JPS623273B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a weft yarn, or a core yarn for the weft yarn, having a suitable elongation for uniformly distributing the arrangement of a large number of tire cords in a tire. Traditionally, tire reinforcing fabrics have generally been fabrics called sudare-ori, in which tire cords are densely arranged and weft yarns are arranged at coarse intervals. It was common for tires to be made by heating and molding them together with rubber. On the other hand, as radial tires become more popular, there is an increasing demand for uniform distribution of tire cords in the tire, and cotton yarn, which has been mainly used as weft yarn, has a low elongation of around 8%, so Unable to keep up with the large size, the yarn breaks at weak points depending on unevenness in the longitudinal direction, and accordingly, the distribution of the warp yarns that make up the tire cord becomes asymmetrical, making it difficult to achieve high performance such as radial tires. It has become unsuitable for the required tires. On the other hand, there are recent examples in which undrawn synthetic fiber yarns with high tensile properties are used as core yarns, coated with stable fibers such as cotton, and used as core yarns as weft yarns (U.S. Pat. No. 4,024,895), or non-drawn polyester yarns. Residual shrinkage after heat treatment of drawn yarn (dry heat 150℃)
An example of using a ratio of ±2% or less (Unexamined Japanese Patent Publication No. 52
70167) and an example using highly oriented polyester filament with an orientation degree of 13×10 ^-3 to 80×10 ^-3 (Japanese Patent Application Laid-Open No. 124973/1983). However, in the case of the first two, the covered fibers are hard and cover and constrain the core yarn, so even though the core yarn itself has high extensibility, when it undergoes stretching deformation, the load is first shared by the covered fibers. When this breaks, local elongation stress concentrates on the core yarn at the breaking point, and the core yarn also breaks from that point, making it difficult to obtain sufficient elongation. can be,
Moreover, it was expensive. On the other hand, if the ratio of coated fibers is lowered so as not to hinder the elongation of the core yarn, incomplete coverage tends to occur, and the undrawn yarn that is the core yarn is subject to thermal deterioration during high-temperature processing such as baking after applying the resin liquid. As a result, the desired degree of elongation could not be obtained. Furthermore, even if multifilaments with special physical properties such as the latter two are used, they are difficult to handle because they are not twisted, and the filaments are easily dispersed in the fabric, resulting in a large amount of resin liquid adhering to them, resulting in poor stretching after baking. There was a tendency for the level to drop significantly. Furthermore, when cotton yarn is wound around a multifilament with a low residual shrinkage rate, the tensile stress behavior of the cotton yarn becomes dominant and it is not only difficult to stretch, but also excessive stress is applied to the high elongation filament yarn when the cotton yarn is cut. The problem was that they were cut at the same time. The present inventors conducted extensive research to develop a weft for tire reinforcing fabrics that does not have the above-mentioned drawbacks, and as a result, they arrived at the weft of the present invention. That is, the weft of the tire reinforcing fabric of the present invention is a polyester multifilament with a breaking elongation of 80% or more and 200% or less, and the fiber surface is covered with a thin film of non-thermofusible melamine resin. It is characterized by The weft yarns used in tire reinforcing fabrics must retain a residual elongation of 60% or more even after being impregnated with resin liquid and subjected to baking treatment at a high temperature of 240°C or higher for several minutes, and a large number of yarns interlaced with the weft yarns must remain. The two essential qualities are maintaining the book's warp threads uniformly at a predetermined density. For this first purpose, it is first required that the elongation of the multifilament yarn is sufficiently large before baking at room temperature.
Moreover, it is necessary to maintain high elongation even after undergoing severe heat treatment at high temperatures as described above.
As a result of various studies on filaments having such properties, we found that it is necessary for polyester-based unstretched multifilaments with a breaking elongation of 60% or more and 200% or less to be covered with a thin film of a non-thermofusible heat-resistant polymer material. It became clear. As such heat-resistant polymer substances, so-called thermosetting resins that form a network molecular structure and are non-thermofusible are used. It is important to protect the interior against heat treatment, and to not easily break against large deformations during tire molding and prevent the high elongation properties of the polyester multifilament coated with the resin. Although it depends on the fiber, a coating amount of about 0.5 to 10% by weight, preferably about 1.5 to 8%, based on the weight of the fibers has a good effect. The most preferred example of a resin having such properties is melamine resin.
Melamine resin is extremely stable against heat;
There is almost no change below 300℃, and in air
At temperatures above 300°C, the triazine ring decomposes, but
In a nitrogen stream, it is stable with little weight loss up to 400℃, and yarns with less than 10% weight of this attached to polyester fibers have the same weight loss compared to yarns that are not attached, as shown in the example below. It has an extremely superior residual elongation when subjected to high temperature treatment in a hot blast oven. If the fiber surface is evenly coated in this range, the thickness is usually less than 10 μm, preferably 0.1 to several μm, and the thickness can be seen from the cross-sectional micrograph. can. If the breaking elongation of undrawn polyester multifilament is less than 80%, it is difficult to increase the residual elongation after baking to 60% or more.
If it is 200% or more, the degree of molecular orientation is small, so the change over time when left standing is significant, and there are also problems with the heat resistance of the polyester fiber itself, so it cannot be used.
Although the undrawn polyester yarn used here is coated with a heat-resistant substance as described above, it is necessary that the fiber itself has a certain degree of heat resistance.
One factor is a certain degree of molecular orientation, which is shown by an elongation of 200% or less, and another is the large size of the constituent molecules. Normally, the size of a molecule is expressed as the limiting viscosity when the amount of solvent becomes 0 from the viscosity of a solution dissolved in a certain solvent, but in general polyester fibers, phenol/tetrachloroethane (3/2 weight ratio) in mixed solvent
Except for those with special intrinsic viscosity measured at 30℃
A value of 0.55 to 0.60 is used. Even if weft yarns are manufactured according to the present invention using polyester fibers in such a range, a fairly good effect is shown, but depending on the machinery used for baking tire reinforcing fabrics, the set temperature tends to vary. There is,
In some cases, processing is carried out at abnormally high temperatures, so a high intrinsic viscosity is preferable. When subjected to high-temperature heat treatment, undrawn yarns with low intrinsic viscosity undergo severe thermal deterioration and can only maintain extremely low residual elongation. However, if an undrawn polyester yarn with a high intrinsic viscosity is used, the degree of this problem can be alleviated to a large extent. Naturally, the higher the intrinsic viscosity, the higher the heat resistance tends to be, but in the present invention, if it is 0.55 or more, the objective can be almost fully achieved. However, a particularly preferred intrinsic viscosity is 0.65 or more. Now, the second requirement for weft yarns for tire reinforcing fabrics is
It is necessary to stably arrange the warp yarns, and for this purpose, it is particularly preferable to wind short fibers as core yarns around undrawn polyester yarns. However, in the present invention, since the core undrawn polyester yarn itself has heat resistance, the covering short fibers are not required to have the function of thermally protecting the core yarn, and the number of short fibers is much smaller than in the usual case. Even with this ratio, sufficient anchoring can be achieved at the intersection points with the warp threads. As the ratio of short fibers increases, the elongation of the core yarn tends to be restricted; however, as in the present invention, when the ratio is small, the elongation of the core yarn can be made closer to that of the core yarn. Needless to say, the important performance required of the short fibers covering the undrawn yarns is that they have no heat meltability. If it has heat-melting properties, it depends on its heat resistance properties, but in general, it is the inner core yarn that comes into contact with the high-temperature hot air first during baking, and the part that melts even if it does not lose its shape. This is because it restricts the undrawn polyester yarn and inhibits its retained extensibility. Therefore, cotton and short cellulose fibers such as Tuffcell are the most preferred materials. However, since the film of the heat-resistant polymer material that is the subject matter of the present invention usually has a coefficient of friction that is larger than that of polyester fibers, it is possible to sufficiently maintain the points of intersection with the warp yarns without covering with such short fibers. Therefore, it is not necessary to use an undrawn polyester yarn coated with a heat-resistant polymeric material as the core yarn unless there is a special requirement. Undrawn polyester yarn is usually nearly untwisted, so the filaments come apart and are difficult to handle. Also, since it has no cohesiveness when subjected to heat treatment during baking, it has no protective effect on the internal fibers and tends to have poor heat resistance, so it is preferable that the twist coefficient is about 1000 to 16000. . Here, the twist coefficient K=number of twists (T/M)×√total denier, and the number of twists is expressed based on the length of the untwisted yarn. Various methods can be used to produce the weft for tire reinforcing textiles of the present invention, but first, to obtain undrawn polyester yarn, polyester resin is melted and discharged through a large number of pores, and then cooled.
It is sufficient to wind at a winding speed of 4000 m/min or less. At that time, undrawn yarn with a slow spinning speed and low degree of orientation will change significantly over time when left unused and will have ^poor heat resistance. It is necessary to perform highly oriented spinning to achieve this. The upper limit of birefringence is 80
About ×10 ⁻³ is preferable. Such undrawn polyester yarn is treated with a treatment solution containing a resin initial condensate as described below, and is usually squeezed and wound up into a package, and then reacted to form crosslinks on the fiber surface, or subjected to heat treatment etc. before being wound up. After the reaction is carried out by an appropriate means, a ripening treatment or the like may be further performed as desired. The preferred treatment liquid used in the present invention is a liquid that mainly contains a resin initial condensate that can form a network molecular structure through a chemical reaction, such as polymethylolmelamine or its etherified product, and a reaction aid such as a catalyst. The treatment includes, for example, about 5% by weight of trimethoxymethylmelamine and about 2% by weight of monoammonium phosphate, with a pH of 4 to 6.
After applying an aqueous solution with a solid content of approximately 4% using an oiling roller, it is rolled up and left in a room at a room temperature of 25°C for 24 hours, then rolled again, rinsed with water, and dried. When the obtained yarn is used as a weft yarn for blind fabrics, it shows little deterioration during baking, is much superior to untreated yarn, and has a large residual elongation. Furthermore, if the intrinsic viscosity [η] of the undrawn polyester yarn used is 0.65 or more, the heat resistance of the polymer itself will be improved compared to yarns with a lower intrinsic viscosity. It maintains extremely stable physical properties even when subjected to high-temperature baking, making it possible to obtain yarn with even higher performance. When the surface and cross-section of the fibers subjected to such treatment are observed under a microscope, it is clearly seen that a uniformly thin film mainly composed of melamine is formed on the surface (side surface) of the fiber, and the thickness of the film is Although strictly speaking it is difficult to measure, it is usually 10μ or less, preferably 0.1 to several μ. It is thought that this film prevents the internal polyester resin from deteriorating from the heat treatment during baking. In addition, it is possible to add an appropriate twist to the undrawn polyester yarn that has been subjected to such treatment and bundle it to improve ease of handling as a weft yarn, as well as to provide the effect of protecting the internal fibers during heat treatment.
It is valid. The number of twists in this case is preferably in the range of 1,000 to 16,000.If the number of twists is less than this, the convergence during handling will be insufficient and the fibers will easily come apart. The elongation tends to be inhibited, which gradually deviates from the purpose of using the weft yarn of the present invention. The surface of such fibers is fed to the front roller of a spinning machine using an undrawn polyester yarn protected with a heat-resistant polymeric substance as a core yarn, and then wrapped with non-thermofusible short fibers and twisted. So-called core yarns that have been removed can also be suitably used as weft yarns in the present invention. In this case, cotton, Tuffcell, etc. are preferred materials for short fibers, but Tuffcell, which has strong cutting strength, may inhibit the elongation of the core yarn during stretching, so the coverage rate is lowered and the weight of the undrawn polyester yarn is reduced. The twist coefficient (K ₂ =
It is also desirable to lower N (cotton count, TW': TRI) in TW'/√. The present invention will be explained below with reference to Examples. In addition,
The percentages in the examples are percentages by weight, except for the percentage of elongation. Examples Polyethylene terephthalate resins with various degrees of polymerization were melted, and highly oriented undrawn yarns were spun while applying emulsion type oil by varying the discharge amount and winding speed. The target denier was 155 and the number of filaments was 18, and although some differences in the denier of the undrawn yarns were observed depending on the combination of conditions, this was within a range that did not impede the purpose of the present invention. Next, these undrawn yarns are unwound and introduced into a tank containing a scouring agent to thoroughly remove oil, and then added to a processing liquid containing 4.8% trimethoxymethylmelamine and 1.6% monoammonium phosphate dissolved in water. After immersing the material and spreading it to a predetermined adhesion rate as shown in Table 1, it was left in a packaged room at 20°C for about 30 hours with gentle rotation. Thereafter, the yarn was unwound from the package, thoroughly washed with water, wound up, centrifugally dehydrated and dried, and then processed as shown in Table 1. These yarns were inserted as the wefts of a blind fabric with tire cord 1000D/2 as the warp, impregnated with a rubber adhesion improver (phenol-formaldehyde resin initial condensate), and then baked at a high temperature. Next, the weft yarn was taken out from the fabric and its residual elongation was measured using a Tensilon. The results are shown in Table-1. Samples Nos. 1 to 7 with different spinning speeds were coated with about 2.2% melamine resin, twisted at about 400 T/M in the Z direction, and then subjected to a 20-minute kneading process at 65°C. Although it is a yarn, undrawn yarn with low spinning speed and high elongation (hereinafter referred to as undrawn yarn)
(No. 7) and conversely, when using POY with a high spinning speed and low elongation (No. 7).
1), the residual elongation was less than 60% and the performance was unsatisfactory, but all the POYs with an elongation of 80 to 200% had a sufficiently large residual elongation and showed favorable results. These residual elongation values were much larger than those of the sample without melamine resin coating (No. 10), and the coating effect was clearly recognized. In addition, the example No. 4 does not require moist heat treatment (kier treatment) after twisting, and the torque is strong and it is a little easy to crack, so the handleability is rather poor, but when moist heat treatment is applied. No particular effect on residual elongation was observed compared to the above. In addition, in cases where the degree of polymerization of the polymer is rather low, and therefore the intrinsic viscosity of the undrawn yarn is low, the number of twists applied to the POY coated with melamine resin is changed as the viscosity decreases, as shown in Nos. 13-17. When the twist coefficient was in the range of 100 to 15,000, the residual elongation was large and showed a more favorable tendency. In addition, when the number of twists is 0, it tends to fall apart during weft winding and weaving, and the variation in residual elongation is much larger than when the yarn is twisted. POY coated with melamine resin
After winding cotton with a spinning machine as a core yarn to make a core yarn, the core yarn is processed at 65℃ for 20 minutes.
Examples in which the weight ratio of cotton to the core yarn was changed are Nos. 18 to 22, and all cases in which the weight ratio of cotton yarn to the core yarn was changed from 15 to 60% showed particularly good residual elongation. When it exceeded 60%, the elongation decreased, probably because the cotton inhibited the elongation of the core yarn. No.3 and No.20 from these samples
was selected and used as a reinforcing cloth for radial tires,
There are no unevenness on the sidewall of the tire after molding.
Each radial force variation weighs 8.4Kg,
The weight was 8.2Kg, which was an extremely good result. 【table】

Claims (1)

[Claims] 1. A polyester multifilament having a breaking elongation of 80% or more and 200% or less, characterized in that the fiber surface is covered with a thin film of non-thermofusible melamine resin. Weft yarn of tire reinforcement fabric. 2 Polyester multifilament has intrinsic viscosity
Claim 1 or 2 which is 0.65 or more
The weft yarn of the tire reinforcing fabric described in Section 1. 3 Polyester multifilament twist coefficient
Claim 1 having a twist of 1000 to 16000;
The weft of the tire reinforcing fabric according to item 2 or 3. 4. Claims 1, 2, 3, or 4, in which polyester multifilament is used as the core yarn of a core yarn coated with non-heat-fusible short fibers of 60% by weight or less of the weight of the filament. The weft of the tire reinforcing fabric according to item 4. 5. After attaching 0.5 to 10% by weight of a thermosetting melamine resin initial condensate capable of forming a non-thermofusible heat-resistant polymer film to a polyester multifilament with a cutting elongation of 80% or more and 200% or less, A method for producing weft yarns of a tire reinforcing fabric, which comprises curing the weft yarns. 6. A method for producing a weft for a tire reinforcing fabric according to claim 6 or 7, which uses a polyester multifilament having an intrinsic viscosity of 0.65 or more. 7. A method for producing a tire reinforcing fabric weft according to claim 6, 7 or 8, which uses a polyester multifilament with a twist coefficient of 1,000 to 16,000. 8 60% by weight of polyester multifilament
The weft of the tire cord reinforcing fabric according to claim 6, 7, 8 or 9, which uses a polyester multifilament core yarn coated with the following non-thermofusible short fibers.