KR101736422B1 - Polyester fiber and preparation method thereof - Google Patents

Abstract

The present invention at room temperature indicating the ratio (T ⁰ / S ⁰⁾ of the tensile strength (T ⁰⁾ and a tensile elongation (S ⁰⁾ of the yarn measurements, and more particularly, at ordinary temperature of the polyester yarn available on the fabric for an air bag The strength index (X ⁰ ); And a ratio of the tensile strength (T ¹ ) to the tensile elongation (S ¹ ) (T ¹ / S ¹ ) of the yarn measured after heat treatment for 168 hours under the condition of 95 賊 5% (X ¹ ) is optimized to a predetermined range, a method for producing the polyester yarn, and a fabric for an air bag produced therefrom.
The polyester yarn of the present invention has excellent initial mechanical properties at high temperature and high humidity conditions together with a low initial modulus, thereby providing excellent airtightness with excellent storage stability and shape stability when used as a fabric for an airbag. At the same time, So that the occupant can be safely protected.

Description

[0001] POLYESTER FIBER AND PREPARATION METHOD THEREOF [0002]

More particularly, the present invention relates to a polyester yarn of high strength and high elongation low modulus having excellent mechanical properties, flexibility and shape stability under severe conditions of high temperature and high humidity, and a polyester yarn And an airbag fabric using the same.

Generally, an air bag is used to detect a collision shock applied to a vehicle at the time of a frontal collision at a speed of about 40 km / h or more at a speed of about 40 km / h by a shock sensor, To expand the inflator, thereby protecting the driver and the passenger.

The required items for the airbag are low air permeability for smooth deployment in the event of collision, high strength for preventing damage and rupture of the airbag itself, high heat resistance and flexibility for reducing passenger impact.

Particularly, the airbag used in an automobile is manufactured in a certain shape, and then folded to minimize the volume of the airbag. The folded state of the airbag is maintained when the inflator is operated, So that it can be expanded and deployed.

Therefore, in order to effectively maintain the folding property and the package property of the airbag when the vehicle is mounted, to prevent damage and rupture of the airbag itself, to exhibit excellent airbag cushion deployment performance and to minimize the impact on passengers, Along with flexibility to reduce folding and impact on passengers is very important. However, there has been no proposal of a fabric for an air bag which can maintain sufficient air-blocking effect and flexibility at the same time for the safety of passengers, can withstand the impact of the air bag, and can be effectively installed in the vehicle.

Conventionally, polyamide fibers such as nylon 66 have been used as materials for yarns for airbags. However, nylon 66 is superior in impact resistance, but is inferior to polyester fiber in wet heat resistance, light resistance and form stability, and has a high raw material cost.

On the other hand, Japanese Patent Application Laid-Open No. 04-214437 proposes the use of a polyester fiber in which such drawbacks are alleviated. However, when the conventional polyester yarn is used to manufacture an air bag, it is difficult to accommodate the air bag in a narrow space due to its high stiffness, and excessive heat shrinkage due to a high elastic modulus and low elongation And it has been difficult to maintain sufficient mechanical properties and development performance under severe conditions of high temperature and high humidity.

Accordingly, it is an object of the present invention to provide a fiber yarn which maintains excellent mechanical properties and air blocking effect suitable for use as a fabric for airbags for automobiles, flexibility for reducing impact on passengers, retention and excellent mechanical properties under severe conditions of high temperature and high humidity Research on development is needed.

The present invention aims to provide a polyester yarn which ensures excellent mechanical properties, flexibility and shape stability for use in airbag fabrics, and maintains sufficient performance under severe conditions of high temperature and high humidity.

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

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

The present invention relates to a room temperature strength index (X ⁰ ) indicating a ratio (T ⁰ / S ⁰ ) of a tensile strength (T ⁰ ) and a tensile elongation (S ⁰ ) of a yarn measured at room temperature; (T ¹ / S ¹ ) of the tensile strength (T ¹ ) and tensile elongation (S ¹ ) of the yarn measured after heat treatment for 168 hours under the conditions of 85 ° C. and 95 ± 5% (X ¹ ); provides a polyester yarn as shown in the following formula ( ¹ ).

[Equation 1]

0.65? X ¹ / X ⁰ ? 0.93

X ⁰ is a normal temperature strength index (X ⁰ ) representing the ratio (T ⁰ / S ⁰ ) of the tensile strength (T ⁰ ) to the tensile elongation (S ⁰ ) of the polyester yarn measured at room temperature, and X ¹ represents the ratio (T ¹ / S ¹ ) of the tensile strength (T ¹ ) and the tensile elongation (S ¹ ) of the polyester yarn measured after heat treatment at 85 ° C and 95 ± 5% RH for 168 hours High-humidity strength index (X ¹ ).

The present invention also relates to a process for producing a polyester non-drawn yarn, comprising melt-spinning a polyester polymer having an intrinsic viscosity of 1.2 dl / g or more at 270 to 310 ° C to prepare a polyester undrawn yarn, A method of manufacturing a yarn is provided.

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

Hereinafter, a polyester yarn according to a specific embodiment of the invention, a method for producing the same, and a fabric for an air bag produced from the polyester yarn will be described in detail. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined by the appended claims.

In addition, throughout this specification, "comprising" or "containing ", unless specifically stated, refers to including any and all components (or components) Can not be interpreted as excluding.

The fabric for the polyester airbag is produced by melt spinning a polymer containing polyethylene terephthalate (hereinafter referred to as "PET") to prepare an undrawn yarn, stretching it to obtain a drawn yarn, And can be manufactured by weaving. Therefore, the properties of the polyester yarn are directly or indirectly reflected in the physical properties of the polyester airbag fabric.

However, in order to apply polyester as an airbag yarn in place of conventional polyamide fibers such as nylon 66, there is a problem in that the polyester yarn has a high modulus and a low degree of folding due to the lubrication and a high degree of high temperature and high humidity Under these conditions, it is necessary to be able to overcome the deterioration of the physical properties and the deterioration of the expansion performance.

Particularly, in order to be applied as a fabric for airbags, it is necessary to possess properties of high strength, high strength and high heat shrinkage like nylon yarn, but the conventional polyester yarn does not simultaneously satisfy the properties of such strength, elongation and dry heat shrinkage . Since the required physical properties of the conventional PET yarn are different from that of the nylon, it is difficult to provide a good air-blocking effect when the heat treatment process is performed during manufacturing of the fabric, because the strength and elongation of the fabric are low as well as the air- . In addition, since the conventional polyester yarn has a rigid molecular chain, when it is used as a fabric for airbags and mounted on an automobile, the packing is remarkably deteriorated. Furthermore, the carboxyl end group (hereinafter referred to as "CEG") in the polyester molecular chain attacks the ester bond under high temperature and high humidity conditions to cause molecular chain cleavage, .

Accordingly, the present invention can optimize mechanical properties such as toughness, air blocking performance, and the like, while remarkably lowering the linerity by optimizing the range of physical properties such as strength and elongation under severe conditions of high temperature and high humidity in polyester yarn So that it can be effectively applied to the fabric for airbags.

Particularly, as a result of experiments conducted by the inventors of the present invention, it has been found that by fabricating a fabric for airbags from polyester yarn having predetermined characteristics, it is possible to provide a fabric having improved folding ability, form stability, durability and air- It has been found that excellent mechanical properties, air leakage prevention, airtightness and the like can be maintained even under severe conditions of excellent packing and high temperature and high humidity.

According to one embodiment of the invention, the present invention provides a polyester yarn having certain properties. Such a polyester yarn has a normal temperature strength index (X ⁰ ) indicating a ratio (T ⁰ / S ⁰ ) of a tensile strength (T ⁰ , g / de) measured at room temperature to a tensile elongation (S ⁰ ,%); And the ratio (T ¹ / S ¹ ) of the tensile strength (T ¹ , g / de) and tensile elongation (S ¹ ,%) of the yarn measured after heat treatment at 85 ° C and 95 ± 5% RH for 168 hours (X ¹ ) is optimized to a predetermined range will be.

Such a polyester raw material preferably contains polyethylene terephthalate (PET) as a main component. In this case, the PET may be added with various additives in its production stage. In order to exhibit properties suitable for the fabric for airbags, the PET may be a yarn containing at least 70 mol%, more preferably at least 90 mol% have. Hereinafter, the term " PET " means that the PET polymer is present in an amount of 70 mol% or more without any particular explanation.

The polyester yarn according to one embodiment of the present invention is produced under melt spinning and stretching conditions to be described later and has a ratio of a tensile strength (T ⁰ , g / de) and a tensile elongation (S ⁰ ,%) A room temperature strength index (X ⁰ ) indicating a temperature T ⁰ / S ⁰ ; And the ratio (T ¹ / S ¹ ) of the tensile strength (T ¹ , g / de) and tensile elongation (S ¹ ,%) of the yarn measured after heat treatment at 85 ° C and 95 ± 5% RH for 168 hours The first high-humidity strength index (X ¹ ) of FIG.

[Equation 1]

0.65? X ¹ / X ⁰ ? 0.93

In the formula,

X ⁰ is a normal temperature strength index (X ⁰ ) indicating the ratio (T ⁰ / S ⁰ ) of the tensile strength (T ⁰ , g / de) and the tensile elongation (S ⁰ ,%) of the polyester yarn measured at room temperature ,

X ¹ is the ratio (T ¹ / S) of the tensile strength (T ¹ , g / de) and the tensile elongation (S ¹ ,%) of the polyester yarn measured after heat treatment for 168 hours under the conditions of 85 ° C. and 95 ± 5% ¹ "). ≪ / ^RTI >

In addition, room temperature gangsindo index (X ⁰ indicating a ratio (T ⁰ / S ⁰⁾ of the tensile strength (T ^0, g / de) and tensile elongation (S ^0,%) of the living said polyester original yarn measured at room temperature ); And the ratio (T ² / S ² ) of the tensile strength (T ² , g / de) and tensile elongation (S ² ,%) of the yarn measured after heat treatment at 85 ° C and 95 ± 5% RH for 360 hours The second high-strength luminescence strength index (X ² ) may be as shown in the following equation ( ² ).

[Equation 2]

^{0.65 ≤ X 2 / X 0 ≤} 0.93

In the formula,

X ⁰ is a normal temperature strength index (X ⁰ ) indicating the ratio (T ⁰ / S ⁰ ) of the tensile strength (T ⁰ , g / de) and the tensile elongation (S ⁰ ,%) of the polyester yarn measured at room temperature ,

X ² is the ratio (T ² / S) of the tensile strength (T ² , g / de) and the tensile elongation (S ² ,%) of the polyester yarn measured after heat treatment for 360 hours at 85 ° C. and 95 ± 5% ² ) indicating the second high-humidity strength index (X ² ).

The polyester yarn has a normal temperature strength index (X ⁰ ) indicating a ratio (T ⁰ / S ⁰ ) of a tensile strength (T ⁰ , g / de) and a tensile elongation (S ⁰ ,%) of a yarn measured at room temperature; And the ratio (T ³ / S ³ ) of the tensile strength (T ³ , g / de) and tensile elongation (S ³ ,%) of the yarn measured after heat treatment for 504 hours at 85 ° C. and 95 ± 5% The third high-moisture strength index (X ³ ) may be as shown in the following equation ( ³ ).

[Equation 3]

^{0.65 ≤ X 3 / X 0 ≤} 0.93

In the formula,

X ⁰ is a normal temperature strength index (X ⁰ ) indicating the ratio (T ⁰ / S ⁰ ) of the tensile strength (T ⁰ , g / de) and the tensile elongation (S ⁰ ,%) of the polyester yarn measured at room temperature ,

X ³ is a non (T ³ / S of 85 ℃ and 95 ± 5% after heat-treated for 504 hours under RH conditions, the tensile strength of a measuring polyester yarns (T ^3, g / de) and tensile elongation (S ^{3,%) 3} ), which is a third-order high-humidity strength index (X ³ ).

As described above, a general polyester has a structure having a rigid molecular chain and a high stiffness according to its molecular structure, and thus exhibits a high modulus characteristic. When used as a fabric for airbags, foldability and packing The packing is remarkably reduced, and it becomes difficult to store in a narrow space of the automobile. In addition, a carboxyl end group (hereinafter referred to as "CEG") in a polyester molecular chain attacks an ester bond under high temperature and high humidity conditions to cause molecular chain cleavage, . However, the polyester yarn of the present invention, obtained through controlled melt spinning and stretching process using a high viscosity chip, exhibits high tenacity low modulus characteristics and is superior to previously known polyester industrial yarns in terms of excellent mechanical properties under severe conditions of high temperature and high humidity . In particular, the polyester yarns of the present invention have the feature that stretching is minimized with a low initial modulus.

That is, the ratio of the tensile strength (T ⁰ , g / de) of the yarn to the tensile elongation (S ⁰ ,%) (T ⁰ / S ⁰ ) of the polyester yarn measured at room temperature (65 ± 5% RH at 25 ° C.) A room temperature strength index (X ⁰ ) indicating the room temperature; (T ¹ , T ² , T ³ , g / de) and tensile elongation (S ¹ ) of the yarn measured after heat treatment for 168 hours, 360 hours, and 504 hours at 95 ° C Secondary, and tertiary hyperbaric laparoscopic indices (X ¹ , S ² , S ³ ,%) indicating the ratio (T ¹ / S ¹ , T ² / S ² , T ³ / S ³ ) , X ^2, X ³⁾ in the formula 1, 2, room temperature, as shown in 3 gangsindo index (X ⁰⁾ 1, second and third high-humidity gangsindo index (X ^1, X ^2, X's on the ^{3) the} ratio ^{(X 1 / X 0, X} 2 / X 0, X 3 / X 0) that are each 0.65 to 0.93, preferably of 0.67 to 0.91 may be. This characteristic of the polyester yarn can be achieved by optimizing the tensile strength and the tensile elongation of the yarn under severe conditions such as room temperature and high temperature and high humidity, by optimizing melt spinning and stretching conditions in the manufacturing process as described above. In the case of the thus-produced yarn, the lowering of the intrinsic viscosity (IV) of the yarn during melt spinning is minimized and the excellent tensile properties are obtained through appropriate stretching conditions. Thus, the fabric for airbags manufactured from the high- The stiffness problem of the conventional PET fabric can be solved, and excellent foldability, flexibility, and retention can be exhibited.

In the present invention, in order to withstand the inflator gas pressure instantaneously at high temperature / high pressure during operation of the airbag, the toughness of the yarn can be adjusted to the optimum range, thereby improving the mechanical properties and foldability of the final fabric. Also, in order to secure the instantaneous impact energy of the exhaust gas generated by the explosive explosion of the air bag inside the fabric safely at an early stage, and at the same time, to have an effective airtightness and folding property, the modulus of the yarn and the DPF Also needed. Particularly, considering that the development performance evaluation is carried out after the airbag module is treated in a high temperature / high humidity condition for a long time, in the present invention, the strength index of the yarn after heat treatment under severe conditions of high temperature / high humidity, It is necessary to satisfy the ratio range as described above.

In particular, the formula 1, 2, the primary and ambient gangsindo index of yarns in the third, second, third and humidity ratio ^{(X 1 / X 0, X} 2 / X 0, X 3 / X 0) of gangsindo index of the air bag The strength of the fabric can be 0.65 or more in terms of maintaining excellent physical properties and can be 0.93 or less in terms of ensuring excellent foldability of the airbag fabric. The ratio (X ¹ / X ⁰ , X ² / X ⁰ , X ³ / X ⁰ ) of the room temperature strength index of the yarn and the primary, secondary and tertiary high humidity strength indexes as shown in the above equations 1, In the case where the above ranges are not satisfied, the airbag fabric may be insufficient in the toughness of the fabric or may be increased in the lubrication of the fabric. When the room temperature strength index and the high-humidity strength index (X ¹ / X ⁰ , X ² / X ⁰ , X ³ / X ⁰ ) of the yarn are less than 0.65, the strength properties of the airbag fabric are drastically reduced, It may be difficult to apply. On the other hand, if the room temperature gangsindo index and high humidity gangsindo index ^{(X 1 / X 0, X} 2 / X 0, X 3 / X 0) of the yarn exceeds 0.93, the fabric is in the toughness side glass one fabric stiffness becomes Which is disadvantageous in terms of folding.

(T ⁰ / S ⁰ ) of the tensile strength (T ⁰ ) of the polyester yarn measured at room temperature to the tensile elongation (S ⁰ ) of the yarn expressed by X ⁰ in the above equations 1, 2 and 3, ) Can be 0.35 to 0.70, preferably 0.38 to 0.68. Here, tensile strength at room temperature of the yarn denoted as T ⁰ , that is, tensile strength at room temperature (25 ° C and 65 ± 5% RH) The tensile strength of the ester yarn may be 8.9 g / de to 11.0 g / de, preferably 9.0 g / de to 10.0 g / de, more preferably 9.1 g / de to 9.8 g / de. In addition, the tensile elongation at room temperature of the yarn represented by S ⁰ , that is, the tensile elongation of the polyester yarn measured at room temperature (25 ° C and 65 ± 5% RH) without any heat treatment is 15% to 30% 16% to 26%, and more preferably 17% to 25%.

Further, under the conditions of the first, second, and third high-humidity strength indexes of the yarn represented by X ¹ , X ² and X ³ in the above-described equations 1, 2 and 3, that is, at 85 ° C and 95 ± 5% RH, 168 hours, 360 hours after the heat treatment during, and 504 hours the tensile strength of the measured yarn ^{(T 1, T 2, T} 3) and a non (T ¹ / S ¹ of the tensile elongation ^{(S 1, S 2, S} 3), T ² / S ² , and T ³ / S ³ ) may be 0.65 to 0.93, preferably 0.67 to 0.91. Here, the high-and-low tensile strengths of primary, secondary, and tertiary yarns represented by T ¹ , T ² , and T ³ are 168 hours, 360 hours, and The tensile strength of the polyester yarn measured after heat treatment for 504 hours may be 8.2 g / de to 9.5 g / de, preferably 8.3 g / de to 9.3 g / de, respectively. Further, under the conditions of the first, second and third high humidity tensile elongation of the yarn represented by S ¹ , S ² and S ³ , that is, under the conditions of 85 ° C. and 95 ± 5% RH, 168 hours, 360 hours, and 504 hours The tensile elongation of the polyester yarn measured after the heat treatment may be 16% to 30%, preferably 18% to 28%.

The polyester yarn was obtained by measuring the tensile strength of the yarn measured after heat treatment for 168 hours, 360 hours, and 504 hours under the conditions of 85 ° C and 95 ± 5% RH at room temperature (25 ° C and 65 ± 5% RH) Or 90% to 100%, preferably 91.5% or 91.5% to 100% of the tensile strength of the film. The polyester yarn was measured for tensile elongation measured after heat treatment for 168 hours, 360 hours, and 504 hours at 85 ° C and 95 ± 5% RH, respectively, at a room temperature (25 ° C and 65 ± 5% RH) Or 100% to 200%, preferably 103% or 103% to 180%, more preferably 105% or 105% to 160%, based on the tensile elongation at break.

As described above, the polyester yarn of the present invention minimizes the strength drop of the yarn even after heat treatment for a long period of time under high temperature and high humidity conditions of 85 ° C. and 95 ± 5% RH, while increasing the elongation of the yarn, , It can provide an improved air blocking effect with excellent mechanical properties resulting from high toughness in processing into an airbag fabric. However, when the tensile strength, tensile elongation, and strength index of the yarn can not be maintained at least the minimum value, the toughness of the fabric is too low when the airbag fabric is applied, which may cause tearing of the cushion upon deployment of the airbag. If the maximum value is exceeded, the degree of lubrication of the fabric may become too high when the airbag fabric is applied, which may cause a problem that the airbag folding property deteriorates.

In the present invention, in order to absorb impact energy generated instantaneously during operation of the airbag, the mechanical properties of the final fabric and the foldability can be increased by adjusting the strength curve of the yarn to the optimal range. The need for a high strength, high initial modulus of low initial elongation is required to ensure that the fabric absorbs the instantaneous impact energy of the exhaust gas generated by the explosive explosion of the gunpowder in the airbag, while at the same time having an excellent airtightness and folding ability, Do. Particularly, in the present invention, it is required that the strength curve of the yarn after heat treatment under specific conditions meets the modulus range according to the elongation range with respect to the strength condition as described below.

In this respect, the Young's modulus of the yarn measured by the method of the American Society for Testing and Materials (ASTM D 885) after heat treatment for 168 hours, 360 hours, and 504 hours at 85 ° C and 95 ± 5% Is 45 to 70 g / de, preferably 50 to 67 g / de at 1% elongation, that is to say at 1% elongation, and 30 to 52 g / de at elongation 2% , Preferably 34 to 50 g / de. In addition, the polyester yarn has a Young's modulus of the yarn measured at a room temperature (25 ° C and 65 ± 5% RH) by the method of the American Society for Testing and Materials Association standard ASTM D 885 at an elongation of 1% 60 to 110 g / de, preferably 75 to 105 g / de at the point of elongation, and 50 to 87 g / de, preferably 55 to 85 g / de at 2% elongation, . In the case of polyester yarn as a conventional general industrial yarn, the modulus (Young's modulus) at the 1% elongation point measured at room temperature after the heat treatment as described above is 72 g / de and 115 g / Compared to the moduli at the 2% elongated points of greater than 53 g / de and greater than 90 g / de, respectively, the polyester yarns of the present invention can have significantly lower modulus at room temperature as well as after heat treatment.

In this case, the modulus of the polyester yarn is a physical property value of the elastic modulus obtained from the elastic section slope of the stress-strain diagram obtained in the tensile test. When the object is stretched from both sides, the elastic modulus . ≪ / RTI > If the modulus of the fiber is high, the elasticity is good, but the stiffness of the fabric can be deteriorated. When the modulus is too low, the liner degree of the fabric is good but the elastic recovery force is low and the toughness of the fabric may be deteriorated. As described above, the airbag fabric made from polyester yarn having an initial modulus lower than that of conventional ones at room temperature as well as after heat treatment solves the problem of high stiffness of conventional polyester fabric, Flexibility, and retention.

At the same time, the polyester yarn has a higher intrinsic viscosity, that is, greater than 0.8 dl / g or 0.8 to 1.2 dl / g, preferably 0.85 dl / g or 0.85 to 1.15 dl / g, more preferably greater than 0.9 dl / g, or 0.9 to 1.1 dl / g. The intrinsic viscosity is preferably in the above-mentioned range in order to prevent thermal deformation in the coating process or the like when the polyester yarn is used as an airbag application.

If the intrinsic viscosity of the yarn is 0.8 dl / g or more, the yarn can exhibit high strength by low stretching to satisfy the required strength of the airbag yarn, and if not, the yarn can not exhibit physical properties by high elongation. When such high-stretching is applied, the degree of orientation of the fibers increases and high modulus properties are exhibited, so that it is difficult to achieve excellent foldability of the fabric. Therefore, it is preferable to maintain the intrinsic viscosity of the yarn at 0.8 dl / g or more so as to enable low-modulus expression by applying low-stiffness. If the yarn viscosity is 1.2 dl / g or more, the stretching tension during stretching may rise and cause a problem in the process, and therefore, 1.2 dl / g or less is more preferable. Particularly, the polyester yarn of the present invention maintains such high degree of intrinsic viscosity, thereby providing low mechanical strength at low drawing and providing sufficient mechanical properties, impact resistance, toughness and the like to the fabric for airbags High-strength characteristics can be further given.

Therefore, it is possible to manufacture a fabric for airbags which exhibits excellent mechanical properties and storage stability, shape stability, impact resistance and air-blocking effect simultaneously by using polyester yarn exhibiting such low initial modulus and high elongation, preferably high intrinsic viscosity It becomes. Therefore, by using the above-mentioned polyester yarn, it is possible to obtain a fabric for airbags exhibiting excellent impact resistance, shape stability, mechanical properties, and airtightness, while exhibiting lower lubrication, folding, flexibility and retention. This polyester fabric for airbags has excellent mechanical properties, shape stability and air-blocking effect, but also provides excellent folding and retention when mounted in a narrow space of an automobile, while at the same time minimizing impact on passengers with excellent flexibility, So that it can be suitably applied as a fabric for an airbag or the like.

The polyester yarns of the present invention can also be produced under melt spinning and stretching conditions to be described below and have a carboxyl end group (CEG) content that is significantly lower than previously known polyester yarns, i.e., 45 meq / kg or less, (CEG) content of not more than 40 meq / kg, more preferably not more than 35 meq / kg. The polyester yarn has a carboxyl end group (CEG) carboxyl end group (CEG) content measured after heat treatment for 168 hours, 360 hours, and 504 hours at 85 ° C and 95 ± 5% / kg, preferably not more than 50 meq / kg, more preferably not more than 45 meq / kg. The carboxyl end group (CEG) in the polyester molecular chain attack the ester bond under high temperature and high humidity conditions, resulting in molecular chain breakage, thereby deteriorating the physical properties after aging. Particularly, when the CEG content exceeds 45 meq / kg, the CEG content is lowered to 45 meq / kg because the ester bond is cut off by the CEG under high humidity conditions when applied to airbags Do. The carboxyl end group (CEG) content of the polyester yarn measured after heat treatment for 168 hours, 360 hours, and 504 hours under the conditions of 85 캜 and 95 賊 5% RH so as to prevent deterioration of the properties of the fabric for airbags Are each preferably not more than 60 meq / kg.

Meanwhile, as described above, the polyester yarn according to one embodiment of the present invention has a tensile strength of yarn measured after heat treatment for 168 hours, 360 hours, and 504 hours under conditions of 85 ° C and 95 ± 5% RH, respectively, g / de to 9.5 g / de, preferably 8.35 g / de to 9.25 g / de, and a tensile elongation of 16% to 30%, preferably 18% to 28%. The tensile strength of the yarn measured at room temperature (25 ° C and 65 ± 5% RH) without additional heat treatment may be 8.9 g / d to 11.0 g / d, preferably 9.0 g / d to 10 g / d, preferably from 9.1 g / d to 9.8 g / d, and the tensile elongation may represent from 15% to 30%, preferably from 16% to 26%, more preferably from 17% to 25% .

The polyester yarn may have a toughness of 70 to 120 J / m < 3 >

[Equation 4]

In the above equation 4,

F represents a load applied when the length of the polyester yarn is increased by dl,

dl represents the length of the length of the polyester yarn.

The polyester yarn has a higher level of toughness than conventional polyester yarn, so that it can effectively absorb and withstand the energy of the high-temperature and high-pressure gas. Particularly, the polyester yarn has a toughness of 70 J / m 3 to 120 J / m 3, preferably 75 J / m 3, as determined from the strength curve of the yarn measured after heat treatment at 185 ° C for 2 minutes, M 3 to 110 J / m 3. The toughness of the yarn measured at room temperature may also be in the range of 70 J / m 3 to 120 J / m 3, preferably 85 J / m 3 to 115 J / . The polyester yarn of the present invention has a low initial modulus characteristic of high strength and high elongation so that the degradation of tensile strength is minimized even after heat treatment for 168 hours, 360 hours, and 504 hours under the conditions of 85 ° C and 95 ± 5% RH By securing an improved elongation, excellent toughness (wave single) can be secured in the same range as the toughness (wave single) measured at room temperature (25 ° C and 65 ± 5% RH). However, in some cases, the polyester yarn may have the toughness of the yarn measured after heat treatment for 168 hours, 360 hours, and 504 hours at 85 ° C and 95 ± 5% RH, respectively, against the toughness of the yarn measured at room temperature Or more, preferably 93% or more, more preferably 95% or more. Since the polyester yarn of the present invention exhibits a high level of toughness at both the room temperature and after heat treatment, the polyester yarn effectively absorbs and can absorb the energy of the high-temperature and high-pressure gas, .

The term "toughness" as used herein means an energy consumed until the fiber (here, the fiber includes the yarn or the fabric) is torn by the tensile force as shown by the above-mentioned formula 4, and the resistance of the fiber to the sudden impact . When the length of a certain fiber is increased from 1 to l + dl in the load F, the work becomes F · dl at this time, so that the toughness required for cutting the fiber is as shown in the above equation (1). That is, this toughness indicates the cross-sectional area of the steel-elongated curve of the yarn and the fabric (see Fig. 2). The higher the strength and elongation value of the yarn used in the fabric, the higher the toughness expressed in the fabric. Particularly, when the toughness of the fabric for airbags is lowered, the resistance of the fabric, which can sufficiently absorb the momentary deployment impact of the inflator having a high temperature and a high pressure during deployment of the airbag, is lowered. Therefore, when the toughness of the polyester yarn is less than 70 kJ / m < 3 > in the present invention, it may be difficult to use the fabric for the airbag.

As described above, by securing the intrinsic viscosity, the initial modulus and the elongation range in the optimum range, the polyester yarn of the present invention can secure strength and physical properties to an excellent degree, and can exert excellent performance in manufacturing as an airbag fabric .

In particular, the polyester yarn according to one embodiment of the present invention has a dry heat shrinkage of 1.0% or more, or 1.0% to 10%, preferably 1.5% or 1.5% to 8.0%, more preferably May be 2.0% or more or 2.0% to 6.0%. By maintaining the dry heat shrinkage ratio of the polyester yarn in the optimal range in this manner, it is possible to secure the excellent strength and flexibility with the low modulus characteristic of high strength and high elongation, and to control effectively the air permeability of the fabric through the excellent shrinkage characteristic, The physical properties can be improved.

The polyester yarn preferably has a shrinkage stress at 150 DEG C of from 0.005 to 0.075 g / d, which corresponds to the laminate coating temperature of a typical coated fabric of yarn, The shrinkage stress is preferably 0.005 to 0.075 g / d. That is, when the shrinkage stress at 150 ° C and 200 ° C is 0.005 g / d or more, the sagging of the fabric due to heat during the coating process can be prevented. When the shrinkage stress is less than 0.075 g / d, The relaxation stress can be relaxed. The shrinkage stress is based on a value measured under a fixed load of 0.10 g / d.

As described above, in order to prevent deformation in a heat treatment process such as coating, the polyester raw material preferably has a crystallinity of 40% to 55%, preferably 41% to 52%, more preferably 41% to 50% . When the crystallinity of the yarn is applied to a fabric for airbags, it must be 40% or more for maintaining the thermal stability of the yarn, and when the crystallinity exceeds 55%, the noncrystalline region decreases, And is preferably 55% or less.

Further, the polyester raw material may have a single fiber fineness of 2.5 to 6.8 DPF, preferably 2.92 to 4.55 DPF. In order to effectively use the yarn for the airbag fabric, the folding performance of the cushion and the absorption performance capable of absorbing the development energy of the high-temperature-high-pressure airbag when the airbag is deployed must be maintained at a low- 400 to 650 denier, preferably 400 to 650 denier, and preferably 420 to 630 denier. As the number of filaments of the yarn increases, the soft feel can be given. However, the number of filaments may be in the range of 96 to 160 because too much radioactivity may not be good.

On the other hand, the polyester yarn according to one embodiment of the invention as described above can be produced by a method of melt spinning PET to prepare an undrawn yarn and stretching the undrawn yarn, and as described above, The specific conditions and the method of proceeding are directly or indirectly reflected in the physical properties of the polyester yarn to produce the polyester yarn having the above-mentioned physical properties.

In particular, a room temperature strength index (X ⁰ ) indicating the ratio (T ⁰ / S ⁰ ) of the tensile strength (T ⁰ ) and the tensile elongation (S ⁰ ) of the yarn measured at room temperature through the above process optimization; (T ¹ / S ¹ ) of the tensile strength (T ¹ ) and tensile elongation (S ¹ ) of the yarn measured after heat treatment for 168 hours under the conditions of 85 ° C. and 95 ± 5% (X ^1); in the normal temperature gangsindo index (X ⁰⁾ is the first ratio (X ¹ / X ⁰⁾ of the humidity gangsindo index (X ¹⁾ to be secured to a polyester yarn for a 0.65 to 0.93 airbag in . Further, in the present invention, optimization of the melt spinning and drawing process can minimize the carboxyl end group (CEG) which is present as an acid under high humidity conditions and causes the basic molecular chain breakage of the polyester yarn . Therefore, such a polyester yarn can be suitably applied to a fabric for an air bag which exhibits a low initial modulus and a high elongation range at the same time, and has excellent mechanical properties and retention properties, shape stability, impact resistance and air barrier effect.

The method for producing such polyester yarn will be described in more detail as follows.

The method for producing polyester yarn for airbags comprises the steps of melt spinning a polymer having an intrinsic viscosity of 1.2 dl / g or more at 270 ° C to 310 ° C to prepare polyester undrawn yarn, and stretching the polyester undrawn yarn do.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG.

FIG. 1 is a process diagram schematically showing a polyester yarn manufacturing process including the melt spinning and stretching steps according to an embodiment of the present invention. FIG. As shown in FIG. 1, the polyester yarn for an airbag according to the present invention is produced by melting a polyester chip produced in the above-described manner, cooling the molten polymer emitted through the spinneret by quenching-air And the emulsion imparted to the undrawn yarn using an emulsion roll (or oil-jet, 120), and the emulsion imparted to the undrawn yarn at a constant air pressure using a pre-interlacer 130, It can be uniformly dispersed on the surface. Then, after the stretching process through the stretch unit (141-146) of the multi-stage, and finally second home shorthand (2 ^nd Interlacer, 150) Issues in inter minggeul (intermingle) to coiler 160, the yarn at a constant pressure in the It is possible to produce yarn by taking.

On the other hand, in the manufacturing method of the present invention, first, a high viscosity polymer including polyethylene terephthalate is melt-spun to produce a polyester undrawn yarn.

At this time, in order to obtain a polyester undrawn yarn satisfying a low initial modulus and a high elongation range, it is preferable that the melt spinning process is performed in a low temperature range so as to minimize pyrolysis of the PET polymer. In particular, low temperature radiation such as 270 to 310 < 0 > C, for example, can be used to minimize degradation of process properties due to intrinsic viscosity and CEG content of the PET polymer of high viscosity, i.e. to maintain the high viscosity and low CEG content of the PET polymer. , Preferably from 275 to 305 캜, more preferably from 280 to 300 캜. Here, the spinning temperature refers to the extruder temperature, and when the melt spinning process is performed at a temperature higher than 310 ° C, a large amount of pyrolysis of the PET polymer occurs, resulting in a decrease in the molecular weight and an increase in the CEG content And it may cause deterioration of the overall property due to surface damage of the yarn, which is undesirable. On the other hand, when the melt spinning process is conducted at a temperature lower than 270 ° C, it may be difficult to melt the PET polymer, and the N / Z surface cooling may lower the spinnability, so that the melt spinning process is preferably performed within the temperature range .

As a result of the experiment, it has been found that, by progressing the melt spinning process of PET in such a low temperature range, the decomposition reaction of PET is minimized, high intrinsic viscosity is maintained and high molecular weight is ensured, A strong yarn can be obtained, and it is found that polyester yarn satisfying the above properties can be obtained because the modulus can be effectively lowered as the low stretching process can be performed.

In addition, the melt spinning process may be carried out at a rate of 300 m / min, for example, such that the melt spinning process can be carried out at a lower radiation tension in order to minimize the PET polymer decomposition reaction, min to 1,000 m / min, and preferably from 350 to 700 m / min. As the melt spinning process of PET undergoes such selective low spinning tension and low spinning speed, the decomposition reaction of PET can be further minimized.

On the other hand, the amount of undrawn yarn obtained through such a melt spinning process is 0.8 dl / g or more, 0.8-1.2 dl / g, preferably 0.85 dl / g or 0.85-1.15 dl / g, more preferably 0.9 dl / Or an intrinsic viscosity of 0.9 to 1.1 dl / g. In addition, the intramolecular CEG content of the undrawn liquor obtained through such low-temperature radiation may be 45 meq / kg or less, preferably 40 meq / kg or less, more preferably 35 meq / kg or less. The intramolecular CEG content of this unstretched yarn can be maintained at the same level in the drawn yarn subjected to the subsequent stretching process, that is, the polyester yarn.

Particularly, as described above, in order to produce a polyester yarn of high strength and low modulus, it is preferable to use a high viscosity PET polymer, for example, having an intrinsic viscosity of 1.2 dl / g or more or 1.2 to 1.8 dl / g, It is preferable to use a PET polymer having a viscosity of 1.25 dl / g or 1.25 to 1.75 dl / g for melt spinning and stretching to maintain such a high viscosity range as high as possible, Do. However, it is more preferable that the intrinsic viscosity is 1.8 dl / g or less in order to prevent the molecular chain breaking due to the increase of the melting temperature of the PET polymer and the pressure increase due to the discharge amount in the spinning pack. The polyester raw material of the present invention has such a high viscosity PET polymer that its molecular weight is increased and it is not readily decomposed even under a high temperature heat and a large amount of moisture condition and a carboxyl terminal group (CEG) It is not easily decomposed even under the condition, and excellent physical properties can be maintained.

On the other hand, in order to maintain excellent physical properties even under high temperature and high humidity conditions when the polyester yarn is applied as a fabric for airbags, the intramolecular CEG content of the PET polymer is preferably 30 meq / kg or less. Here, the CEG content of the PET polymer is kept as low as possible even after the melt spinning and stretching process, so that the polyester yarn finally produced has high strength and excellent shape stability, mechanical properties and excellent physical properties It is preferable to make it possible to secure it. In this respect, when the CEG content of the PET chip exceeds 30 meq / kg, the intracellular CEG content of the polyester yarn finally produced through the melt spinning and stretching process is excessively increased, for example, from 30 meq / kg to 45 meq / kg, and the ester bond is cleaved by CEG under high humidity conditions, resulting in deterioration of the properties of the yarn itself and the fabric produced therefrom.

Particularly, such a PET polymer having a high viscosity and a low CEG content is subjected to melt spinning under low temperature conditions as described above to minimize the thermal decomposition of the PET polymer, thereby minimizing the difference in intrinsic viscosity and CEG content between the PET polymer and the polyester raw material can do. For example, the intrinsic viscosity difference between the PET polymer and the polyester source may be less than 0.7 dl / g or 0 to 0.7 dl / g, preferably 0.5 dl / g or 0.1 to 0.5 dl / g, Process can be performed. The process is also carried out so that the difference in intramolecular CEG content between the PET polymer and the polyester source is 20 meq / kg or less, or 0 to 20 meq / kg, preferably 15 meq / kg or less, or 3 to 15 meq / kg .

The present invention can minimize the intrinsic viscosity reduction and the increase in the CEG content of the PET polymer as much as possible, thereby maintaining excellent mechanical properties of the polyester yarn and securing an excellent elongation. The present invention also provides a high strength low modulus yarn suitable for an airbag fabric Can be manufactured.

It is preferable that the PET chip is radiated through a nip designed to have a monofilament fineness of 2.5 to 6.8 DPF, preferably 2.92 to 4.55 DPF. That is, the monofilament denier should be at least 2.5 DPF in order to reduce the possibility of yarn breakage due to interferences between the yarn during the spinning and cooling. In order to increase the cooling efficiency, the monofilament has a fineness of 6.8 DPF or less .

Further, after the PET is melt-spun, the PET non-drawn filament can be produced by adding a cooling step. It is preferable that the cooling process is performed by applying cooling wind at 15 to 60 캜, and it is preferable to adjust the cooling air flow rate at 0.4 to 1.5 m / s under each cooling wind temperature condition. As a result, it is possible to more easily manufacture the PET unstretched yarn exhibiting all the physical properties according to one embodiment of the invention.

On the other hand, after the polyester undrawn yarn is produced through such a spinning step, the undrawn yarn is stretched to produce a drawn yarn. At this time, the stretching process may be performed under a total mint condition of 5.0 to 6.5, preferably 5.0 to 6.2. The polyester undrawn yarn optimizes the melt spinning process to maintain high intrinsic viscosity, low initial modulus, and minimized intracellular CEG content. Therefore, if the stretching process is carried out under a high stretching ratio condition of more than 6.5, it is possible to produce a new yarn, and the yarn can be cut or gathered, and the yarn of a low elongation modulus can be produced . Particularly, when the elongation of the yarn is lowered and the modulus is increased under such a high stretching ratio condition, folding property and retention property may not be good when applied as a fabric for an airbag. On the other hand, if the stretching process is carried out under a relatively low stretching ratio, the degree of fiber orientation is low and the strength of the polyester yarn produced therefrom may be partially lowered. However, when the stretching process is performed at a stretching ratio of 5.0 or more in terms of physical properties, it is possible to produce a polyester yarn of high strength and low modulus suitable for application to, for example, airbag fabrics and the like, It is preferable to proceed under the condition.

According to another preferred embodiment of the present invention, in order to produce a low-modulus polyester yarn while simultaneously satisfying the properties of high strength and low shrinkage by a direct spinning stretching process, melt spinning is carried out using a high viscosity polyethylene terephthalate polymerized chip , And a step of stretching, heat fixing, loosening, and winding up through a multi-stage godet roller until winding on the winder.

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

The relaxation rate in the relaxation process may be 14% or less or 1% to 14%, preferably 10% or less, or 1% to 10%, more preferably 7% or 1.1% to 7% have. The lower limit may be selected within a range that allows the yarn to exhibit a sufficient shrinkage ratio, for example, 1% or more. In some cases, if the relaxation rate is too small, for example, less than 1%, it may become difficult to manufacture a high elongation low modulus fiber according to the formation of a high fiber orientation likewise under a high stretching ratio condition. In addition, when the relaxation rate exceeds 14%, flickering on the godet roller becomes severe and it may be difficult to ensure workability.

Meanwhile, in the stretching step, the heat-setting step of heat-treating the undrawn yarn at a temperature of approximately 170 to 250 ° C may be further performed, and preferably 172 to 245 ° C, more preferably, Can be heat-treated at a temperature of 175 to 220 ° C. If the temperature is less than 170 ° C, the thermal effect is insufficient and the relaxation efficiency is low to achieve the shrinkage rate. When the temperature exceeds 250 ° C, the yarn strength is lowered due to pyrolysis and the tar is increased. . Particularly, when the heat fixation process is performed in a lower temperature range and the relaxation efficiency is controlled to an optimum range, excellent airtightness due to the shrinkage characteristic optimized at the time of manufacture with the airbag fabric can be secured.

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

According to another embodiment of the present invention, there is provided a polyester fabric for an air bag comprising the above-mentioned polyester yarn.

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

More particularly, the present invention relates to a polyester yarn having a high modulus and a low elongation and a modulus lower than that of a conventional polyester yarn, and a polyester yarn having an optimized tensile strength and tensile elongation under severe conditions of room temperature and high temperature and high humidity, It is possible to provide a polyester fabric for airbags having not only excellent energy absorption ability at the time of use, but also excellent shape stability, air barrier properties, excellent foldability, flexibility and retention. In addition, the polyester fabric has excellent physical properties at room temperature, and can maintain excellent mechanical properties and airtightness even after aging under severe conditions of high temperature and high humidity.

More specifically, the polyester fabric of the present invention has a tensile strength of 200 to 370 kgf / inch, preferably 210 to 340 kgf / inch, measured at room temperature by the American Society for Testing and Materials ASTM D 5034 method . The tensile strength is preferably 200 kgf / inch or more from the viewpoint of required airbag requirements, and is preferably 370 kgf / inch or less in view of physical properties.

The polyester fabric may have a cut elongation of 20% to 60%, preferably 30% to 50%, measured at room temperature by the American Society for Testing and Materials (ASTM D 5034) standard. The cut elongation is preferably 20% or more in view of the required properties of the conventional airbag, and is preferably 60% or less in view of physical properties.

The polyester fabric may have a fabric toughness of 3.5 to 6.0 kJ / m < 3 > as defined by the following equation (5).

[Equation 5]

In the above equation 5,

F represents the load applied when the length of the polyester fabric is increased by dl,

dl represents the length of the polyester fabric increased in length.

The polyester fabric has a higher level of toughness than conventional polyester fabrics, thereby effectively absorbing and absorbing the energy of the high-temperature and high-pressure gas. Particularly, since the toughness of the polyester fabric for airbags is from 3.5 kJ / m 3 to 6.0 kJ / m 3, preferably from 3.8 kJ / m 3 to 5.7 kJ / m 3, it is possible to effectively absorb and withstand the energy of the high- Which can be very effectively used as yarns and fabrics for airbags. If the toughness of the airbag fabric is lowered, the resistance of the fabric, which can sufficiently absorb the momentary deployment impact of the inflator having high-temperature and high-pressure, is lowered during deployment of the airbag. Accordingly, when the toughness of the fabric in the present invention is less than 3.5 kJ / m < 3 >, for example, it may be difficult to apply the fabric to the airbag.

In addition, since the polyester fabric is rapidly expanded by high-temperature and high-pressure gas, an excellent tear strength level is required. The tear strength indicating the rupture strength of the airbag fabric is determined by the American Society for Testing and Materials And can be from 18 to 30 kgf when measured by the ASTM D 2261 TONGUE method and the tear strength to the coated fabric can be from 30 to 60 kgf when measured by the American Society for Testing and Materials ASTM D 2261 TONGUE method. Here, when the tear strength of the fabric for airbags is lower than the lower limit values of 18 kgf and 30 kgf, respectively, in the uncoated fabric and the coated fabric, rupture of the airbag occurs in deployment of the airbag, It is possible. On the other hand, when the tear strength of the fabric for airbags exceeds the upper limit values of 30 kgf and 60 kgf, respectively, in the uncoated fabric and the coated fabric, the edge comb resistance of the fabric is lowered, It may be undesirable because the air barrier properties are rapidly deteriorated.

As described above, the polyester fabric is excellent in mechanical properties of the final fabric, energy for high-temperature and high-pressure gas, and the like, by using a yarn having excellent modulus of elasticity and low modulus and excellent shrinkage- Absorbing performance, and folding ability can be improved at the same time. In particular, the polyester fabric according to the present invention is characterized in that the resistance to breakage, measured at room temperature (25 DEG C), by the American Society for Testing and Materials Association standard ASTM D 6479 is 350 N or more, or 350 to 1000 N, preferably 380 N or 380 to 970 N. ≪ / RTI > In addition, the polyester fabric may have a resistance to breakage of 300 N or more, or 300 to 970 N, preferably 320 N or 320 to 950 N, measured at 90 캜. At this time, when the polyester fabric has a breaking resistance of less than 350 N or less than 300 N measured at room temperature (25 占 폚) and 90 占 폚, the fabric strength at the airbag cushion sewing site is drastically deteriorated when the airbag is deployed, It may be undesirable because a pin hole is generated in the fabric and a fabric tear phenomenon occurs due to a pushing-up phenomenon.

In order to ensure airtightness at the polyester fabric, the elongation is minimized by enduring the tensile force by high-pressure air or the like. At the same time, in order to secure sufficient mechanical properties in the operation of the air bag, energy absorption performance is maximized at high- very important. Accordingly, the fabric is optimized to have a cover factor of 1,800 to 2,460, preferably 1,880 to 2,360, by the following equation (6), thereby improving airtightness and energy absorption performance at the time of deploying the airbag.

[Equation 6]

Cover Factor (CF)

When the cover factor of the fabric is less than 1,800, there is a problem that the air is easily discharged to the outside during the air inflation. When the cover factor of the fabric is more than 2,460, the air bag cushion It can fall.

The polyester fabric according to the present invention may have a fabric shrinkage ratio of 1.0% or less, preferably 0.8% or less, in the warp direction and the weft direction measured by the method of American Society for Testing and Materials ASTM D 1776, The fabric shrinkage ratio in the warp direction and the warp direction may be respectively 1.0% or less, preferably 0.8% or less. In view of the shape stability of the fabric, it is most preferable that the fabric shrinkage ratio in the warp direction and the warp direction do not exceed 1.0%.

As described above, the polyester fabric can use polyester yarn having high-strength and low-modulus properties to maintain the toughness and tear strength of the fabric and to significantly reduce the stiffness of the fabric. The fabric for the airbag has a lubrication of 1.5 kgf or less, or 0.3 to 1.5 kgf, preferably 1.2 kgf or less, or 0.3 to 1.2 kgf, more preferably 0.8 kgf or less, or 0.3 to 1.2 kgf, according to the American Society for Testing Materials ASTM D 4032 method. 0.8 kgf. As the stiffness of the fabric is significantly lowered compared to conventional polyester fabrics, the fabric for the airbag of the present invention can exhibit excellent folding and flexibility, and improved retention for airbag mounting. As the stiffness of the fabric is significantly lowered compared to conventional polyester fabrics, the fabric for the airbag of the present invention can exhibit excellent folding and flexibility, and improved retention for airbag mounting.

The fabric of the present invention preferably maintains the above-mentioned lubrication range in order to be used for an air bag. If the lubrication degree is too low, it may fail to provide a sufficient protective support function when the air bag inflates and deploys. So that the retractability may be deteriorated. Further, in order to prevent collapsing due to difficulty in folding, the degree of lubrication is preferably 1.5 kgf or less, more preferably 0.8 kgf or less in the case of less than 460 denier, and 1.5 kgf Or less.

The static air permeability of the polyester fabric according to the American Society for Testing and Materials Association ASTM D 737 method is 10.0 cfm or less, or 0.3 to 10.0 cfm, preferably 8.0 cfm or less, or 0.3 cfm or less when? P is 125 pa, To 8.0 cfm, more preferably 5.0 cfm or less, or 0.3 to 5.0 cfm, and when? P is 500 pa, 14 cfm or less, or 4 to 14 cfm, preferably 12 cfm or less, or 4 to 12 cfm . Also, the dynamic air permeability according to the American Society for Testing and Materials Standards ASTM D 6476 method is less than or equal to 1,700 mm / s, preferably less than or equal to 1,600 mm / s, or from 200 to 1,600 mm / To 1,400 mm / s. In this case, the static air permeability refers to the amount of air passing through the fabric when a certain pressure is applied to the fabric for the airbag, and the lower the density of the fabric, the smaller the Denier per filament and the higher the density of the fabric. Also, the dynamic air permeability refers to the degree of air permeation to the fabric when an average instantaneous differential pressure of 30 to 70 kPa is applied. As the static fineness of the yarn is small and the density of the fabric is high, Lt; / RTI >

In particular, the air permeability of the polyester fabric can be significantly lowered by including a rubber component coating layer in the fabric, and air permeability close to 0 cfm can be ensured. However, when such a rubber component coating is performed, the coating fabric for an airbag of the present invention has a static air permeability according to the American Society for Testing and Materials Association standard ASTM D 737 of less than or equal to 0.1 cfm when? P is 125 pa , Preferably 0.05 cfm or less, or 0 to 0.05 cfm, and may be 0.3 cfm or less, or 0 to 0.3 cfm, preferably 0.1 cfm or 0 to 0.1 cfm when? P is 500 pa.

Here, when the polyester fabric of the present invention exceeds the upper limit value of the static air permeability range or the upper limit value of the dynamic air permeability range with respect to the uncoated fabric and the coated fabric, respectively, airtightness of the airbag fabric is maintained Which may be undesirable.

Further, according to another embodiment of the present invention, there is provided a method of manufacturing a fabric for an air bag using polyester yarn. The method for producing a polyester fabric according to the present invention includes the steps of weaving a raw material for an airbag using the polyester yarn, refining the raw material for the airbag weaving, and tentering the refined fabric .

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

In particular, the polyester fabric according to the present invention can be produced by beaming, weaving, refining, and tentering processes using the polyester yarns as weft yarns and warp yarns. The fabric may be manufactured using a conventional weaving machine, and is not limited to the use of any specific loom. However, plain weave fabrics may be manufactured using a Rapier Loom, an Air Jet Loom, or a Water Jet Loom, and the OPW type fabric may be manufactured using Jacquard looms Loom. ≪ / RTI >

In addition, it is preferable that the polyester fabric of the present invention further comprises a coating layer formed of at least one of a silicone resin, a polyvinyl chloride resin, a polyethylene resin, and a polyurethane resin coated or laminated on the surface thereof. But is not limited to the above-mentioned materials. The resin coating layer can be applied by a knife coating method, a doctor blade method, or a spray coating method, but this is not limited to the above-mentioned methods.

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

The coated polyester fabric is manufactured in the form of an airbag cushion having a certain shape while being cut and sewed. The airbag is not limited to a particular type and can be manufactured in a general form.

According to another embodiment of the present invention, there is provided an airbag system including the airbag. The airbag system may comprise conventional equipment well known to those skilled in the art. The airbag can be broadly divided into a frontal airbag and a side curtain airbag. The frontal airbag includes a driver's seat, a passenger's seat, a side protection, a knee protection, an ankle protection, and a pedestrian protection airbag. The side curtain type airbag protects the passenger in the event of a side collision or an overturning accident. Therefore, the airbag of the present invention includes both the front airbag and the 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.

INDUSTRIAL APPLICABILITY According to the present invention, there is provided a polyester yarn capable of producing a fabric for an airbag that is optimized in strength, elongation, and the like under severe conditions of normal temperature and high temperature and high humidity, and has excellent mechanical properties and excellent flexibility and foldability.

These polyester yarns are low modulus yarns of high strength and high elongation, and their strength, elongation and the like are optimized under severe conditions such as room temperature and high temperature and high humidity, so that they have excellent shape stability, mechanical properties and air blocking effect , And at the same time, excellent folding and flexibility can be ensured, thereby remarkably improving the retractability of the vehicle when mounted, and at the same time minimizing the shock to the passenger, thereby safely protecting the occupant.

Accordingly, the polyester yarn of the present invention and the polyester fabric using the polyester yarn can be very preferably used for the manufacture of air bags for automobiles.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a process diagram schematically showing a polyester yarn manufacturing process for an airbag according to an embodiment of the present invention. FIG.
Fig. 2 shows an example of a steel-elongation curve of a general fiber. The area of this steel-elongation curve can be defined as toughness (wave single, J / m < 3 >).
3 shows a steel-elongation curve measured at room temperature of a polyester yarn according to Example 5 of the present invention.
4 shows the steel-elongation curve measured after heat treatment for 168 hours under the conditions of 85 ° C and 95 ± 5% RH of the polyester yarn according to Example 5 of the present invention.
5 shows a steel-elongation curve measured at room temperature of a polyester yarn according to Comparative Example 5 of the present invention.
6 shows a steel-elongation curve measured after heat treatment for 168 hours under the conditions of 85 ° C and 95 ± 5% RH of the polyester yarn according to Comparative Example 5 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

A polyester yarn was produced by preparing a polyester undrawn yarn by melt spinning and cooling a PET polymer having a predetermined intrinsic viscosity and a CEG content, then stretching the undrawn filament yarn at a predetermined draw ratio and performing heat treatment. The intrinsic viscosity and intramolecular CEG content of the PET polymer, the spinning speed and the spinning tension during the melt spinning process, the spinning temperature condition, the stretching ratio and the heat treatment temperature are shown in Table 1 below, To follow the usual conditions for.

division Example 1 Example 2 Example 3 Example 4 Example 5 PET content (mol%) 100 100 100 100 100 Intrinsic viscosity (dl / g) of PET chip 1.25 1.33 1.40 1.50 1.60 The CEG (meq / kg) 30 27 24 23 22 Radiation temperature (℃) 293 295 295 295 295 Total mystery 5.99 6.03 6.07 6.11 6.15 Heat treatment temperature (캜) 235 239 243 240 244 Relaxation rate (%) 5.6 5.7 5.8 6.1 6.3

The properties of the polyester yarn prepared according to Examples 1 to 5 were measured at room temperature (25 ° C and 65 ± 5% RH) without any heat treatment by the following method, and the measured physical properties are summarized in Table 2 below .

1) Tensile strength and tensile elongation

US Material Test Specimens Tensile strength and elongation at break of polyester yarns were measured using a universal material tester (Instron) according to ASTM D 2256, the gauge length was 250 mm, the tensile speed was 300 mm / min The initial load was set to 0.05 g / d, and the tensile strength (T ⁰ , g / d) of the yarn at 60 to 120 times of twisting was measured using a rubber faced grip ) And tensile elongation (S ⁰ ,%) were measured.

2) Dry Heat Shrinkage

Using a Testrite MK-V instrument from the British Testrite, dry heat shrinkage was measured for 2 minutes at a temperature of 180 ° C and a super tension (30 g).

3) Young's modulus

Young's modulus and strength were measured by the method of American Society for Testing and Materials Standards ASTM D 885 and the moduli at the elongation 1% and 2%, respectively, at 1% and 2% stretched points are shown in Table 2 below.

4) Toughness of yarn

The toughness (J / m < 3 >) value of the yarn was calculated by the following equation (4).

[Equation 4]

In the above equation 4,

F represents a load applied when the length of the polyester yarn is increased by dl,

dl represents the length of the length of the polyester yarn.

5) Crystallinity

The density ρ of the polyester yarn was measured at 25 ° C. according to the density gradient method using n-heptane and carbon tetrachloride, and the crystallinity was calculated according to the following formula 7.

[Equation 7]

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 amorphous (1.336 g / cm ^{3 for} PET).

6) Intrinsic viscosity

The emulsion was extracted from the sample using carbon tetrachloride and dissolved in OCP (Ortho Chloro Phenol) at 160 ± 2 ° C. The viscosity of the sample was measured at 25 ° C using an automatic viscometer (Skyvis-4000) , And the intrinsic viscosity (IV) of the polyester yarn was calculated according to the following equation (8).

 [Equation 8]

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

In this formula,

이고,

ego,

이다.

to be.

7) CEG content

In a 50 mL Erlenmeyer flask, 0.2 g of a sample is added to 20 mL of benzyl alcohol, and a hot plate (hot) is added to the carboxyl end group (CEG, Carboxyl End Group) of the polyester yarn in accordance with ASTM D 664 and D 4094, The plate was heated to 180 ° C for 5 minutes to completely dissolve the sample. After cooling to 160 ° C, 5-6 drops of phenol phthalene was added at 135 ° C, and the solution was titrated with 0.02N KOH, The CEG content (COOH million equiv. / Kg of sample) was calculated by the following equation (9).

[Equation 9]

CEG = (A-B) x 20 x 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 (g) of the sample.

8) Single yarn fineness

The single yarn fineness was measured by taking the yarn of 9,000 m using a bobbin and measuring the total fineness (Denier) of the yarn by dividing it by the number of filaments.

division Example 1 Example 2 Example 3 Example 4 Example 5 Crystallinity (%) 43.2 43.9 45.2 45.6 46.3 Intrinsic viscosity of yarn (dl / g) 0.92 0.96 0.98 1.01 1.04 CEG of yarn (meq / kg) 33 29 27 26 26 Modulus of yarn
(At 1% of elongation, g / de) 99 96 97 94 98 Modulus of yarn
(At 2% of elongation, g / de) 78 76 77 76 77 The tensile strength at room temperature (T ⁰ , g / d) 9.1 9.15 9.20 9.3 9.33 Tensile elongation at room temperature (S ⁰ ,%) 16.5 17 18.5 17.2 17.6 The room temperature strength index (T ⁰ / S ⁰ , X ⁰ ) 0.552 0.538 0.497 0.541 0.530 Dry Heat Shrinkage (%) of Yarn 5.2 5.3 3.8 4.5 5.3 Stiffness of Yarn
(Toughness, J / m 3) 96.5 97 99 103 106 Single yarn fineness (DPF) 3.82 3.23 2.92 4.61 4.17 The total fineness of the yarn (de) 420 420 420 600 600 Number of filaments of yarn 110 130 144 130 144

After heat treatment for 168 hours, 360 hours and 504 hours at 85 ° C. and 95 ± 5% RH, respectively, the polyester yarn prepared according to Examples 1 to 5 had tensile strengths T ¹ , T ² , T ³ ) and tensile elongation (S ¹ , S ² , S ³ ) were measured. The measured physical properties are summarized in Table 3 below.

division Example 1 Example 2 Example 3 Example 4 Example 5 85 [deg.] C, 95 5% RH, 168 hours
Tensile strength after heat treatment (T ¹ , g / d) 8.76 8.81 8.86 8.96 8.98 85 [deg.] C, 95 5% RH, 168 hours
Tensile elongation of yarn (S ¹ ,%) 17.8 18.7 20.2 18.6 19.5 The first high-humidity strength index (T ¹ / S ¹ , X ¹ ) 0.492 0.471 0.439 0.482 0.460 85 ° C, 95 ± 5% RH, 360 hours
Tensile strength after heat treatment (T ² , g / d) 8.57 8.62 8.67 8.76 8.79 85 ° C, 95 ± 5% RH, 360 hours
Tensile elongation of yarn (S ² ,%) 18.8 19.9 21.3 21.0 22 Second high-humidity strength index (T ² / S ² , X ² ) 0.456 0.433 0.407 0.417 0.399 85 ° C, 95 ± 5% RH, 504 hours
Tensile strength after heat treatment (T ³ , g / d) 8.39 8.44 8.48 8.57 8.6 85 ° C, 95 ± 5% RH, 504 hours
Tensile elongation of yarn (S ³ ,%) 19.6 20.6 21.6 22.0 23.4 The third high-humidity strength index (T ³ / S ³ , X ³ ) 0.427 0.410 0.392 0.389 0.367 Compared to room temperature strength index
The ratio of the first high-humidity strength index
(X ¹ / X ⁰ ) 0.892 0.875 0.883 0.892 0.868 Compared to room temperature strength index
The ratio of the second high-humidity strength index
(X ² / X ⁰ ) 0.826 0.805 0.819 0.772 0.754 Compared to room temperature strength index
Ratio of the third high-humidity strength index
(X ³ / X ⁰ ) 0.775 0.762 0.788 0.720 0.693

Comparative Example  1-5

The polyester yarns of Comparative Examples 1 to 5 were prepared in the same manner as in Examples 1 to 5 except for the conditions described in Table 4 below.

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 PET content (mol%) 100 100 100 100 100 Intrinsic viscosity (dl / g) of PET chip 0.80 0.83 0.88 0.91 0.92 The CEG (meq / kg) 52 49 45 45 43 Radiation temperature (℃) 301 302 305 302 305 Total mystery 4.95 5.03 5.10 5.03 5.10 Heat treatment temperature (캜) 220 223 227 223 227 Relaxation rate (%) 4.7 4.75 4.8 4.75 4.8

The polyester yarns prepared according to Comparative Examples 1 to 5 were measured for physical properties of yarn at room temperature (25 ° C and 65 ± 5% RH) in the same manner as in Examples 1 to 5 without any heat treatment, Are summarized in Table 5 below.

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Crystallinity (%) 41.7 41.9 41.9 41.9 41.9 Intrinsic viscosity of yarn (dl / g) 0.59 0.60 0.61 0.61 0.62 CEG of yarn (meq / kg) 59 55 55 53 51 Modulus of yarn
(At 1% of elongation, g / de) 115 119 125 119 125 Modulus of yarn
(At 2% of elongation, g / de) 90 93 93 92 92 The tensile strength at room temperature (T ⁰ , g / d) 6.9 7.2 7.3 7.2 7.7 Tensile elongation at room temperature (S ⁰ ,%) 10 11 13.0 13.8 14.2 The room temperature strength index (T ⁰ / S ⁰ , X ⁰ ) 0.690 0.655 0.562 0.522 0.542 Dry Heat Shrinkage (%) of Yarn 15.5 13.6 11.4 12.0 11.8 Stiffness of Yarn
(Toughness, J / m 3) 59 63 67 63 67 Single yarn fineness (DPF) 7.35 6.94 6.94 10.0 9.14 The total fineness of the yarn (de) 500 500 500 680 680 Number of filaments of yarn 68 72 72 68 72

The polyester yarns prepared according to Comparative Examples 1 to 5 were heat-treated for 168 hours, 360 hours, and 504 hours under the conditions of 85 ° C and 95 ± 5% RH, respectively, and the tensile strength T ¹ , T ² , T ³ ) and tensile elongation (S ¹ , S ² , S ³ ) were measured. The measured physical properties are summarized in Table 6 below.

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 85 [deg.] C, 95 5% RH, 168 hours
Tensile strength after heat treatment (T ¹ , g / d) 5.80 6.12 5.91 6.12 6.7 85 [deg.] C, 95 5% RH, 168 hours
Tensile elongation of yarn (S ¹ ,%) 8.5 9.8 10.8 12.2 13.0 The first high-humidity strength index (T ¹ / S ¹ , X ¹ ) 0.682 0.624 0.548 0.502 0.515 85 ° C, 95 ± 5% RH, 360 hours
Tensile strength after heat treatment (T ² , g / d) 5.11 5.69 5.18 5.47 5.85 85 ° C, 95 ± 5% RH, 360 hours
Tensile elongation of yarn (S ² ,%) 7.4 9.1 9.4 11.0 11.2 Second high-humidity strength index (T ² / S ² , X ² ) 0.690 0.625 0.551 0.497 0.523 85 ° C, 95 ± 5% RH, 504 hours
Tensile strength after heat treatment (T ³ , g / d) 4.69 5.33 4.82 5.04 5.78 85 ° C, 95 ± 5% RH, 504 hours
Tensile elongation of yarn (S ³ ,%) 6.4 8.4 8.8 9.7 10.6 The third high-humidity strength index (T ³ / S ³ , X ³ ) 0.733 0.634 0.548 0.520 0.545 Compared to room temperature strength index
The ratio of the first high-humidity strength index
(X ¹ / X ⁰ ) 0.988 0.954 0.975 0.961 0.950 Compared to room temperature strength index
The ratio of the second high-humidity strength index
(X ² / X ⁰ ) 1,000 0.955 0.982 0.953 0.964 Compared to room temperature strength index
Ratio of the third high-humidity strength index
(X ³ / X ⁰ ) 1.063 0.969 0.975 0.996 1.005

The steel-elongation curves measured at room temperature and the steel-elongation curves measured after heat treatment for 168 hours under the conditions of 85 ° C. and 95 ± 5% RH of the polyester yarn according to Example 5 are shown in FIGS. 3 and 4, respectively . The steel-elongation curves measured at room temperature and the steel-elongation curves measured after heat treatment for 168 hours under the conditions of 85 ° C and 95 ± 5% RH of the polyester yarn according to Comparative Example 5 are shown in FIGS. 5 and 6, respectively.

As shown in Fig. 3 and Fig. 4, the polyester yarn according to Example 5 had a slight decrease in the yarn tensile strength after heat treatment for 168 hours at 85 DEG C and 95 5% RH relative to the normal temperature, And the elongation is remarkably improved by rearrangement of the molecular orientation of the PET polymer, so that the toughness of the final yarn is not significantly lower than the room temperature. Therefore, the polyester yarn according to the fifth embodiment has excellent properties such that the toughness after the heat treatment is maintained compared with the room temperature, so that it is possible to secure sufficient toughness resistance and sufficient toughness resistance when applied to a vehicle airbag fabric.

On the other hand, as shown in FIG. 5 and FIG. 6, the yarn for airbag according to Comparative Example 5 was heat treated for 168 hours under the conditions of 85 ° C. and 95 ± 5% RH relative to room temperature, Is decreased. As described above, the polyester yarn according to Comparative Example 5 exhibits a characteristic that the toughness after the heat treatment is drastically lowered compared with the room temperature. Thus, the polyester yarn according to Comparative Example 5 has an ability to absorb instantaneous high temperature / high pressure inflator gas pressure It is not suitable for use as an airbag fabric.

Manufacturing example  1-5

Fabrics for airbags were weaved through a rapier loom using a polyester yarn produced according to Examples 1 to 5 and subjected to a refining and tentering process to prepare a fabric for an airbag. A liquid silicone rubber (LSR ) A silicone coated fabric was prepared by coating the resin with a knife over roll coating method.

At this time, the warp and weft density of the fabric, the weaving pattern and the resin coating amount were as shown in Table 7 below, and the remaining conditions were in accordance with the usual conditions for producing the polyester fabric for airbags.

division Example 1 Example 2 Example 3 Example 4 Example 5 Weaving density (warp x weft) 49x49 49x49 49x49 43x43 43x43 Weaving type Plain weave Plain weave Plain weave Plain weave Plain weave Heat treatment / vulcanization temperature (캜) 180 185 190 185 190 Rubber component Liquid silicone Liquid silicone Liquid silicone Liquid silicone Liquid silicone Amount of resin coating (g / m ² ) 25 25 25 25 25

The properties of each polyester fabric for airbags prepared using the polyester yarn produced according to Examples 1 to 5 were measured by the following methods and the measured properties are summarized in Table 8 below.

(a) Toughness of the fabric

The toughness (J / m < 3 >) value of the fabric was calculated by the following equation (6).

[Equation 5]

In the above equation 5,

F represents the load applied when the length of the polyester fabric is increased by dl,

dl represents the length of the polyester fabric increased in length.

At this time, the toughness of the fabric was measured with the uncoated fabric before the coating treatment.

(b) Tear strength

The tear strength of uncoated fabrics was measured according to the American Society for Testing and Materials Standards ASTM D 2261 TONGUE.

First, each of the specimens was cut into a width of 75 mm and a length of 200 mm using an uncoated fabric before coating, and then the upper and lower portions of the specimen were cut from the top and bottom of the apparatus according to the American Society for Testing and Materials Standards ASTM D 2261 TONGUE Between the left and right spaces of the jaw faces of the jaw faces. Thereafter, the spacing of the jaw faces is shifted in the opposite direction with respect to 76 mm, that is, the upper binding device is moved upward and the lower device is moved downward at a speed of 300 mm / min The strength of the fabric when it ruptured was measured.

(c) Tensile strength and cutting elongation

The specimens were cut into uncoated fabrics before coating and fixed to the lower clamp of a tensile strength measuring device according to American Society for Testing and Materials ASTM D 5034 and the strength and elongation at break of the airbag fabric specimen Were measured.

(d) resistance to attack

Uncoated fabrics before coating treatment were used to measure the resistance to tearing of the fabric at room temperature (25 DEG C) and 90 DEG C, respectively, according to the American Society for Testing and Materials Association standard ASTM D 6479.

(e) Cover factor (CF)

The cover factor value for the uncoated fabric was calculated by the following equation (6).

[Equation 6]

Cover Factor (CF)

(f) Inclination and weft direction fabric shrinkage

The fabric shrinkage in the light / weft direction was measured according to the American Society for Testing and Materials Standards ASTM D 1776. First, the specimens were cut into uncoated fabrics before coating, 20 cm in length before shrinkage in the warp and weft directions, and shrinked lengths of the specimens after heat treatment in the chamber at 149 ° C for 1 hour were measured. And the fabric shrinkage in the direction of weft {(length of shrinkage-length after shrinkage) / length of shrinkage x 100%}.

(g) Lecture

The uncoated fabric before the coating treatment was measured for its lubrication by a Circular Bend method using a lubrication measuring apparatus according to the American Society for Testing and Materials (ASTM D 4032). In addition, the cantilever method can be applied to the cantilever measurement method, and the cantilever can be measured by measuring the bending length of the cantilever using a cantilever measuring device, which is a test bench having a predetermined angle of inclination to bend the fabric.

(h)

The finish of the uncoated fabric before coating treatment was measured according to the American Society for Testing and Materials Standards ASTM D 1777.

(i) air permeability

Uncoated fabrics before coating treatment according to American Society for Testing and Materials Standards ASTM D 737 were allowed to stand at 20 ° C and 65% RH for at least one day and then air having a pressure of 125 pa and 500 pa respectively of 38 cm ² The amount through the circular cross section was measured and expressed as static air permeability.

The dynamic air permeability of the uncoated fabric was measured using a dynamic air permeability tester (TEXTEST FX 3350 Dynamic Air Permeability Tester) according to ASTM D 6476.

division Example 1 Example 2 Example 3 Example 4 Example 5 Fabric toughness
(Toughness, kJ / m3) 3.75 3.83 3.92 5.4 5.6 Fabric Tearing Strength (kgf) / Uncoated 19 19 20 26 26 Fabric Tear Strength (kgf) / Coating 36 37 38 38 40 Fabric Tensile Strength (kgf / inch) 227 230 234 297 305 Cutting Elongation (%) 37 37 39 38 40 Fabric resistance resistance (25 ℃) 430 446 450 520 535 Fabric resistance to breaking (90 ℃) 380 390 415 480 495 Fabric Cover Factor 2,008 2,008 2,008 2,107 2,107 Fabric shrinkage
(%) slope 0.5 0.5 0.4 0.4 0.5 Weft 0.3 0.3 0.4 0.3 0.3 Lecture (kgf) 0.40 0.40 0.35 1.00 0.90 Fillet (mm) 294 294 295 338 338 silence
Air permeability
(cfm) P = 125 Pa 1.0 0.9 0.8 0.6 0.6 P = 500 Pa 9.5 9.3 9.2 5.4 5.4 Dynamic air permeability (mm / s) 620 610 590 450 430

Comparative Production Examples 1 to 5

Except that polyester yarns of Comparative Examples 1 to 5 were used in place of the polyester yarns prepared in Examples 1 to 5, The polyester fabric was prepared and the physical properties thereof were measured and summarized in Table 9 below.

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Fabric toughness
(Toughness, kJ / m3) 2.5 2.7 2.9 2.7 2.9 Fabric Tearing Strength (kgf) / Uncoated 13 14 15 19 20 Fabric Tear Strength (kgf) / Coating 21 23 23 23 24 Fabric Tensile Strength (kgf / inch) 183 182 185 195 198 Cutting Elongation (%) 20 21 22 20 22 Fabric resistance resistance (25 ℃) 270 280 285 320 327 Fabric resistance to breaking (90 ℃) 255 263 269 295 298 Fabric Cover Factor 2,192 2,192 2,192 2,243 2,243 Fabric shrinkage
(%) slope 1.3 1.3 1.2 1.2 1.1 Weft 1.2 1.0 0.9 1.0 0.9 Lecture (kgf) 2.1 1.9 1.8 2.3 2.3 Fillet (mm) 303 305 305 350 350 silence
Air permeability
(cfm) P = 125 Pa 2.4 2.3 2.2 2.2 2.1 P = 500 Pa 13.5 13.3 13.0 12.6 12.5 Dynamic air permeability (mm / s) 1,900 1,850 1,800 1,950 1,850

As shown in Table 8, the fabric for airbags of Production Examples 1 to 5 using the polyester yarns of Examples 1 to 5, in which the tensile strength and elongation range were optimized under severe conditions of room temperature and high temperature and high humidity, had a toughness of 3.75 to 5.6 kJ / m ^3, and a tear strength of the non-coated fabric is 19 to 26 kgf, and a tensile strength of 227 to 305 kgf / inch, the fabric shrinkage is 0.4% to 0.5% and from 0.3 to 0.4 in the oblique direction and the weft direction %, Respectively. At the same time, it was confirmed that the polyester fabrics for airbags of Production Examples 1 to 5 had an excellent optimum range of 0.35 to 1.0 kgf in terms of the degree of lubrication, and thus had superior form stability and mechanical properties as well as excellent folding and retention properties .

Particularly, the fabric for airbags of Production Examples 1 to 5 was fabricated by using a low-modulus yarn of high strength and high strength, the static air permeability (DELTA P = 125 pa) of uncoated fabric was in the range of 0.6 to 1.0 cfm and the static air permeability P = 500 pa) is in the range of 5.4 to 9.5 cfm, so that excellent airtightness results can be obtained. In addition, although the cover factor value of the fabric was lower than Comparative Production Examples 1 to 5, the resistance values at 25 ° C and 90 ° C were 430 ~ 535 N and 380 ~ 495 N, respectively, It can be seen that the seam jamming phenomenon at the seam part outside the cushion can be greatly improved upon deployment.

On the other hand, as shown in Table 9, it was confirmed that the airbag fabrics of Comparative Production Examples 1 to 5 using the polyester yarns of Comparative Examples 1 to 5 did not satisfy these characteristics. In particular, the airbag fabrics of Comparative Production Examples 1 to 5 had a shrinkage ratio in the warp direction and the warp direction of 0.9% to 1.3%, a tensile strength of 182 to 198 kgf / inch and a tear strength of the uncoated fabric of 13 to 20 kgf. < / RTI > When the fabric having such a low mechanical strength such as tensile strength and tear strength is used in an airbag device, there may arise a problem due to deterioration of mechanical properties such as rupture of the airbag when the airbag is deployed.

The static air permeability (AP = 125 pa) of the uncoated fabric according to Comparative Production Examples 1 to 5 was in the range of 2.1 to 2.4 cfm and the static air permeability (AP = 500 pa) was in the range of 12.5 to 13.5 cfm It can be seen that the airtightness is decreased and the airtightness is increased, the air can easily escape during the deployment of the airbag and the airbag can not be sufficiently performed. The cover factor values of the fabric were higher than those of Production Examples 1 to 5, but the resistance values at 25 ° C and 90 ° C were significantly lowered to 270 to 327 N and 255 to 298 N, respectively, It can be seen that there is a large gap between the seam and the seam at the outer periphery, which may cause a serious problem to the safety of the customer.

Experimental Example  One

An airbag cushion was produced using the polyester non-coated fabric for airbags which had not been subjected to the coating process in the above-mentioned Production Examples 1 to 5 and Comparative Production Examples 1 to 5, and as shown in the following Table 10, a DAB (driver airbag) Assembly or PAB (passenger airbag) cushion assembly. The thus completed vehicle airbag was subjected to a static test under the following three heat treatment conditions (room temperature: 25 ° C × 4 hr, oven left, hot: 85 ° C. × 4 hr, oven left, cold: ). The result of the above static test is evaluated as "Pass" in the case where no tearing, pinhole, or raw carbonization phenomenon occurs, and tearing of a fabric, occurrence of a pin hole in a sewing part, Failure occurred when any one of the carbonization phenomena occurred.

The evaluation results of the static test of the airbag cushions produced using the polyester non-coated fabrics for airbags of Production Examples 1 to 5 and Comparative Production Examples 1 to 5 are shown in Table 10 below.

division Cushion Specifications Decompression inflator pressure (kPa) Room temperature
Deployment test Hot
Deployment test Cold
Deployment test Example 1 DAB 190 Pass Pass Pass Example 2 DAB 190 Pass Pass Pass Example 3 DAB 190 Pass Pass Pass Example 4 PAB 330 Pass Pass Pass Example 5 PAB 330 Pass Pass Pass Comparative Example 1 DAB 190 Fail Fail Fail Comparative Example 2 DAB 190 Fail Fail Fail Comparative Example 3 DAB 190 Fail Fail Fail Comparative Example 4 PAB 330 Fail Fail Fail Comparative Example 5 PAB 330 Fail Fail Fail

As shown in Table 10, the fabric for airbags according to Production Examples 1 to 5 using the polyester yarns of Examples 1 to 5, in which the tensile strength and elongation range were optimized under severe conditions of normal temperature and high temperature and high humidity, The airbags for automobiles were left in the oven under the three different heat treatment temperature conditions and subjected to the development test. As a result, there was no occurrence of tearing of fabric, occurrence of pin holes in the sewing part, Performance. ≪ / RTI >

On the other hand, as a result of the development test for the air bag for automobiles including the fabric for airbags of Comparative Production Examples 1 to 5 using the polyester yarns of Comparative Examples 1 to 5, there was a tendency that tearing of the fabric and pin- , Fabric carbonization phenomenon, etc., all of the cushions are evaluated as "Fail", so that it can not be used as an actual air bag. Particularly, in the development test for DAB (driver airbag) cushion assembly including the fabrics of Comparative Production Examples 1, 2 and 3, the fabric tear occurred at the outer contact portion of the cushion. In Comparative Production Example 4, Tearing of the fabric occurred. In the case of Comparative Production Example 5, the fabric tear occurred at the main panel facing portion. Further, in the development test for the vehicle airbags including the fabrics of Comparative Production Examples 1 to 5, it was confirmed that the fabric tearing occurred together with the occurrence of pin hole and carbonization of sewing part. Therefore, the fabric for airbags of Comparative Manufacturing Examples 1 to 5 may cause a great risk to the airbag function due to the airbag rupture or the like when it is applied to an actual vehicle airbag cushion.

Claims (19)

A normal temperature strength index (X ⁰ ) indicative of a ratio (T ⁰ / S ⁰ ) of a tensile strength (T ⁰ ) and a tensile elongation (S ⁰ ) of a yarn measured at room temperature; And
(T ¹ / S ¹ ) of the tensile strength (T ¹ ) and tensile elongation (S ¹ ) of the yarn measured after heat treatment at 85 ° C and 95 ± 5% RH for 168 hours X ¹ );
Is as shown in the following formula 1,
Polyester yarn having a Young's modulus of 94 to 99 g / de at 1% elongation and 76 to 78 g / de at 2% elongation measured by the method of American Society for Testing and Materials Standards ASTM D 885 at room temperature,
[Equation 1]
0.65? X ¹ / X ⁰ ? 0.93
In the formula,
X ⁰ is a normal temperature strength index (X ⁰ ) indicating the ratio (T ⁰ / S ⁰ ) of the tensile strength (T ⁰ ) and the tensile elongation (S ⁰ ) of the polyester yarn measured at room temperature,
X ¹ represents the ratio (T ¹ / S ¹ ) of the tensile strength (T ¹ ) to the tensile elongation (S ¹ ) of the polyester yarn measured after heat treatment at 85 ° C and 95 ± 5% RH for 168 hours (X ¹ ). The method according to claim 1,
A normal temperature strength index (X ⁰ ) indicative of a ratio (T ⁰ / S ⁰ ) of a tensile strength (T ⁰ ) and a tensile elongation (S ⁰ ) of a yarn measured at room temperature; And
(T ² / S ² ) of the tensile strength (T ² ) and tensile elongation (S ² ) of the yarn measured after heat treatment at 85 ° C. and 95 ± 5% RH for 360 hours X ² );
Is a polyester yarn as shown in the following formula 2:
[Equation 2]
^{0.65 ≤ X 2 / X 0 ≤} 0.93
In the formula,
X ⁰ is a normal temperature strength index (X ⁰ ) indicating the ratio (T ⁰ / S ⁰ ) of the tensile strength (T ⁰ ) and the tensile elongation (S ⁰ ) of the polyester yarn measured at room temperature,
X ² indicates the ratio (T ² / S ² ) of the tensile strength (T ² ) and the tensile elongation (S ² ) of the polyester yarn measured after heat treatment for 360 hours at 85 ° C and 95 ± 5% The car has a high degree of strength index (X ² ). The method according to claim 1,
A normal temperature strength index (X ⁰ ) indicative of a ratio (T ⁰ / S ⁰ ) of a tensile strength (T ⁰ ) and a tensile elongation (S ⁰ ) of a yarn measured at room temperature; And
(T ³ / S ³ ) of the tensile strength (T ³ ) and tensile elongation (S ³ ) of the yarn measured after heat treatment at 85 ° C and 95 ± 5% RH for 504 hours X ³ );
Is a polyester yarn as shown in the following formula 3:
[Equation 3]
^{0.65 ≤ X 3 / X 0 ≤} 0.93
In the formula,
X ⁰ is a normal temperature strength index (X ⁰ ) indicating the ratio (T ⁰ / S ⁰ ) of the tensile strength (T ⁰ ) and the tensile elongation (S ⁰ ) of the polyester yarn measured at room temperature,
X ³ represents the ratio (T ³ / S ³ ) of the tensile strength (T ³ ) to the tensile elongation (S ³ ) of the polyester yarn measured after heat treatment for 504 hours at 85 ° C and 95 ± 5% (X ³ ). delete The method according to claim 1,
Polyester yarn having a toughness of 70 J / m < 3 > to 120 J / m < 3 &
[Equation 4]

In the above equation (4), F represents a load applied when the length of the polyester yarn is increased by dl. The method according to claim 1,
A polyester yarn having a dry heat shrinkage of 1.0% or more. The method according to claim 1,
A polyester yarn having a crystallinity of 40% to 55%. The method according to claim 1,
Polyester yarn having a total fineness of 400 to 650 denier. The method according to claim 1,
A polyester yarn having a single fiber fineness of 2.5 to 6.8 DPF and comprising 96 to 160 filaments. Melt spinning a polyester polymer having an intrinsic viscosity of 1.25 to 1.60 dl / g at 293 to 295 DEG C to prepare a polyester undrawn yarn, and
Stretching the polyester undrawn yarn so as to have a total mint ratio of from 5.99 to 6.15, and
Performing the relaxation process to a relaxation rate of 5.6% to 6.3% after stretching the undrawn fiber;
10. A method of producing a polyester yarn according to any one of claims 1 to 3 or 5 to 9, 11. The method of claim 10,
Wherein a difference in intrinsic viscosity between the polyester polymer and the polyester yarn is 0.7 dl / g or less. delete The method of claim 10, wherein
Further comprising a heat setting step at a temperature of 170 to 250 DEG C after stretching the undrawn yarn. delete A polyester fabric comprising the polyester yarn of any one of claims 1 to 3 or 5 to 9 and having a lubrication according to the American Society for Testing and Materials ASTM D 4032 method of 1.5 kgf or less. delete 16. The method of claim 15,
The static air permeability according to the American Society for Testing and Materials ASTM D 737 method is less than 10.0 cfm when ΔP is 125 pa and less than 14 cfm when ΔP is 500 pa. 16. The method of claim 15,
Polyester fabric with a dynamic air permeability of less than 1,700 mm / s according to the American Society for Testing and Materials Standards ASTM D 6476 method. 16. The method of claim 15,
A polyester fabric having a resistance to breakdown of at least 350 N measured at room temperature by the American Society for Testing and Materials ASTM D 6479 method and a resistance to breakdown of at least 300 N measured at 90 ° C.

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