JPS6245739A - Dip cord for reinforcing tire - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dipped cord for tire reinforcement. For more details? The present invention relates to a dipped cord for reinforcing tires that has excellent fatigue resistance and is made of fibers made of Leepara-phenylene terephthalamide-based polymers (hereinafter abbreviated as PPTA-based fibers).

[Conventional technology]

Generally, tire reinforcing materials are used in the form of woven fabrics. The dipped cord is made up of all the warp threads of such a sudare fabric, and is made by first twisting and final twisting one or more yarns, and applying an adhesive, such as a polyhydric phenol and formalin condensate, to the yarn. An aqueous dispersion containing latex (hereinafter referred to as RF/L) is applied and heat-cured.

Among tire reinforcing materials, PPTA fibers have excellent durability, rigidity, dimensional stability, and heat resistance, as expected from the molecular structure of the polymer, and have high strength. It is expected to be applied to large tires for various fields such as trucks, passes, construction vehicles, and aircraft.

However, even though PPTA fibers have higher strength than, for example, nylon fibers, which are conventionally used in large quantities as tire reinforcing materials, these tires are more durable than passenger car tires. The amount of reinforcing material used per unit is extremely large, and a large amount of energy and fuel consumption are required.

On the other hand, reflecting the recent rise in raw material and fuel prices, there is an increasing trend toward energy conservation and fuel efficiency, and tires are also being made lighter by reducing the number of layers of reinforcing material and by reducing the number of reinforcing materials inserted. There is a strong demand for

In addition, along with such weight reduction, it is highly expected that fatigue resistance will be improved by reducing the amount of heat generated while the tire is running, and productivity will be improved in the tire molding process.

To achieve this, it is necessary to replace the currently used PPTA fibers or their dip cords with even stronger PPTA fibers.
A fiber or its dipped cord must be developed.

Generally, it is known that high-strength PPTA fibers can be obtained by dissolving a polymer with a high degree of polymerization in a solvent such as sulfuric acid at a high concentration and spinning the resulting fiber. However, PPTA type? Since remer is poorly soluble, it is difficult to dissolve polymers with a high degree of polymerization at high concentrations, and it is extremely difficult to dramatically improve strength.

Furthermore, although such fibers have superior heat resistance compared to nylon fibers, etc., which have traditionally been widely used as tire reinforcing materials, they cannot be used in the derag process for making dip cords or in the processing for compounding with rubber. It is undeniable that the strength and elongation decrease in the sulfurization process, and as a result, the toughness, which affects tire performance such as durability and impact resistance, decreases, making it impossible to exhibit sufficient performance.

[Problem that the invention seeks to solve]

In view of the above-mentioned drawbacks, the present inventor made various attempts to increase the strength of PPTAPPA fibers. However, even if a dipped cord for tire reinforcement is made using high-strength PPTA fibers, in the derag process or vulcanization process,
If the decrease in strength, elongation, etc. is large, the performance cannot be improved to the extent that the weight of the tire can be reduced.

Therefore, the inventors of the present invention focused on the correlation between tire performance, particularly fatigue resistance, and the characteristics of tire reinforcing dip cords, and conducted intensive studies, and further developed di-zo methods for demonstrating and improving the characteristics. The present invention was completed by conducting research on the above.

An object of the present invention is to provide a tire reinforcing cord with excellent fatigue resistance, which can reduce the weight of a tire without reducing tire performance.

[Means for solving problems]

The object of the present invention is to have fibers consisting essentially of poly-paraphenylene terephthalamide polymer, (1) Breaking strength: 13 g/d or more (ii) Breaking elongation: 5 inches or more GiD Expressed by formula (1) Parameter (G);
1. However, in formula (1), BS is breaking strength g/d, I
s, IE, and IMI are the inflection before rupture of the differential modulus stretch curve obtained by plotting the modulus at each stretch rate (this is called the differential modulus) against the stretch rate based on the load-stretch curve. Intensity at a point (Is:
g/d), elongation (181%), modulus (rM
x: g/d).

A tire reinforcement diode characterized by satisfying the following.

This is accomplished by using code.

The dipped cord of the present invention is constructed using fibers made of borino-9-raphenylene terephthalamide-based polymer as yarn.

The phenylene terephthalamide-based polymer used in Polyno is a general term for poly-79 rough phenylene terephthalamide and copolyamides each substituted with other aromatic diamino residues or/and other aromatic dicarboxyl residues. , these and mixtures of these PPTA-based polymers may be used. The degree of polymerization of such a PPTA-based polymer has a large influence on physical properties such as breaking strength and elongation when fibers are formed.

Usually, it is expressed in terms of intrinsic viscosity (η1nh) of at least 3.
It is preferably 5 or more, particularly 4.5 or more.

The yarn of the PPTA-based fiber constituting the dip cord of the present invention is not made of the above-mentioned PPTA-based polymer.
5 g/D (Denier D refers to the total denier of the PPTA fiber yarn and is different from the denier d of the adhesive-applied di-cod itself), preferably 18 g/D.
Breaking strength of D or more, more preferably 20 g/D or more,
and an elongation at break of 3.5% or more, preferably 4.0 inches or more. The fiber form of the raw yarn is usually a multifilament yarn, and in this case, the denier of the single fibers constituting the raw yarn and the total denier D of the raw yarn are the same as the dipcoat P of the present invention.
Although not particularly limited, single fibers are usually 1 to 10 deniers, preferably 1 to 5 deniers, and raw yarns are 500 to 10,000 deniers, particularly 1,000 to 10,000 deniers.
Preferably it is 6000 denier.

The PPTA fibers constituting the di-pucord of the present invention are:
A yarn obtained by first twisting and final twisting the above-mentioned raw yarn, that is, a twisted cord, where the number of twists varies depending on the type and shape of the tire used, the total denier of the raw yarn, etc. However, it is not particularly specified in the present invention, and usually,
When the number of twists per 10 crn is T, and the total denier of the yarn constituting the cord is D, the twist coefficient determined by K = TX is 1500≦≦220-0, preferably 1600.
The range is ≦≦2100.

The adhesive may be any adhesive used in ordinary dip cords for reinforcing tires, and in many cases, an aqueous dispersion of polyhydric phenol and formalin metal condensate with rubber latex added thereto is used. The amount of adhesive applied is usually 3 to 7% by weight, preferably 4 to 6% by weight.

The dip cord of the present invention has a breaking strength of 13 g/d or more,
Preferably it has 15 g/d or more. Breaking strength is 13
If it is less than g/d, reduce the number of layers of reinforcing material,
It is not possible to reduce the weight of tires. Here, d represents the denier of the di-pcord itself, which includes the solid content of the adhesive adhered by the dipping process, the number of twists, the moisture content of 4.5%, etc.

Further, the dip cord of the present invention needs to have a breaking elongation of 5 inches or more. When the breaking elongation is less than 5 inches, the breaking energy given as the area of the cord's load-elongation curve is small, and the fatigue resistance is significantly reduced.
Decreases tire performance. In some cases, the material cannot function as a tire reinforcing material.

Furthermore, the dip cord of the present invention has the strength (Is:
g/d), elongation (IE:chi), modulus (IMI
It is important that the parameter G expressed by equation (1) by BS : g/d) and breaking strength (BS : g/d) is 1 or more.

In order to achieve weight reduction without reducing tire performance, a breaking strength of 13 g/d or higher is required as mentioned above, and higher breaking strength is more preferable, but simply having a high breaking strength does not lead to fatigue. No improvement in characteristics can be obtained, and in some cases, the characteristics may even be deteriorated. Tire reinforcement di to bring out excellent tire performance! It is essential that the cord has toughness against the repeated stretching and compression cycles within the tire.

The stress meter G represents both the fracture energy that is effectively used in practice and the stress-strain characteristics before rupture (1), and only when it is 1 or more can dramatic fatigue resistance be achieved. improvement is realized. When the /f parameter G is less than 1, the strength and elongation in subsequent processing steps, such as the vulcanization step, are significantly reduced, and fatigue resistance as a tire performance cannot be improved.

Note that here, the parameter G is specifically determined by the following method.

FIG. 1 is a schematic diagram of a load-elongation curve of a D,P cord made of PPTA fibers, and A is the breaking point. Divide the obtained load-elongation curve into at least 100 equal sections up to the elongation at break (point 0 in Figure 1), and draw a perpendicular line from each division point to the load-elongation curve. , from the slope of the tangent at this point of intersection (point D in FIG. 4), the simozilus is determined by a conventional method and taken as the differential modulus value. The denier used to calculate the modulus at that time is the load -
Total denier d of dip cord before being subjected to elongation test
Use.

Note that the load-elongation curve of dipcord made of PPTA fibers is often linear, and it may be difficult to draw tangents at each point appropriately. In this case, the intersection points (D-10, D+1 in FIG. 1) corresponding to the dividing points before and after the point to be found (point D in the example in FIG. 1)
The modulus can be calculated using the slope of the straight line between 0 points). In this case, the width between the front and rear division points is set so that the width of the expansion rate is 0.1% or less, and the front and rear widths are set at equal intervals.

For measurement, the electrical signals of the load and elongation rate of the tensile tester to determine the load-elongation curve are input into a data processor as digital signals at minute intervals, and the differential modulus value for each elongation rate is calculated or directly Drawing a differential monolase-elongation curve is an extremely effective method in terms of measurement accuracy and efficiency.

The differential mono- and lath values for each elongation rate thus obtained are plotted on a graph to create a differential modulus-elongation curve. Figure 2-A shows the differential modulus-elongation curve obtained from the di, 'f code of the present invention, and Figure 2-B shows the differential modulus-stretching curve obtained from the di, f code of the present invention (each proto and g are smoothed). (obtained as a curve connecting to ) is shown. Let the elongation and differential modulus values corresponding to the inflection point (1) before the break point of this curve be IE and IMi, respectively. Is
is the load j! corresponding to IE from the load-extension curve. (stress)
Required as a value.

The tire reinforcing dip cord of the present invention has the above-mentioned essential characteristics, but other characteristics may have the same values as ordinary tire reinforcing dip cords.

Furthermore, the tire reinforcing di-pcord of the present invention contains additives that are normally contained in tire cord fibers or dipped cords, such as heat stabilizers, antioxidants, light stabilizers, lubricants, and thickeners. May include.

The tire reinforcing dipped cord of the present invention is manufactured as follows.

FIG. 3 shows a dip manufacturing apparatus.

In Fig. 3, 1 is a twisting and feeding device for Nenshito, 2.
3 is an adhesive dipping device, 4 and 5 are tension control devices, and 8 is a dip cord winding device. 9 and 9' are the first zones, 10 is the second zone, the tension in the first zone is between 2 and 4 or between 3 and 4, and the tension in the second zone is between 4 and 5.

In general, raw yarn made of PPTA fibers having a breaking strength of 15 g/D or more, preferably 18 g/D or more, and a breaking elongation of 3.5% or more, preferably 4.0% or more, as described above, is used as a base material. After twisting and ply twisting, the following dipping treatment is performed to obtain a twisted yarn, that is, a twisted cord.

(1) Before the D and F treatments, the yarn or twisted cord is subjected to relaxation heat treatment at 250° C. or higher for 1 minute or more.

(ii) Cord tension during RF/L immersion (in Figure 3,
RF/L is immersed at 2 or 3 and tensioned between 2 and 4 or 3 and 4) at 2.5 kp/cod or more.

(iiD Then 4 including the 10 second zones in Figure 3)
Cord tension between and 5 to 0.8 to 9/cord or more, 2.
5 is treated as 5+/code or less.

As disclosed, in the case where fibers that have already been subjected to relaxation heat treatment in the process of producing PPTA-based fibers are used as raw yarns, it is possible to omit the heat treatment shown in (1) above, and it is preferable that the present invention It is possible to obtain D and F cords for reinforcing tires.

〔Example〕

Hereinafter, the present invention will be explained in more detail and concretely by referring to all embodiments. Various characteristic values used in the Examples were measured by the following methods.

In the examples, unless otherwise specified, "" and "" indicate weight %.

<Method for Measuring Intrinsic Viscosity> The intrinsic viscosity (+71nh) of the polymer and fiber is 98.
A solution prepared by dissolving a polymer or fiber at a concentration (C) of 0.2 g/dt in 5% by weight concentrated sulfuric acid is measured at 30°C by a conventional method.

Strength and elongation characteristics of the raw yarn> The strength and elongation of the raw yarn were determined at 10c prior to measurement in accordance with JIS standards. Regarding the yarn with 8 twists added,
A load-elongation curve was drawn using a constant-speed elongation type strength and elongation tester at υ, grip length 20σ, and tensile speed 50 inches/min, and the strength at break (g/D) and elongation (i) ) is the average value of 10 measurements.

<Strength and elongation characteristics of dipped cord> A load-elongation curve was drawn for the dipped cord using the same testing machine as described above, and the strength was calculated by the method described above.

<Nogurameter G> Measurement 1 was carried out in accordance with the method described in the "Means for Solving Problems" section of this specification.

That is, when measuring the strength and elongation characteristics of the dip cord, the output data (electrical signals) of the elongation rate and load (stress) of the constant speed extension type strength and elongation tester were pulsed and input online into the digital memo tie day.

The data input speed is 100 paint/min.
The differential modulus value is calculated by the usual method from the slope of the straight line connecting the points 10 points before and 10 points after the measurement point, and the horizontal axis extends (4), and the vertical axis shows the differential modulus (g/d). was printed out using a line printer (Figure 2-A).

(See Figure 2-B). The obtained data plot of the differential modulus for each elongation rate is smoothed to obtain a differential mosola-elongation curve, and the IMi at the inflection point is calculated using the method described in this article.

IE and Is were determined, and the G value was calculated using equation (1).

Fatigue Resistance> Fatigue resistance is the fracture time of Chi-f (u = 4) in a cheap fatigue test conducted according to JISL-1017. The bending angle of the tube is 1000, the number of cords in the cheap is 1500, 65 for D/2, 2
In the case of 000D/2, there are 45 lines.

Cheeve internal pressure is 3.5 kg/cm2, rotation speed is 85
0 rpm.

Example 1 Polymer phenylene terephthalamide with an intrinsic viscosity (11 nh) of 7.05 was mixed with a polyamide phenylene terephthalamide at a concentration of 18.7%.
While maintaining the temperature at 80°C, the mixture was added to 99.7% concentrated sulfuric acid and dissolved with stirring to prepare a dope for spinning. It was confirmed by polarizing microscope observation under an orthogonal mirror that this dope exhibits optical anisotropy. Further, the viscosity of the dope at 80°C was 5750 poise.

This dough f was allowed to stand under vacuum (0.5 Torr) for 2 hours to defoam, and then used for spinning. The dough was introduced through a gear pump into a candle filter wrapped in 300 mesh stainless steel wire mesh T-8 times, and then passed through a candle filter with a pore size of 0.0.
It was discharged from a spinneret having a diameter of 7 m and 1000 holes. The discharge linear velocity at this time was 44.2 m/min.

The dough extruded from the spinneret was guided into the coagulation bath through eight layers of air. As the coagulation liquid, a 10% aqueous sulfuric acid solution cooled to 1.5°C was used.

The yarn coagulated in the coagulation bath was then drawn out together with the coagulation liquid through a pore installed at a depth of 30+ m from the surface of the coagulation bath, together with the bottom of the coagulation bath.

The drawn yarn is then changed direction by a direction changing roll installed 400 m below the pore, and then pulled by a Nelson roll at a speed of 300 rn/min. Using the device shown in the publication, the yarn is passed through a pair of gears m;

The yarn was transferred onto a reversing net using a grol (gear-like rolls are shallowly engaged and the yarn is fed out between them), and then the yarn was reversed and placed on a processing conveyor. The piles placed on the processing conveyor are washed with water using a shower, then treated with an oil solution containing 1 g of mineral oil dispersed in water using an emulsifier, and then heated with hot air at 200°C. After being subjected to relaxation heat treatment at 280° C. for 90 seconds, it was taken up from the conveyor and wound onto a pg upper pin using a winder.

The obtained PPTA fiber had a denier of 1505), a breaking strength and an elongation of 23. sg/D, 5.2chi.

These two raw yarns are separately twisted (in the Z direction) 38 times/1.
Add 0, align the two and further twist (1B direction) to 38
1515 D/2 yarn (twisted cord) was created by adding 1515 D/2 threads/10 cm.

Then, dipping treatment was performed using the dip cord manufacturing apparatus shown in FIG. RF/L was attached using the dipping device 3 in FIG. 3, and the tension was adjusted to 3-OkII/cord between 3 and 4.

At that time, the processing temperature of the first zone indicated by 9' was 25
0℃, processing time: 72 seconds, cord processing speed: 20m
/minute. Then the code runs at the same speed and at a processing temperature of 2.
4 into the second zone (10) at 30°C and a treatment time of 50 seconds.
The tension was adjusted so that the tension was 1 cord/cord between 1 and 5, and the cord was wound up by a winding device 8 after passing through a direction change roll.

The differential monocular-elongation curve of the obtained dip cord is shown in FIG. 2-A, and each characteristic is shown in Table 1.

It is clear from comparison with Comparative Example 1 that the f4 tube cord of the present invention has excellent fatigue resistance.

Comparative Example 1 During the production of the PPTA fiber of Example 1, only relaxation drying with 200°C hot air was performed, and PP was not heat-treated.
Except for using TA fiber as the raw yarn, the same treatment as in Example 1 was carried out to obtain di-pucord.

The differential modulus-elongation curve of the obtained dip cord is shown in Figure 2-B, and all the characteristics are shown in Table 1.

Although this dipped cord had a breaking strength equal to or higher than that of the dipped cord of the present invention obtained in Example 1, it was confirmed that the fatigue resistance was clearly inferior.

Example 2゜PPTA used in Comparative Example 1 without heat treatment
fII fiber was used as the raw yarn, and the same yarn twisting treatment as in Example 1 was performed to obtain a twisted cord.

Next, this twisted cord was placed in a hot air circulation constant temperature bath with an ambient temperature of 270° C. and subjected to a relaxation heat treatment for 3 minutes, and then subjected to the same dipping treatment as in Example 1 to obtain a dip cord.

Table 1 shows each characteristic value of the nine codes obtained.

Example 3゜2000 by the same spinning method and relaxation heat treatment as in Example 1
Obtained 0/1000f PPTA fiber.

The breaking strength of this yarn is 22.7 g/D, and the breaking elongation is 4.
．． Just in case it's 9%.

These two raw yarns are separately twisted D (Z direction) t-32 times/
10c1n was added to the cord, and the two cords were pulled together and twisted 32 times/10cm (in the S direction) to obtain a twisted cord of 2010D/2. Then, dipping treatment was performed using the dip cord manufacturing apparatus shown in FIG. RF/L is applied by the immersion device 2 in Figure 3, and the tension between 2 and 4 is adjusted to 3.5 to 9.
/Kept in code. The temperature of the first zone represented by 9 and 9' was 260°C, and the processing time was 96°C for the entire first zone.
seconds, and the processing speed is 25 m/min. Next, at the same speed, the second zone (10
) and was wound up using a winding device while adjusting the tension between 4 and 5 to give 1 kg/cord.

The characteristic values of the obtained fiber and powder were consistent with those shown in Table 1, indicating excellent fatigue resistance.

Example 4 In the same manner as in Example 1, poly-paraphenylene terephthalamide with an intrinsic viscosity of 7.68 was treated with ? Rimmer concentration is 19%
After dissolving 1c in 99.8% sulfuric acid and defoaming, the number of holes was 1000. Discharged from a spinneret with a hole diameter of 0.06 mmφ (
The discharge linear velocity was 3Q, 8 m/min). It was then introduced into a water coagulation bath at 3 to 4°C through a 10 m air layer, pulled out from the same spinning bath device as used in Example 1, shaken out as a pile on a net conveyor, and then washed with water. .

After washing the yarn pile with water, apply an oil agent containing 1% mineral oil that has been dispersed in water using an emulsifier, and then lift the yarn from the top of the netcon 4A.The diameter is 300wφ and the length is 1000m.
It was pulled out with a pair of Nelson heated rolls (rolls that are heated to a surface temperature of 125°C by blowing steam into them), wrapped 90 times, dried, and then rolled on a wine rack at 200 m/min. I wound it up at speed.

The obtained PPTA fiber has a breaking strength of 1520D and 24.3.
g/D and elongation at break were 4.1%. This yarn was twisted into a twisted cord under the same conditions and method as in Example 1, and then subjected to relaxation heat treatment under the same conditions as in Example 2, followed by dipping treatment. y4. The conditions for the f process are the same as in Example 1. The characteristic values of the obtained dipped cord are as shown in Table 1, and it exhibits superior fatigue resistance compared to Comparative Example 2 listed in parallel.

Comparative Example 2 A twisted hood made of PPTA fibers obtained in Example 4 was treated in the same manner as in Example 4, except that the relaxation heat treatment was not performed to obtain a dipped cord. The fatigue resistance of the hood was extremely low, proving how excellent the 7" yp cord of the present invention is.

〔Effect of the invention〕

The tire reinforcing dip coat according to the present invention is constructed as described above, and has improved strength in the vulcanization process for compounding with rubber. It has strength and toughness, and can significantly improve the tire's fatigue resistance and impact resistance, as well as reduce the weight of the tire.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a load-elongation curve of a dipped cord made of PPTAPPA fibers. Fig. 2 shows the differential modulus-stretch curve of the di and f chord, Fig. 2-A shows the dip code of the present invention, and Fig. 2-8 shows the di, f code of the invention.
represents the code. FIG. 3 is a diagram showing an example of the dip cord manufacturing apparatus of the present invention. In FIG. 3, 1 is a twisted yarn feeding device, 2 and 3 are adhesive dipping devices, 4 5 is a tension control device, 8 is a dip cord winding device, and 9, 9' and 1o are heating zones for adhering the dipping liquid to the cord. '$1 Figure 2B

Claims (1)

[Scope of Claims] 1. Consisting of fibers substantially consisting of poly-paraphenylene terephthalamide polymer, (i) breaking strength; 1
3 g/d or more (ii) Breaking elongation; 5% or more (iii) Parameter (G) expressed by formula (1); 1
More than G=(100×IS×IE)/(IMi×BS)
(1) However, in formula (1), BS is breaking strength g/d, IS,
IE and IMi are the strength (IS ;g/d)
, elongation (IE; %), and modulus (IMi; g/d). A dip cord for tire reinforcement that satisfies the following. 2. The dipped cord for tire reinforcement according to claim 1, wherein the polymer is poly-paraphenylene terephthalamide, or a polymer in which 90 mol% or more of the repeating units constituting the polymer are paraphenylene terephthalamide units.