dimensionally stable polyesters replacing rayon in european tire market. - pet manufacturing process
At present, the global tire yarn consumption trend predicts the future growth of PET demand (
Or polyester industrial Yam for passenger transport.
During the five-year period ended 1995, global consumption of PET tire yam is expected to increase by 30% at the expense of artificial silk (
90% of rayonmarket is located in Europe, especially in Europe).
The artificial silk provides good adhesive rubber and provides moisture-
It can reduce up, especially at high temperature, a good combination of strength and modulus.
However, environmental and increasing cost issues have led tire manufacturers to look for an acceptable alternative artificial silk as a tire carcass enhancement material for major passenger cars.
Extensive research and development has produced a new generation of PET with stable size (DSP)
Designed for high performance tire body. In the mid-
1980 s, the first generation of DSP fiber for enhancement is introduced through AlliedSignal.
These fibers improve the performance standard of American tire reinforcementS.
At the same time, the new EU directive aimed at reducing environmental pollution makes the production cost of artificial silk higher than ever before.
Second generation of environmental protection
Friendly DSP fibers with elastic/shrinkage properties comparable to artificial silk have been developed, but greater toughness is also provided. These advanced(1X40/1X43)
DSP fiber is a replacement for artificial silk, enabling tire manufacturers to "drop" them into existing production procedures for using artificial silk.
An inherent advantage of polyester fiber is that by adjusting the shrinkage level, rope handling can be customized to achieve maximum tire uniformity.
The new DSP fiber is designed as rayonreply;
Tire manufacturers do not need new manufacturing equipment to use it, which makes it easier to convert to DSP.
In addition to matching the performance of the artificial wire, this DSP fiber saves weight (
Thus saving costs)
According to the specific tire application, 10% to 30%.
The following is a prediction of the depression of the tire side wall (SWIs)
, Growth, uniformity, and treatment during operation, based on laboratory simulations, which replicate the conditions that must be borne by tire ropes.
They can be used as a guide for tire manufacturers and engineers, and they can now consider polyester fiber as a major replacement for artificial silk as a tire enhancement material.
Four 1100 decitex polyester yams produced by AlliedSignal fiber were used in this study: IW70, a conventional polyester fiber;
1X90, first generation DSP fiber for tire reinforcement;
1X30, the second generation of high toughness materials;
1X40, second generation advanced polyester with ultra high performance
High dimensional stability tailored for the European tire market.
All twisted into 3-
Layout wiring (315 tpm)
, Immersed in the adhesive, heated and stretched.
Artificial yarn (1850 decitex)
Twisted into 2-
Layout wiring (480tpm)
And is soaked, heated and stretched in the same way.
These are commercial structures that are widely used in polyester and artificial silk threads, so they are more effective.
The dimensional stability of PET treated tires directly affects the manufacturing process of tires and the resulting tire uniformity and appearance (figure 1).
The curve is generated by processing the rope into a different net stretch, thus changing the tensile stiffness (
LASE or load at specific elongation; LASE-
X indicates stress atX % elongation).
As expected, increasing the tensile stiffness of agiven materials by processing to a higher stretch also increases the tendency to shrink when exposed to the curing temperature.
Therefore, meaningful comparisons should be made based on constant shrinkage or LASE.
For example, 1 is obtained through treatment.
5% freeshrinkage, 1X40 DSP fiber provides higher tensile stiffness (23cN/tex)
Standard polyester materials such as 1W70 (11 cN/tex).
Dry artificial silk has LASE-5 of 26 cN/tex.
Compared with similar shrinkage, LASE of 1x40dsp fiber is 50% higher than 1W70, but still lower than dry artificial silk.
However, the toughness of polyester fiber and artificial silk (figure 2).
Although the rope performance of dry artificial wire treatment can be effectively used for quality control purposes, they do not represent ropes in tires where moisture is present.
When the artificial silk is completely dry, the toughness and LASE are maximized, but the strength and LASE are significantly reduced as the moisture content increases.
This effect was not observed with polyester fiber. In-
Tire curtain performance curing tireA curing/running tire (C/RT)
Simulation was developed to evaluate the performance changes from treated curtain cloth to cured tire, which were caused by the shrinkage of the curtain during curing.
In the C/RT test, the treated wires bear the specified load in the tubular oven.
The load and temperature are adjusted to reflect the tire setting process to be simulated or specific parts of the conditions of use: curing, curing injection and tire use at the specified inflation pressure.
Monitor the length of the command and measure the result line properties after the critical step (figure 3).
By comparing the rope properties after the simulation step with the properties of the solidified tire rope, the appropriate load can be determined. Post-Treat inflation (PCI)
Not included due to industry trends in the US. S.
To eliminate the widespread lack of such facilities in it and in Europe.
The simulation is as follows: * curing-
Load corresponding to the wire retraction force generated at 177 [degrees]C (
Typical curing temperature)
Apply for 20 minutes.
* Therapeutic jet-
Remove the load, turn off the oven and allow cooling for 30 minutes.
* Joints and wires in adjacent non-joints
The undergonesimilar length of the cold junction area is reduced due to shrinkage (
Consistent with the rope analysis taken out of the cured tire).
After exposure to the simulation, the wire modulus will be reduced compared to the original treated wire/fabric.
According to the specific position in the tire (
Crown or side wall)
The elastic modulus, degree of shrinkage and the resulting performance changes of uncured rubber will vary.
There are several mechanisms for this to happen: * shrinkage during curing can occur evenly along the length of the wire (figure 4a).
If the rope is pulled around the beads, this can be detected by shortening the part of the wire in the rotation.
If the curing pressure is maintained before the tire cools,-
The solidified tires will be uniform along the entire length.
In the curing process, the normal force acting on the beads reduces the distribution of this mechanism.
* Or, it will shrink without holding the beads.
On the contrary, the rope passes through the inner lining (figure 4b).
Similarly, if the pressure is maintained, the modulus of the wire is uniform along the length of the wire.
Visual Analysis of tire crossing
This section provides insights into the contribution of this mechanism.
* If the tire pops out of the curing machine when overheating, the rope shrinks because the curing pressure no longer limits the tire to a given shape.
Assuming that the degree of bending of the ply skin is sufficient to limit the rope movement in the rubber matrix, the double shrinkage of the rope in the thin side wall may be sufficient to cause the overall shortening of the side wall.
The quality of the Beadand tread areas will help to prevent shrinkage in these areas.
Therefore, the rope modulus generated in the side wall will be lower than the modulus under the Crown (figure 4c).
* During the expansion of the green tire in the mold, the belt under the electric bow will have a significant impact on the loss of modulus under the Crown.
Due to the mechanical force of the wires to "shrink", the degree of the electric bow is very small, resulting in a decrease in the modulus of the wires under the Crown.
"If the floodlight is excessive, the wires can actually be compressed during expansion and cause significant loss of strength and modulus.
In this case, the glass under the tread will be lower than the side wall.
* At high temperature, the polyester rope loses the elasticity of the internal stress relaxation.
Experiments show that this mechanism is not a major contribution to the loss of modulus.
* Treating polyester into a variety of net stretches can lead to different levels of shrinkage.
The LASE after the free contraction remains constant unless the rope goes through a net stretch that is too low (figure 5).
For example, when withdrawing (shrinkages)
1X90 DSP fiber is different during free shrinkage, and the LASE values after free shrinkage are similar (12 cN/tex)
Regardless of the original net stretch (stretch/relax).
However, for example, if the original treated wire is treated as 10cN/tex, there is no power to increase the pull-side shrinkage to 12 cN/tex.
This is important to determine the optimal polyester treatment conditions.
The inherent advantage of polyester fiber is that by adjusting the amount of shrinkage, rope processing can be customized to achieve maximum tire uniformity.
Unlike polyester, the shrinkage of artificial silk has nothing to do with the treatment conditions.
The study shows that the water content of the artificial wire rope of the uncured tire is 4%-6%.
Therefore, it is appropriate to compare polyester properties with artificial silk threads containing moisture (figure 6).
Under these practical conditions, the dimensional stability of the 1x40 DSP fiber is better than that of the artificial silk.
The artificial silk taken out of the tire is mixed with a rope treated with artificial silk containing 6% moisture, confirming previous studies.
Running the tireThe C/RT simulation can continue to evaluate the impact of tireservice on wire performance.
After the line is cooled, the load is applied to simulate the tension experienced when the tire is inflated.
To study the joint effect, it is assumed that the rope load in the joint is 1-for single-layer tires-
Anon-half of the power cord loadsplice cord (
[Inflation] the oven is heated to 100 【degrees]
C. simulation of super-running tires-high speeds (
Assuming the pressure remains the same).
After five hours, the power of the oven is turned off and the wires can gradually cool down;
This simulates parking after five hours of operation (figure 7).
Alternatively, you can go through ASTM or free shrink test cords in this simulation, but expect similar results.
Prediction of side wall dents of tire performance (factory)
The extension of the "inflation" tension depends on the joint or non-joint
Splicing is being simulated;
Their differences in elongation are shown in figure 4.
This difference should be directly related to the SWI level measured by the factory.
To convert the elongation difference D to SWI depth, a simplified model can be used.
In the model, the side wall away from the joint is approximately a half circle of radius r2.
At the mold joint, the radius is r1.
SWI equals the difference of radius R2-Rl.
The elongation difference D is equivalent to the arc length difference of the two lines.
Since the radius is proportional to the arc length, SWI = R2-
R1 = DL/P when DL = D (
Side Wall arc length w/oinflation).
For a given tire structure, D is proportional to the predicted SWI depth (table 1).
Advanced 1X40 DSP fibers are expected to have more than 37% shallow erswis compared to standard polyester fibers of-
Solidified expansion of tires.
Dent in the side wall (run tire)
SWIs for all materials increased significantly after operation.
However, compared to the standard 1W70 polyester fiber, the DSP fiber starts at a lower level and maintains its advantages.
Tire Test wheel experiments show that the addition of this SWI represents what actually happens in the tire.
Tire testing also showed that SWIs grew to a level of balance achieved after about 1500 km in use.
Increments obtained immediately after running (
Same as obtained after cooling, so SWIs should remain the same.
Tire Test wheel experiments confirm that SWIs will not change after a car is parked and the tires have a chance to cool down.
Uniformity the uniformity of the tire is measured according to the change of the radial force around the tire in contact with the test wheel.
Therefore, it is mainly to measure the deformation capacity (radial modulus)
Part of the tire in contact with the test wheel.
The non-uniformity of rubber and carcass curtain layer materials and the non-uniformity of the curtain layer during the construction process will lead to excessive changes in the radial force of the final tire.
Due to uneven treatment conditions, the uneven thickness of the carcass may include variable line spacing in the fabric, and even changes in rope performance.
However, in order to be detected, many adjacent lines need to significantly increase the modulus in a sufficiently wide area.
Experiments show that the difference in temperature around the injection during and after curing can lead to different shrinkage inside the tire;
Hot parts tend to generate low points on the radial force curve.
Therefore, samples with increased dimensional stability (i. e.
, Lower shrinkage of a line with a given starting LASE)
There should be better uniformity, reducing the degradation and scrapping of tires.
Due to the similar dimensional stability of 1x40 DSP and artificial wire, tireunisity should also be comparable.
For safety reasons, it is important for tires to scratch or resist.
The energy absorption properties of the tire determine its high-
There are obstacles on the road that impact the speed or travel on the rugged terrain. The U. S.
The Department of Transport requires Static determination of this resistance by measuring the piston energy on the tire tread.
Some tire manufacturers also determine the side wall impact resistance by pressing the piston on the side wall and measuring the force and displacement properties.
This measurement is mainly determined by the energy absorption properties of the body rope.
For tread and side wall impact, the relative performance of different body ropes can be independently evaluated by toughness measurement, especially for ropes with LASE-like in intermediate strain.
Rope toughness is measured after free shrinkage, and free shrinkage best represents the condition of the rope in the tire (
Here, toughness is defined by the total energy of a wire failure).
1X40 DSP fiber has 7% toughness over standard polyester fiber and 29% toughness over artificial silk based on the same weight.
Therefore, the 1X40 DSP fiber should provide better impact resistance than other polyester fibers, especially artificial silk.
The toughness of 1X40 DSP fiber is slightly lower than that of standard polyester fiber, but its toughness is higher (
The toughness and toughness of all polyester are much higher than that of artificial silk).
Historically, the tire was designed to meet certain minimum strength requirements.
This overall approach may be necessary for conventional ropes, as there is a direct correlation between the final rope strength and modulus under intermediate loads (e. g. ,LASE-5).
However, with the emergence of a new generation of advanced polyester such as DSP fibers, there is a choice between high toughness wires and wires with slightly lower strength but higher modulus, toughness and higher breaking elongation.
Conclusion considering the environmental problems, performance targets and the increase in the cost of artificial silk, advanced polyester provides a potential alternative to artificial silk.
Polyester such as 1X30 DSP and 1X40 DSP fiber can provide excellent uniformity and durability due to its high dimensional stability (
Resistance to bruises)
And physical appearance (
In terms of reducing SWIs and growth resistance).
In addition, predictable and controllable responses to processing conditions allow custom rope performance to meet the special needs of a given tire manufacturer.