xl of the sample solution, the relative viscosity RV is calculated using the following formula.

RV=T’t　/T.

<Measurement method of birefringence (ΔN)> Nikon polarized light microscope? Ikt1. P OHV Life Co., Ltd.'s Beretsu convenser was used, and the light source was a spectral light source starting device (Toshiba 5LS-8-B type), fc (N
a light source). A sample was cut at an angle of 45 degrees to the fiber axis with a length of 5 to 61aI, with the cut surface facing upward.

Place it on a glass slide. Place the sample slide glass on the rotating stage so that the sample is at a 45 degree angle to the polarizer1.
After adjusting the rotary stage by rotating it and inserting the analyzer to obtain a dark field, set the compensator to 30 and count the number of stripes (n pieces). The compensator scale a, :l is the point at which the sample first becomes dark when the compensator is turned clockwise. The compensator scale bt is the point at which the sample first becomes darkest when the compensator is turned left. - After measuring (all read to 1/10 scale).

Return the compensator to 30, remove the analyzer, measure the diameter d of the sample, and calculate the birefringence (ΔN) based on the following formula (average value of 20 measurements).

ΔN=r/d (r Niterapion?”=Nλo+g)λo=
589.3 mμ ε: C/100 in Finn's compensator manual
From 00 and i.

1=(a-b) (: Difference in convencator reading) <Measurement method of strength and elongation characteristics of fibers and cords> JIS-L
By Denrin of 1017. Place the sample upside down at 20°C.
After leaving it for 24 hours in a temperature and humidity controlled room at 65% RH,
#'Tensilon" UTM-4L type tensile testing machine [manufactured by Toyo Baldwin ■] was used.

Measurement was performed with a sample length of 2 Qcm and a tensile speed of 20 crn/min.

Measuring method of dry heat shrinkage SHD〉 Take a sample in the form of a skein, 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. A sample with a length of 1o was left under no tension in an open oven at 150°C for 30 minutes, then taken out from the open and left in the above temperature and humidity control room for 4 hours, and then the above load was applied again to measure the length. difference! ! It was calculated from the following formula.

Calculation formula for twist coefficient〉 Twist coefficient = Number of twists x (denier) T Number of twists: turn / 10cm Measuring method of disk fatigue〉 Created by embedding dip cord and vulcanizing using a normal disk fatigue tester The test piece was compressed using Seriton and the compression ratio was 1.
After applying forced fatigue by rotating at a speed of 250 rpm for 48 hours under an elongation ratio of 2.5% and an elongation ratio of 6.3%, the dipped cord was taken out from the rubber and its residual strength was measured.

Measuring method of intermediate elongation> According to the definition of JIS-L1017. Measure the elongation rate under a constant load W (height). Conditions for measuring elongation: Follow the conditions for measuring strength and elongation properties. The constant load W is defined by the following formula.

, 12H sample denier lv, dlB standard denier is 840 denier lv for raw yarn and 1680 denier for cord.

Method for measuring strength after vulcanization> After applying a tension of 1532 to each dip cord, the cords were fixed at a constant length and arranged in parallel. This was sandwiched between sheets of unvulcanized rubber with a thickness of 2 cm, and put into a mold.
Vulcanization bonding was performed for 20 minutes using a heat press maintained at 0.180'e. 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 its residual strength was measured.

Production Example> Polycaproamide with a relative viscosity shown in Table 1 (measured after the original drawing) and an undrawn yarn with a relative viscosity shown in Table 1 were obtained.

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.

A drawn yarn having the quality shown in Table 3 was obtained.

Table 3 shows the yarn quality of the commercially available polycaproamide 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 Table 2 Table 3 The resulting yarns each have 47 T/l Q cm
.

42T/10c1n and 37T/I Qcrn were twisted and twisted to form a two-strand cord of 840 d/2 ply.

The raw cord thus obtained is immersed in a nylon 6 dip solution consisting of resorcinol, formalin, and latex solution,
It was then dried with hot air at 120° C. for 2 minutes under a 1.5% stretch.

Next, introduce it to the hot stretch zone.

After 1%, 3%, and 7% hot stretching in heated air at 200°C, a further heat treatment was performed for 36 seconds in heated air at 200°C for a fixed length to produce a dip cord.

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, has low intermediate elongation, and has a small dry heat shrinkage rate, which is a measure of dimensional stability, and has a low twist region. It also has excellent fatigue resistance.

<Example> A tire as shown in FIG. 3 was manufactured using '4fc nylon 6 coat Ft- in Invention 1 of manufacturing examples. In other words, tires are made of ply made of cords woven in a tandem manner.

Bead wires 2 are disposed on both left and right sides of a carcass ply layer 1 consisting of one or more plies, and the force cusp layer 1 is curved into a circular arc shape.

The carcass ply layer 1 is reinforced by providing a belt layer 4 on its crown portion 3, and the periphery of these constituent layers is further covered with a rubber layer (tread) 5 to obtain the tire of the present invention. There is no particular restriction on the material of the rubber layer; 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 comparative consideration of the above production examples and comparative production examples, the nylon 6 cord used in the tires of the present invention possesses the excellent strength of the yarn itself, and as a result, as exemplified by the example The tire wire of the present invention exhibits excellent performance such as high toughness and resistance to vulcanization deterioration, and exhibits performance that cannot be obtained with tires using conventional nylon 6 cord.

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 is determined by the dip code in Table 4 at 160°C.

The strength of the dip cord of the present invention after vulcanization is much better than that of the comparative example. Also, there is little loss of strength after vulcanization.

[Brief explanation of the drawing]

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 related to the present invention. This is an area showing the characteristics of the dip cord. Fig. 2 is a graph showing a comparison of raw cord strength, dip cord strength, and strength after vulcanization. ) shows the dip code of the comparative example. Fig. 3 is a half-sectional view of the essential parts of the tire of the present invention. 1... Carcass ply layer 2... Bead wire 3... Crown portion 4... Belt Part 5... Tread patent applicant Toyobo Co., Ltd. Volume 1 t! 1 ? Between 4 degrees ('/,) No. 21! 1 No. 31! 1

Claims (1)

[Claims] 1.5-caproamide repeating structural unit is 95 moA/%
It is made of the above polycapfumide polymer and has a high degree of polymerization with a sulfuric acid relative viscosity of 3.0 or more. One or more types of fibers are made of polycapramide fibers containing two or more types of copper salts and/or an inorganic or organic antioxidant other than the above-mentioned copper salts, and are coated with a dip liquid to improve adhesion to rubber. A polycapramide dip cord with a twist coefficient of 2,000 to 1,300, both twisted and untwisted, which has high strength and modulus and also has the following special orders, as well as significantly improved dimensional stability and fatigue resistance. A tire characterized by using a cord for the carcass ply. (a) Dip cord breaking strength A≧8.5 f/
d(b) Intermediate elongation of dip cord B≦9% (C)
Dry heat shrinkage rate of dip hood C≦7% (d) C≦−
4B+39-2, in claim 1, the breaking strength of the dip cord is 9. A tire characterized by using a polycapramide dip cord having a dry heat shrinkage rate of Of/d or more and a dry heat shrinkage rate of 5% or less. 3. A tire according to claim 1 or 2, characterized in that a polycapramide dip cord having a twist coefficient of 1,800 to 1,400 is used.