JPS6125801B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to yarn for weft of tire cord fabric and tire cord fabric. More specifically, the present invention relates to weft yarns for tire cord fabrics that can be uniformly and continuously stretched during tire molding, particularly as the carcass expands (spreading), and tire cord fabrics using the weft yarns. It is well known that cotton yarn has been used as the weft for tire cord fabrics until now.
The cotton yarn has significant unevenness in strength and elongation, and furthermore, it has low elongation, which together cause various problems. A typical problem is asymmetry in molded tires, which is caused by uneven cutting of the weft yarns during the tire molding and curing process as the carcass expands and transforms into a toroidal shape. There is. During normal molding, the carcass expands by around 60 to 80% of its original width, and the weft threads must elongate to match this, but such elongation cannot be expected with cotton threads. One of the proposals made to eliminate these disadvantages is to use synthetic filament yarns that are partially unoriented and have an elongation of at least 50% as weft yarns. (U.S. Patent No.
3395744), and the other uses a so-called core spun yarn, which is a synthetic fiber filament with an elongation of at least 80% wrapped with cotton, as the weft (U.S. Pat. No. 3,677,318, U.S. Pat. No. 4,024,895). No. Specification). According to these proposals, since a raw yarn that is easy to stretch is used as the weft yarn, it seems at first glance that satisfactory results can be obtained in terms of preventing weft yarn breakage during tire molding. However, the use of undrawn or partially oriented yarn, which is extremely thermally unstable, poses another serious problem, and in reality, the elongation of the yarn almost disappears during tire molding. It turned out that this was the case. First, undrawn yarns or partially oriented yarns change over time even at room temperature and therefore have poor dimensional stability, which directly appears as a drawback of tire cord fabrics. Furthermore, tire cord fabrics are subjected to dip treatment (for example, heat treatment at 240°C or higher with resorcinol-formaldehyde-latex attached) before tire molding.
The undrawn yarn or partially oriented yarn cannot withstand such severe heat treatment, and after the heat treatment, it turns into a resin and loses most of its original elongation. The figure shows partially oriented yarn with elongation of 140% (birefringence 0.035)
This shows the stress-elongation behavior of 150de/36fil, and the yarn itself has a primary yield point as shown by the curve.
After Y ₁ , the stress drops once but rises slowly, and breaks at around 140%. However, when this yarn was steam-set at a fixed length (135℃ x 30 minutes) to improve its dimensional stability, the yarn changed as shown below. 2
After heat treatment for a minute, the elongation is extremely reduced as shown in the curves and. At 245°C, which is the heat treatment condition corresponding to actual dip treatment, the elongation is more than 30%, and in reality, tires are molded in this state. Therefore, the weft threads cannot follow the expansion of the carcass portion by about 60 to 80%, and uneven cutting of the weft threads still occurs. On the other hand, the stress-elongation curve of the weft yarn (after being treated at 245° C. for 2 minutes) obtained by covering the high elongation yarn with cotton yarn as described above behaves slightly differently from the curve of the raw yarn, as shown in . In other words, the primary yield point is apparently high, but this is due to the strength of the cotton yarn itself.
As the cotton yarn is cut, the stress drops once and then rises again. Since this rising process is the behavior of the core filament yarn, the breaking point is _E1 , and uneven cutting is inevitable during tire molding. In this way, in the tire cord fabric weft,
It proves extremely difficult to provide a uniform tire that substantially retains the original elongation characteristics during tire molding. Therefore, an object of the present invention is to provide a tire cord fabric weft that can sufficiently withstand severe heat treatment in dip treatment, has heat resistance that can substantially maintain the elongation before treatment, and thereby enables uniform tire molding. Our goal is to provide yarn for use. A further object of the present invention is to provide a filament yarn that can substantially maintain its original elongation even when heat treated at 245° C. for 2 minutes. Another object of the present invention is to provide a filament yarn as described above by simpler and more practical means. The present inventors have previously discovered that even in high elongation polyester filament yarns with poor thermal stability, especially filament yarns with an elongation of 70% or more, a small amount of a polymer having a higher glass transition temperature is blended with the polyester. We discovered a unique and surprising phenomenon in that when adding this material, there was almost no change in elongation before and after heat treatment, and based on this we proposed a blended spun yarn. After that, as a result of various studies, we found that when a small amount of a polymer precursor, such as a monomer or a prepolymer, is added and reacted with a high glass transition temperature when made into a polymer before the completion of polyester polymerization, the filament yarn obtained before and after heat treatment. The present invention was achieved by discovering a phenomenon in which there is almost no change in elongation. Thus, according to the present invention, before the completion of polymerization of a polyester containing ethylene terephthalate as a main repeating unit, a monomer of an ester having a condensed polycyclic ring or at least two benzene rings, or a precipitate is added to either the dicarboxylic acid component or the dioxy component. It is a spun yarn made of polyester made by adding 0.5 to 7.0 wt% of polymer and reacting it at the end, and the elongation at break (DE) is 70 to 200%.
Dry heat shrinkage (DHS) at 150℃ for 30 minutes is +5%~
-2% and a filament yarn for tire cord textile wefts characterized by an elongation (DEA) of 60% or more after free shrinkage treatment at 245° C. for 2 minutes. The polyester referred to in the present invention has ethylene terephthalate repeating units as its main component, and polyethylene terephthalate is the main target, but to this, various dicarboxylic acids, dioxy compounds, etc. are added as a third component in an amount of 15 mol% or less. In addition, additives well known in the art, in particular heat stabilizers such as sterically hindered phenols ("Irgarvox"), aromatic diamines ("Sumilizer PB"), phosphorus-containing compounds, sulfur-containing compounds ("Sumilizer TPL") are added. Additive inclusion is also useful in the present invention. However, the intrinsic viscosity of these polymers is important to some extent, and a value of 0.5 or more is generally preferably used after completion of polymerization. In the present invention, before the polymerization of the polyester is completed, 0.5% of a monomer or prepolymer of an ester having a condensed polycyclic ring or at least two benzene rings is added to either the dicarboxylic acid component or the dioxy component.
~7.0wt% is added and reacted at the ends of the polyester. Examples of the acid component having a condensed polycyclic ring or at least two benzene rings include the following.

[Formula] and its isomers

[Formula] and its isomers Furthermore, examples of the dioxy component having a condensed polycyclic ring or at least two benzene rings include the following. 4,4'-dihydroxydiphenyl-1,1-ethane 4,4'-dihydroxydiphenyl-1,1-butane 4,4'-dihydroxydiphenyl-1,1-isobutane 4,4'-dihydroxydiphenyl -2,2-propane 4,4'-dihydroxydiphenyl-2,2-butane 4,4'-dihydroxydiphenyl-2,2-pentane 4,4'-dihydroxydiphenyl-4,4-heptane 4, 4'-dihydroxydiphenyl-phenylmethylmethane 4,4'-dihydroxydiphenyl-diphenylmethane 4,4'-dihydroxydiphenyl-1,1-cyclopentane 4,4'-dihydroxy-3,3'-dichlorodif enyl-2,2-propane 4,4'-dihydroxy-3,3',5,5'-tetrachlorodiphenyl-2,2-propane In the present invention, equimolar amounts of the aforementioned acid component and, for example, ethylene glycol An ester is formed from an aliphatic diol such as, and added as a polymer precursor, that is, in the form of a monomer, oligomer, or prepolymer, before the completion of polymerization of the polyester, or equimolar amounts of the dioxy component and the ester-forming ability are added. A polymer precursor of a monomer, oligomer, or prepolymer obtained by reacting the polyester with an acid component is added before the polymerization of the polyester is completed. In the present invention, at least the above-mentioned rigid acid component is added to the molecular terminal of the linear polyethylene terephthalate before completion of polymerization in an amount of 0.5 to 7.0 wt% based on the polyester so that the dioxy component reacts effectively.
It is necessary to add it within the range of 280°C or higher. If the amount added is less than 0.5 wt%, the desired heat resistance stability (for example, no change in elongation occurs even after free shrinkage treatment at 245°C for 2 minutes) is not achieved, or
If it exceeds 7 wt%, the acid component or dioxy component will be randomly incorporated into the molecular chain of the linear polyethylene terephthalate, resulting in a large drop in the melting point of the resulting polyester composition, making it impossible to obtain the desired heat resistance stability. In the present invention, the above-mentioned polyester composition is fed continuously or after being pelletized to a spinning machine equipped with an extruder, and is discharged through a spinneret while being melted, preferably at 2000 m/min.
The yarn is taken up at a high speed of 2500 m/min or more, and the elongation of the yarn is adjusted to 70-200%. Or increase the spinning speed to 2000
m/min, especially 800 to 1500 m/min, and then winding it as a drawn yarn, and then rewinding it at a low magnification (1.3 to 1,500 m/min).
3.0) to increase the final elongation of the drawn yarn to 70-200%.
It may be adjusted to What is important here is that the elongation of the wound yarn (semi-drawn yarn or partially oriented yarn) finally obtained is 70 to 200%, and this range is within the range of 70% to 200%. This corresponds to a birefringence of approximately 0.025 to 0.12. It is noteworthy that, as a characteristic of this spun yarn, its elongation does not substantially change even after being subjected to free shrinkage treatment at 245° C. for 2 minutes. However, some deterioration over time is unavoidable, and if the weft is inserted as it is, problems such as uneven width of the tire cord fabric will occur. Therefore, in order to ensure the dimensional stability of the spun yarn at room temperature, the dry heat shrinkage rate at 150° C. for 30 minutes is taken up as a guideline. When the shrinkage rate is between +5 and -2%, sufficiently satisfactory dimensional stability at room temperature can be obtained. For this purpose, it is effective to subject the spun yarn to steam treatment, and the steam treatment itself gives the spun yarn the required number of twists (usually 10 to 130 T/M) as a weft, and winds it into a cylinder in this state ( Cheese) from 120
Just set it at 160℃ for 1 to 90 minutes. As a result, the dry heat shrinkage rate, which was 40 to 50% before treatment, increased by +5
% to -2%, ensuring stability over time. Other methods include running the wound yarn in boiling water for several minutes, or running it in an atmosphere of 100 to 180 degrees Celsius (dry heat) for 60 minutes.
It may be run in seconds or less. Also, low spinning speed,
In order to reduce the dry heat shrinkage rate of the raw yarn obtained under low-ratio stretching, heat shrinkage treatment may be performed during the stretching, subsequent to the stretching, or in a separate step. The elongation of the heat-treated yarn thus obtained remains the same, that is, 70 to 200%, and the dry heat shrinkage rate at 150°C for 30 minutes is +5% to -2%, making it ideal as a raw yarn for weft yarns of tire cord fabrics. Become something. In other words, in a tire cord fabric (gray fabric) using the heat-treated yarn as the weft yarn, the weft yarn has excellent dimensional stability at room temperature, so there is no concern about uneven width of the gray fabric due to uneven shrinkage of the weft yarn, and the warp yarns are spaced evenly apart. is retained. Moreover, the elongation of the weft yarns of this gray fabric does not substantially decrease even after dip treatment, so the weft yarns stretch uniformly during tire molding (especially during inflation), resulting in uniform warp spacing and a homogeneous tire. It will be done. In particular, such a woven fabric has the advantage of being used in mono or ply form as a carcass member of a radial tire. Here, the elongation of the weft yarn of 70 to 200% (preferably 80 to 150%) is important. If the elongation is less than 70%, the elongation after dip treatment may be less than 60%. The elongation after this dip treatment corresponds to the elongation (DEA) of the weft yarn after free contraction at 245° C. for 2 minutes, and the DEA must be 60% or more. If DEA is less than 60%, during the tire molding process, when the carcass part is expanded and converted into a toroidal shape, the weft yarns will not stretch enough and will break during the expansion process, resulting in warp yarns. It becomes impossible to maintain uniform spacing, and a homogeneous tire cannot be obtained. In order to set the DEA to 60%, it is necessary to keep the elongation at 70% or more. On the other hand, if it exceeds 200%, the weft yarns exhibit easy elongation behavior, making it difficult to maintain the warp yarns at equal intervals. When such filament yarns are used as weft yarns for tire cord fabrics, they are usually provided in a thickness of 75 to 200 deniers. The yarn of the above thickness obtained in the spinning or spinning/drawing process is twisted to 10 to 130 T/M, wound on cinder, and set in steam in this state to have a dry heat shrinkage rate of +5% to -2%. After being adjusted, it is subjected to a weaving process. At this time, cords of high-strength synthetic fibers such as polyester, polyamide, polypropylene, etc. are used as the warp threads. These cords usually have a strength of 8 g/de or more,
Preferably, it has an elongation of 10-40%. Tire cord fabrics are typically subjected to a blazing process before being dip-treated. This softening treatment was originally aimed at making the warp yarns softer and more flexible, but the weft yarn arrangement may be disturbed during this treatment. In order to prevent this disturbance, it is useful to attach a rubbery latex to the weft after the cylinder is set. As for the method of attachment itself, the threads may be immersed in the latex or run in contact with the surface of a rotating roller provided in the latex. In this case, the amount of latex deposited is approximately 0.3 to 3.0% by weight based on the yarn, and this increases the slip resistance of the weft yarn. The latex itself may be of any known type. Examples of these include styrene-butadiene rubber latex, vinyl pyridine latex, nitrile latex, and natural rubber latex. Furthermore, if strong adhesion of latex is expected, epoxidized latex (e.g. epoxidized polybutadiene, epoxidized styrene) may be used.
butadiene copolymers, epoxidized nitrile butadiene copolymers) are preferably used. Another characteristic of this latex-treated weft yarn is that it exhibits a uniform covering effect when it is covered with cotton (yarn). In conventional covering yarns, the cotton (thread) was directly wrapped around the filament yarn (weft), which is prone to slipping, so slips were likely to occur between the two, resulting in the problem of warp yarn disorder due to uneven winding. Ta.
In this regard, since a stable winding effect can be obtained with latex-treated weft yarns, there is no fear of warp yarn disorder. The covering itself may be a complete covering, but
Considering the adhesive effect between the warp and weft in the subsequent dip treatment, regular intermittent winding is preferable. That is, when an intermittently wound yarn is used as a weft, a minute gap is created at the intersection with the weft due to the change in thickness, and the adhesive easily enters this gap, promoting the adhesive effect. In order to create such a gap, a covering ratio of 20% to 70% is appropriate. In addition, the covering rate is based on the following definition. Covering rate (%) = Area covered by cotton yarn/Surface area of weft yarn x 100 Also, cotton yarn refers to sliver and spun yarn, and these are wound to the same thickness as the weft yarn or slightly less than the thickness of the weft yarn. Bye. As described above, according to the present invention, a composition in which a special weft filament yarn is added and reacted before completion of polymerization, which can substantially maintain its original elongation even under heat treatment at 245° C. or higher throughout the tire manufacturing process, is produced. It is provided by a simple process of spinning. Then, the yarn can be used as a weft by simply reducing its DHS by once being heat-treated without causing width irregularity warp disorder in the fabric, thereby making it possible to obtain a homogeneous tire. Moreover, in recent years, there has been a demand for more complete adhesion between rubber and fibers in the carcass of radial tires, and in this sense, the fabric of the present invention can be used as a monoply in the carcass, and is extremely useful. The present invention will be described in detail below with reference to Examples, and the elongation (DE, DEA) and dry heat shrinkage (DHS) used here are measured according to the following measurement method. [] DE, DEA Measure with an autograph type manufactured by Toyo Sokki Co., Ltd. at a sample length of 20 cm and a tensile speed of 100%/min. Read the elongation E (cm) at the time when the highest stress is exhibited before cutting, and use the following calculation formula. It was calculated by DE, DEA = E / 20 x 100 (%) [] DHS After marking every 100cm on the yarn under a load of 1/30g/de, it is recognized as approximately 20cm, and at 150℃ in a free state. Process in air for 30 minutes. After cooling the treated yarn to room temperature, the length L (cm) between the marks is measured again under a load of 1/30 g/de and calculated using the following formula. DHS=100-L/100×100 (%) Example 1 Ethylene terephthalate was polymerized by a conventional method,
15 minutes before the completion of polymerization, carbonate trimer from bisphenol A, which had been prepared separately, was added and heated to 300°C.
The mixture was reacted for 15 minutes to obtain a polyester composition with an intrinsic viscosity of 0.62. This composition was fed into a spinning machine equipped with an extruder, melted at 300°C, and extruded through a spinneret at 3500 deg/48 fil.
A partially oriented yarn was obtained by winding at m/min. Each wound yarn was twisted to 100 t/m and wound back onto the cylinder, and in this state was steam-treated at 135° C. for 30 minutes.
Elongation (DE) of this set yarn, (a) Dry heat shrinkage rate (DHS) after free heat treatment at 150℃ x 30 minutes, (b) 245
Table 1 shows the elongation (DEA) after free heat treatment at °C for 2 minutes.

【table】

[Table] Example 2 Ethylene terephthalate was polymerized by a conventional method,
Ethylene was prepared separately 10 minutes before polymerization was completed.
Add 2,6-naphthalate pentamer and heat at 320°C.
A polyester composition having an intrinsic viscosity of 0.67 was obtained by reacting for 10 minutes. This composition was fed into a spinning machine equipped with an extruder, melted at 330°C, and extruded through a spinneret at 2500 deg/30 fil.
A partially oriented yarn was obtained by winding at m/min. The durability was evaluated in the same manner as in Example 1, and the results are shown in Table 2.

【table】

【table】 [Brief explanation of the drawing]

The attached drawing is a graph showing the stress-elongation curve of a partially oriented yarn (original yarn) with an elongation of 140%. Curves - Stress in yarn - elongation curves, curves -
...Stress-elongation curve, curve of the yarn after the yarn was steam-set (135℃ x 30 minutes)...The yarn was steam-set (135℃ x 30 minutes), and further 230℃
The stress-stretch curve of the raw yarn after heat treatment at ℃ for 2 minutes, the curve -...The raw yarn was steam set (135
℃ × 30 minutes), and then heat treated at 240℃ for 2 minutes, the stress-elongation curve of the raw yarn, the curve -... The yarn was steam set (135℃ × 30 minutes), and then further heat treated at 245℃
Stress-elongation curve of raw yarn after heat treatment for 2 minutes, curve -... After heat treating raw yarn covered with cotton yarn under the conditions of curve -,
Stress-elongation curve of covering yarn.

Claims (1)

[Claims] 1. Before completing the polymerization of polyester containing ethylene terephthalate as the main repeating unit,
Add 0.5 to 7.0 wt of ester monomer or prepolymer having a fused polycyclic ring or at least two benzene rings to either the dicarboxylic acid component or the dioxy component.
It is a spun yarn made of polyester made by adding % and reacting it at the end, and has a breaking elongation (DE) of 70~
200%, dry heat shrinkage (DHS) at 150℃ for 30 minutes is +5% to -2%, and elongation (DEA) after free shrinkage treatment at 245℃ for 2 minutes is 60% or more. Raw yarn for weft yarns for tire cord fabrics, which are characterized by: