KR101025598B1 - Polyester yarn for air bag and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a polyester yarn that can be used in the fabric for airbags, in particular, elongation is at least 0.5% at 1.0 g / d stress of the polyester yarn measured at room temperature, elongation is 4.3% or more at 4.0 g / d stress And a polyester yarn for an airbag having an elongation of at least 7.5% at a stress of 7.0 g / d and an initial modulus of 40 to 100 g / d of the polyester yarn, and a method for manufacturing the same, and a fabric for an airbag manufactured therefrom. It is about.
The polyester yarn of the present invention significantly lowers the stiffness and secures excellent mechanical properties, thereby providing excellent storage properties, shape stability, and air blocking effect when used as an airbag fabric, and at the same time minimizing the impact on the passengers to safely occupy the occupants. I can protect it.

Description

Polyester yarn for air bag and manufacturing method thereof {POLYESTER FIBER FOR AIRBAG AND PREPARATION METHOD THEREOF}

The present invention relates to a polyester yarn that can be used in fabrics for airbags, and more particularly, to a polyester yarn of high strength and low modulus having excellent mechanical properties, shape stability, storage properties, and the like, and a method for manufacturing the same, It is about.

In general, an air bag detects a collision shock applied to the vehicle at a speed of about 40 km / h or more at a speed of about 40 km / h, and then explodes a gun powder to supply gas into the airbag. Refers to a device that protects the driver and the passenger by inflating, and the structure of a general airbag system is as shown in FIG.

As shown in FIG. 1, a general airbag system includes an inflator 121 that generates gas by ignition of the primer 122, and an airbag 124 that is inflated and deployed toward the driver of the driver's seat by the generated gas. The airbag module 100 mounted on the steering wheel 101, the impact sensor 130 for generating a shock signal in a collision, and the electronic control module for igniting the primer 122 of the inflator 121 according to the impact signal ( Electronic Control Module 110 is included. The airbag system configured as described above transmits a signal to the electronic control module 110 by detecting a shock from the impact sensor 130 when the vehicle is in front of the vehicle. At this time, the electronic control module 110 that recognizes this ignites the primer 122, and burns the gas generating agent inside the inflator 121. The gas generator thus burned inflates the airbag 124 through rapid gas generation. The inflated and deployed airbag 124 partially absorbs the impact load caused by the collision while contacting the driver's front upper body and may collide with the inflated airbag 124 as the head and chest of the driver move forward by inertia. In this case, the gas of the airbag 124 is rapidly discharged to the discharge hole formed in the airbag 124 and is buffered to the front part of the driver. Therefore, the secondary injury can be reduced by effectively buffering the impact force transmitted to the driver during frontal collision.

As described above, after the airbag used in the vehicle is manufactured in a predetermined form, the inflator 121 operates by being mounted on the handle of the vehicle, the side glass window or the side structure of the vehicle in a folded state to minimize the volume thereof, and maintaining the folded state. Allow the airbag to inflate and deploy.

Therefore, in order to effectively maintain the folding and packageability of the airbag when installing the vehicle, to prevent damage and rupture of the airbag itself, to exhibit excellent airbag cushion deployment performance, and to minimize the impact on passengers, the airbag fabric has excellent mechanical properties. In addition, foldability and flexibility to reduce the impact on passengers is very important. However, there is no proposal for an airbag fabric that maintains excellent air blocking effect and flexibility at the same time for the safety of the passenger, and is capable of sufficiently enduring the impact of the airbag and being effectively mounted in an automobile.

Conventionally, polyamide fibers such as nylon 66 have been used as a material for yarn for airbags. However, nylon 66 is excellent in impact resistance, but inferior in terms of moisture resistance, light resistance, shape stability and high raw material cost compared to polyester fiber.

On the other hand, Japanese Patent Application Laid-Open No. 04-214437 proposes the use of polyester fibers in which such defects are alleviated. However, in the case of manufacturing air bags using conventional polyester yarns, it is difficult to store them in a narrow space when mounted in a vehicle due to high modulus, and there is a limit in maintaining sufficient mechanical properties and deployment performance under severe conditions of high temperature and high humidity. come.

Therefore, the fiber yarn is maintained to maintain excellent shape stability and air blocking effect, and to maintain excellent mechanical properties under the harsh conditions of high temperature and high humidity, while maintaining excellent shape stability and air blocking effect, suitable for use as an airbag fabric. There is a need for research.

The present invention is to provide a polyester yarn for airbags to ensure excellent shape stability, flexibility, storage properties, and to maintain sufficient performance under the harsh conditions of high temperature and high humidity to be used in the fabric for airbags.

The present invention also provides a method for producing the polyester yarn.

The present invention also provides a fabric for an air bag manufactured using the polyester yarn.

The present invention has an elongation of at least 0.5% at a 1.0 g / d stress of polyester yarn measured at room temperature, an elongation of at least 4.3% at a stress of 4.0 g / d, and an elongation of at least 7.5% at a stress of 7.0 g / d. It provides a polyester yarn for the airbag, the initial modulus of the polyester yarn is 40 to 100 g / d.

The present invention also provides a polyester unstretched yarn by melt spinning a polyester polymer having an intrinsic viscosity of 0.85 dl / g or more at 270 to 300 ° C., and stretching the polyester unstretched yarn for the airbag. Provided is a method for producing a polyester yarn.

The present invention also provides a fabric for an air bag manufactured using the polyester yarn.

Hereinafter, a polyester yarn for an airbag according to a specific embodiment of the present invention, a manufacturing method thereof, and an airbag fabric prepared therefrom will be described in more detail. However, this is presented as an example of the invention, whereby the scope of the invention is not limited, it is apparent to those skilled in the art that various modifications to the embodiments are possible within the scope of the invention.

In addition, unless otherwise indicated throughout the specification, "including" or "containing" refers to the inclusion of any component (or component) without particular limitation and refers to the addition of another component (or component). It cannot be interpreted as excluding.

The fabric for the polyester airbag is melt spun to a polymer including polyethylene terephthalate (hereinafter referred to as "PET") to produce an unstretched yarn, which is stretched to obtain a stretched yarn (ie, yarn), and then through this process. It can be produced by weaving the obtained polyester yarn. Therefore, the properties of the polyester yarn is directly or indirectly reflected in the physical properties of the fabric for the polyester airbag.

In particular, in order to apply polyester as an airbag yarn instead of polyamide fibers such as conventional nylon 66, the high temperature and high humidity stiffness resulting from the low fusion heat capacity and the low melting heat capacity due to the high modulus and stiffness of the polyester yarn Under the conditions, it should be possible to overcome the deterioration of physical properties and consequently the deterioration of development performance.

Polyester has a high stiffness structure compared to nylon in the molecular structure has a high modulus characteristics. For this reason, when used as a fabric for airbags to be mounted on a car, the packing (packing) is significantly reduced. In addition, the carboxyl end groups (hereinafter referred to as "CEG") in the polyester molecular chain attack the ester bond under high temperature and high humidity conditions to cause molecular chain breakage, thereby deteriorating physical properties after aging. Becomes

Accordingly, the present invention by optimizing the physical properties range, such as initial modulus and elongation in the polyester yarn, it is possible to maintain the excellent mechanical properties such as toughness (toughness) and air barrier performance while significantly lowering the stiffness It can be applied effectively.

In particular, as a result of the experiments of the present inventors, by manufacturing the fabric for the airbag from a polyester yarn having a predetermined characteristic, it shows more improved folding properties, form stability, and air blocking effect, when used as a fabric for airbags, better storage performance in the vehicle mounting, etc. It has been found that even under the harsh conditions of packing and high temperature and high humidity, excellent mechanical properties, air leakage prevention, airtightness and the like can be maintained.

According to one embodiment of this invention, the present invention is provided with a polyester yarn having certain characteristics. These polyester yarns have elongation of at least 0.5% at 1.0 g / d stress measured at room temperature, 4.3% elongation at 4.0 g / d stress, and 7.5% elongation at stress of 7.0 g / d. The initial modulus of the polyester yarn may be 40 to 100 g / d.

It is preferable that such polyester yarn contains polyethylene terephthalate (PET) as a main component. At this time, the PET is a variety of additives can be added in the manufacturing step, in order to exhibit suitable properties for the fabric for the air bag may be a yarn containing at least 70 mol% or more, more preferably 90 mol% or more. have. Hereinafter, the term PET means a case where the PET polymer is 70 mol% or more without any special explanation.

Polyester yarn according to one embodiment of the invention is prepared under melt spinning and stretching conditions described below, the initial modulus is 40 to 100 g / d, 0.5 when subjected to 1.0 g / d stress of the yarn measured at room temperature Elongation of more than%, when subjected to a stress of 4.0 g / d, elongated by 4.3% or more, and when subjected to a stress of 7.0 g / d is characterized by elongation of more than 7.5%.

In general, polyester has a structure of high stiffness compared to nylon due to its molecular structure, and thus exhibits high modulus characteristics, and when used as a fabric for airbags, the folding and packing properties are remarkably reduced, resulting in a narrow automobile. Storage in the space becomes difficult. By the way, the polyester yarn obtained through the controlled melt spinning and stretching process exhibits properties of high strength low modulus and is lower in initial modulus than previously known polyester industrial yarns, i.e. 40 to 100 g / d, preferably 50 An initial modulus of from 100 to 100 g / d, more preferably from 55 to 95 g / d. In this case, the modulus of the polyester yarn is a physical property value of the elastic modulus obtained from the slope of the elastic section of the stress-strain diagram obtained in the tensile test, and when the object is stretched from both sides, the elastic modulus indicating the degree of stretching and deformation of the object The value corresponds to In addition, the initial modulus of the yarn is the modulus value of the elastic modulus at the point where the elastic section starts after the "0" point in the stress-strain. If the initial modulus of the yarn is high, the elasticity is good, but the stiffness of the fabric may be poor. If the initial modulus is too low, the stiffness of the fabric may be good, but the elasticity of the fabric may be low, and thus the toughness of the fabric may be deteriorated. By the way, the polyester yarn of the present invention is optimized in the range that the initial modulus is much lower than the conventional polyester industrial yarn. As such, fabrics for airbags made from polyester yarns having a lower initial modulus than conventional ones solve high stiffness problems of conventional polyester fabrics, and exhibit excellent folding, flexibility, and storage properties. Can be.

The polyester yarn also has a feature of minimal elongation with low initial modulus. For this reason, when the polyester yarn is subjected to a stress of 1.0 g / d at room temperature, the polyester yarn may be stretched at least 0.5% or 0.5% to 1.5%, preferably 0.7% to 1.2%, and subjected to a stress of 4.0 g / d. At least 4.3% or 4.3% to 20%, preferably 4.3% to 15%, and at least 7.5% or 7.5% to 25%, preferably 7.5% to 20% when subjected to a stress of 7.0 g / d. It can be stretching. Due to this property, the airbag fabric manufactured from the polyester yarn can solve the high stiffness problem of the existing polyester fabric, and can exhibit excellent folding property, flexibility, and storage property.

At the same time, the polyester yarn has an improved intrinsic viscosity, i.e., 0.8 dl / g or more or 0.8 dl / g to 1.2 dl / g, preferably 0.85 dl / g to 1.15 dl /, as compared to previously known polyester yarns. g, more preferably 0.90 dl / g to 1.10 dl / g. Intrinsic viscosity is preferably secured in the above range in order to prevent thermal deformation in the coating process, etc. when the polyester yarn is applied to the air bag.

The intrinsic viscosity of the yarn should be 0.8 dl / g or more to exert high strength at low stretching to satisfy the required strength of the airbag yarn, and otherwise it may be forced to express physical properties with high stretching. When the high stretching is applied, the degree of orientation of the fiber is increased to obtain high modulus physical properties. Therefore, it is preferable to maintain the intrinsic viscosity of the yarn at 0.8 dl / g or more to enable low modulus expression by applying low stretching. In addition, since the yarn viscosity is greater than 1.2 dl / g, the stretching tension may increase during stretching, which may cause a process problem, so 1.2 dl / g or less is more preferable. In particular, the polyester yarn of the present invention maintains such a high degree of intrinsic viscosity, while providing low ductility with low stretching, and at the same time can provide sufficient mechanical properties, impact resistance, toughness, etc. for the fabric for the airbag. The high strength characteristic which can be further given.

Therefore, it is possible to manufacture a fabric for an airbag which simultaneously exhibits excellent mechanical properties and storage properties, form stability, impact resistance, and air barrier effect by using a polyester yarn exhibiting such low initial modulus and high elongation, preferably high intrinsic viscosity. Become. Therefore, by using the polyester yarn, it is possible to obtain a fabric for an air bag, which exhibits lower ductility and folding property, flexibility, and storage property, but also exhibits excellent impact resistance, shape stability, mechanical properties, and airtightness. These polyester fabrics for airbags exhibit excellent mechanical properties, shape stability, and air barrier effects, while providing excellent folding properties and storage properties when mounted in tight spaces of cars, while minimizing the impact on passengers with excellent flexibility. Since it can protect, it can be preferably applied as a fabric for airbags.

In addition, the polyester yarn of the present invention may be prepared under the melt spinning and stretching conditions described below to exhibit a significantly lower carboxyl end group (CEG) content compared to previously known polyester yarns. That is, the polyester yarn may exhibit a CEG content of 50 meq / kg or less, preferably 40 meq / kg or less, more preferably 30 meq / kg or less. The carboxyl end groups (CEG) in the polyester molecular chains attack ester bonds at high temperature and high humidity to cause molecular chain breakage, thereby degrading physical properties after aging. Particularly, if the CEG content exceeds 50 meq / kg, the ester bond is cleaved by the CEG under high humidity conditions when the air bag is used for application, so that the physical property is degraded, so the CEG content is preferably 50 meq / kg or less. Do.

Meanwhile, the polyester yarn according to the embodiment of the present invention has a tensile strength of 6.5 g / d or more or 6.5 g / d to 11.0 g / d, preferably 7.5 g / d or more or 7.5 g / d to 10.0 g / d, and elongation at break may be at least 13% or 13% to 35%, preferably at least 15% or 15% to 25%. Further, the yarn has a dry heat shrinkage of 10.0% or less, or 2.0% to 10.0%, preferably 2.2% or less, or 2.2% to 10.0%, and a toughness value of 30 × 10 ⁻¹ g / d or more or 30 × 10 ⁻¹ g / d to 46 × 10 ⁻¹ g / d, preferably 31 × 10 ⁻¹ g / d or more, or 31 × 10 ⁻¹ g / d to 44 × 10 ⁻¹ g / d. As described above, by securing the intrinsic viscosity, initial modulus, and elongation range in an optimum range, the polyester yarn of the present invention can not only secure strength and physical properties to an excellent degree, but also exhibit excellent performance when manufactured as a fabric for airbags. Can be.

In addition, the polyester yarn of the present invention preferably has a shrinkage stress of 0.005 to 0.075 g / d at 150 ℃ corresponding to the laminate coating temperature of the general coating fabric, at 200 ℃ corresponding to the sol coating temperature of the general coating fabric It is preferable that the shrinkage stress of is 0.005 to 0.075 g / d. That is, the shrinkage stress at 150 ° C. and 200 ° C. should be 0.005 g / d or more, respectively, to prevent sagging of the fabric due to heat during the coating process, and should be 0.075 g / d or less to be cooled at room temperature after the coating process. Relaxation stress can be alleviated. The shrinkage stress is based on values measured under a fixed load of 0.10 g / d.

In order to prevent deformation in the heat treatment process such as coating as described above, the polyester yarn is also 40% to 55% crystallinity, preferably 41% to 52%, more preferably 41% to 50% Can be. The degree of crystallinity of the yarn is preferably 40% or more in order to maintain thermal form stability when applied to the fabric for airbags, and when the crystallinity exceeds 55%, the problem that the impact absorption performance is lowered because the amorphous region is reduced It is preferable that it can become 55% or less.

In addition, the polyester yarn may be a single yarn fineness of 0.5 to 20 denier, preferably 2.0 to 10.5 denier. In order to effectively use the polyester yarn in the airbag fabric, it is necessary to maintain low fineness and high strength in terms of storage, so that the total fineness of the applicable yarn is 200 to 1,000 denier, preferably 220 to 840 denier, more preferably 250 To 600 denier. In addition, the more filaments of the yarn may give a soft touch, but in the case of too many yarns, the radioactivity may not be good, so the number of filaments may be 50 to 240, preferably 55 to 220, and more preferably 60 to 200. Can be.

On the other hand, the polyester yarn according to an embodiment of the present invention as described above may be prepared by melt spinning a polyester polymer, for example PET chip to produce a non-drawn yarn, the method of stretching the non-drawn yarn, As described above, the specific conditions or processing methods of each of these steps may be directly or indirectly reflected in the physical properties of the polyester yarn, thereby producing a polyester yarn having the above-described physical properties.

In particular, this process optimization results in an initial modulus of 40 to 100 g / d, elongation of 0.5% or more when subjected to 1.0 g / d stress at room temperature, and 4.3% or more when subjected to 4.0 g / d stress. When it was subjected to a stress of 7.0 g / d, it was found that a polyester yarn for an air bag that stretched by 7.5% or more could be secured. In addition, the optimization of the melt spinning and stretching process in the present invention, it is possible to minimize the carboxyl end group (CEG, Carboxyl End Group) which is present as an acid under high humidity conditions to cause the basic molecular chain cleavage of polyester yarn It turns out that. Therefore, such a polyester yarn exhibits a low initial modulus and a high elongation range at the same time, and thus can be preferably applied to fabrics for airbags having excellent mechanical properties and storage properties, shape stability, impact resistance, and air blocking effect.

When explaining the polyester yarn manufacturing method in more detail for each step as follows.

The method of manufacturing a polyester yarn for airbags comprises the steps of melt spinning a polyester polymer having an intrinsic viscosity of 0.85 dl / g or more at 270 to 300 ° C. to produce a polyester non-drawn yarn, and stretching the polyester non-drawn yarn. Include.

First, with reference to the accompanying drawings, it can be briefly described an embodiment of the melt spinning and stretching process of the present invention to be easily carried out by those skilled in the art.

2 is a process diagram schematically showing a polyester yarn manufacturing process including the melt spinning and stretching step according to an embodiment of the present invention. As shown in Figure 2, the production method of the polyester yarn for the airbag of the present invention melts the polyester polymer prepared in the manner described above, cooling the molten polymer spun through the detention with quenching-air The emulsion is applied to the undrawn yarn using the emulsion roll 120 (or oil-jet), and the oil applied to the undrawn yarn is subjected to a constant air pressure by using a pre-interlacer 130. It can disperse | distribute uniformly on the surface of a yarn. Then, after the stretching process through the multi-stretching apparatus (141 ~ 146), and finally by interlacing the yarn at a constant pressure in the second collector (2 ^nd Interlacer, 150) (winding in the winding machine 160) Can be produced to produce yarn.

On the other hand, the production method of the present invention, in order to manufacture a high-strength low modulus polyester yarn that can be effectively used in the fabric for airbags, it can be used to prepare a high viscosity polyester polymer. In particular, the polyester polymer may be prepared by additionally adding a glycol after the polycondensation reaction during polyester production using dicarboxylic acid and glycol. The polyester polymer thus prepared has a low carboxyl end group (CEG) content with high intrinsic viscosity, so that excellent mechanical properties and air leakage prevention, airtightness, etc., even after aging under severe conditions of high temperature and high humidity when processed into a polyester yarn It can be effectively applied to fabrics for airbags.

In the production method of the present invention, the polyester polymer is a) ester reaction of dicarboxylic acid and glycol, b) polycondensation reaction of the oligomer produced by the ester reaction, and c) glycol to the polycondensed polymer It may be prepared by a process comprising the step of further adding and reacting under reduced pressure.

In this case, the dicarboxylic acid is a group consisting of aromatic dicarboxylic acid having 6 to 24 carbon atoms, alicyclic dicarboxylic acid having 6 to 24 carbon atoms, alkane dicarboxylic acid having 2 to 8 carbon atoms, and ester forming derivatives thereof. It may be one or more selected from. More specifically, dicarboxylic acids or ester forming derivatives thereof that can be used to prepare the polyester yarn of the present invention include terephthalic acid, isophthalic acid, biphenyldicarboxylic acid, 1,4-naphthalene dicarboxylic acid, C6-C24 aromatic dicarboxylic acid, such as 1, 5- naphthalene dicarboxylic acid, its ester formation derivatives, C6-C24 alicyclic dicarboxylic acid, such as 1, 4- cyclohexane dicarboxylic acid Acid, a C2-C6 alkane dicarboxylic acid, etc. are mentioned.

Among these, it is preferable to use terephthalic acid in consideration of economy and physical properties of the finished product, and in particular, when one or more compounds are used as the dicarboxylic acid, it is preferable to use one containing 70 mol% or more of terephthalic acid.

In addition, the glycols used in each of the steps a) and c) may be the same or different from each other, and the glycols usable in the present invention may be a C 2-8 alkane diol, a C 6-24 alicyclic diol, or C 6 6 And at least one selected from the group consisting of 24 aromatic diols, and ethylene oxide or propylene oxide adducts thereof. More specifically, the glycols that can be used to prepare the polyesters of the invention include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5 -C2-C8 alkanediols, such as pentanediol and 1, 6- hexanediol, C6-C24 alicyclic diols, such as 1, 4- cyclohexanediol and 1, 4- cyclohexane dimethanol, and bisphenol Ethylene oxide or a propylene oxide adduct of C6-C24 aromatic diol and aromatic diol, such as A and bisphenol S, etc. are mentioned.

The polyester polymer manufacturing process may be applied to a TPA (Terephthalic Acid) process for reacting and esterifying dicarboxylic acid with glycol, a dihydric alcohol. The general polyester TPA method is a direct reaction in which an acid reaction is carried out without using a catalyst in an ester reaction in which the dicarboxylic acid and glycol are esterified. For example, as shown in following Reaction Scheme 1, the method of producing polyethylene terephthalate (PET) directly by esterification of tetraphthalic acid and ethylene glycol is mentioned.

Scheme 1

This TPA reaction requires high temperatures to be maintained due to insolubility and low reactivity of the dicarboxylic acids. The oligomer prepared as described above may be subjected to a polycondensation reaction at high temperature while adding a catalyst under high vacuum to obtain a polymer having a predetermined viscosity. The polymer thus produced is discharged through a nozzle using a gear pump or a high pressure inert gas (N ₂ ). The polymer thus discharged is solidified with cooling water and cut into suitable sizes.

When preparing polyester according to the general TPA method as described above, carboxyl end groups are generated by pyrolysis caused by ester reaction and polycondensation reaction proceeding at high temperature, and dicarboxylic acid having carboxyl end groups is used as a raw material. As a result, the polyester final polymer produced contains a large amount of carboxyl end groups. In addition, in the case of applying a polyester yarn containing a large amount of carboxyl end groups to the fabric for the air bag, as described above, the terminal carboxyl group existing as an acid under high temperature and high humidity causes the existing molecular chain cleavage, thereby reducing the physical properties of the fabric Is caused.

Therefore, in the present invention, in the preparation of the polyester polymer, the glycol is further added after the polycondensation reaction of dicarboxylic acid and glycol, and the reaction is carried out under reduced pressure, thereby minimizing the content of such carboxyl end groups, It is possible to produce highly reactive hydroxy end groups and further increase the molecular weight of the polymer.

In the present invention, the esterification reaction and the polycondensation reaction of the dicarboxyl and glycol may be performed according to a conventional method known as the TPA method, and are not particularly limited to separate process conditions.

However, according to a preferred embodiment of the present invention, the molar ratio of dicarboxylic acid and glycol in the step a) is 1: 1 to 1: 1.5, preferably 1: 1.1 to 1: 1.45, more preferably 1: 1.2 to 1: 1.4, it is preferable to maintain the molar ratio of the reactants as described above in terms of improving the physical properties and productivity of the polymer.

The ester reaction of step a) may be carried out at 230 to 300 ℃, preferably 250 to 280 ℃, the reaction time may be carried out for 2 hours to 7 hours, preferably 3 to 5 hours. At this time, the reaction time and the reaction temperature can be carried out by adjusting in terms of improving the physical properties and productivity of the polymer.

In addition, the polycondensation reaction of step b) may be carried out at a temperature of 280 to 310 ℃, preferably 285 to 295 ℃, it may be carried out at a pressure of 0 to 10 Torr, preferably 0 to 5 Torr. At this time, the reaction time may be carried out for 1 to 5 hours, preferably 2 to 4 hours, the reaction time and the reaction temperature may be carried out by adjusting in terms of improving the physical properties and productivity of the polymer.

After completion of the polycondensation reaction, in the present invention, by adding an additional glycol as described above to perform an additional reaction under reduced pressure conditions, the resulting hydroxy end groups at the same time as blocking the carboxyl end groups in the resulting polymer Can be used to increase the molecular weight of the final polymer.

In step c), the glycol may be further added in an amount of 0.001 to 20% by weight, preferably 0.01 to 15% by weight, and more preferably 0.01 to 10% by weight, based on the total amount of glycol added in step a). In addition, it is preferable to keep the content of glycol added in the above range in terms of improving the physical properties and productivity of the polymer.

In addition, the addition of the glycol may be carried out while maintaining the atmospheric pressure, and after the addition of the glycol is carried out further reaction under reduced pressure conditions. In this case, the additional reaction may be carried out under reduced pressure of 1 to 10 Torr, preferably 0 to 5 Torr, it is preferable to maintain the pressure range in terms of improving the physical properties and productivity of the polymer.

In step c), glycol is added immediately after the polycondensation reaction is discarded and maintained at normal pressure, and the reaction temperature may vary depending on the reduced pressure conditions. In addition, the reaction time for performing the glycol additional charge reaction may be carried out for 5 minutes to 1 hour, preferably 5 minutes to 30 minutes. At this time, the reaction time and the reaction temperature can be carried out by adjusting in terms of improving the physical properties and productivity of the polymer.

After additionally adding glycol to carry out a reduced pressure reaction, the resulting polyester polymer, ie, the melt polymerized polymer chip, has an inherent viscosity of at least 0.4 dl / g or 0.4 to 0.9 dl / g, preferably 0.5 It is preferable to improve the physical properties of the polymer so that it can be dl / g or more or 0.5 to 0.8 dl / g.

In addition, if necessary, after the reduced-pressure reaction of step c), it may further comprise the step of solid-phase polymerization of the resulting polyester polymer. At this time, the solid phase polymerization reaction may be carried out at a temperature of 220 to 260 ℃, preferably 230 to 250 ℃, it may be carried out at a pressure of 0 to 10 Torr, preferably 1.0 Torr or less. At this time, the reaction time may be within 10 to 40 hours, preferably within 30 hours, the reaction time and the reaction temperature may be carried out by adjusting in terms of improving the final viscosity and radioactivity.

The polyester polymer further subjected to the solid phase polymerization has an intrinsic viscosity of at least 0.7 dl / g or 0.7 to 2.0 dl / g, preferably at least 0.85 dl / g or 0.85 to 2.0 dl / g, more preferably 0.90 dl It is preferable to improve the physical properties and the radioactivity of the yarn so that it can be more than / g or from 0.90 dl / g to 2.0 dl / g. The intrinsic viscosity of the chip should be 0.7 dl / g or more to produce a yarn having desirable high strength and high elongation characteristics, and should be 2.0 dl / g or less when cutting the molecular chain and increasing the melt temperature of the chip. It can prevent the pressure increase.

However, as described above, in order to manufacture a high-strength low modulus polyester yarn, melt spinning using a high-viscosity polyester polymer, for example, a polyester polymer having an intrinsic viscosity of 0.85 dl / g or more in an unstretched yarn manufacturing process And it is desirable to effectively lower the modulus by maintaining the high viscosity range through the stretching process to exhibit high strength with low stretching. In addition, it is more preferable that the intrinsic viscosity is 2.0 dl / g or less in order to prevent the molecular chain cutting and the pressure increase due to the discharge amount in the spinning pack due to the rise of the melting temperature of the polyester polymer.

In addition, in order to maintain a good physical properties even under high temperature and high humidity conditions when applied to the fabric for the air bag by using a polyester yarn, the molecular weight of the polyester polymer is preferably 30 meq / kg or less. Here, the CEG content of the polyester polymer is maintained in the lowest range even after the process of melt spinning and stretching, so that the final polyester yarn is characterized by high strength and excellent morphological stability, mechanical properties, excellent properties of expression properties under severe conditions It is desirable to be able to secure. In this respect, if the CEG content of the polyester polymer exceeds 30 meq / kg, the intramolecular CEG content of the polyester yarn finally produced through melt spinning and stretching processes is excessive, such as 30 meq / kg to 50 meq. Increasing to more than / kg, the ester bond is cleaved by the CEG under high humidity conditions may cause a decrease in the properties of the yarn itself and the fabric produced therefrom.

Preferably, the polyester polymer contains polyethylene terephthalate (PET) as a main component, and in order to secure mechanical properties as a yarn for airbags, it preferably contains 70 mol% or more, more preferably 90 mol% or more. Can be.

On the other hand, the polyester yarn manufacturing method of the present invention melt-spun the polyester polymer of the high intrinsic viscosity and low CEG content to produce a polyester non-drawn yarn.

In this case, in order to obtain a polyester non-drawn yarn satisfying a low initial modulus and a high elongation range, the melt spinning process is preferably performed at a low temperature range to minimize thermal decomposition of the polyester polymer. In particular, the low-temperature spinning, for example, 270 to the intrinsic viscosity and CEG content of the high-viscosity polyester polymer to minimize the decrease in physical properties according to the process, that is, to maintain the high viscosity and low CEG content of the polyester polymer It may be carried out at a temperature of 300 ℃, preferably 280 to 298 ℃, more preferably 282 to 298 ℃. Here, the spinning temperature refers to the extruder temperature, and when the melt spinning process is performed above 300 ° C., thermal decomposition of the polyester polymer occurs in a large amount, thereby lowering the intrinsic viscosity and increasing the CEG content. May be large, and the surface damage of the yarn may result in deterioration of overall physical properties, which is undesirable. On the contrary, when the melt spinning process is performed at less than 270 ° C., melting of the polyester polymer may be difficult, and radioactivity may be deteriorated by N / Z surface cooling, and thus, the melt spinning process may be performed within the above temperature range. Do.

As a result of the melt spinning process of the polyester polymer in this low temperature range, the decomposition reaction of the polyester polymer is minimized to maintain a high intrinsic viscosity to secure a high molecular weight, thereby achieving a high stretching ratio in a subsequent stretching process. It is found that a yarn of high strength can be obtained without applying, and thus, a low drawing process can be performed, thereby effectively lowering the modulus, thereby obtaining a polyester yarn satisfying the above-described physical properties.

In addition, the melt spinning process may be carried out at a lower spinning tension, i.e., to minimize spinning tension, in order to minimize the polyester polymer decomposition reaction, for example, to speed up the melt spinning of the polyester polymer. It can be adjusted at a low speed of 300 to 1,000 m / min, preferably from 350 to 700 m / min. By selectively proceeding the melt spinning process of the polyester polymer under such a low spinning tension and low spinning speed, the decomposition reaction of the polyester polymer can be further minimized.

On the other hand, the unstretched yarn obtained through such a melt spinning process is at least 0.8 dl / g or 0.8 dl / g to 1.2 dl / g, preferably at least 0.85 dl / g or 0.85 dl / g to 1.15 dl / g, more preferably May represent an intrinsic viscosity of 0.90 dl / g or more or 0.90 dl / g to 1.10 dl / g. In addition, the CEG content in the molecule of the unstretched yarn obtained through low temperature spinning may be 50 meq / kg or less, preferably 40 meq / kg or less, and more preferably 30 meq / kg or less. The intramolecular CEG content of these untwisted yarns can be maintained at the same level in the stretched yarn, that is, the polyester yarn, which has undergone the subsequent stretching process.

In particular, such a high viscosity and low CEG content polyester polymer performs melt spinning under the low temperature conditions as described above to suppress the thermal decomposition of the polyester polymer as much as possible, thereby intrinsic viscosity and CEG content of the polyester polymer and the polyester yarn The difference can be minimized. For example, the difference in intrinsic viscosity between the polyester polymer and the polyester yarn may be melt spun to 0.5 dl / g or less, or 0 to 0.5 dl / g, preferably 0.4 dl / g or 0.1 to 0.4 dl / g. The process can then be carried out. In addition, the process is carried out so that the difference in the intramolecular CEG content between the polyester polymer and the polyester yarn is 20 meq / kg or less or 0 to 20 meq / kg, preferably 15 meq / kg or less or 3 to 15 meq / kg can do.

The present invention by suppressing the decrease in the intrinsic viscosity and increase in the CEG content of the polyester polymer as described above, it is possible to ensure excellent elongation while maintaining excellent mechanical properties of the polyester yarn, high strength low modulus yarn suitable for airbag fabric Can be prepared.

And, the polyester polymer, for example PET chip, is preferably spun through a mold designed such that the fineness of the monofilament can be 0.5 to 20 denier, preferably 1 to 15 denier. That is, the denier of the monofilament should be 1.5 denier or more in order to reduce the possibility of the trimming caused by the interference between each other during the generation of the trimming during the spinning and cooling, and the fineness of the monofilament should be 15 denier or less to increase the cooling efficiency. .

In addition, after melt spinning the polyester polymer, a cooling step may be added to produce the polyester non-drawn yarn. It is preferable to proceed with this cooling process by the method of adding the cooling wind of 15-60 degreeC, and it is preferable to adjust the cooling air quantity to 0.4-1.5 m / s in each cooling wind temperature conditions. As a result, it is possible to more easily produce a polyester non-stretched yarn showing physical properties according to an embodiment of the invention.

On the other hand, after producing the polyester non-drawn yarn through this spinning step, the non-drawn yarn is drawn to prepare a drawn yarn. In this case, the stretching process may be performed under a stretching ratio of 5.0 to 6.0, preferably 5.0 to 5.8. The polyester non-drawn yarn is optimized to melt spinning process to maintain a high intrinsic viscosity and low initial modulus and to minimize the intramolecular CEG content. Therefore, when the drawing process is carried out under a high draw ratio condition of more than 6.0, it may be over-stretched, so that cutting or wool may occur in the drawn yarn, and a yarn having a low elongation and high modulus may be manufactured by a high degree of fiber orientation. . In particular, when the elongation of the yarn is lowered and the modulus is increased under such high draw ratio conditions, the folding and storage properties may be poor when applied as an airbag fabric. On the other hand, when the drawing process is performed under a relatively low draw ratio, the fiber orientation is low, and the strength of the polyester yarn manufactured therefrom may be partially lowered. However, when the stretching process is performed under a stretching ratio of 5.0 or more in terms of physical properties, for example, a high strength low modulus polyester yarn suitable for application to an airbag fabric, etc. can be manufactured, and thus, the stretching process may have a stretching ratio of 5.0 to 6.0. It is preferable to proceed under conditions.

According to another suitable embodiment of the present invention, a melt spinning process using a high viscosity polyester polymerized chip to produce a low modulus polyester yarn while simultaneously satisfying the properties of high strength and low shrinkage in a direct spinning process, The process may include stretching, heat setting, relaxing and winding up through a multi-stage high-speed roller to wind up the winder.

The stretching process may be performed after passing the undrawn yarn through a roller roller under the condition of 0.2% to 2.0% of oil pick-up amount.

In the relaxation process, the relaxation rate is preferably 1% to 14%, and when it is less than 1%, it is difficult to express the shrinkage rate, and it may be difficult to manufacture high elongation low modulus fibers as high fiber orientation is formed, as in the high draw ratio conditions. If it exceeds 14%, the noise on the high-pressure roller becomes severe and workability cannot be secured.

In addition, the stretching process may further perform a heat-setting process for heat-treating the undrawn yarn at a temperature of approximately 170 to 250 ℃, preferably 175 to 240 ℃, more preferably for the proper progress of the stretching process May be heat treated at a temperature of 180 to 245 ° C. Here, if the temperature is less than 170 ℃ thermal effect is not enough to reduce the relaxation efficiency is difficult to achieve the shrinkage rate, if it exceeds 250 ℃, the yarn strength due to thermal decomposition and the generation of tar on the rollers increases the workability is deteriorated Can be.

At this time, the winding speed may be performed at 2,000 to 4,000 m / min, preferably 2,500 to 3,700 m / min.

In accordance with another embodiment of the present invention, there is provided a polyester fabric for an air bag comprising the polyester yarn described above.

In the present invention, the airbag fabric refers to a woven fabric or a nonwoven fabric used for manufacturing an airbag for an automobile, and is characterized by being manufactured using a polyester yarn manufactured through the process as described above.

In particular, the present invention by using a polyester fiber having a high-strength low modulus rather than a polyester fiber having a high strength-low elongation and a high modulus, not only the energy absorption capacity at the time of inflating the air bag, but also excellent It is possible to provide a polyester fabric for airbags having morphological stability, air barrier properties, and excellent folding, flexibility and storage properties. In addition, the airbag fabric is not only excellent in room temperature physical properties, but also maintains excellent mechanical properties and airtightness after aging (aging) under severe conditions of high temperature and high humidity.

More specifically, the fabric for the air bag of the present invention may be a tensile strength of 220 kgf / inch or 220 to 350 kgf / inch measured at room temperature by the American Society for Testing and Materials Standard ASTM D 5034 method, preferably 230 kgf / inch or 230 to 300 kgf / inch. In the case of the tensile strength, it is preferable to be 220 kgf / inch or more in terms of properties of existing airbags, and in reality, it is preferable to be 350 kgf / inch or less in terms of physical properties.

The fabric for the air bag may be 20% or more or 20% to 60% cutting elongation measured at room temperature by the American Society for Testing and Materials ASTM D 5034 method, preferably 30% or more, or 30% to 50% It can be a range. In the case of the cutting elongation, it is preferable to be 20% or more in terms of physical properties required for existing air bags, and in reality, it is preferable to be 60% or less in terms of physical properties.

In addition, since the coating material for airbags is rapidly expanded by hot-high pressure gas, an excellent tear strength level is required. The tear strength indicating the burst strength of the coating fabric for airbags is determined by the American Society for Testing and Materials ASTM D 2261 method. When measured at room temperature may be 23 kgf or more or 23 to 60 kgf, preferably 25 kgf or more or 25 to 55 kgf. Here, when the tear strength of the coated fabric is less than the lower limit, that is, 23 kgf at room temperature, the airbag may burst when the airbag is deployed, which may cause a great risk to the airbag function.

The fabric for the airbag according to the present invention may be less than 4.0%, preferably less than 2.0% of the fabric shrinkage in the warp direction and the weft direction, respectively, measured by the ASTM D 1776 method. Here, in terms of the shape stability of the fabric, it is most preferable that the fabric shrinkage ratio in the warp direction and the weft direction do not exceed 1.0%.

The fabric may have an air permeability of 10.0 cfm or less, or 0 to 10.0 cfm, measured at room temperature by the American Society for Testing and Materials Standard ASTM D 737 method. In particular, the air permeability of the fabric for the airbag can be significantly lowered by including the rubber component coating layer in the fabric, it is possible to ensure the air permeability of the value close to almost 0 cfm. However, when the rubber coating is not carried out, the uncoated fabric of the present invention has an air permeability of 10.0 cfm or less or 0 to 10.0 cfm, preferably 3.5, measured at room temperature by the American Society for Testing and Materials Standard ASTM D 737 method. cfm or less, or 0.1 to 3.5 cfm, more preferably 1.5 cfm or less, or 0.5 to 1.5 cfm. At this time, when the air permeability exceeds 10.0 cfm, more preferably 3.5 cfm, it may not be preferable in terms of maintaining the airtightness of the fabric for the airbag.

In addition, the fabric for the air bag of the present invention can be a ductility measured at room temperature by the American Material Testing Association standard ASTM D 4032 method of 0.2 kgf or more or 0.2 to 1.2 kgf, preferably 0.5 kgf or more or 0.5 to 1.0 kgf. . In particular, when 530 denier or more may be less than 1.2 kgf, when less than 460 denier may have a range of 0.8 kgf or less.

In order to use the fabric of the present invention, it is preferable to maintain the above-described stiffness range, and if the stiffness is too low, less than 0.2 kgf, the protective bag may not have sufficient protective support during airbag expansion and deployment. Even in the case of poor shape retention performance, the storage performance may be reduced. In addition, in order to prevent the deterioration of the storage property by becoming too hard and difficult to fold, and to prevent discoloration of the fabric, the stiffness is preferably 1.2 kgf or less, particularly when less than 460 denier, 0.8 kgf or less. In the case of more than 530 denier, it is preferable to be 1.2 kgf or less.

In addition, according to another embodiment of the present invention, there is provided a method for producing an airbag fabric using a polyester yarn. The fabric manufacturing method for the airbag of the present invention includes the step of weaving the dough for the airbag using the polyester yarn, the step of refining the woven fabric for the airbag, and the step of tentering the refined fabric.

In the present invention, the polyester yarn may be produced as a final airbag fabric through a conventional weaving method, refining and tentering process. At this time, the woven form of the fabric is not limited to a specific form, both the plain type and OPW (One Piece Woven) type of woven form is preferred.

In particular, the fabric for the airbag of the present invention can be produced through a beaming, weaving, refining, and tenterizing process using the polyester yarn as a weft and warp yarn. The fabric can be produced using a conventional weaving machine, and is not limited to using any particular loom. However, plain weave fabrics can be manufactured using rapier looms, air jet looms, or water jet looms. OPW fabrics are Jacquard looms. Loom).

In addition, the airbag fabric of the present invention preferably further comprises a coating layer consisting of at least one of a silicone resin, polyvinyl chloride resin, polyethylene resin, polyurethane resin, or the like coated or laminated on the surface, the kind of coating resin It is not limited only to the above-mentioned materials. The resin coating layer may be applied by the knife coating method, the doctor blade method, or the spray coating method, but this is also not limited to the above-mentioned method.

The coating amount per unit area of the resin coating layer may be used to 20 to 200 g / m ² , preferably 20 to 100 g / m ² . Particularly, in the case of OPW (One Piece Woven) type side curtain airbag fabric, the coating amount is preferably 30 g / m ² to 95 g / m ² , and in the case of plain weave fabric for air bag, the coating amount is 20 g / m ² to 50 g / m ² levels are preferred.

The coated airbag fabric is manufactured in the form of an airbag cushion having a predetermined shape while undergoing cutting and sewing. The airbag is not limited to a particular form and may be manufactured in a general form.

On the other hand, according to another embodiment of the present invention, there is provided an airbag system including the above airbag. The airbag system can be equipped with conventional devices well known to those skilled in the art. The airbag may be largely classified into a frontal airbag and a side curtain airbag. The frontal airbag includes a driver's seat, a passenger seat, a side protection, a knee protection, ankle protection, a pedestrian protection airbag, and the side curtain type airbag protects passengers in a vehicle collision or rollover accident. Accordingly, the airbag of the present invention includes both a frontal airbag and a side curtain airbag.

In the present invention, matters other than those described above can be added or subtracted as required, and therefore, the present invention is not particularly limited thereto.

According to the present invention, the initial modulus, elongation, etc. are optimized in a predetermined range, thereby providing a polyester yarn for an airbag, which can produce a fabric for an airbag having excellent flexibility and folding property with excellent mechanical properties.

These polyester yarns for airbags are optimized for low modulus, high strength, and high elongation, which not only provide excellent morphological stability, mechanical properties, and air barrier effect when used in fabrics for airbags, but also ensure excellent folding and flexibility. This greatly improves the storage performance when the vehicle is mounted, and at the same time minimizes the impact on the passengers to protect the occupants safely.

Therefore, the polyester yarn of the present invention and the polyester fabric using the same can be very preferably used for manufacturing a vehicle airbag.

1 is a view showing a general airbag system.
Figure 2 is a process diagram schematically showing a polyester yarn manufacturing process for an airbag according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the scope of the present invention is not limited to the following examples.

Example  1-5

The process conditions as shown in Table 1 below, so that the molar ratio (ethylene glycol / terephthalic acid) of terephthalic acid and ethylene glycol is 1.3, the ester reaction was carried out between 250 ~ 280 ℃ for 4 hours. After the ester reaction, the resulting oligomer was subjected to a polycondensation reaction for 3 hours 30 minutes between 280-290 ° C. to produce a polymer.

After completion of the polycondensation reaction, ethylene glycol was added at an amount of 1% and 3% to the total amount of glycol initially added while maintaining the atmospheric pressure, and then additional reaction was performed for at least 1 minute at a high vacuum of 0.5 Torr. It was. At this time, the additional reaction was performed so that the intrinsic viscosity (IV) of the melt-polymerized polyester polymer (chip) produced through the additional reaction could be about 0.5 ~ 0.8 dl / g.

In addition, the polyester polymer (chip) produced through the polycondensation reaction and the addition reaction is further subjected to a solid phase polymerization between 220 ~ 245 ℃ polyester intrinsic viscosity (IV) of 0.7 ~ 1.3 dl / g Chips were prepared.

The polyester solid-state polymerization chip was prepared by spinning and stretching in the process as shown in Figure 1 to prepare a polyester yarn for airbags.

In particular, the polyester solid-state polymerization chip is melted at a temperature of 283 ~ 295 ℃ to discharge the molten polyester through the spinneret, and delayed by passing the discharged molten polyester through a delayed cooling section consisting of a hood-heater and a heat insulating plate Delayed quenching.

The delayed quenched polyester fiber was imparted with an emulsion using an emulsion imparting device in roll form. At this time, the amount of the emulsion is 0.8 parts by weight based on 100 parts by weight of yarn, the emulsion used is ethylene oxide / propylene oxide addition diol ester (30 parts by weight), ethylene oxide addition diol ester (15 parts by weight), glyceryl tri A spinning emulsion comprising an ester (10 parts by weight), trimethylpropane triester (10 parts by weight), and a small amount of antistatic agent was used.

The emulsified yarn was passed through a pre-collector and stretched using a roller.

After the stretching, the second yarn (2 ^nd Interlacer) was used to impart an interconnect to the stretched polyester yarn, and then wound with a winding machine to prepare a polyester yarn.

At this time, the molar ratio of glycol / dicarboxylic acid, ester reaction, polycondensation reaction, glycol addition reaction, temperature, pressure, reaction time of solid state polymerization reaction, intrinsic viscosity and intramolecular CEG content of PET polymer, Spinning speed and spinning tension, spinning temperature conditions, elongation ratio, heat treatment temperature and the like are shown in Table 1 below, the remaining conditions were in accordance with conventional conditions for the production of polyester yarns.

division Example 1 Example 2 Example 3 Example 4 Example 5 Glycol / Dicarboxylic Acid Molar Ratios 1.3 1.3 1.3 1.3 1.3 Ester Reaction Temperature (℃) 250-280 250-280 250-280 250-280 250-280 Ester Reaction Time (Hr) 4 4 4 4 4 Polycondensation reaction temperature (℃) 280-290 280-290 280-290 280-290 280-290 Polycondensation reaction time (℃) 3.5 3.5 3.5 3.5 3.5 Polycondensation vacuum degree (Torr) 1.0 or less 1.0 or less 1.0 or less 1.0 or less 1.0 or less Additional glycol inputs /
Initial input (%) One One 3 3 3 Additional reaction time (minutes) 10 20 10 10 20 Additional Reaction Pressure (Torr) 1.0 or less 1.0 or less 1.0 or less 1.0 or less 1.0 or less Raw Chip IV (dl / g) 0.69 0.71 0.69 0.71 0.71 Solid State Polymerization Reaction Temperature (℃) 235 235 235 235 235 Solid State Polymerization Reaction Time (℃) 13 11 13 13 11 Solid State Vacuum Degree (Torr) 1.0 or less 1.0 or less 1.0 or less 1.0 or less 1.0 or less IV after solid state polymerization (dl / g) 2.0 or less 2.0 or less 2.0 or less 2.0 or less 2.0 or less PET content (mol%) 100 100 100 100 100 CEG of Chip (meq / kg) 25 23 18 16 14 Spinning temperature (℃) 283 290 293 295 295 Elongation ratio 5.7 5.6 5.5 5.4 5.3 Heat treatment temperature (℃) 240 235 235 235 240

Physical properties of the polyester yarns prepared according to Examples 1 to 5 were measured by the following methods, and the measured physical properties are summarized in Table 2 below.

1) Crystallinity

The density ρ of the polyester yarn was measured at 25 ° C. according to the density gradient pipe method using n-heptane and carbon tetrachloride, and the crystallinity was calculated according to the following formula 1.

[Calculation 1]

Where ρ is the density of the yarn, ρ _c is the density of the crystal (1.457 g / cm ^{3 for} PET), and ρ _a is the density of the amorphous (1.336 g / cm ^{3 for} PET).

2) intrinsic viscosity

Extract the emulsion from the sample using carbon tetrachloride, melt with OCP (Ortho Chloro Phenol) at 160 ± 2 ° C, and measure the sample viscosity in the viscous tube at 25 ° C using an automatic viscosity meter (Skyvis-4000). To obtain the intrinsic viscosity (IV) of the polyester yarn in accordance with the following formula (2).

[Equation 2]

Intrinsic Viscosity (IV) = {(0.0242 × Rel) +0.2634} × F

Where

이고,

ego,

이다.

to be.

3) CEG content

Carboxyl End Groups (CEGs) of polyester yarns are prepared by placing 0.2 g of a sample into a 50 mL Erlenmeyer flask, adding 20 mL of benzyl alcohol, according to the requirements of ASTM D 664 and D 4094. plate) up to 180 ℃, hold for 5 minutes to completely dissolve the sample, then cooled to 160 ℃, 5-6 drops of phenolphthalene when the temperature reaches 135 ℃, titrated with 0.02 N KOH, colorless to pink The CEG content (COOH million equiv./kg of sample) was calculated by the following equation 3 at the titration point.

[Calculation 3]

CEG = (A-B) × 20 × 1 / W

Where A is the amount of KOH consumed in the titration of the sample (mL), B is the amount of KOH consumed in the titration of the blank sample (mL), and W is the weight of the sample (g).

4) initial modulus

Initial modulus was measured by calculating the elastic modulus from the slope of the elastic section of the stress-strain graph obtained in the tensile test according to the method of the American Society for Testing and Materials, ASTM D 885.

5) Tensile strength and elongation at break

Tensile strength and elongation at break of polyester yarn were measured using a universal testing machine (Instron), the sample length was 250 mm, the tensile speed was set to 300 mm / min, the initial load was set to 0.05 g / d.

6) Dry Heat Shrinkage

Dry heat shrinkage was measured for 2 minutes at a temperature of 180 ° C. and an ultra-tension (30 g) using Testrite MK-V equipment manufactured by Testrite of England.

7) Toughness value

Toughness (10 ⁻¹ g / d) values were calculated by the following Equation 4.

[Calculation 4]

8) single yarn fineness

Single yarn fineness was measured by taking the yarn by 9000 m and measuring its total fineness (Denier) of the yarn and dividing it by the number of filaments.

9) Elongation

The tensile strength and the cutting elongation were measured in the same manner as in the method, and an elongation value corresponding to each load was confirmed on the SS curve.

division Example 1 Example 2 Example 3 Example 4 Example 5 Crystallinity (%) 47.4 45.2 43.5 43.2 42.9 Yarn specific viscosity (dl / g) 0.85 0.88 0.92 0.97 1.01 Yarn CEG (meq / kg) 29 27 25 24 22 Initial modulus (g / d) 80 78 75 73 66 Tensile strength (g / d) 7.5 7.8 8.0 8.2 8.4 Elongation at break (%) 14 16 17 18 19 Dry heat shrinkage (%) 2.0 1.9 1.8 1.8 1.6 Toughness value (× 10 ^-1 g / d) 28.1 31.2 33 34.8 36.6 Single Sand Island (de) 7.7 7.7 8.3 4.2 4.7 Total fineness (de) 460 460 500 500 460 Filament number 60 60 60 120 120 Elongation
(%) At 1.0 g / d stress 0.7 0.74 0.78 0.84 0.90 At 4.0 g / d stress 7.0 7.5 8.1 8.6 9.5 7.0 g / d stress 10.4 11.3 12.1 13.2 14.4

Comparative example  1-5

A polyester yarn of Comparative Examples 1 to 5 was prepared according to the same method as Examples 1 to 5 except for the conditions described in Table 3 below.

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Glycol / Dicarboxylic Acid Molar Ratios 1.3 1.3 1.3 1.3 1.3 Ester Reaction Temperature (℃) 250-280 250-280 250-280 250-280 250-280 Ester Reaction Time (Hr) 4 4 4 4 4 Polycondensation reaction temperature (℃) 280-290 280-290 280-290 280-290 280-290 Polycondensation reaction time (℃) 3.5 3.5 3.5 3.5 3.5 Polycondensation vacuum degree (Torr) 1.0 or less 1.0 or less 1.0 or less 1.0 or less 1.0 or less Additional glycol inputs /
Initial input (%) - - - - - Additional reaction time (minutes) - - - - - Additional Reaction Pressure (Torr) - - - - - Raw Chip IV (dl / g) 0.69 0.71 0.69 0.71 0.71 Solid State Polymerization Reaction Temperature (℃) 235 235 235 235 235 Solid State Polymerization Reaction Time (℃) 15 15 13 13 11 Solid State Vacuum Degree (Torr) 1.0 or less 1.0 or less 1.0 or less 1.0 or less 1.0 or less IV after solid state polymerization (dl / g) 2.0 or less 2.0 or less 2.0 or less 2.0 or less 2.0 or less PET content (mol%) 100 100 100 100 100 CEG of Chip (meq / kg) 30 23 20 17 15 Spinning temperature (℃) 302 302 305 307 310 Elongation ratio 6.05 6.0 5.95 5.9 5.85 Heat treatment temperature (℃) 220 220 220 210 210

Physical properties of the polyester yarn prepared according to Comparative Examples 1 to 5 are summarized in Table 4 below.

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Crystallinity (%) 48.2 47.9 47.8 47.3 47 Yarn specific viscosity (dl / g) 0.60 0.65 0.70 0.85 0.88 Yarn CEG (meq / kg) 55 53 50 47 44 Initial modulus (g / d) 110 107 104 103 101 Tensile strength (g / d) 7.5 7.7 7.9 8.0 8.3 Elongation at break (%) 10 11 12 12 12 Dry heat shrinkage (%) 4.0 3.8 3.6 4.2 4.3 Toughness value (× 10 ^-1 g / d) 24.9 26.7 27.4 28.8 29.9 Single Sand Island (de) 1.25 6.0 6.0 3.0 3.3 Total fineness (de) 200 240 600 700 800 Filament number 160 40 50 230 240 Elongation
(%) At 1.0 g / d stress 0.4 0.43 0.45 0.47 0.49 At 4.5 g / d stress 3.7 3.9 3.9 4.0 4.1 7.0 g / d stress 7.1 7.1 7.3 7.4 7.4

Production Example  1-5

Weaving fabrics for airbags using a rapier weaving machine using polyester yarns prepared according to Examples 1 to 5, manufacturing fabrics for airbags through refining and tentering processes, and polyvinyl chloride (PVC) ) Was coated by a knife over (knife over ro1l coating) method to prepare a PVC coated fabric.

At this time, the inclination and weft density of the fabric, weaving form, the resin coating amount is as shown in Table 5, the remaining conditions were in accordance with the conventional conditions for the manufacture of polyester fabric for airbags.

division Example 1 Example 2 Example 3 Example 4 Example 5 Weaving Density
(Bevel X weft) slope 53 53 53 49 49 Weft 53 53 53 49 49 Weaving type (plain weave / opw) Plain weave Plain weave Plain weave Plain weave Plain weave Resin Coating Amount (g / m ² ) 25 25 25 30 30

Physical properties of the polyester fabric for each air bag manufactured using the polyester yarn prepared according to Examples 1 to 5 were measured by the following method, and the measured physical properties are summarized in Table 6 below.

(a) Tensile strength and elongation at break

The specimen was cut from the airbag fabric and fixed to the lower clamp of the tensile strength measuring device according to the American Society for Testing and Materials, ASTM D 5034. The strength and elongation at the time of breaking the airbag fabric specimen were measured while moving the upper clamp upward.

(b) tear strength

The tear strength of the fabric for airbags was measured according to the American Society for Testing and Materials, ASTM D 2261.

(c) Fabric shrinkage in warp and weft directions

Fabric shrinkage in the warp / weft direction was measured according to the American Society for Testing and Materials, ASTM D 1776. First, after cutting the specimen from the OPW airbag fabric, mark the length before shrinkage in the direction of warp and weft, and measure the contracted length of the specimen heat-treated in the chamber for 1 hour at 149 ° C. Fabric shrinkage ratio of {(length before shrinkage-length after shrinkage) / length before shrinkage x 100%} was measured.

(d) lecture

The ductility of the fabric was measured by the circular bend method using a ductility measuring device according to the American Material Testing Association standard ASTM D 4032. In addition, the cantilever method can be applied as a method of measuring the stiffness, and the stiffness can be measured by measuring the bend length of the fabric using a cantilever measuring device, which is a test bench that is inclined at a predetermined angle to give a bend to the fabric.

(e) after

The thickness of the fabric for airbags was measured according to the American Society for Testing and Materials, ASTM D 1777.

(e) air permeability

According to the American Society for Testing and Materials, ASTM D 737, the airbag fabric was allowed to stand at 20 ° C. and 65% RH for at least one day, and then the amount of air passing through a circular section of 38 cm ² was measured at 125 Pa.

division Example 1 Example 2 Example 3 Example 4 Example 5 Tensile strength (kgf / inch) 235 240 242 244 249 Elongation at break (%) 35 37 38 40 41 Tear strength (kgf) 15 17 19 19 21 Fabric Shrinkage
(%) slope 0.7 0.6 0.6 0.5 0.5 Weft 0.6 0.4 0.5 0.4 0.3 Lecture degree (kgf) 0.79 0.75 0.73 0.65 0.54 Air permeability (cfm) 1.4 1.4 1.3 1.3 1.2

compare Production Example  1-5

Except for using a polyester yarn prepared according to Comparative Examples 1 to 5 according to the same method as Preparation Examples 1 to 5 to prepare a polyester fabric for air bags and to measure the physical properties are summarized in Table 7 below.

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Tensile strength (kgf / inch) 220 222 225 227 229 Elongation at break (%) 23 24 24 26 28 Tear strength (kgf) 10 12 13 13 14 Fabric Shrinkage
(%) slope 1.2 1.1 1.1 0.9 0.8 Weft 1.1 1.0 0.9 0.8 0.7 Lecture degree (kgf) 1.2 1.2 1.1 1.1 1.1 Air permeability (cfm) 1.8 1.8 1.7 1.9 2.0

As shown in Table 6, fabrics for airbags of Preparation Examples 1 to 5 manufactured from polyester yarns prepared from Examples 1 to 5 having high intrinsic viscosity, elongation and low initial modulus, and the like, have tensile strength of 235 to 249. It can be seen that the kgf / inch, the tear strength is 15 ~ 21 kgf, and the fabric shrinkage rate is very excellent properties of 0.5% to 0.7% and 0.3% to 0.6% in the warp direction and the weft direction, respectively. At the same time, at the same time, the polyester fabrics for airbags of the production examples 1 to 5 have an excellent optimum range of 0.54 to 0.97 kgf of stiffness, thereby having excellent foldability and storage properties together with excellent morphological stability and mechanical properties. You can check it.

In particular, it can be seen that the airbag fabrics of Preparation Examples 1 to 5 can obtain excellent airtightness results of 1.4 cfm or less of air permeability of the coated fabric using a high strength low modulus yarn.

On the other hand, as shown in Table 7, it was confirmed that the fabric for airbags of Comparative Preparation Examples 1 to 5 using the polyester yarns of Comparative Examples 1 to 5 did not satisfy these characteristics. In particular, fabrics for airbags of Comparative Production Examples 1 to 5 were obtained to a similar degree of tensile strength, but the fabric shrinkage ratios were 0.8% to 1.2% and 0.7% to 1.1%, respectively, in the warp direction and the weft direction. It can be seen that it falls significantly in kgf. As such, when a fabric having a significantly lower fabric shrinkage rate and tear strength is used in the airbag device, a problem may occur due to a decrease in mechanical properties such as an airbag bursting when the airbag is deployed.

In addition, it can be seen that the air permeability of the coated fabric according to Comparative Preparation Examples 1 to 5 greatly increased to 1.7 to 2.1 cfm, thereby decreasing the airtightness. You may have problems you won't be able to.

Claims (26)

Elongation is not less than 0.5% at 1.0 g / d stress of polyester yarn measured at room temperature, 4.3% or more at 4.0 g / d stress, 7.5% or more at stress of 7.0 g / d,
Polyester yarn for airbags wherein the initial modulus of the polyester yarn is 40 to 100 g / d. The method of claim 1,
Polyester yarn for air bags with an intrinsic viscosity of at least 0.8 dl / g. The method of claim 1,
Polyester yarn for airbags having a carboxyl end group content of 50 meq / kg or less. The method of claim 1,
Polyester yarns for airbags with a crystallinity of 40% to 55%. The method of claim 1,
Polyester yarn for airbags having a tensile strength of 6.5 g / d or more and an elongation at break of 13% or more. The method of claim 1,
A polyester yarn for airbags having a dry heat shrinkage of 10% or less and a toughness value of 30 × 10 ⁻¹ g / d or more. The method of claim 1,
The yarn is a polyester yarn for airbags having a single yarn fineness of 0.5 to 20 denier. The method of claim 1,
The yarn is a polyester yarn for air bags having a total fineness of 200 to 1,000 denier. The method of claim 1,
Polyester yarn for airbags having a filament number of 50 to 240 of the yarn. Preparing a polyester non-drawn yarn by melt spinning a polyester polymer having an intrinsic viscosity of 0.85 dl / g or more at 270 to 300 ° C., and
Drawing the polyester undrawn yarn
A method for producing a polyester yarn for airbags according to any one of claims 1 to 9, including. The method of claim 10,
The polyester polymer is a polyester yarn for airbags containing more than 70 mol% polyethylene terephthalate. The method of claim 10,
Method of producing a polyester yarn that the difference in intrinsic viscosity of the polyester polymer and the yarn is 0.5 dl / g or less. The method of claim 10,
The method of producing a polyester yarn having a carboxyl end group content of the polyester polymer is 30 meq / kg or less. The method of claim 10,
A method for producing a polyester yarn having a difference in content of carboxyl end groups of the polyester polymer and the yarn of 20 meq / kg or less. The method of claim 10,
Method for producing a polyester yarn for airbags to perform the spinning process under a spinning speed of 300 m / min to 1,000 m / min. The method of claim 10,
A method for producing a polyester yarn for airbags, which carries out an extending drawing process at a drawing ratio of 5.0 to 6.0. The method of claim 10,
A method for producing a polyester yarn for airbags, wherein the unstretched yarn is subjected to a drawing process after passing a roller roller under a condition of 0.2% to 2.0% of oil pickup amount. The method of claim 10
After stretching the unstretched yarn, a method for producing a polyester yarn for airbags further comprising a heat setting step at a temperature of 170 to 250 ℃. The method of claim 10
A method for producing a polyester yarn for airbags, further comprising a relaxation process of 1% to 14% relaxation rate after stretching the unstretched yarn. The method of claim 10
After stretching the unstretched yarn further comprises a winding step of winding speed of 2,000 to 4,000 m / min. A polyester fabric for an airbag comprising the polyester yarn according to any one of claims 1 to 9. The method of claim 21,
The fabric is a polyester fabric for air bags having a tensile strength of 220 kgf / inch or more measured by the American Society for Testing and Materials Standard ASTM D 5034 method. The method of claim 21,
The fabric is a polyester fabric for airbags with a tear strength of 23 kgf or more measured by the American Society for Testing and Materials Standard ASTM D 2261 method. The method of claim 21,
The fabric is a polyester fabric for airbags having a fabric shrinkage of 4.0% or less in the warp direction and the weft direction measured by the American Society for Testing and Materials Standard ASTM D 1776 method. The method of claim 21,
The fabric is a polyester fabric for airbags with a ductility of 0.2 kgf or more measured by the American Society for Testing and Materials Standard ASTM D 4032 method. The method of claim 21,
The fabric is a polyester fabric for airbags having an air permeability of 10.0 cfm or less measured by the American Society for Testing and Materials Standard ASTM D 737 method.

Images