JP2006183205A - Base fabric for air bag - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a base fabric which has excellent heat resistance, especially little changes dimension, has good daily pressure resistance, can be produced at a low cost, and gives little loads to environments. <P>SOLUTION: This base fabric is characterized by using polycaproamide fibers having a temperature of 195 to 220°C at the maximum stress time determined from a thermal shrinkage stress curve and containing a copper compound in an amount of 10 to 350 ppm as a copper metal amount, in at least a part constituting the base fabric of the air bag. Therein, a DSC melting peak temperature by a constant length-constraining method and a tanδ peak temperature, which are parameters showing the inner structures of the polycaproamide fibers, are preferably in specific ranges, respectively. It is preferable to contain any other heat-resistant agent such as a thermally oxidative deterioration-preventing agent in addition to the copper compound. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an air bag base fabric excellent in heat resistance and mechanical characteristics, and more specifically, by using a polycapramide fiber, the air excellent in heat resistance, thermal dimensional stability, environmental characteristics, and low cost. The present invention relates to a base fabric for bags.

  In recent years, in order to protect an occupant from an impact such as an automobile accident, the mounting of an air bag on a vehicle is rapidly progressing. In the event of a collision, equipment such as side airbags and knee airbags are being put into practical use in addition to driver and passenger airbags as airbags that are inflated by gas or the like to protect the occupant's body.

  In addition, the interior of an automobile is extremely hot during summer and daytime, and low during winter and nighttime. Therefore, the heat resistance required for airbag fabrics stored for a long period of time in the automobile includes heat resistance and acid resistance. In the normal use environment that is repeatedly exposed to high and low temperature atmospheres, the misalignment and physical properties due to dimensional changes do not change, and the daily pressure resistance of the airbag fabric is improved. It is very important not to change.

  Conventionally, as shown in Patent Documents 1 and 2, etc., airbags using polyamide fibers or polyester fibers have been proposed. Polyamide, nylon 6-6, nylon 4-6, nylon 10 and the like are exemplified as polyamide. However, as described on page 243 of Non-Patent Document 1, most airbag base fabrics particularly from the viewpoint of heat resistance. Nylon 6-6 is currently used as the fiber for use. Furthermore, even if it sees the Example of patent document 1 and 2 etc., most are the technology regarding nylon 6-6, and since the technology regarding a polycapramide is not indicated, development of an airbag is advanced mainly by nylon 6-6. Yes.

  As a factor that polycapramide is not widely used for airbag fabric use, there is a problem that heat resistance is inferior to nylon 6-6 fiber as described in Non-Patent Document 1, and a method for improving this heat resistance is disclosed in Patent Document 3 and Patent Document 4.

  Patent Document 3 discloses an airbag base using a fiber having both heat resistance and low cost by using a composite fiber having polycapramide as a core component and nylon 4-6, which is a polyamide having excellent heat resistance, as a sheath component. A method of obtaining a fabric is described. When this technique is used, it can be manufactured at a lower cost than when ordinary nylon 4-6 fiber is used, and the heat resistance is improved as compared with the case where polycapramide is used alone. However, there are problems such as an increase in equipment cost due to the fiber core / sheath composite, a deterioration in productivity due to an abnormal core / sheath composite, and an increase in price compared to the polycapramide fiber.

  Patent Document 4 describes a technique for improving the heat resistance of polycapramide fibers for airbags by incorporating a copper compound during spinning. However, merely improving the heat resistance by the copper compound is not sufficient for practical use.

  In Examples of Patent Documents 5 to 7 and the like, technologies relating to airbag fabrics using polycapramide fibers are disclosed, but there is no description regarding improvement of heat resistance of polycapramide fibers, and characteristic production thereof is also disclosed. No method is described. It is difficult to obtain a base fabric for an air bag excellent in heat resistance with a conventionally known polycapramide fiber.

  Further, according to the knowledge of the present inventors, ordinary polycapramide fibers have a problem that they are inferior in heat shrinkage properties compared to nylon 6-6 fibers, and heat resistance, that is, shrinkage / relaxation of the base fabric over time, etc. It has the problem that a base fabric dimensional change and a misalignment occur.

As described above, although studies are being conducted on airbag fabrics using polycapramide fibers that can be manufactured at a lower cost than nylon 6-6 fibers, a fabric that satisfies both cost and heat resistance in a well-balanced manner is obtained. The current situation is not.
JP-A-10-195727 JP 2003-301349 A JP-A-8-158160 Japanese Patent Laid-Open No. 10-60750 JP-A-6-299465 JP-A-9-324337 Special table 2003-521589 gazette Industrial Textile Handbook (First Edition) Nikkan Kogyo Shimbun, Textile Society

  The present invention relates to an airbag base fabric that protects the human body from impacts such as collisions, and solves the problems of the prior art, and not only has low cost but also a low environmental load, as well as heat resistance, particularly heat. It is an object of the present invention to provide a base fabric for an air bag having a small dimensional change due to the above.

  As a result of diligent investigation in view of the background of such conventional technology, the present inventors have found that a base fabric for airbags using nylon fibers having the following characteristics has a low environmental load and is excellent in heat resistance while being low in cost. The present invention has been found.

  That is, in the airbag fabric of the present invention, at least a part of the airbag fabric is 195 to 220 ° C. at the highest stress obtained from the heat shrinkage stress curve, and the copper compound is copper. A base fabric for an air bag characterized by being a polycapramide fiber containing 10 to 500 ppm of metal.

In addition, the airbag fabric of the present invention is preferably in the following forms (a) to (e), and includes side airbags, knee airbags, inflatable curtain air as well as driver and passenger airbags. It can be suitably used for various airbag applications such as bags and airbags.
(A) Temperature at which DSC (differential scanning calorimetry) melting peak temperature in the constant length constraint method of polycapramide fiber is 222 to 270 ° C., and tan δ exhibits a maximum value in a temperature dependence test of dynamic viscoelasticity (Tmax) is 90 to 120 ° C.
(B) The strength of the polycapramide fiber is 6 to 11 cN / dtex, the elongation is 15 to 35%, the boiling water shrinkage is 5 to 15%, the total fineness is 100 to 840 dtex, and the single yarn fineness is 1 to 15 dtex.
(C) The polycapramide fiber contains other heat-resistant agent in addition to the copper compound.
(D) The heat-resistant agent added with a copper compound is an aromatic mercapto compound, and contains 300 to 3000 ppm of the aromatic mercapto compound.
(E) The single yarn cross section of the polycapramide fiber is an irregular cross section. The cross section of the single yarn is more preferably flat.

  According to the present invention, an air bag base fabric excellent in heat resistance, in particular, aging pressure resistance, can be obtained with good yarn-forming properties by using a polycapramide fiber excellent in heat-resistant strength retention. In addition, it is possible to obtain an airbag base fabric that is low in cost and has a low environmental load.

  In response to the “Act on Recycling Used Cars” scheduled to be enforced in January 2005, it is desired that airbags, which are safety devices for automobiles, can also be recycled. The base fabric for airbags of the present invention needs to use polycapramide fibers in order to facilitate recycling. Compared to polyamides obtained by polycondensation of dicarboxylic acid and diamide represented by nylon 6-6 fiber, polycapramide fibers obtained by polycondensation of aminocarboxylic acid or its lactam are easy to reuse by depolymerization. Excellent recyclability of base fabric for bags. Polyamide fiber obtained by polycondensation of aminocarboxylic acid or its lactam includes nylon 10 and the like in addition to polycapramide fiber, but from the viewpoint of price, polycapramide fiber is essential.

  From the viewpoint of easy recycling, it is preferable that all components such as warp, weft and sewing thread constituting the airbag fabric of the present invention are the same material, but not limited thereto, and at least a part of polycapramide fiber is used. Use it.

  In addition, the polycapramide fiber used for the airbag fabric of the present invention may contain a copolymer compound, a different polymer, or the like as long as the effect of the invention is not impaired, preferably 10% by weight or less.

Regarding the polycapramide fiber used in the airbag fabric of the present invention, the temperature at the maximum stress (T _ΔSmax ) determined from the heat shrinkage stress curve needs to be 195 to 220 ° C., and a preferable range of T _ΔSmax is as _follows . Examples include 197 ° C to 220 ° C. The heat shrinkage stress at that time is 0.2 to 0.5 cN / dtex in most cases. T _ΔSmax indicates the temperature at which the force at which the fiber contracts is _maximized , that is, the mobility of the molecular chain. When T _ΔSmax is less than 195 ° C., the molecular chain in the polycapramide fiber tends to move when the airbag base fabric is stored in a vehicle or a warehouse. That is, while being repeatedly exposed to a high temperature atmosphere and a low temperature atmosphere, there is a possibility that the characteristics at the time of designing the base fabric for an air bag may change due to the shrinkage accompanying the molecular motion of the polycapramide fiber, as well as repeated shrinkage and relaxation. As a result, the base fabric for the airbag is misaligned, and the pressure resistance of the base fabric is deteriorated, that is, the air permeability of the base fabric is increased. A higher T _ΔSmax is preferable, but it is currently difficult to produce a polycapramide fiber having a T _ΔSmax exceeding 220 ° C.

  Further, it is essential to contain 10 to 500 ppm of a copper compound as the amount of copper metal in order to prevent the heat and strength deterioration of the polycapramide fiber constituting a part of the airbag fabric of the present invention. When the amount of copper metal is less than 10 ppm, the effect of improving the heat resistance by the copper compound is low, and when the amount of copper metal exceeds 500 ppm, there is a risk that the copper compound becomes a foreign substance and the spinning performance is deteriorated. The amount of copper metal contained is preferably 20 to 300 ppm, more preferably 30 to 250 ppm.

  Examples of the copper compound include, but are not limited to, copper iodide, copper chloride, copper bromide, and the like, and conventionally known inorganic and organic copper salts and simple copper metals can be used.

  It is preferable that the polycapramide fiber constituting a part of the airbag fabric of the present invention contains other heat-resistant agent in addition to the copper compound.

  Examples of the heat-resistant agent include amine compounds, mercapto compounds, phosphorus compounds, hindered phenol compounds, halogen compounds, alkali metal halides, alkaline earth metal halides, etc., but are not limited thereto, and these Two or more types may be combined. By including other heat-resistant agents in addition to the copper compound, it is possible to dramatically improve the thermal oxidation degradation characteristics of the polycapramide fibers used in the airbag fabric. In this case, the amount of the heat-resistant agent added is preferably 300 to 3000 ppm from the viewpoints of thermal oxidative degradation prevention and yarn-forming properties.

  Examples of amine compounds include N, N′-diphenyl-p-phenylenediamine, diallyl-p-phenylenediamine, and di-β-naphthyl-p-phenylenediamine. Examples of mercapto compounds include 2-mercaptobenzo Examples thereof include imidazole and 2-mercaptothiazole. Examples of the phosphorus compound include, but are not limited to, stearyl phosphate, organic / inorganic phosphoric acid such as phosphorous acid or a salt thereof, and the like.

  However, as the heat-resistant agent added together with the copper compound, a mercapto compound is preferable, and it is most preferable to combine 2-mercaptobenzimidazole in particular.

  The copper compound and the heat-resistant agent may be added separately or may be added after forming a complex.

  The sulfuric acid relative viscosity of the polycapramide fiber used in the airbag fabric of the present invention is preferably 3 to 4.5. It is difficult to obtain polycapramide fibers having a high degree of polymerization with a relative viscosity of sulfuric acid exceeding 4.5 with high productivity and low cost. Moreover, when the relative viscosity of sulfuric acid is less than 3, it is difficult to obtain a fiber having a desired strength, and there is a possibility that the physical properties are greatly deteriorated during long-time storage.

  The polycapramide fiber used for the airbag fabric of the present invention preferably has a DSC melting curve melting peak temperature of 222 to 270 ° C by the constant length constraint method, and more preferably 225 ° C to 240 ° C. Moreover, it is preferable that the crystal fusion heat amount at that time is 30-100 J / g. The melting peak temperature in the DSC curve in the constant length constraint method corresponds to the degree of crystal orientation of the molecule, and the heat of crystal melting corresponds to the amount of crystal. If the melting peak temperature is less than 222 ° C, the crystal orientation of the polycapramide fiber molecular chain is low, that is, the degree of freedom of molecules in the crystal is high, so the molecular chain in the crystal can move easily at high temperatures and the crystal may collapse. It is difficult to obtain a base fabric for an air bag having excellent heat resistance as in the present invention. In addition, when the melting peak temperature exceeds 270 ° C., it is necessary to apply high stress to the fiber in the fiber manufacturing process, so that the fiber is easily broken and stable production of the polyamide fiber becomes difficult.

  In addition, when the heat of crystal fusion is less than 30 J / g, the amount of crystals in the fiber is small, so it is difficult to obtain a polycapramide fiber having excellent heat resistance, and the fiber with a heat of crystal fusion exceeding 100 J / g is stable. This is difficult to obtain with current technology.

  The polycapramide fiber used for the airbag fabric of the present invention preferably has a temperature (Tmax) of 90 to 120 ° C. when tan δ exhibits a maximum value in a dynamic viscoelasticity temperature dependence test. Tmax obtained by the temperature dependence test of dynamic decisiveness corresponds to the movement restraining force of the molecular chain, and the higher the Tmax, the larger the movement restraining force of the molecular chain. When Tmax is less than 90 ° C., fibers having high molecular chain mobility at high temperatures, that is, excellent heat resistance cannot be obtained. In addition, it is currently difficult to obtain fibers having a Tmax higher than 120 ° C. with good spinning properties.

  The total fineness of the polycapramide fiber of the present invention is preferably 100 to 840 dtex, and the single yarn fineness is preferably 1 to 15 dtex. In order to make the airbag fabric thinner, it is preferable that the total fineness is originally small. However, when the total fineness is less than 100 dtex, the productivity of the raw yarn is reduced, resulting in an increase in cost, and when the airbag is deployed, the airbag may burst due to partial lack of strength. The safety of the human body may be impaired. When the total fineness exceeds 840 dtex, safety is ensured, but the resulting airbag base fabric is a thick product with poor storage. As a preferable total fineness, a range of 200 to 500 dtex can be exemplified.

  In addition, as the fiber having a smaller single yarn fineness is used, the obtained base fabric is more flexible and better in storage property, and the covering property is improved and the air permeability of the base fabric can be suppressed. For this reason, the smaller the single yarn fineness, the better. However, when the single yarn fineness is less than 1 dtex, the single yarn may break due to friction of a guide or the like during weaving or the like, which may deteriorate the process passability. When the single yarn fineness exceeds 15 dtex, the storage property of the base fabric is deteriorated, and further, there is a possibility that the sufficient function as an airbag base fabric may not be achieved with an increase in air permeability. Examples of the preferable single yarn fineness range include 1.5 to 7 dtex, and more preferably 1.5 to 5 dtex.

  In addition, various additives such as a light proofing agent, a flame retardant, a pigment, a flame retardant, a matting agent, and a lubricant may be used for the polycapramide fiber used in the airbag fabric of the present invention.

  The polycapramide fiber used for the airbag fabric of the present invention preferably has a strength of 6 to 11 cN / dtex and an elongation of 15 to 35%. When the strength is less than 6 cN / dtex, the number of fibers required when obtaining a base fabric having the strength required as an airbag base fabric is increased. The product is thick and inferior in storage. There is no particular upper limit to the strength, but it is difficult with current technology to obtain a fiber having a strength exceeding 11 cN / dtex at low cost.

  When the elongation is less than 15%, it is not possible to obtain satisfactory shock absorption characteristics when the airbag is inflated. There is essentially no upper limit to the elongation, but when a polycapramide fiber that satisfies the scope of the present invention is produced, most of the elongation is 35% or less.

  The boiling water shrinkage of the polycapramide fiber needs to be 5 to 15%. When the boiling water shrinkage rate is larger than the above range, the dimensional stability is deteriorated, so that there is a possibility of causing problems such as wrinkles and air permeability variation of the obtained base fabric. The lower the boiling water shrinkage rate, the better. However, it is difficult to obtain fibers satisfying the boiling water shrinkage rate of less than 5% with the current technology.

  The single-filament cross-section of the polycapramide fiber used in the airbag fabric of the present invention may be an irregular cross-section, and the cross-sectional shape is flat, triangular, C-type, Y-type, dumpling type, hollow type, or those Combinations and the like can be exemplified, but are not limited thereto. However, a flat cross-section yarn that can reduce the thickness of the base fabric during weaving, improve the storage capacity of the base fabric for airbags, and reduce the amount of coating agent due to less surface irregularities when used as a coated airbag It is preferable that There is no particular rule for the flatness and the degree of profile, and it is sufficient that the profile cross-section yarn can be obtained with good productivity.

  The number of entanglement of the polycapramide fibers used for the airbag fabric of the present invention is preferably 3 to 50 / m, more preferably 3 to 30 / m, and still more preferably 3 to 20 / m. When the number of entanglements is less than 3 / m, the single yarn is caught by a loom or the like during weaving or the like and the process passability is deteriorated.

  The number of entanglement of the polycapramide fibers obtained by disassembling the airbag fabric of the present invention is preferably 10 pieces / m or less, and more preferably 5 pieces / m or less. The number of entanglement of the polycapramide fiber obtained by decomposing the base fabric indicates the number of entanglement of the polycapramide fiber in the base fabric. When the number of entanglement of the polycapramide fiber obtained by disassembling the base fabric exceeds 5 / m, there are many irregularities due to the entangled portion in the base fabric, the deterioration of the air permeability of the base fabric for airbag and the thickness of the meat There is concern about thickening.

  The airbag fabric of the present invention is low in cost as compared with the airbag fabric using the nylon 6-6 fiber that is usually used, as long as the above-mentioned polycapramide fiber is used as at least a part of the constituent elements. However, from the viewpoint of recycling, at least 50% by weight is preferably the above-mentioned polycoupler fiber, and all of the warp and the weft are preferably made of the above-mentioned polycoupler fiber.

  Next, a method for producing a polycapramide fiber used in the airbag fabric of the present invention will be described with reference to FIG. 1, but the method for producing a polycapramide fiber is not limited thereto.

  A polycapramide resin having a relative viscosity of 3 to 4.5 sulfuric acid mixed with a copper compound, an aromatic amine compound, an aromatic mercapto compound, a phosphorus compound, and a hindered phenol compound in advance is melted and spun from the die 1. The spinning temperature can be appropriately changed depending on the type and amount of the compound to be copolymerized, but is preferably 250 to 320 ° C. When spinning at less than 250 ° C, there is a possibility that sufficient fluidity cannot be obtained when the polymer is melted. At temperatures exceeding 320 ° C, the polymer is decomposed, and the polycapramide fiber used in the present invention cannot be obtained. There is sex. When producing a modified cross-section yarn, it may be designed so as to obtain a fiber having a cross-section intended for the shape of the die hole.

  A slow cooling region composed of the heating tube 2 or the heat insulating tube may be provided immediately below the spinneret 1 and the spun yarn may be passed through a high temperature atmosphere of 180 to 350 ° C.

  The spun unstretched yarn is then preferably cooled and solidified by blowing air of 10 to 100 ° C., preferably 15 to 75 ° C., with the cooling device 3. When the cooling air is less than 10 ° C., a large cooling device is required separately from the normal device, which is not preferable. In addition, when the cooling air exceeds 100 ° C., the single yarn swaying during spinning becomes large, so that the single yarns collide with each other, making it difficult to produce fibers with good yarn forming properties. The cooling device 3 by air cooling may be a horizontal blowing type or an annular blowing type.

  The unstretched yarn that has been cooled and solidified is then applied with an oil agent by an oil supply device 4 having an oil agent roller. The oil agent may be aqueous or non-aqueous, but is preferably a non-water-containing oil in consideration of the hygroscopic properties of polycapramide. Preferred examples of the oil composition include an alkyl ether ester as a smoothing agent component, an alkylene oxide adduct of a higher alcohol as a surfactant component, and a non-aqueous oil agent in which an organic phosphate salt or the like is diluted with mineral oil as an extreme pressure agent component. .

  The unstretched yarn to which the oil agent is applied is wound around the take-up roller 5 and taken up. The undrawn yarn that has been taken up is subjected to a drawing step after being wound up or continuously without being wound up. Similar to the take-up roller 5, a Nelson type roller having two rollers as a unit is a yarn feeding roller 6, a first stretching roller 7, a second stretching roller 8, a first relaxing roller 9, and a second relaxing roller 10. Are arranged side by side, and the drawing heat treatment is performed by sequentially winding the yarn, but the number of drawing stages is not particularly limited.

  Usually, stretching is performed between the take-up roller 5 and the yarn supply roller 6 in order to converge the yarn. A preferable stretch ratio is in the range of 1 to 5%. The surface temperature of the take-up roller 5 may be 20 to 80 ° C.

  Stretching is performed between the yarn feeding roller 6 and the first stretching roller 7 and between the first stretching roller 7 and the second stretching roller 8. The temperature of the yarn feeding roller 6 is 30 to 170 ° C., and the temperature of the first stretching roller 7 is The yarn is stretched at 90 to 230 ° C. When the two-stage stretching method is adopted, the stretching ratio at each stage number can be appropriately changed depending on the stretching conditions. Here, in order to obtain a polycapramide fiber in which the temperature at the maximum stress obtained from the heat shrinkage stress curve falls within the range of the present invention, a heat setting roller, that is, the first stretching roller 7 in the case of one-stage stretching, two-stage stretching. In this case, it is important that the temperature of the final stretching roller such as the second stretching roller 8 is 150 to 230 ° C, preferably 190 to 220 ° C.

  The yarn after heat setting is subjected to a relaxation (relaxation) treatment of 7% or less, more preferably 0.5 to 5% between the second stretching roller 8 and the first relaxation roller 9. In order to obtain a base fabric for an air bag excellent in heat resistance, it is preferable to perform a relaxation process of 7% or less between the first relaxation roller 9 and the second relaxation roller 10 as the second relaxation process.

  The yarn subjected to the relaxation treatment is wound up by the winder 12. In the relaxation treatment, not only the strain caused by thermal stretching can be removed, but also the structure achieved by stretching can be fixed, the orientation of the amorphous region can be relaxed, and the thermal shrinkage rate can be lowered. As the relaxation roller, a non-heated roller or a roller heated to 160 ° C. or less is used. Even when a non-heated roller is used, the surface temperature of the first relaxation roller 9 is normally 120 ° C. or higher due to heat brought in from the stretching process.

  Further, in order to reduce the generation of fuzz and obtain a high-quality polycapramide fiber, a high-pressure fluid is sprayed on the fiber yarn between the yarn feeding roller 6 and the first drawing roller 7 in which one-stage drawing is performed, The yarn constituting the fiber may be slightly entangled and stretched while converging the yarn.

  The device for entanglement of the yarn is usually just before winding the yarn, and in the case of this production example, the entanglement nozzle 11 is installed between the second relaxing roller 10 and the winder 12 to give the yarn entanglement. To do. Thus, the polycapramide fiber used for the airbag fabric of the present invention can be obtained.

  The airbag fabric of the present invention has a tensile strength measured according to JIS L1096 (6.12.1A method) of preferably 500 N / cm or more, and more preferably 550 N / cm or more. The tear strength measured by the method of JIS L1096 (6.15.2A-2 method) and obtained from the average value in the warp direction and the weft direction is preferably 200 N or more, more preferably 250 N or more. Airbag base fabrics having such a tensile strength and tear strength within this range include all types of airbag fabrics such as driver airbags, passenger airbags, side airbags, knee airbags, and airbags for inflatable cartons. It is possible to withstand the impact force at the time of unfolding the back when applied to any of the above. The higher the tensile strength value and tear strength value of the airbag fabric, the better.

  The thickness of the base fabric for an air bag of the present invention is preferably 0.15 to 0.5 mm, and more preferably 0.2 to 0.35 mm. The airbag fabric having a thickness in such a range has sufficient heat resistance against the high-temperature gas injected from the inflator, and can be suitably mounted on a small vehicle or the like that requires stricter storage.

  When the polycapramide yarn used for the airbag fabric of the present invention has an atypical cross-section, particularly a flat cross-section, when compared with the thickness of the base fabric made of a conventional circular cross-section yarn, compared with the same cover factor, It can be made thinner by about 15% or more, and is characterized by excellent compactness and storage.

The cover fabric for the airbag of the present invention preferably has a cover factor of 1500 to 2400, more preferably 1700 to 2200. Here, the cover factor is the total fineness of the warp D ₁ (dtex), the weave density N ₁ (lines / 2.54 cm), the total weft fineness D ₂ (dtex), and the weave density N ₂ (lines / 2.54 cm), it is a value represented by (D ₁ × 0.9) ^1/2 × N ₁ + (D ₂ × 0.9) ^1/2 × N ₂ . The cover factor is directly related to the storage properties such as the thickness and flexibility of the base fabric, and mechanical properties such as tensile strength and tear strength. .

The air bag base fabric of the present invention has an air permeability according to the method of JIS L1096 (1990) (6.27.1A method). In a fabric sample having a length of 20 cm and a width of 15 cm, a laminar flow tube type is used in a circular portion having a diameter of 10 cm. It is preferable that the amount of air (cc / cm ² / sec) that passes when air adjusted to a pressure of 19.6 KPa is passed using an air permeability meter is 0 to ²⁰ cc / cm ² / sec. When the air permeability exceeds 20 cc / cm 2 / sec, when the airbag is inflated due to a collision or the like, the air inside the airbag may leak to the outside, and the safety of the passenger may be impaired.

  The airbag base fabric of the present invention can be suitably used regardless of the presence or absence of coating. Silicone resin, chloroprene resin, polyurethane resin, and the like can be used as the resin elastomer applied to the surface of the base fabric when coating is performed, and among these, silicone resin is preferable. When the polycapramide fiber used in the airbag fabric of the present invention has an atypical cross section, particularly a flat cross section, the unevenness of the surface of the base fabric is reduced, so that the effect of reducing the resin adhesion can be expected.

0.1-80 g / m < ² > is preferable, as for the resin elastomer adhesion amount coated on the base fabric surface for airbags, More preferably, it is 5-30 g / m < ² >, More preferably, it is 10-20 g / m < ² >. When the resin adhesion amount is less than 0.1 g / m ² , it is difficult to uniformly apply the resin to the entire surface of the base fabric, and there is a risk of causing air leakage when the airbag is inflated or bursting due to stress concentration. Further, when the resin coating amount exceeds 80 g / m ² , the storage property and flexibility may be deteriorated.

  Next, although the manufacturing method of the base fabric for airbags of this invention is illustrated, it is not limited to this.

  The polycapramide fiber obtained by the above production method is warped and woven. The loom is often a water jet type, but is not limited to a rapier type or an air-jet type. In addition, the base fabric is usually plain weave, but any structure such as oblique weave, satin weave, or a combination thereof may be used.

  Further, the above obtained base fabric may be subjected to a heat and pressure processing, so-called calendar processing. The calendering machine may be an ordinary calendering machine. The calendering temperature is preferably 180 to 220 ° C., the pressure is 3000 to 10000 N / cm, and the speed is preferably 4 to 50 m / min. If the calendering is performed on at least one side, sufficient performance can be obtained.

  If necessary, the base fabric is coated with a resin elastomer and heat set to form a base fabric for a coated airbag. In some cases, scouring can be performed after weaving, and the resin elastomer can be subsequently applied.

  As a method of coating the surface of the base fabric with a resin elastomer, the base fabric is immersed in a resin solution tank, and then excess resin is removed and homogenized using a mangle, vacuum, coating knife, etc., spray device And a method of spraying resin using a forming apparatus is common. Of these, the knife coating method is preferable from the viewpoint of applying the resin uniformly and in a small amount, but it is not limited at all.

  As described above, the resin elastomer to be applied is preferably a silicone resin, chloroprene resin, polyurethane resin, polyamide-based resin, or the like that is excellent in flame retardancy, heat resistance, air blocking property, and the like.

  Note that the order of the high-order processing is not limited as long as the effects of the present invention are not impaired.

  Thus, the airbag fabric of the present invention can be obtained. When the obtained airbag base fabric is used as an airbag, it is preferable that the sewing thread is made of the same material as the airbag base fabric or a material that can be easily separated by a specific gravity difference from the viewpoint of facilitating recycling.

  Hereinafter, embodiments of the present invention will be described in more detail by way of examples. The definition and measurement method of the characteristics used in the specification text and examples are as follows.

[Fineness, strength, elongation, shrinkage of boiling water]
It measured according to JIS L1017 (2002).

[Temperature measurement at maximum stress obtained from heat shrinkage stress curve]
A sample was set in a strain gauge with a length of 25 cm and an initial load of 0.045 cN / dtex. In a dry heat state, the temperature was increased from 25 ° C. to 150 ° C. at a rate of temperature increase of 10 ° C./min, and from 150 ° C. to 250 ° C. at a rate of temperature increase of 3 The shrinkage stress when the temperature was raised at 0 ° C./min was detected with SS-207D-UE manufactured by Toyo Baldwin, and after drawing a heat shrinkage stress curve, the temperature at which the shrinkage stress was maximized was determined. TKC-IIIS manufactured by Toyo Baldwin Co. was used as a heating furnace. The measurement was performed twice for each sample, and the average value was adopted.

[DSC measurement by the fixed length constraint method]
J. Polym. Sci. Phy. Ed., VOL. 15, 1507 The following measurement was carried out according to the method of Todoki et al. Described in “Melting of Constrained Drawn Nylon 6 Yarns”. The weighed fiber sample is wrapped around a 4 x 2.5 x 0.4 mm ³ aluminum plate so that there is no slack, and is fixed to the aluminum plate using a thin wire tied to both ends of the sample, and placed in an aluminum standard container for measurement. A sample was used. The measurement was performed from 30 ° C. to 250 ° C. using a SSC5200 thermal analysis system manufactured by Seiko Instruments Inc. at a heating rate of 10 ° C./min. Each sample was measured twice and the average value was adopted.

[Dynamic viscoelasticity measurement]
Using a DDV-II type dynamic viscoelasticity measuring device manufactured by Orientec Co., Ltd., measuring at a frequency of 110 Hz and a temperature rising rate of 3 ° C./min in the range from room temperature to 200 ° C., the loss tangent (tan δ) The temperature at which the peak was maximum was determined. Each sample was measured twice and the average value was adopted.

[Number of confounding]
The number of entangled portions having a length of 1 mm or more was measured by a water immersion method and converted to the number per 1 m. A water immersion bath having a length of 70 cm, a width of 15 cm, and a depth of 5 cm, and a partition plate provided at 10 cm from both ends in the longitudinal direction was used. The bath was filled with pure water to a depth of about 3 cm, the raw yarn sample was immersed in water, and the number of entangled portions was measured. In addition, in order to exclude the influence of impurities, such as an oil agent, the pure water was replaced | exchanged for every measurement. The average of the measurement results of 10 raw yarns was taken as the number of entanglements.

[Sulfuric acid relative viscosity]
A polymer sample was dissolved in 98% sulfuric acid at a concentration of 1% by weight, measured at 25 ° C. using an Ostwald viscometer, and determined according to the following formula. Sulfuric acid relative viscosity (ηr) = (sample solution dropping time) / (sulfuric acid solution dropping time). Each sample was measured twice and the average value was adopted.

[Spinning property]
The evaluation was made in two stages from the occurrence of yarn breakage and fluff when continuous spinning was performed.
○: Good and stable long-time yarn production is possible. Fluff incidence is less than 1 / 10,000m.
X: Unstable. Fluff incidence is 1 / 10,000m or more.

[Heat resistance retention test]
The tensile strength after the fiber was left in a constant temperature oven at 180 ° C. for 40 hours under no load condition was measured, and the strength retention was determined according to the following formula. {Strength retention (%)} = {Strength before heat test} / {Strength after heat test} × 100. Each sample was measured twice and the average value was adopted.

[Basement air permeability]
A base fabric sample having a length of 20 cm and a width of 15 cm was stretched and held in the vertical direction, and the amount of air passing through when air adjusted to a pressure of 19.6 kPa was passed through the center was measured. Each sample was measured twice and the average value was adopted.

[Measurement of fabric permeability after forced heat treatment]
The obtained base fabric was heat-treated in an oven at 120 ° C. for 50 hours and then allowed to stand in a 25 ° C. atmosphere for 50 hours, and then the cycle was repeated five times. The amount of air passing through when the air adjusted to a pressure of 19.6 kPa was passed through the central portion was measured. Each sample was measured twice and the average value was adopted.

(Example 1, Comparative Example 1, Comparative Example 2)
Extruder extruder is a polycapramide polymer (sulfuric acid relative viscosity 3.8) to which copper iodide is added so as to have a copper metal content shown in Table 1, and 2-mercaptobenzimidazole is added in the amount shown in Table 1. And continuously melted at 285 ° C. The melted polymer passed through a pipe at 285 ° C., was measured with a gear pump so as to have the fineness shown in Table 1, and then led to a spin pack at 290 ° C. In the pack, it passed through a 15-micron cut filter, and the yarn was extruded from a die having a hole diameter of 0.3 mm, a hole length of 0.4 mm, and a hole number of 72. A 25 cm heating cylinder was attached just below the base, and the inside atmosphere temperature was heated to 250 ° C. The in-cylinder atmosphere temperature here is the air layer temperature at a portion 1 cm away from the inner wall of the central portion of the heating cylinder. A uniflow type chimney was installed immediately below the heating cylinder, and cold air of 30 ° C. was blown onto the yarn at a speed of 40 m / min to solidify by cooling. After applying an oil agent to the solidified yarn, it was taken up with a take-up roller without being wound once.

  The taken yarn is stretched between the take-up roller and the yarn feeding roller, the first stage is drawn between the yarn feeding roller and the first drawing roller, and the second stage is drawn between the first drawing roller and the second drawing roller. Was stretched. The stretched yarn was subjected to a relaxation treatment between the second stretching roller and the first relaxation roller, and further subjected to a relaxation treatment between the first relaxation roller and the second relaxation roller, and wound with a winder.

  The temperatures of the take-up roller, the yarn feeding roller, the first stretching roller, the second stretching roller, the first relaxing roller, and the second relaxing roller are respectively unheated, 50 ° C., 100 ° C., 200 ° C., 150 ° C., 150 ° C., The surface speed of the roller is 941 m / min, 988 m / min, 2917 m / min, 3763 m / min, 3612 m / min, 3500 m / min, the number of windings of the yarn on the roller is 3, 3, 5, 9 times. 5 times and 5 times. The total draw ratio at this time was 4.5 times, and 80% of the overall relaxation rate was performed in the first-stage relaxation step. The properties of the obtained fiber are shown in Table 1.

  The resulting polycapramide fiber is warped at a speed of 300 m / min, and then weaved using a water jet loom (ZW303) manufactured by Tsudakoma at a weaving density of 50 yarns / inch and a rotational speed of 1000 rpm, respectively. Got. The obtained raw machine was directly passed through a heat treatment apparatus, passed through a drying zone at 100 ° C., and then subjected to heat treatment at 180 ° C. for 1 minute to obtain an airbag base fabric. The properties of the obtained base fabric are shown in Table 1.

(Example 2)
The surface speed of each of the take-up roller, the yarn feeding roller, the first stretching roller, and the second stretching roller was changed so that the relaxation rate was 10%, and the discharge amount was adjusted so that the total fineness described in Table 1 was obtained. Except that, the same procedure as in Example 1 was performed.

(Example 3)
The discharge amount of the polymer was changed to the fineness shown in Table 1, and the same drawing ratio was used as in Example 1 except that the drawing ratio between the rollers was the same and the overall drawing ratio was 4.7 times.

(Example 4)
The hole length is 0.6 mm, the shape is the same as that of Example 1 of Japanese Patent Application Laid-Open No. 2003-55861, the yarn is extruded from the mouthpiece with 72 holes, and the take-up roller, the yarn feeding roller, The temperatures of the first stretching roller, the second stretching roller, the first relaxing roller, and the second relaxing roller are respectively unheated, 50 ° C., 100 ° C., 200 ° C., 150 ° C., 150 ° C., and the roller surface speed is 941 m / min. 988 m / min, 2917 m / min, 3763 m / min, 3612 m / min, 3500 m / min, and the number of times the yarn was wound on the roller was 3, 3, 5, 9, 5, 5 Except for this, the same procedure as in Example 1 was performed.

(Comparative Example 3)
The stretching ratio between the rollers was the same, and the same procedure as in Example 1 was performed except that the overall stretching ratio was 2.5 times and the relaxation rate was 4%. Further, 100% of the relaxation treatment was performed in the first-stage relaxation process, and the second-stage relaxation rate was 0%.

(Comparative Example 4)
The same operation as in Example 1 was performed except that the temperature of the second stretching roller was 100 ° C.

(Example 5)
The same procedure as in Example 1 was performed except that the polymer was measured using a die having a number of holes of 108 so that the total fineness shown in Table 1 was obtained.

(Example 6)
This was carried out in the same manner as in Example 1 except that the weight of the polymer was reduced so that the total fineness shown in Table 1 was obtained using a base having 30 holes.

  As is apparent from Table 1, the polycapramide fiber constituting the airbag fabric of the present invention is excellent in strength retention after the heat test, and the airbag fabric using the fiber is also in a high temperature atmosphere. Has excellent strength retention when exposed. In addition, if the strong retention after a heat test is 65% or more, it can be said that it has sufficient heat resistance for actual use as an airbag base fabric.

  When a polycapramide fiber inferior in strength retention after a heat resistance test as in Comparative Example 1 is used as a base fabric for an air bag, there is a concern that the air bag may burst during a collision or the like in actual use in a vehicle or the like. .

  Regarding Comparative Example 2, although it contained a large amount of copper metal and a heat-resistant agent, it not only had a strong retention after heat test almost the same as Example 2, but also had poor yarn-making properties. It was.

In addition, the airbag fabric using the polycapramide fibers whose T _ΔSmax is outside the range of the present invention has an overwhelmingly large air permeability after the forced heat treatment compared to the air permeability before the heat treatment. It was inferior to.

  Further, the base fabric using the polycapramide fiber of Example 5 was thicker and slightly inferior to the base fabric obtained in Examples 1 to 4, but the daily fabric pressure resistance It was excellent in properties. The base fabric using the polycapramide fiber of Example 6 was slightly inferior in air permeability of the base fabric after weaving, but was excellent in the daily pressure resistance of the base fabric.

It is an example of the manufacturing method of the polycapramide fiber which comprises the base fabric for airbags of this invention.

Explanation of symbols

1: Spinneret 2: Heating cylinder 3: Cooling device 4: Oiling device 5: Take-up roller 6: Yarn feeding roller 7: First stretching roller 8: Second stretching roller 9: First relaxing roller 10: Second relaxing roller 11: Entangling device 12: Winder

Claims (7)

At least a part of the airbag base fabric has a maximum stress temperature (T _ΔSmax ) determined from a heat shrinkage stress curve of ₁₉₅ to 220 ° C., and contains a copper compound as a copper metal content in an amount of 10 to 500 ppm. A base fabric for an air bag characterized by being a polycapramide fiber.  The DSC (Differential Scanning Calorimetry) melting peak temperature in the constant length constraint method of the polycapramide fiber is 222 to 270 ° C., and the temperature at which tan δ shows the maximum value in the temperature dependence test of dynamic viscoelasticity (Tmax The base fabric for an air bag according to claim 1, wherein the temperature is 90 to 120 ° C.   The polycapramide fiber has a strength of 6 to 11 cN / dtex, an elongation of 15 to 35%, a boiling water shrinkage of 5 to 15%, a total fineness of 100 to 840 dtex, and a single yarn fineness of 1 to 15 dtex. The base fabric for airbags as described in 1 or 2.   The base fabric for an air bag according to any one of claims 1 to 3, wherein the polycapramide fiber contains another heat-resistant agent in addition to the copper compound.   The base fabric for an air bag according to claim 4, wherein the heat-resistant agent is an aromatic mercapto compound and contains 300 to 3000 ppm of the aromatic mercapto compound.   The base fabric for an air bag according to any one of claims 1 to 5, wherein a single yarn cross section of the polycapramide fiber is an irregular cross section.   The airbag fabric according to claim 6, wherein the polycapramide fiber has a flat cross section.

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