KR20200088992A - Method for Manufacturing Airbag Fabric - Google Patents

Abstract

Provided is a method for manufacturing airbag fabric, in which a coating layer has high adhesive force for a fiber substrate without containing volatile organic compounds (VOC), such that excellent airtightness of an airbag is secured. According to the present invention, the method comprises the following steps: weaving the fiber substrate; modifying a surface of the fiber substrate through a corona discharge process; and coating a coating agent on the modified surface of the fiber substrate. The fiber substrate is woven by PET fiber, surface treatment is performed by a discharge energy per unit area of 0.3 to 11.0 J/cm^2, and the VOC content in the coating agent measured based on VDA 278, which is a German automotive material test standard, is 50 ppm or less.

Description

Method for Manufacturing Airbag Fabric}

The present invention relates to a method of manufacturing an airbag fabric, and more specifically, a method of manufacturing an airbag fabric capable of ensuring excellent airtightness of an airbag by having a high adhesion to the fiber substrate without the coating layer containing a volatile organic compound. It is about.

When the impact detection sensor detects the impact on the vehicle during a collision or overturning of a vehicle that is traveling at a predetermined speed or higher, the airbag expands and expands by the high temperature and high pressure air provided from the inflator to protect the driver and passengers of the vehicle from accidents. do.

In general, an airbag includes a fiber substrate and a coating layer thereon.

When the adhesive strength between the fiber substrate and the coating layer is low, the friction between the airbag fabric and its surrounding structures is caused by vibration of the airbag module mounted in the vehicle, and the peeling of the coating layer from the fiber substrate is unintentionally caused. Can. In addition, when the airbag is deployed by high temperature and high pressure air, the coating layer may be peeled from the fiber substrate. Such peeling of the coating layer makes it impossible to keep the airbag in an inflated form in the event of an accident, and as a result, it is impossible to properly protect the occupant from a vehicle accident.

Primers can be added to the elastomeric coating material to increase the adhesion between the fiber substrate and the coating layer, but the production cost is increased due to the use of the primer, as well as environmental pollution caused by volatile organic compounds (VOC). .

As an alternative method to increase the airtightness of the airbag without using a primer, it is possible to increase the amount of the elastomer coating, but this also not only entails an increase in manufacturing cost, but also increases the airbag weight, thereby reducing vehicle fuel efficiency.

On the other hand, Korean Registered Patent No. 10-1590152 (hereinafter referred to as'prior art') describes corona discharge as one of various examples of the pretreatment method while explaining pre-treatment for improving adhesion between the fiber substrate and the coating layer. To mention. However, the prior art only abstractly explains that a conventional method may be used in connection with corona discharge.

That is, in order to maximize the adhesion between the fiber substrate and the coating layer, how to set each of the specific conditions of corona discharge has not been studied at all.

Accordingly, the present invention relates to a method of manufacturing an airbag fabric that can satisfy the needs of the related technical field as described above.

One aspect of the present invention, to provide a method for manufacturing an airbag fabric that can ensure excellent airtightness of the airbag by having a high adhesion to the fibrous substrate, the coating layer containing substantially no volatile organic compounds (substantially VOC-free) will be.

In addition to the above-mentioned aspects of the present invention, other features and advantages of the present invention are described below, or it will be clearly understood by those skilled in the art from the description.

According to one aspect of the present invention as above, weaving the fiber substrate; Modifying the surface of the fiber substrate through a corona discharge treatment; And applying a coating agent on the modified surface of the fiber substrate, wherein the fiber substrate is woven from PET fibers, and the surface treatment is performed with a discharge energy per unit area of 0.3 to 11.0 J/cm ² , Germany An airbag fabric manufacturing method is provided in which the volatile organic compound content in the coating agent measured in accordance with the automotive material test standard VDA278 is less than 50 ppm.

The surface modification step may include continuously moving the fiber substrate between the first and second electrodes facing each other.

The first electrode may include one or more electrode bars, and the second electrode may be a roll electrode supporting the continuously moving fiber substrate.

The distance between the first electrode and the second electrode may be 1 to 3 mm.

The fiber substrate may continuously move between the first and second electrodes at a linear speed of 2 to 20 m/min.

The corona discharge treatment may be performed for 0.1 to 0.8 seconds.

The coating agent may be applied on the fiber substrate in an amount of 5 to 120 g/m ² .

The airbag fabric manufacturing method may further include attaching a nonwoven fabric having a weight per unit area of 5 to 50 g/m ² on the coating agent applied on the fiber substrate.

The coating agent may be a PET-based elastomer, and the non-woven fabric may be formed of PET fibers.

Both the above general description and the following detailed description are only intended to illustrate or describe the present invention, and should be understood to provide a more detailed description of the invention of the claims.

According to the present invention, the coating layer does not contain a volatile organic compound and has a high adhesion to the fiber substrate. Therefore, it is possible to satisfy the high airtightness and durability required for the airbag without causing environmental problems.

The accompanying drawings are intended to help the understanding of the present invention and constitute a part of the present specification, and exemplify embodiments of the present invention, and describe the principles of the present invention together with a detailed description of the present invention.
1 is a cross-sectional view of a fiber substrate according to an embodiment of the present invention,
Figure 2 schematically shows a corona discharge device according to an embodiment of the present invention,
3 is a cross-sectional view of an airbag fabric according to an embodiment of the present invention,
4 is a cross-sectional view of an airbag fabric according to another embodiment of the present invention.

Hereinafter, embodiments of the method for manufacturing an airbag fabric of the present invention will be described in detail with reference to the accompanying drawings. However, the embodiments described below are presented for illustrative purposes only to assist in a clear understanding of the present invention, and do not limit the scope of the present invention.

First, as shown in FIG. 1, the fiber substrate 110 is woven.

The fiber substrate 110 is woven from synthetic fibers, preferably polyethylene terephthalate (PET) fibers, which can prevent the airbag from being ruptured by high and high pressure air supplied from the inflator.

According to an embodiment of the present invention, the fiber substrate 110 may be a fabric including PET fibers as warp yarns 111 and weft yarns 112. For example, the fiber substrate 110 is a conventional fabric used when manufacturing an airbag according to a'Cut & Sew' method, or a one-piece having an expanded portion (chamber region) and a non-expanded portion It may be a woven (OPW) type of fabric.

In order to have sufficient mechanical strength to prevent the airbag from being ruptured by the high temperature and high pressure air supplied from the inflator during airbag deployment, the fineness of the theodolites 111 and 112 is preferably 210 denier or more. On the other hand, for the folding property and weight reduction of the airbag, the fineness of the warp yarns 111 and 112 is preferably 1500 denier or less.

In addition, from the viewpoint of flexibility, smoothness of the coated surface, etc., it is preferable that each of the warp yarns 111 and 112 is a multifilament comprising 72 strands or more of filaments 111a and 112a.

After weaving the fiber substrate 110 with PET fiber, a refining step, a water washing step, and a drying and/or heat treatment step for removing the emulsion or sizing agent that has been imparted to the PET yarn may be sequentially performed to improve the weaving properties. have.

After the heat treatment step, the warp density and the weft density of the fiber substrate 110 may be 40 to 80 th/inch, respectively (for OPW fabric, the density is based on one layer of the chamber area).

Subsequently, as illustrated in FIG. 2, the surface of the fiber substrate 110 is modified through corona discharge treatment.

As described above, the fiber substrate 110 is preferably woven from PET fibers having excellent mechanical properties. However, since the PET itself lacks a functional group capable of bonding with the coating agent, the adhesive force with the coating agent may be particularly problematic in the fiber substrate 110 woven from the PET fiber. Therefore, the surface treatment of the present invention is particularly required for the fiber substrate 110 woven from PET fibers.

The following three effects can be obtained through the corona discharge treatment of the present invention.

(i) Physical effect: High-energy charged particles collide with the surface of the fiber substrate 110 to create fine irregularities or micro craters on the surface. The fine concavo-convex or micro-crater not only increases the contact area with the coating agent, but also serves as an anchor to hold the coating agent.

(ii) Effect of electrets: When a high voltage is applied to the surface of the fiber substrate 110, surface charge is induced on the surface of the fiber substrate 110, and the induced charge is due to the high insulating properties of the polymer material (ie PET). It permanently remains on the surface, causing surface polarization. The surface polarization acts as an attractive force on an adhesive having a polar group, thereby improving wettability and adhesion.

(iii) Chemical effect: A gas having a high oxidizing property such as oxygen is sufficiently accelerated by a high voltage to strongly collide with the surface of the fiber substrate 110, thereby forming free groups on the surface of the fiber substrate 110 to increase surface reactivity. The free group refers to an atom, molecule or ion having unpaired electrons.

As illustrated in FIG. 2, according to an embodiment of the present invention, the surface modification step continuously moves the fiber substrate 110 between the first electrode 210 and the second electrode 220 facing each other. Steps.

The first electrode 210 may include one or more electrode bars, and the second electrode 220 may be a roll electrode supporting the continuously moving fiber substrate 110. Can.

According to the present invention, the corona discharge treatment is performed with a discharge energy per unit area of 0.3 to 11.0 J/cm ² .

The discharge energy per unit area is calculated by Equation 1 below.

* Equation 1: Ec = (k·V·I)/(L·S)

Here, Ec is the discharge energy per unit area (J/cm ² ), the constant k is 0.6 (m·sec)/(cm·min), V is the applied voltage (V), and I is the current (A), L is the length (cm) in the width direction (TD) of the fiber substrate 110, and S is the moving linear velocity (m/min) of the fiber substrate 110.

If the discharge energy per unit area is less than 0.3 J/cm ² , since the surface of the fiber substrate 110 is not sufficiently modified, the adhesive force between the fiber substrate 110 and the coating layer cannot be significantly increased. On the other hand, when the discharge energy per unit area exceeds 11.0 J/cm ² , it is difficult to form fine unevenness, so the physical effect of the above-mentioned corona discharge treatment is rather reduced.

In order to sufficiently modify the surface of the fiber substrate 110 through the corona discharge treatment, it is also necessary to properly adjust the distance between the first electrode 210 and the second electrode 220. For example, an interval between the first electrode 210 and the second electrode 220 may be 1 to 3 mm.

According to an embodiment of the present invention, the fiber substrate 110 may continuously move between the first and second electrodes 210 and 220 at a linear speed of 2 to 20 m/min. When the linear velocity is less than 2 m/min, the discharge energy applied per unit area is too large to form a fine pattern. On the other hand, when the linear velocity exceeds 20 m/min, the discharge energy applied per unit area is too small to achieve a desired surface modification effect.

The corona discharge treatment may be performed for 0.1 to 0.8 seconds. If the corona discharge treatment time is less than 0.1 seconds, it is difficult to achieve a desired effect of increasing the adhesion. On the other hand, after the corona discharge treatment for 0.8 seconds, even if the above treatment is further performed, since it is difficult to form fine irregularities, it is no longer possible to expect a significant adhesion improvement effect. Therefore, corona discharge treatment exceeding 0.8 seconds is not preferable from the viewpoint of productivity.

Subsequently, as illustrated in FIG. 3, a coating agent 120 is applied on the modified surface of the fiber substrate 110 to form a coating layer for providing airtightness required for the airbag.

The coating method is not particularly limited, but a knife coating method, a roll coating method, a T die method, or the like can be used.

The coating agent 120 may include a thermosetting elastomer such as polyurethane, silicone, and polychloroprene, or a thermoplastic elastomer such as polyamide and PET.

According to an embodiment of the present invention, a PET-based elastomer may be used as the coating agent 120. When a PET-based elastomer is used as the coating agent 120, the fiber substrate 110 and the coating agent 120 are formed of the same type of polymer (ie, PET), and thus the fiber substrate 110 is discarded when the airbag is discarded. The airbags can be easily recycled by melting them together without the need to separate the coating layers from.

According to the present invention, the content of the volatile organic compound in the coating agent 120 measured according to the German automotive material test standard VDA278 is less than 50 ppm. Since the coating agent 120 is applied on the surface of the fiber substrate 110 properly modified through the above-mentioned corona discharge treatment, the fiber substrate without adding a large amount of a primer made of a volatile organic compound (VOC) to the coating agent 120 Sufficient adhesion between the 110 and the coating agent 120 (that is, the coating layer) can be secured. Therefore, according to the present invention, it is possible to prevent or minimize environmental pollution due to the use of volatile organic compounds (VOC).

The coating agent 120 may be applied on the modified surface of the fiber substrate 110 in an amount of 5 to 120 g/m ² . If the application amount is less than 5 g/m ^{2, the} airbag cannot have satisfactory pressure-resistance. On the other hand, when the application amount exceeds 120 g/m ² , the folding property (ie, storage property) of the air bag deteriorates.

Optionally, as illustrated in FIG. 4, the method of manufacturing the airbag fabric of the present invention may further include attaching a nonwoven fabric 130 on the coating agent 120 applied on the fiber substrate 110. .

Since the coating layer becomes sticky with the passage of time, when the airbag is stored in a vehicle for a long time in a folded state, adhesion of faces that are folded and folded may be caused. The non-woven fabric 130 attached to the coating agent 120 prevents the adhesion of the airbags when they are embedded in the vehicle by preventing the surfaces of the coating layers that are folded and facing each other from contacting each other or by minimizing the contact area.

According to an embodiment of the present invention, a PET-based elastomer is used as the coating agent 120, and the nonwoven fabric 130 is formed of PET fibers. Since the fiber substrate 110, the coating agent 120, and the nonwoven fabric 130 are formed of the same type of polymer (ie, PET), when disposing of the airbags, the airbags can be easily melted by melting them together without the need to separate them from each other. Can be recycled.

The non-woven fabric 130 may have a weight per unit area of 5 to 50 g/m ² . If the weight per unit area of the nonwoven fabric 130 is less than 5 g/m ² , it is impossible to properly prevent the surfaces of the coating layers that are folded and face each other from adhering to each other. On the other hand, if the weight per unit area of the nonwoven fabric 130 exceeds 50 g/m ² , the weight of the airbag increases only without a significant increase in adhesion prevention function, so that it is unable to satisfy the vehicle's lightweighting needs.

Subsequently, a coating layer is formed by drying the coating agent 120.

When a thermosetting elastomer is used as the coating agent 120, it is heated in a range between 30°C and 150°C in a tenter oven and dried, followed by heat treatment (heat curing) in a range of 150°C to 180°C. To form.

On the other hand, when a thermoplastic elastomer (for example, a PET-based elastomer) is used as the coating agent 120, a coating layer is formed through a cooling process. When the cooling process and the pressing process are performed simultaneously using a roll, a coating layer with improved adhesion to the fiber substrate 110 may be obtained.

Hereinafter, the present invention will be described in detail through specific examples. However, the following examples are only to aid the understanding of the present invention, and the scope of the present invention should not be limited thereby.

Example One

Plain weaving was performed with PET yarn to prepare a fiber substrate. The fibrous substrate was sequentially passed through a refining tank and a water washing tank, followed by drying and heat treatment (inclination density: 57th/inch, weft density: 49th/inch).

Corona discharge treatment (current (I): 1A, fiber substrate linear velocity (S): 15 m/min, discharge energy per unit area (Ec): 0.3 J/) while continuously supplying the fiber substrate to the corona discharge device (220 V) cm ² , spacing between the first and second electrodes: 2 mm] was performed to modify the surface of the fiber substrate. The width (TD) length (L) of the fiber substrate was 30 cm.

Using a T die (die) coating method, a silicone coating agent to which no adhesive primer was added was uniformly applied in an amount of 50 g/m ² on the modified surface of the fiber substrate. Subsequently, the airbag fabric was completed by heating it in a tenter oven in a range between 80°C and 150°C and drying it, followed by heat treatment at 180°C to form a coating layer.

Example 2

An airbag fabric was obtained in the same manner as in Example 1 except for the conditions of the corona discharge treatment (current: 3A, fiber base line speed: 10 m/min, discharge energy per unit area: 1.3 J/cm ² ).

Example 3

An airbag fabric was obtained in the same manner as in Example 1, except for the conditions of corona discharge treatment (current: 5A, fiber substrate linear speed: 10 m/min, discharge energy per unit area: 2.2 J/cm ² ).

Example 4

An airbag fabric was obtained in the same manner as in Example 1 except for the conditions of the corona discharge treatment (current: 10A, fiber base line speed: 10 m/min, discharge energy per unit area: 4.4 J/cm ² ).

Example 5

An airbag fabric was obtained in the same manner as in Example 1 except for the conditions of the corona discharge treatment (current: 10A, linear velocity of the fiber substrate: 4 m/min, discharge energy per unit area: 11.0 J/cm ² ).

Comparative example One

An airbag fabric was obtained in the same manner as in Example 1, except that the corona discharge treatment was omitted.

Comparative example 2

An airbag fabric was obtained in the same manner as in Example 1 except for the conditions of the corona discharge treatment (current: 0.5 A, fiber base line speed: 25 m/min, discharge energy per unit area: 0.1 J/cm ² ).

Comparative example 3

An airbag fabric was obtained in the same manner as in Example 1 except for the conditions of the corona discharge treatment (current: 10 A, line speed of the fiber substrate: 3 m/min, discharge energy per unit area: 14.7 J/cm ² ).

The (i) fiber base wettability and (ii) coating layer adhesion of the airbag fabrics of Examples and Comparative Examples prepared as above were measured as follows, and the results are shown in Table 1 below.

* Measurement of wettability on a fiber base

Samples were taken from a portion of the fiber substrate immediately before application of the coating (i.e., immediately after the corona discharge treatment in the examples), and then the rate at which water droplets penetrated the fiber substrate (i.e., water contact smear rate) was measured. Specifically, KRUSS, DSA100 tester dropped 3µl (1.4mm diameter) drop of water onto the sample and measured the time (seconds) until the angle of the drop becomes 0°. 1.4 mm) to calculate the water contact smear rate.

* Coating layer adhesion ( Scrub resistance ) Measure

Aging was performed by leaving the fabric sample under a temperature of 70±2° C. and a relative humidity of 95±2% for 408 hours. Subsequently, the scrub resistance of the airbag fabric measured in accordance with ISO 5981 standards for the warp direction and the weft direction was measured. Specifically, the fabric sample was repeatedly reciprocated in a state where 10 N load was applied to the fabric sample while both ends of the fabric sample were fixed with clamps. After performing 500 reciprocating motions (that is, 1000 strokes), which is more severe than the 300 reciprocating motions (that is, 600 strokes), which is an airbag test criterion, the presence or absence of the coating layer dropout was observed.

Corona discharge treatment conditions Water contact smear rate
(mm/sec) Whether the coating layer is removed V
(V) I
(A) L
(cm) S
(m/min) Ec
(J/cm ² ) Example 1 220 One 30 15 0.3 2.0 No Example 2 220 3 30 10 1.3 3.5 No Example 3 220 5 30 10 2.2 4.2 No Example 4 220 10 30 10 4.4 4.9 No Example 5 220 10 30 4 11.0 5.5 No Comparative Example 1 - - - - - 1.2 Yes Comparative Example 2 220 0.5 30 25 0.1 1.5 Yes Comparative Example 3 220 10 30 3 14.7 1.5 Yes

110: fiber base 120: coating agent
130: nonwoven fabric 210: first electrode
220: second electrode

Claims (8)

Weaving the fiber substrate;
Modifying the surface of the fiber substrate through a corona discharge treatment; And
Applying a coating agent on the modified surface of the fiber substrate
Including,
The fiber substrate is woven from PET fibers,
The corona discharge treatment is performed with a discharge energy per unit area of 0.3 to 11.0 J/cm ² ,
The content of volatile organic compounds in the coating agent measured in accordance with the German automotive material test standard VDA278 is less than 50 ppm,
Airbag fabric manufacturing method. According to claim 1,
The surface modification step includes continuously moving the fiber substrate between the first and second electrodes facing each other,
The first electrode includes one or more electrode bars,
The second electrode is a roll electrode that supports the continuously moving fiber substrate,
Airbag fabric manufacturing method. According to claim 2,
The distance between the first electrode and the second electrode is 1 to 3 mm,
Airbag fabric manufacturing method. According to claim 3,
The fiber substrate continuously moves between the first and second electrodes at a linear speed of 2 to 20 m/min,
Airbag fabric manufacturing method. According to claim 4,
The corona discharge treatment is performed for 0.1 to 0.8 seconds,
Airbag fabric manufacturing method. According to claim 1,
The coating agent is applied on the fiber substrate in an amount of 5 to 120 g / m ² ,
Airbag fabric manufacturing method. According to claim 1,
Further comprising the step of attaching a non-woven fabric having a weight per unit area of 5 to 50 g / m ² on the coating agent applied on the fiber substrate,
Airbag fabric manufacturing method. The method of claim 7,
The coating agent is a PET-based elastomer,
The non-woven fabric is formed of PET fibers,
Airbag fabric manufacturing method.

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