Polyamide composition containing low silicon, method for producing same, and fiber, woven

Abstract

According to the present invention, it is possible to provide a polyamide composition in which, during melt processing such as melt spinning, the flow path of a filter of a processing device or a filter of a processing device is not easily clogged, and the processing device can be continuously operated for a long period of time. The present invention provides a regenerated polyamide composition containing a silicon compound, in which the silicon atom content quantified by X-ray fluorescence analysis is 1000 ppm or less.

Description

Technical Field

[0001] The present invention relates to a polyamide composition capable of preventing clogging of a processing apparatus for a long time continuously with less clogging during melt processing, a method for producing the same, and fibers, woven fabrics, and airbags. Background Art

[0002] Polyamides such as polyamide 6 and polyamide 66, which are representative engineering plastics, have heat resistance and good mechanical properties, and are widely used in fibers, automotive parts, electrical product parts, etc., and have become one of the irreplaceable materials in modern society. Among them, in particular, polyamide 66 used in applications requiring heat resistance and durability in harsh environments is of very high importance.

[0003] In recent years, in order to save resources and achieve carbon neutrality, technological development on the reuse of plastics has been actively carried out, and polyamides are no exception.

[0004] Reuse is roughly classified into: granulating again the substance that has been formed once, which is called material recycle, and recycling monomers through depolymerization, which is called chemical recycle. In material recycle, since the deterioration of the polymer contained in the molded article or the added components will directly remain in the recycled polymer, there is a concern that the quality cannot be stabilized. However, since there is no chemical reaction involved and the required auxiliary raw materials are also few, and it can be completed with less input of resources and energy, material recycle is selected in cases such as recycling for fixed uses. In addition, when removing additives, coatings, etc. from processed and used polyamides recovered from factories or the market before implementing chemical recycle, the process of recycled and cleaned polyamides will also be the same as that of material recycle. Therefore, material recycle technology is also a useful technology for carrying out chemical recycle.

[0005] As described above, there are various inclusions in processed and used polyamides, so it is necessary to change the recovery method according to the use. There are various uses of polyamides, and one of the uses of polyamide 66 can be cited as automotive uses that require high safety. For example, it is used in components around the engine that require high heat resistance, or the base fabric of airbags that require durability at the time of rupture. Among them, the base fabric of airbags is less deteriorated and suitable for material recycle. Not only used airbags, but also scraps generated after cutting accessories during the manufacture or sewing of airbag base fabrics can be objects of reuse.

[0006] Generally, the base fabric of an airbag can be made by covering a woven fabric formed by spinning and weaving polyamide 66 with a silicone resin. Therefore, when material recycling the airbag base fabric, it is necessary to separate this coating from polyamide 66.

[0007] As a physical method for removing inclusions from polyamide containing inclusions to obtain a clean state, methods such as specific gravity separation after shredding recyclables can be cited (Patent Document 1). Although this method can perform separation with less energy, in the case of an airbag fabric in which inclusions and polyamide are strongly bonded due to mixing, joining, adhesion, etc., it is difficult to perform separation.

[0008] In addition, there is also a method in which a part or all of unnecessary inclusions such as silicone are dissolved and removed by a solvent (for example, Patent Document 2). The recovered polyamide is recovered in the form of shredded cloth. The used airbags and manufacturing scraps have various shapes, and it is difficult to directly reuse them in the original shape or in the shape of fiber scraps obtained by cutting them, and they must be melted and pelletized, etc.

[0009] Contrary to the aforementioned method, a method can also be considered in which polyamide is first dissolved by a solvent, then the inclusions are removed as insoluble substances, and then polyamide is precipitated and recovered by certain methods. However, the solvents for dissolving polyamide are strong acids such as formic acid and sulfuric acid or expensive solvents such as HFIP, and most solvents are not suitable for industrial use. As an example of the use of an industrially easy-to-use solvent, there is a method of dissolution and recovery with ethylene glycol (Patent Document 3). However, in this method, extremely high-temperature treatment is required, and there is a concern about the occurrence of glycolysis of polyamide, and the solvent used must be completely distilled off and dried from the slushy solid. Together with the heating during the reaction, it can be considered that a large amount of energy must be consumed. Therefore, as a method that is carried out at low temperature and uses general raw materials, there is also a dissolution method using an alcohol solution of calcium chloride. For example, Patent Document 4 describes a method in which a cloth of polyamide coated with silicone is treated with a methanol solution of calcium chloride to dissolve the polyamide, and then diluted with a large amount of water or methanol to obtain the target polyamide in powder form.

[0010] Regarding the polyamide regenerated from silicone-coated polyamide as described above, problems have been clarified when actually obtained. As a problem, it has been clarified that when this regenerated polyamide is actually used for spinning, etc., if it passes through a filter to remove foreign substances, it will immediately become clogged, and thus continuous operation is impossible. Since spinning requires continuous and stable production of products, raw materials that have eliminated as many factors restricting continuous operation as possible must be used.

[0011] On the other hand, when using polyamide fiber as the fiber for airbags, in the production process of the airbag base fabric, generally, the following operation is carried out: make the production dates of the raw filaments used within the same base fabric as close as possible. This is because when using raw filaments with different production dates, the following problems will occur: the performance unevenness of the time-dependent shrinkage of the fiber, resulting in density deviation of the base fabric, and thus causing poor appearance (hereinafter also referred to as "barre").

[0012] Prior art documents

[0013] Patent documents

[0014] Patent Document 1: Japanese Patent No. 5841598 Gazette

[0015] Patent Document 2: Japanese Patent No. 7024037 Gazette

[0016] Patent Document 3: Japanese Unexamined Patent Application Publication No. 2018-172618

[0017] Patent Document 4: Japanese Patent No. 5110704 Gazette Summary of the invention

[0018] Problems to be solved by the invention

[0019] An object of the present invention is to provide a polyamide composition that can make the flow path of a filter or the like of a processing device not easily blocked during melt processing such as melt spinning and can enable the processing device to continuously operate for a long time. Furthermore, the present invention preferably provides a polyamide raw filament that does not limit the production date interval of the raw filament and suppresses the barre defect of the base fabric.

[0020] Solutions for solving the problems

[0021] After detailed research on the blockage during processing such as spinning, it was clarified that one of the reasons lies in the silicone resin mixed into the polyamide.

[0022] When the silicone resin covers the base fabric of the polyamide, it penetrates into the interior of the fibers of the base fabric and hardens. Therefore, even if one tries to peel off the silicone, the silicone resin remaining inside the polyamide fiber will still remain in the recycled polyamide.

[0023] In the polyamide recovery method using a calcium chloride methanol solution, since the polyamide is dissolved, the residual amount of the silicone resin inside the polyamide fiber can be reduced. However, the covered silicone resin is thin and fine, and thus it will be mixed into those cut into tiny pieces by a stirring blade or the like. If only most of the peeled-off silicone is removed, the residual amount of the silicone resin in the recycled polyamide cannot be sufficiently reduced.

[0024] In-depth research was conducted to solve this problem, and as a result, it was found that recycled polyamide, which uses a polyamide base fabric covered with silicone as a raw material and is not easily clogged during spinning, can be obtained.

[0025] In addition, the inventors of the present invention conducted in-depth discussions and carried out multiple experiments. As a result, it was unexpectedly found that in order to suppress the decrease in the time-dependent shrinkage of polyamide fibers, the content of oligomers (polyamide components with a degree of polymerization of 5 or less) in the fibers is important, thus completing the invention.

[0026] That is, the present invention is as described below. [1]

[0028] A polyamide composition, which is a polyamide composition containing a silicon compound, wherein the silicon atom content quantified by X-ray fluorescence analysis is 1000 ppm or less. [2]

[0030] The polyamide composition according to [1], which is a recycled polyamide composition. [3]

[0032] The polyamide composition according to [1] or [2], wherein the silicon atom content quantified by X-ray fluorescence analysis is 30 ppm or more and 1000 ppm or less.

[0033] [3a]

[0034] The polyamide composition according to any one of [1] to [3], which is in the form of powder.

[0035] [3b]

[0036] The polyamide composition according to any one of [1] to [3], which is for fibers. [4]

[0038] The polyamide composition according to any one of [1] to [3b], wherein the silicon compound contains an organosilicon compound.

[0039] [4a]

[0040] The recycled polyamide composition according to any one of [1] to [4], which further contains a calcium compound, and the calcium atom content quantified by X-ray fluorescence analysis is 1000 ppm or less.

[0041] [4b]

[0042] The recycled polyamide composition according to any one of [1] to [4b], which further contains a zinc compound, and the zinc atom content quantified by X-ray fluorescence analysis is 1000 ppm or less. [5]

[0044] The polyamide composition according to any one of [1] to [4], wherein the content of the polyamide component having a degree of polymerization of 5 or less is 10,000 ppm or less. [6]

[0046] The polyamide composition according to any one of [1] to [5], wherein the polyamide contains polyamide 66. [7]

[0048] A method for producing a polyamide composition, which includes a step of dissolving polyamide from an organosilicon-coated polyamide base fabric, and the step is carried out using a container having a mechanism in which a portion that rotates due to external power during dissolution does not contact the organosilicon-coated polyamide base fabric.

[0049] [7a]

[0050] A production method, which is the production method of the polyamide composition according to any one of [1] to [6], and includes a step of dissolving polyamide from an organosilicon-coated polyamide base fabric, and the step is carried out using a container having a mechanism in which a portion that rotates due to external power during dissolution does not contact the organosilicon-coated polyamide base fabric.

[0051] [7b]

[0052] A production method, which is the production method of the polyamide composition according to any one of [1] to [6], and includes a step of dissolving polyamide from an organosilicon-coated polyamide base fabric, and the step is carried out using a container having a mechanism for continuously recovering the organosilicon resin generated during dissolution. [8]

[0054] According to the method for producing a polyamide composition according to any one of [7] to [7b], wherein the dissolution of the polyamide is carried out using a metal chloride alcohol solution.

[0055] [8a]

[0056] According to the method for producing a polyamide composition according to [8], wherein the metal chloride is zinc chloride or calcium chloride.

[0057] [8b]

[0058] According to the method for producing a polyamide composition according to [8a], wherein the metal chloride is calcium chloride.

[0059] [8c]

[0060] According to the method for producing a polyamide composition according to any one of [8] to [8a], wherein the alcohol is methanol. [9]

[0062] A polyamide fiber, wherein the content of the polyamide component having a degree of polymerization of 5 or less is 20,000 ppm or less, and the content of silicon atoms quantified by X-ray fluorescence analysis is 50 ppm or more and 1000 ppm or less.

[10]

[0064] A polyamide fiber obtained from the polyamide composition according to any one of [1] to [6], wherein the content of the polyamide component having a degree of polymerization of 5 or less is 20,000 ppm or less, and the content of silicon atoms quantified by X-ray fluorescence analysis is 50 ppm or more and 1000 ppm or less.

[11]

[0066] The polyamide fiber according to [9] or

[10] , wherein in the dynamic viscoelasticity measurement, tanδ does not have a peak in the range of -50 °C to +50 °C, and tanδ has a peak in the range of +90 °C to +130 °C, and the peak value of tanδ is 0.1 or more and 0.15 or less.

[12]

[0068] The polyamide fiber according to any one of [9] to

[11] , which is a multifilament having the following physical properties (1) to (7):

[0069] (1) A total fineness of 150 dtex or more and 2500 dtex or less;

[0070] (2) A strength of 6.0 cN / dtex or more and 11.0 cN / dtex or less;

[0071] (3) An elongation at break of 15% or more and 25% or less;

[0072] (4) A boiling water shrinkage rate of 4.0% or more and 11.0% or less;

[0073] (5) A finishing agent adhesion rate of 0.5% by weight or more and 1.5% by weight or less;

[0074] (6) A number of filaments of 30 or more and 400 or less;

[0075] (7) A 3-month shrinkage decrease rate of 12% or less.

[13]

[0077] The polyamide fiber according to any one of [9] to

[12] , wherein the polyamide fiber contains polyamide 66 fiber.

[14]

[0079] A base fabric for an airbag, which contains the polyamide fiber according to any one of [9] to

[13] .

[15]

[0081] An airbag, which comprises the base fabric for airbag described in

[14] .

[16]

[0083] A regenerated fiber, which is obtained by spinning the polyamide composition described in any one of [1] to [6].

[17]

[0085] A regenerated base fabric, which is woven from the regenerated fiber described in

[16] .

[18]

[0087] A regenerated airbag, which uses the regenerated base fabric described in

[17] .

[19]

[0089] A method for manufacturing a polyamide solution, which is characterized by comprising:

[0090] Put a polyamide-containing substance containing an insoluble component in a metal chloride alcohol solution and polyamide into a container made of an insoluble resin having a liquid passage hole, add the metal chloride alcohol solution containing a metal chloride and an alcohol, and stir at 120°C or lower to dissolve the polyamide, thereby separating the aforementioned insoluble component into the container.

[20]

[0092] According to the method for manufacturing a polyamide solution described in

[19] , wherein the insoluble resin is any one or more of polyethylene, polypropylene, polyurethane, polystyrene, polydimethylsiloxane, and polyester.

[21]

[0094] According to the method for manufacturing a polyamide solution described in

[19] or

[20] , wherein the solubility of the polyamide in the metal chloride alcohol solution is at most 1 wt% or more at 120°C or lower.

[22]

[0096] According to the method for manufacturing a polyamide solution described in any one of

[19] to

[21] , wherein the metal chloride is any one of calcium chloride, zinc chloride, and lithium chloride.

[23]

[0098] According to the method for manufacturing a polyamide solution described in any one of

[19] to

[22] , wherein the alcohol is methanol.

[24]

[0100] According to the method for manufacturing a polyamide solution described in any one of

[19] to

[23] , wherein the polyamide comprises: polycaprolactam and / or polyhexamethylene adipamide.

[25]

[0102] A method for manufacturing a polyamide, which precipitates the polyamide from a polyamide solution produced by the method for manufacturing a polyamide solution according to any one of

[19] to

[24] .

[0103] Effects of the Invention

[0104] According to the present invention, a recycled polyamide composition that can prevent the filter from being clogged during melt spinning and enable long-term continuous operation can be provided. In addition, a polyamide fiber that can improve the quality of the airbag base fabric can be provided. Detailed Embodiments

[0105] Hereinafter, the mode for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail.

[0106] The present invention relates to a polyamide composition and a method for manufacturing the same, etc. The polyamide composition can prevent the flow path of a filter or the like of a processing device from being clogged during melt processing such as melt spinning and enable the processing device to operate continuously for a long time.

[0107] 〈Polyamide Composition〉

[0108] In the present invention, the polyamide composition refers to a polymer formed by polymerization through an amide bond, such as a substance obtained by polycondensing a diamine compound and a dicarboxylic acid compound, or a substance obtained by ring-opening polymerization of a cyclic lactam.

[0109] The diamine compound is not particularly limited, and examples thereof include ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, nonanediamine, methylpentanediamine, p-phenylenediamine, etc.

[0110] The dicarboxylic acid compound is not particularly limited, and examples thereof include oxalic acid, glutaric acid, adipic acid, sebacic acid, terephthalic acid, isophthalic acid, etc.

[0111] The cyclic lactam is not particularly limited, and examples thereof include ε-caprolactam, undecanolactam, laurolactam, etc.

[0112] The combination of the diamine compound, the dicarboxylic acid compound, and the cyclic lactam compound is not particularly limited, and a plurality of compounds of each type can also be used in combination. The polyamide is not particularly limited, and examples thereof include polyamide 66, polyamide 6, polyamide 11, polyamide 12, polyamide 610, polyamide 612, polyamide 46, polyamide 6T, polyamide 6I, copolymers thereof, and mixtures thereof, etc. Those containing an aliphatic polyamide are preferred, those containing an aliphatic polyamide are more preferred, and those containing polyamide 66 are most preferred. If it contains polyamide 66, it can be melt-spun, has a high melting point and excellent heat resistance, is flexible, and has a low water absorption rate and is easy to process.

[0113] The polyamide composition of the present invention contains a silicon compound. Examples of the silicon compound include silicone compounds for covering polyamides. That is, it includes fine particles of silicone resin itself or organically treated silica as a filler reinforcing material for silicone resin.

[0114] As a method for quantifying the silicon compound contained in the polyamide composition, X-ray fluorescence analysis that can analyze both inorganic and organic silicon compounds is preferably used. There are no specific limitations on the detailed analysis conditions, as long as the conditions can correctly quantify the trace impurity content contained in the polyamide composition.

[0115] Based on the silicon atom content quantified by X-ray fluorescence analysis, the amount of the silicon compound contained in the polyamide composition is 1000 ppm or less, preferably 700 ppm or less, and more preferably 500 ppm or less. When the amount of the silicon compound is relatively large, it is likely to clog and continuous operation cannot be carried out. In addition, it is preferably 30 ppm or more. When the amount of polyamide components with a polymerization degree of 5 or less is small, the fiber will lose plasticity and hinder stretchability. However, by containing 30 ppm or more of silicon atoms, uniform stretching can be carried out with the silicon compound as a fulcrum during fiber production, compensating for the reduction in stretchability caused by the decrease in the oligomer component.

[0116] Elements contained in the polyamide composition of the present invention that do not originate from silicon and polyamide are not particularly limited, and calcium and zinc (for example, in the form of calcium compounds and zinc compounds) can be cited. Based on the calcium atom content quantified by X-ray fluorescence analysis, the amount of calcium contained in the polyamide composition is preferably 1000 ppm or less, more preferably 700 ppm or less, and further preferably 500 ppm or less. Regarding the amount of zinc contained in the polyamide composition, based on the zinc atom content quantified by X-ray fluorescence analysis, it is preferably 1000 ppm or less, more preferably 700 ppm or less, and further preferably 500 ppm or less. Regarding calcium and zinc, although the influence on clogging during spinning is small, these compounds are prone to absorbing water. When the polyamide composition is melted while maintaining a water-containing state, hydrolysis will occur and the molecular weight will decrease, resulting in a reduction in the durability of the molded article.

[0117] Regarding the content of polyamide components with a degree of polymerization of 5 or less (hereinafter sometimes referred to as "oligomers") in the polyamide composition, based on the content of polyamide components with a degree of polymerization of 5 or less quantified by GPC analysis, it is preferably 10,000 ppm or less, more preferably 5,000 ppm or less, further preferably 2,500 ppm or less, and still further preferably 2,000 ppm or less. In the present embodiment, the degree of polymerization represents the number of the smallest repeating unit structures constituting the polyamide, and the unit structures can be repeated linearly or cyclically. When the amount of polyamide components with a degree of polymerization of 5 or less is large, the mechanical strength after molding will decrease, so it is preferable that the content of polyamide components with a degree of polymerization of 5 or less in the polyamide composition is small.

[0118] The evaluation method for the coloring of the polyamide composition is not particularly limited. From the perspective of the coloring tendency, the yellowness index (hereinafter referred to as YI; ASTM E313) etc. can be used. When the coloring is light and close to white, the whiteness index (hereinafter referred to as WI; CIE Whiteness) etc. can also be used. Regarding the coloring of the polyamide composition, for example, if recorded in terms of YI, it is preferably 20 or less, more preferably 17 or less, and most preferably 13 or less. If recorded in terms of WI, it is preferably 40 or more, more preferably 50 or more, and most preferably 60 or more.

[0119] The shape of the polyamide composition is not particularly limited, and examples include those formed into pellets by melting the polyamide during manufacturing (such as recycling), or those formed into a powder by dissolving in a solvent first and then precipitating.

[0120] The polyamide component with a degree of polymerization of 5 or less in the polyamide fiber of the present embodiment is 20,000 ppm or less, preferably 10,000 ppm or less, and more preferably 5,000 ppm or less. When the polyamide component with a degree of polymerization of 5 or less in the fiber is 20,000 ppm or less, the molecular mobility in the low temperature to normal temperature region can be suppressed, and the 3-month shrinkage decrease rate of the subsequent raw yarn can be suppressed. By melt-spinning the polyamide composition, although the amount of polyamide components with a degree of polymerization of 5 or less in the polyamide fiber increases, if it is 20,000 ppm or less, the temporal stability of the fiber shrinkage rate increases. As a result, even if the production dates are spaced apart, high-quality fabric products can be obtained, and the appearance defects (crosswise streaks) caused by the base fabric density deviation associated with the uneven performance of the fiber's temporal shrinkage decrease can be suppressed. Regarding the fiber obtained by melt-spinning, due to the influence of the heat during melting, the amount of polyamide components with a degree of polymerization of 5 or less will inevitably increase due to the influence of the heat during melting, and it is 100 ppm or more in absolute value.

[0121] The amount of the silicon compound contained in the polyamide fiber of the embodiment is 30 ppm or more and 1000 ppm or less, preferably 50 ppm or more and 700 ppm or less, and more preferably 100 ppm or more and 500 ppm or less, in terms of the silicon atom content quantified by X-ray fluorescence analysis. When the silicon compound contains 30 ppm or more in terms of silicon atoms, uniform stretching can be carried out with the silicon compound as a fulcrum to compensate for the reduction in stretchability caused by the decrease in the oligomer component. On the other hand, when the content of the silicon compound is 1000 ppm or less in terms of silicon atoms, spinning blockage is not likely to occur and continuous operation can be carried out. The silicon compound basically originates from the organosilicon compound used to coat the polyamide article. That is, it can be considered that it is a minute substance of the organosilicon resin itself or organically treated silica as a filler-reinforcing material of the organosilicon resin, which has good affinity with polyamide on the one hand and acts as a thin and evenly dispersed stretching fulcrum in the form of extremely minute solids on the other hand, improving the stretchability.

[0122] The polyamide fiber of this embodiment preferably has no peak in tanδ in the range of -50°C to +50°C in the dynamic viscoelasticity measurement. In addition, in the dynamic viscoelasticity measurement, the value of tanδ in the range of -50°C to +50°C is preferably 0.05 or less. Further, in the range of +90°C to +130°C, tanδ has a peak, and the peak value of tanδ is preferably 0.100 or more and 0.150 or less, more preferably 0.105 or more and 0.140 or less, and still more preferably 0.110 or more and 0.130 or less. The dynamic viscoelasticity measurement can be carried out by the method described in the following examples. By making tanδ have no peak in the range of -50°C to +50°C, the molecular mobility in the low-temperature to normal-temperature region is suppressed, and the 3-month shrinkage reduction rate of the as-described raw filament can be suppressed. By making tanδ have a peak value in the range of +90°C to +130°C and the peak value of tanδ be 0.100 or more and 0.150 or less, sufficient mechanical properties can be obtained in airbag applications.

[0123] The polyamide fiber of this embodiment is preferably a multifilament having the following physical properties (1) to (7):

[0124] (1) A total fineness of 150 dtex or more and 2500 dtex or less;

[0125] (2) A strength of 6.0 cN / dtex or more and 11.0 cN / dtex or less;

[0126] (3) An elongation at break of 15% or more and 25% or less;

[0127] (4) A boiling water shrinkage rate of 4.0% or more and 11.0% or less;

[0128] (5) A finishing agent adhesion rate of 0.5% by weight or more and 1.5% by weight or less;

[0129] (6) A monofilament count of 30 or more and 400 or less;

[0130] (7) A 3 - month shrinkage decline rate of 12% or less.

[0131] When made into an airbag and the base fabric for an airbag, from the perspective of having sufficient mechanical properties, the total fineness of the polyamide fiber of the present embodiment is preferably 150 dtex or more, more preferably 175 dtex or more, and further preferably 200 dtex or more. On the other hand, from the perspective of weight reduction, the total fineness of the polyamide fiber is preferably 2500 dtex or less, more preferably 1500 dtex or less, and further preferably 1000 dtex or less.

[0132] The tensile strength of the polyamide fiber of the present embodiment is preferably 6.0 cN / dtex or more, more preferably 7.0 cN / dtex or more, and further preferably 8.0 cN / dtex or more, preferably 11.0 cN / dtex or less, more preferably 10.0 cN / dtex or less, and further preferably 9.0 cN / dtex or less. When the tensile strength is above the above - mentioned lower limit, the tensile strength is excellent and sufficient mechanical properties can be obtained in airbag applications. On the other hand, when the tensile strength is below the above - mentioned upper limit, production can be carried out without reducing the process stability due to increased fuzzing or end - breakage.

[0133] The elongation at break of the polyamide fiber of the present embodiment is preferably 15% or more, more preferably 16% or more, and further preferably 17% or more, preferably 30% or less, more preferably 28% or less, and further preferably 25% or less. If the elongation at break is above the above - mentioned lower limit, sufficient toughness (an index of strength) can be obtained in airbag applications. In addition, the elongation at break and strength are in a trade - off relationship, and in order to achieve a balance with strength, the elongation at break is preferably below the above - mentioned upper limit.

[0134] The boiling water shrinkage rate of the polyamide fiber of the present embodiment is preferably 4.0% or more, more preferably 5.0% or more, and further preferably 6.0% or more, preferably 11.0% or less, more preferably 10.0% or less, and further preferably 9.0% or less. If the boiling water shrinkage rate is above the above - mentioned lower limit, the fabric can shrink in the post - weaving processing step, which is beneficial for making the finished fabric have a high density. On the other hand, considering other properties and manufacturing costs, etc., it is preferably substantially below the above - mentioned upper limit.

[0135] The number of filaments of the polyamide fiber in this embodiment is preferably 30 or more, more preferably 50 or more, still more preferably 70 or more, preferably 400 or less, more preferably 300 or less, and still more preferably 200 or less. By making the number of filaments of the multifilament above the above lower limit, the specific surface area is increased or it can flexibly respond to external stress, so the air permeability or tear resistance of the base fabric is improved. On the other hand, by making the number of filaments of the multifilament below the above upper limit, welding between filaments during melt spinning can be avoided.

[0136] The 3-month shrinkage decline rate of the polyamide fiber in this embodiment is preferably 12% or less. More preferably 11% or less, still more preferably 10% or less. The 3-month shrinkage decline rate refers to the value obtained by measuring the change rate by comparing the boiling water shrinkage rate over time of the wound product immediately after winding and after storage for 3 months. When using raw filaments with different production dates (especially as weft filaments), due to the shrinkage rate difference before and after the handover of the supply bobbin, tissue relaxation occurs, and sometimes density deviation occurs. By making the 3-month shrinkage decline rate 12% or less, raw filaments with good long-term dimensional stability can be obtained, and appearance defects (horizontal streaks) caused by density deviation during base fabric production can be suppressed.

[0137] The total fineness, strength, elongation at break, boiling water shrinkage rate, finishing agent adhesion rate, and 3-month shrinkage decline rate can be measured by the methods described in the examples, for example.

[0138] In addition, the polyamide fiber in this embodiment is excellent in suppressing the number of broken ends (broken end property) during filament production. The broken end property can be evaluated by the methods described in the examples, for example.

[0139] Examples of the polyamide of the polyamide fiber in this embodiment are the same as the examples of the polyamide illustrated in "Polyamide Composition". Examples of the polyamide fiber in this embodiment include, for example, fibers formed from polyamide 6, polyamide 66, polyamide 11, polyamide 12, polyamide 610, polyamide 612, polyamide 46, polyamide 6T, polyamide 6I, copolymers thereof, and mixtures thereof. Among them, polyamide 66 fibers mainly composed of polyhexamethylene adipamide fibers are preferred. Polyhexamethylene adipamide refers to a polyamide fiber with a melting point of 250 °C or higher composed of 100% hexamethylenediamine and adipic acid. The polyamide 66 fiber of the present invention can also be a fiber formed from a polymer copolymerized or blended with polyamide 8, polyamide 6I, polyamide 10, polyamide 6T, etc. within the range where the melting point does not become less than 250 °C.

[0140] 〈Spinning of Polyamide Fiber〉

[0141] The spinning temperature in melt spinning is preferably 290 °C or higher and 310 °C or lower. By setting the spinning temperature below 310 °C, thermal decomposition of the polyamide is inhibited, which is preferred. More preferably, it is 300 °C or lower, and even more preferably 295 °C or lower. On the other hand, by making the spinning temperature 290 °C or higher, the polyamide exhibits sufficient melt fluidity, the discharge amount between the discharge holes is made uniform, and high magnification stretching can be performed, which is preferred.

[0142] In the melt spinning process, the residence time (the time from when the polyamide resin is melted until it is discharged from the spinneret) is preferably as short as possible. The residence time is preferably 30 minutes or less, more preferably 15 minutes or less, and even more preferably 0.5 minutes or more and 7 minutes or less. At the melting temperature, the polyamide component with a polymerization degree of 5 or less in the polymer increases, so a short time is preferred.

[0143] To achieve thermal stability in a high-temperature and high-humidity environment, it is preferred to add a copper compound so that the copper concentration is 1 to 500 ppm relative to the polyamide, and more preferably 30 to 500 ppm. Thus, even if the product of the present invention is placed in a high-temperature and high-humidity environment for a long time or exposed to an environment containing a large amount of ozone for a long time, a significant reduction in mechanical properties can be effectively suppressed. When the copper content is less than 30 ppm, the heat resistance strength retention rate decreases, and when the addition amount exceeds 500 ppm, the strength decreases.

[0144] Regarding the copper compound, its type is not particularly limited. For example, organic copper salts such as copper acetate or copper halides such as cuprous chloride and copper chloride can be preferably used. The copper compound is more preferably used in combination with a metal halide compound. Examples of the metal halide compound include potassium iodide, potassium bromide, potassium chloride, etc. Preferred combinations in this embodiment are cuprous iodide and potassium iodide, and copper acetate and potassium iodide. It should be noted that the copper content in the polyamide can be measured by atomic absorption spectrometry or colorimetry, etc.

[0145] Although not limited to the following, as stabilizers, organic antioxidants such as hindered phenol antioxidants, sulfur antioxidants, and phosphorus antioxidants, or heat stabilizers, light stabilizers such as hindered amine type, benzophenone type, and imidazole type, or ultraviolet absorbers can also be added. The addition amount only needs to be selected as an appropriate amount, and 1 to 1000 ppm can be added relative to the polyamide. These additives can be used alone or in combination of multiple types.

[0146] In addition, in the melt spinning process, a single-screw or twin-screw extruder is preferably used in the melting section. Through this extruder, the polyamide resin can be guided to the polymer pipe, gear pump, and spinning pack while applying an appropriate pressure to it.

[0147] In addition, in the stage before discharging from the spinneret, it is preferable to filter the polyamide resin with a nonwoven fabric filter of metal fibers, a sand filter, etc. to stabilize the spinning operation. When manufacturing high-strength fibers, it is necessary to perform precision filtration in a manner that can withstand a high draw ratio to remove inclusions such as coarse silicon compounds. However, when there are many inclusions, the filter will become clogged and continuous production cannot be carried out. The mesh size of the precision filtration is preferably 50 μm or less, more preferably 30 μm or less.

[0148] The shape of the spinneret holes in the spinneret can be selected according to the cross-sectional shape of the single fiber constituting the filament to be manufactured. The spun filaments from the spinneret are solidified by cooling air, an oil agent for the process is applied, and after drawing, they are stretched and heat-treated to obtain the polyamide fiber used in the present invention.

[0149] In addition, the adhesion rate of the finishing agent applied to the filament in the silk manufacturing process is preferably in the range of 0.5% by weight or more and 1.5% by weight or less. For a filament with an adhesion rate of the finishing agent of 1.5% by weight or less, there is almost no case where the weft filament is difficult to fly due to stickiness (viscosity). If the adhesion rate of the finishing agent is 0.5% by weight or more, the generation of fuzzing of single filaments during stretching in the silk manufacturing process can be suppressed.

[0150] 〈Polyamide base fabric〉

[0151] In weaving, a water jet loom, an air jet loom, a rapier loom, etc. can be used for the loom. The base fabric for the airbag is a high-density fabric. In the warping process and the weaving process, it is preferable to increase the warp tension and manufacture it in a manner with good process passability. In weaving, the warp tension is set high, the weft filament is inserted in a shuttleless manner, and effective beating-up conditions are created to form a high-density fabric. The shuttleless insertion of the weft filament is carried out through the loom with water, air, or a rapier, and the weft filament is instantaneously conveyed in the width direction of the fabric at high speed.

[0152] The woven fabric can wash off the oil agent for the process of the polyamide fiber in the scouring process.

[0153] The scouring process can select warm water, pressurized hot water, etc., and the treatment process can be a one-stage or multi-stage treatment of two stages or more. In addition, it is preferable to carry out scouring by applying a conventionally well-known scouring agent.

[0154] The fabric is preferably heat-fixed in the heat setting process. The heat setting temperature is preferably 110°C or more and 200°C or less, and the heat setting time can be appropriately selected within the range of 0.1 minute or more and 30 minutes or less. In addition, in the heat setting process, it is preferable to dry while keeping the fabric under tension so that the shrinkage force of the fabric remains at a specified force. If the fabric is heat-fixed, the process stabilization of the subsequent resin coating process can be achieved.

[0155] The fabric after the refining process may also be subjected to a drying treatment as needed before the heat setting process. The drying temperature is preferably in the range of 80°C or higher and 130°C or lower, more preferably 100°C or higher and 120°C or lower. In addition, the treatment time is preferably appropriately selected from 0.1 minute or longer and 30 minutes or shorter. The drying can be carried out with the fabric in a relaxed state or a taut state.

[0156] The polyamide base fabric can be used as an uncoated base fabric after the polyamide fabric has undergone a heat setting process. Furthermore, a coating agent such as silicone or polyurethane can be applied to the polyamide fabric, or a thin film can be thermally laminated or the like and processed to form a coated airbag base fabric.

[0157] The following methods can be used for coating the fabric surface: a method of dipping the fabric in a resin solution tank and then using a mangle, a vacuum machine, a coating knife, etc. to remove the excess resin to form and achieve uniformity; a rod coating method such as a comma coater; a method of blowing the resin using a spray device or a forming device, etc. Among these, from the viewpoint of coating the resin in a uniform and small amount, the knife coating method is preferred.

[0158] The coating amount is 5 g / m 2 or more and 100 g / m 2 or less, more preferably 10 g / m 2 or more and 70 g / m 2 or less, further preferably 15 g / m 2 or more and 30 g / m 2 or less. If the coating amount is 5 g / m 2 or more, the required airtightness can be obtained. On the other hand, if the coating amount is 100 g / m 2 or less, the coated fabric has softness and excellent storage properties, and the weight of the entire airbag is suppressed.

[0159] After coating, it is preferably vulcanized at 150°C or higher and 190°C or lower. The treatment time is preferably appropriately selected from 0.5 minute or longer and 3.0 minutes or shorter. In addition, it is preferably processed while keeping the base fabric taut so that the shrinkage force of the base fabric is maintained at a specified force. If the base fabric is heat-fixed, the dimensional stabilization of the product can be achieved.

[0160] 〈Airbag〉

[0161] The airbag can be appropriately selected from commonly used airbags such as the driver's seat, the front passenger seat, the side (including the inflatable curtain), the rear seat, etc. The cutting shape of the airbag bag body can be any of a circle, an oblong, an ellipse, a rectangle, a polygon, or a combination thereof, etc., as long as it satisfies the desired deployment shape.

[0162] As the stitch shape, there are a single straight line or multiple parallel straight lines, zigzag, combined use of a straight line and a zigzag, a straight line and an oblique line, etc. The sewing method can be a lock stitch, a double-lock stitch, etc., which are commonly used by users. The sewing pitch can be selected within the range of 20 to 60 times / 10 cm. In addition, the thickness of the sewing thread can also be selected from 420d to 3000d, and commercially available sewing threads such as polyamide fiber, polyester fiber, vinylon-based fiber, polyaramide-based fiber, and glass fiber can be used as the material of the thread.

[0163] <Method for manufacturing polyamide composition>

[0164] Hereinafter, examples of the method for manufacturing a polyamide composition will be specifically described, but the following examples do not limit the method for manufacturing a polyamide composition.

[0165] <Step 1 Dissolution step>

[0166] There is a step of dissolving and extracting polyamide from a silicone-coated polyamide base fabric through an alcohol solution of metal chloride.

[0167] The shape of the polyamide base fabric for dissolution is not particularly limited. It can be directly added in the form of scraps generated during the manufacture of the base fabric or the shape of a used airbag, or it can be cut according to the size of the dissolution device.

[0168] The temperature during dissolution is not particularly limited, preferably 40 to 90 °C, more preferably 40 to 60 °C or lower. When it is less than 40 °C, the dissolution rate becomes slow, and when it exceeds 90 °C, it becomes a temperature higher than the boiling point, which is not preferred from the viewpoints of corrosion and decomposition.

[0169] The dissolution can be either batchwise or continuous.

[0170] In the case of batchwise, there is no particular limitation on whether to stir, but stirring is preferably carried out. By stirring, the dissolution rate of the polyamide solid is increased.

[0171] In the case of continuous, for solids, the solvent can be continuously circulated, or the solution can be recycled. Since the amount of solvent used can be reduced, recycling is preferred.

[0172] The shape of the container is not particularly limited, and any shape such as a tank type and a circulation type can be used. The container can have a mechanism in which the part rotating due to external power during dissolution does not contact the silicone-coated polyamide base fabric. In addition, the container can also have a mechanism for continuously recovering the silicone resin generated during dissolution.

[0173] The dissolution time is not particularly limited, preferably 5 minutes to 100 hours.

[0174] The method for making the solution in which polyamide is dissolved into a state not mixed with minute silicone resins is not particularly limited, and various methods can be cited.

[0175] 1) Use a device having a mechanism in which the rotating part during stirring does not directly contact the polyamide base fabric in such a manner that minute silicone wafers are not generated.

[0176] For example, use a structure in which the polyamide base fabric is surrounded by a resin or metal insoluble in the solvent so as not to contact the stirring blade.

[0177] 2) Use a device having a structure in which a net bag having minute liquid passages is pre-suspended during dissolution and silicone wafers are accumulated inside.

[0178] Regarding other coverings of the polyamide composition, it is preferable to remove them simultaneously with the silicone resin.

[0179] Regarding the separated silicone resin and other coverings, since the polyamide solution adheres thereto, it is preferable to wash and recover the polyamide. The solvent for washing is not particularly limited, and a metal chloride alcohol solution is preferred. Examples of the metal chloride of the metal chloride alcohol include zinc chloride and calcium chloride, and calcium chloride is preferred. The alcohol of the metal chloride alcohol can be an alcohol that is a good solvent, and examples include methanol, ethanol, and isopropyl alcohol, and methanol is preferred. The washing method is not particularly limited, and examples include stirring and washing in a tank reactor or flow-through washing in a filter.

[0180] The polyamide solution after removing the silicone resin and other coverings is preferably filtered using a stainless steel mesh filter or a membrane filter. The mesh size of the filter at this time can be appropriately selected in accordance with the various methods described above for preventing minute silicone resins from being mixed in. The mesh size of the filter is preferably 30 μm or less, and more preferably 10 μm or less.

[0181] 〈Step 2 Polyamide Recovery Step〉

[0182] Step 2 is a step of recovering polyamide from the polyamide solution from which the silicone resin has been removed in Step 1.

[0183] The method for precipitating the dissolved polyamide from the aforementioned solution is not particularly limited, and various precipitation methods can be employed depending on the dissolved state.

[0184] In the case of dissolution by heating, precipitation can be considered by cooling utilizing the temperature dependence of the solubility of polyamide. In this case, the dissolved polyamide is precipitated from the solution under the condition of not adding an additional solvent to the solution containing the dissolved polyamide, and the precipitated polyamide is obtained.

[0185] When the temperature dependence of the solubility during dissolution is small, the polyamide can be mixed with a poor solvent for the polyamide to reduce the solubility and cause precipitation. In this case, after adding a poor solvent to a solution containing the dissolved polyamide, the dissolved polyamide is precipitated from the solution to obtain the precipitated polyamide. The poor solvent is not particularly limited, and examples thereof include water and alcohols such as ethanol, n-propanol, and isopropanol. As a method of adding the poor solvent to the polyamide, either a method of adding the polyamide solution to the poor solvent or a method of adding the poor solvent to the polyamide solution can be used, and the addition rate, temperature, stirring speed, etc. during addition are not particularly limited.

[0186] The addition amount of the poor solvent is not particularly limited, and is preferably 0.5 to 50 times the weight, more preferably 1 to 10 times the weight, relative to the weight of the polyamide solution. If the addition amount is less, the recovery rate becomes lower, and if the addition amount is more, the solution amount becomes more, making the treatment time-consuming and energy-consuming.

[0187] When the temperature dependence of the solubility during dissolution is small, the solubility of the polyamide can also be reduced by decreasing the concentration of calcium chloride. The method of adding methanol to decrease the concentration of calcium chloride is not particularly limited, and either a method of adding the polyamide solution to methanol or a method of adding methanol to the polyamide solution can be used, and the addition rate, temperature, stirring speed, etc. during addition are not particularly limited.

[0188] The shape of the container is not particularly limited, and any shape such as a tank type and a circulation type can be used.

[0189] The precipitated polyamide is preferably recovered by solid-liquid separation. Examples of the solid-liquid separation method include filtration, centrifugal separation, and sedimentation separation. Either a batch type or a continuous type can be adopted for any method.

[0190] The polyamide obtained by solid-liquid separation is preferably washed with a solvent. The washing liquid is not particularly limited, and for example, a solution having the composition of the liquid part during precipitation, a good solvent, and a solvent capable of dissolving calcium chloride, etc. can be used. The additional washing liquid used herein is, for example, water and alcohols such as methanol, ethanol, n-propanol, and isopropanol. The additional washing liquid is preferably methanol. The washing can be performed multiple times as needed.

[0191] The washing method is not particularly limited, and examples include: a method of performing batch washing; a method of continuously washing by passing water in a state where the solid is loaded into a solid-liquid separation device such as a filter or a centrifugal separation device; and a method of combining these.

[0192] For the recycled polyamide, the aforementioned copper compounds, metal halide compounds, organic antioxidants such as hindered phenol antioxidants, sulfur antioxidants, and phosphorus antioxidants as stabilizers, or heat stabilizers, light stabilizers such as hindered amine type, benzophenone type, and imidazole type, or ultraviolet absorbers can also be added in a solution state. The addition amount can be selected as an appropriate amount, and 1 to 1000 ppm can be added relative to the polyamide. These additives can be used alone or in combination of multiple types.

[0193] The washed polyamide is made into a dry solid by distilling off the washing solvent by heating and / or reducing the pressure, whereby powdery polyamide can be obtained.

[0194] As described above, the present invention can provide a method for producing a polyamide composition in a high yield from a composition obtained by covering polyamide, which is useful as an engineering plastic, with silicone.

[0195] 〈Use of polyamide composition〉

[0196] By spinning the polyamide composition of the present embodiment, fibers can be obtained. By weaving the fibers of the present embodiment, a woven fabric can be obtained. The woven fabric of the present embodiment can be used for airbags.

[0197] (Method for producing polyamide solution)

[0198] Furthermore, the present specification discloses an invention regarding a method for producing a polyamide solution. The disclosed method for producing a polyamide solution can be, for example, a method for efficiently dissolving polyamide from a polyamide-containing substance.

[0199] The method for producing a polyamide solution according to an embodiment of the present disclosure includes the following steps (sometimes referred to as "separation steps" in the present specification): A polyamide-containing substance containing an insoluble component for a metal chloride alcohol solution and polyamide is charged into a container made of an insoluble resin having a liquid passage hole, the above metal chloride alcohol solution containing a metal chloride and an alcohol is added, and stirring is performed at 120°C or lower to dissolve the polyamide, and the above insoluble component is separated into the container. Other steps may also be included.

[0200] 〈Polyamide-containing substance〉

[0201] In the production method according to an embodiment of the present disclosure, polyamide is dissolved from a polyamide-containing substance.

[0202] The polyamide-containing substance is a raw material for the reuse of polyamide, and examples thereof include fibers using polyamide as a raw material, or process scraps or wastes of molded products such as automotive parts and electrical product parts. Specifically, examples include process scraps or wastes such as clothing items, airbags, tire cords, engine room or intake system, fuel system parts, connectors, fishing nets, and UD tapes, but are not limited to these.

[0203] In the above polyamide-containing substance, it contains at least an insoluble component in the metal chloride alcohol solution and polyamide. With respect to 100% by mass of the above polyamide-containing substance, the ratio of the total mass of the insoluble component and polyamide in the metal chloride alcohol solution is preferably 50 to 100% by mass, more preferably 60% by mass or more, further preferably 70% by mass or more, and particularly preferably 80% by mass or more.

[0204] In addition, with respect to 100% by mass of the above polyamide-containing substance, the mass ratio of polyamide is preferably 10 to 100% by mass, more preferably 20 to 99% by mass, and further preferably 70 to 98% by mass.

[0205] Examples of the insoluble component in the metal chloride alcohol solution include silicone, carbon fiber, glass fiber, polyolefins such as polyethylene and polypropylene, polyester, fluororesin, etc. The insoluble component can be: with respect to the sample, after mixing 10 times the mass of the metal chloride alcohol solution (for example, 20 wt% calcium chloride methanol solution) and stirring at a temperature of 60 °C for 24 hours, the remaining component.

[0206] 〈Metal chloride alcohol solution〉

[0207] In the manufacturing method of the embodiment of the present disclosure, the dissolution of polyamide uses a metal chloride alcohol solution.

[0208] The above metal chloride alcohol solution contains a metal chloride and an alcohol, and may also contain other components. Among them, with respect to 100% by mass of the metal chloride alcohol solution, the total mass ratio of the above metal chloride and the above alcohol is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 100% by mass.

[0209] As the above metal chloride, there is no particular limitation as long as it can be dissolved in the above alcohol used. From the viewpoint of high solubility of polyamide, it is preferably any one of calcium chloride, zinc chloride, and lithium chloride. A single type or a plurality of types can be used. Both hydrates and anhydrous substances can be used, but from the viewpoint of the solubility of polyamide, anhydrous substances are preferably used.

[0210] From the viewpoint of the solubility of polyamide, the water content in the metal chloride alcohol solution is preferably 15 wt% or less. More preferably, it is 10 wt% or less, and still more preferably, it is 7 wt% or less. The water content in the metal chloride alcohol solution can be measured by a known method (for example, a Karl Fischer moisture meter).

[0211] From the high solubility of the above metal chloride, the above alcohol is preferably a lower alcohol having 1 to 4 carbon atoms, particularly preferably methanol or ethanol, and most preferably methanol.

[0212] From the viewpoint of mass productivity, when the polyamide solubility of the metal chloride alcohol solution is 120°C or lower, it is preferably at least 1 wt% at maximum. More preferably, it is at least 3 wt% at maximum, and still more preferably, it is at least 5 wt% at maximum. In addition, from the viewpoint of achieving an appropriate viscosity and good processability, it is preferably 20 wt% or less at maximum, more preferably 18 wt% or less at maximum, and still more preferably 15 wt% or less at maximum.

[0213] 〈Container〉

[0214] In the manufacturing method of the embodiment of the present disclosure, a container formed of an insoluble resin and having a liquid passage hole is used.

[0215] In the conventional method, the separation and removal of silicone, which is an inclusion, may take a very long time. The reason is that the silicone pieces finely cut during stirring cause clogging of the filter of the filter press, making it difficult to separate. This becomes a fatal problem when scaling up. In addition, depending on the hardness of the inclusion, there is also a concern about damaging the inner wall of the reactor or the stirring blade. From the viewpoint of protecting the device, the separation method of separating inclusions from the polyamide-containing substance is also considered a technical problem.

[0216] Therefore, in the method for manufacturing a polyamide solution, by using a container formed of an insoluble resin and having a liquid passage hole, a method for manufacturing a polyamide solution can be provided, which uses industrially suitable raw materials, separates inclusions in the form of insoluble matter from the polyamide-containing substance in a short time without causing low molecular weightization of the polyamide, has little concern about damage to the device by inclusions, has good operability, and has mass productivity.

[0217] The above container may be formed only of an insoluble resin or may also contain other components.

[0218] The so-called insoluble resin means a resin that is insoluble in the metal chloride alcohol solution. Here, the so-called insoluble means that the weight loss after immersion in the metal chloride alcohol solution at 120°C for 24 hours is 1 wt% or less.

[0219] The above-mentioned insoluble resin is not particularly limited. From the viewpoints of easy processing, softness, easy introduction into the reactor, and little concern about device damage, preferred examples include polyethylene, polypropylene, polyurethane, polystyrene, polydimethylsiloxane, and polyester. A single type or multiple types can be used.

[0220] The above-mentioned liquid passage holes separate inclusions such as insoluble components in the metal chloride alcohol solution in the form of insoluble substances into the container and selectively allow the solution to pass through. Regarding the size or number of the liquid passage holes, there is no particular limitation as long as the inclusions can be separated into the container in the form of insoluble substances. From the aspect of facilitating the entry and exit of the metal chloride alcohol solution inside and outside the container and improving the solubility of polyamide, the mesh size is preferably 0.05 cm to 10 cm. The liquid passage holes can be punching holes or in a grid shape.

[0221] By loading the above-mentioned polyamide-containing substance into the above-mentioned container having liquid passage holes, even in the case where the inclusions are fragile, it is not easily cut excessively due to stirring and mixing, so it can be used in combination with a stirrer.

[0222] Regarding the container having liquid passage holes, since it can be used in a size that can be introduced through the manhole of the reactor, no special equipment or operation is required. In addition, since multiple containers can be used, the input amount can be increased.

[0223] Regarding the container having liquid passage holes, it can also be used without being fixed and introduced from the reactor. By stirring, the container is rotated to prevent the liquid passage holes from being blocked by inclusions. In addition, as long as the liquid passage holes are not fixed in one direction, they can also be used in a hanging manner.

[0224] Describe each process in the manufacturing method of the embodiment of the present disclosure.

[0225] 〈Separation process〉

[0226] The temperature for stirring the polyamide-containing substance in the above-mentioned metal chloride alcohol solution is 120 °C or lower. If it is 120 °C or lower, decomposition due to the alcoholysis of polyamide can be suppressed. It is preferably 100 °C or lower, more preferably 80 °C or lower. In addition, it is preferably 0 °C or higher, more preferably 10 °C or higher, and further preferably 20 °C or higher.

[0227] The addition amount of the above-mentioned metal chloride alcohol solution is preferably 2 times or more the mass of the above-mentioned polyamide-containing substance. From the viewpoint of the dissolution efficiency of polyamide, it is more preferably 3 to 100 times, further preferably 5 to 50 times, and particularly preferably 10 to 20 times.

[0228] The above-mentioned polyamide-containing substance can also be cut into a size such that residues such as insoluble components in the metal chloride alcohol solution do not pass through the above-mentioned liquid passage holes and then introduced into the above-mentioned container.

[0229] <Other processes>

[0230] In the manufacturing method of the embodiment of the present disclosure, for the purpose of removing insoluble components of inclusions discharged from the liquid passage holes to the outside of the container in the polyamide solution after the above separation process, the polyamide solution can be further subjected to solid-liquid separation. Since most of the inclusions are separated into the container during the separation process, the filterability is good. Examples of the solid-liquid separation method include filtration, centrifugal separation, etc. Both batch and continuous methods can be adopted in any method.

[0231] Polyamide can be manufactured by precipitating polyamide from the polyamide solution obtained by the manufacturing method of the embodiment of the present disclosure. The precipitation method is not particularly limited, and methods such as crystallization by cooling using the temperature dependence of the solubility of polyamide, or precipitation by mixing with a poor solvent for polyamide to reduce the solubility can be considered. The poor solvent is not particularly limited. The solubility of polyamide can also be reduced by reducing the concentration of metal chloride (such as calcium chloride). The addition method of the poor solvent can be either the method of adding the polyamide solution to the poor solvent or the method of adding the poor solvent to the polyamide solution. There is no particular limitation on the addition rate, temperature, stirring speed, etc. during addition.

[0232] The precipitated solid can also be separated from the solution. Examples of the solid-liquid separation method include filtration, centrifugal separation, sedimentation separation, etc. Both batch and continuous methods can be adopted in any method.

[0233] The solid obtained by solid-liquid separation can also be washed with a solvent. The solvent is not particularly limited, and it is preferably: a solution of the composition of the liquid part during precipitation, a good solvent, a solvent capable of dissolving metal chloride.

[0234] The metal chloride alcohol solution contained in the polyamide solution after separating polyamide can be concentrated and purified for reuse.

[0235] Through the manufacturing method of the embodiment of the present disclosure, a polyamide solution with a low mass ratio of inclusions such as insoluble components to the metal chloride alcohol solution can be obtained with high efficiency.

[0236] The polyamide solution obtained by the manufacturing method of the embodiment of the present disclosure can be used as a raw material for precipitating polyamide and regeneration. The precipitated polyamide can be used as a raw material for polyamide fibers, polyamide base fabrics, airbags, etc.

[0237] <Industrial applicability>

[0238] Through the manufacturing method of the embodiment of the present disclosure, inclusions can be efficiently separated from polyamide-containing substances without using special equipment or reactors. Therefore, it can be expected to be applicable to batch production of polyamide solutions or polyamide reuse.

[0239] Example

[0240] Hereinafter, the embodiments of the present invention will be described in more detail, but the present invention is not limited to these embodiments.

[0241] In this example, the method of X-ray fluorescence analysis is as follows.

[0242] 〈X-ray Fluorescence Analyzer〉

[0243] Measuring device: ZSX Primus II (manufactured by Rigaku Corporation)

[0244] Each component is quantified by a semi-quantitative method using polyamide as an equilibrium component.

[0245] In this example, the method of GPC analysis is as follows.

[0246] 〈GPC Device〉

[0247] Measuring device: HPLC-8420GPC (manufactured by Tosoh Corporation)

[0248] Column: TSKgel Super HM-N (manufactured by Tosoh Corporation)

[0249] Eluent: HFIP-5 mmol / L TFA-Na

[0250] Flow rate: 0.2 ml / min for sample, 0.2 ml / min for reference

[0251] Temperature: 40 °C

[0252] Injection volume: 10 μL

[0253] Sample concentration: 1 mg / mL

[0254] GPC standard: EaslVialPM

[0255] (Agilent PL2020-0201)

[0256] Integrated distribution data with a degree of polymerization of 5 or less is read from the measured value of 1,148 or less in molecular weight, and the polyamide component is calculated.

[0257] In this example, the method for measuring dynamic viscoelasticity is as follows.

[0258] 〈Dynamic Viscoelasticity Measurement〉

[0259] Measuring device: RSA-G2 (manufactured by TA Instrument)

[0260] Sample shape: Length 20 mm (distance between jigs)

[0261] The cross-sectional area is calculated by measuring the weight of a 10 cm sample and converting it using a specific gravity of 1.14

[0262] Measurement frequency: 1 Hz

[0263] Measurement strain: 0.05%

[0264] Heating rate: 5°C / min

[0265] Atmosphere: Nitrogen

[0266] Using the baseline of tanδ drawn in the region from -50°C to +50°C, a value of tanδ that is higher than the baseline and can be regarded as a peak shape is determined as a peak. Also, using the baseline of tanδ drawn in the region from +90°C to +130°C, a value of tanδ that is higher than the baseline and can be regarded as a peak shape is determined as a peak.

[0267] In this embodiment, the method for measuring fineness is as follows.

[0268] 〈Fineness〉

[0269] Measured according to JIS L 1013 8.3.

[0270] In this embodiment, the methods for measuring tensile strength, tensile strength, and elongation are as follows.

[0271] 〈Tensile strength, tensile strength, elongation〉

[0272] According to JIS L 1013 8.5, a 150 mm fiber sample is measured at a tensile speed of 300 mm / min.

[0273] In this embodiment, the evaluation method for the finishing agent adhesion rate is as follows.

[0274] 〈Finishing agent adhesion rate〉

[0275] Measured according to JIS L 1013 8.27 using cyclohexane as a solvent.

[0276] In this embodiment, the methods for measuring the boiling water shrinkage rate and the 3-month shrinkage decline rate are as follows.

[0277] 〈Boiling water shrinkage rate, 3-month shrinkage decline rate〉

[0278] Measured according to JIS L 1013 8.18.

[0279] The boiling water shrinkage rates of the raw yarn production date and 90 days after the production of the raw yarn are measured separately, and the change rate (%) is used as the 3-month shrinkage decline rate.

[0280] In this embodiment, the evaluation method for the breakage during wire making is as follows.

[0281] 〈Breakage〉

[0282] Count the number of breakages after 8 hours of production and make a judgment based on the following criteria.

[0283] A: Less than 3 breakages during 8 hours of production

[0284] C: 3 or more breakages during 8 hours of production

[0285] In this embodiment, the evaluation method for weaving defects is as follows.

[0286] 〈Weaving Defects〉

[0287] Crosswise streak: The so-called crosswise streak refers to a defect of poor appearance with a wrinkled pattern generated in the weft direction and width direction of the base fabric mainly due to the density deviation of the base fabric. As an evaluation method, the fabric is unfolded on an inspection table for inspection, and a technician with more than 3 years of experience in airbag base fabric inspection business makes a judgment by visual inspection. Then, before and after the connection of the weft supply spools, it is evaluated whether there is a wrinkled pattern in the weft direction and width direction of the base fabric. After confirming 10 parts at the connection part of the weft supply spools of the base fabric, make a defect judgment based on the following criteria.

[0288] A: No wrinkled pattern is confirmed.

[0289] B: A wrinkled pattern is observed, but the density deviation is less than ±5%.

[0290] C: There is a wrinkled pattern and the density deviation is ±5% or more.

[0291] [Example 1]

[0292] After cutting 50 kg of a polyamide 66 base fabric (hereinafter referred to as "coated base fabric") composed of 90 wt% of polyamide 66 and 10 wt% of silicone resin into squares with a side length of about 20 cm, it is evenly filled into 20 cylindrical containers made of polyethylene mesh with a diameter of 20 cm, a height of 20 cm, and a mesh size of 5 mm. Then, 480 kg of methanol (manufactured by Wako Pure Chemical Industries, Ltd.) and 120 kg of anhydrous calcium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) are loaded into 1 m 3In a glass-lined reactor, mixing was carried out by stirring blades to prepare a 20 wt% calcium chloride methanol solution. A cylindrical container filled with a polyamide 66 base fabric was impregnated, and stirred at 60 °C for 24 hours to dissolve the polyamide. After dissolution, the silicone resin as an inclusion was separated into the cylindrical container. The obtained polyamide solution was pressure-filtered using a polyethylene filter with a mesh size of 10 μm to remove a small amount of the remaining silicone resin. The filterability was good. Then, the filtrate was dropped into 600 kg of methanol to precipitate a solid. After separating the precipitated solid by pressure filtration, it was mixed with 300 kg of water and subjected to vacuum filtration for washing. After repeating the washing with water 5 times, vacuum drying was carried out at 80 °C, and 40 kg of polyamide (recycled polyamide composition) was recovered.

[0293] For the obtained recycled polyamide composition, analysis by X-ray fluorescence showed that it contained 300 ppm of silicon atoms. In addition, the content of the polyamide component (oligomer) with a degree of polymerization of 5 or less was 1230 ppm.

[0294] This operation was repeated many times to obtain a powder. The obtained powder was melted at a temperature of 300 °C using an extrusion-type extruder, and spun by the melt spinning method with a residence time of 180 seconds at 290 °C. The spun polymer was cooled and solidified by cold air to form a filament. After applying an aliphatic synthetic ester-based spinning oil agent to the solidified filament, drawing and heat treatment were carried out to obtain a recycled polyamide 66 fiber filament with a total fineness of 233 dtex and 36 filaments. Analysis of the recycled polyamide 66 fiber by X-ray fluorescence showed that it contained 320 ppm of silicon atoms. In addition, the content of the polyamide component (oligomer) with a degree of polymerization of 5 or less was 4850 ppm.

[0295] This fiber was warped in a non-twisted and non-sized manner, and the same kind of yarn was also used for the weft. Weaving was carried out by a water-jet loom in a plain weave pattern at a width of 2.0 m and a speed of 650 rpm to produce a recycled polyamide 66 base fabric.

[0296] The evaluation results of the obtained recycled polyamide 66 fiber and recycled polyamide 66 base fabric are shown in Table 1.

[0297] [Example 2]

[0298] In the spinning process, a recycled polyamide 66 fiber filament with a total fineness of 490 dtex and 136 filaments was produced. Except for this, the same procedure as in Example 1 was carried out. The results are shown in Table 1 below.

[0299] [Example 3]

[0300] In the manufacturing process of the polyamide composition, 25 kg of a coated base fabric and 25 kg of a polyamide 66 base fabric (hereinafter referred to as "uncoated base fabric") of 100 wt% polyamide 66 were used, and otherwise, the process was carried out in the same manner as in Example 2. The results are shown in Table 1 below.

[0301] [Example 4]

[0302] In the manufacturing process of the polyamide composition, 10 kg of a coated base fabric and 40 kg of an uncoated base fabric were used, and otherwise, the process was carried out in the same manner as in Example 2. The results are shown in Table 1 below.

[0303] [Example 5]

[0304] In the dissolution process, the mesh of 20 cylindrical containers was set to 10 mm, and otherwise, the process was carried out in the same manner as in Example 2. The results are shown in Table 1 below.

[0305] [Comparative Example 1]

[0306] As an existing polyamide 66 composition resin, sodium hypophosphite as a polymerization catalyst was added to an aqueous solution containing a neutral salt of hexamethylenediamine and adipic acid, and polycondensation was carried out in a continuous polymerization apparatus. Then, an aqueous solution of copper iodide / potassium iodide as a heat stabilizer was added and post-polymerization was carried out to obtain resin pellets. Next, solid-phase polymerization was carried out to obtain a polyamide 66 polymer having a relative viscosity ηr of 3.1. It should be noted that the relative viscosity ηr was obtained by dissolving 2.5 g of the sample in 25 cc of concentrated sulfuric acid (98%) and measuring it using an Ostwald viscometer at a fixed temperature in a constant-temperature bath (25°C).

[0307] For the obtained polymer, the same melt spinning process and weaving process as in Example 2 were carried out. The results are shown in Table 1 below. Although high-strength filaments could be spun, in airbag weaving, bar defects occurred due to the supply of filaments with different production dates.

[0308] [Example 6]

[0309] The pellets obtained in Comparative Example 1 and the powder obtained in Example 1 were successively and equally fed into an extrusion-type extruder, and the same melt spinning process and weaving process as in Example 2 were carried out. The results are shown in Table 1 below.

[0310] [Example 7]

[0311] The pellets obtained in Comparative Example 1 and the powder obtained in Example 5 were successively and equally fed into an extrusion-type extruder, and the same melt spinning process and weaving process as in Example 2 were carried out. The results are shown in Table 1 below.

[0312] [Comparative Example 2]

[0313] In the manufacturing process of the polyamide composition, 50 kg of non-coated base fabric was used, and in other respects, the process was carried out in the same manner as in Example 2. The results are shown in Table 1 below. The spinning of the high-strength filaments was not smooth. It is considered that this was due to the loss of the plasticity of the low-molecular-weight polyamide.

[0314] [Comparative Example 3]

[0315] After cutting 50 kg of the coated base fabric into squares approximately 20 cm on a side, it was stirred and immersed in an aqueous NcOH solution with a pH of 10 and a weight 4 times that of the fabric for 24 hours, and then the base fabric was centrifugally dewatered. Next, the dewatered base fabric was stirred in a rotating container to peel off the coating agent. Then, the base fabric was washed with water in a flowing stream, centrifugally dewatered, and dried. It was remelted in a single-screw extruder at a temperature of 280 °C to produce recycled pellets. Using the obtained pellets, the same melt spinning process and weaving process as in Example 2 were carried out. The results are shown in Table 1 below. The spinning filtration pressure tended to increase, and the tensile strength also increased insufficiently. In addition, in the airbag weaving, horizontal bar defects occurred due to the supply of filaments at intervals in the production dates.

[0316] [Comparative Example 4]

[0317] In the manufacturing process of the polyamide composition, except for using 3 kg of coated base fabric and 47 kg of non-coated base fabric, other operations were carried out in the same manner as in Example 2. The results are shown in Table 1 below. The amount of silicon compound in the polyamide was small, and the stretchability was poor.

[0318] [Comparative Example 5]

[0319] In the dissolution process, dissolution was carried out without using a cylindrical container, and in other respects, the process was carried out in the same manner as in Example 2. The results are shown in Table 1 below. The spinning filtration pressure increased sharply and spinning could not be carried out.

[0320] [Table 1]

[0321]

[0322] For the silicone-coated polyamide 66 base fabric (hereinafter referred to as polyamide 66 base fabric) used in Example 8 and Comparative Examples 6 and 7, 10% of its weight was composed of a silicone resin. The polyamide 66 base fabric was immersed in methanol, and the polyamide component with a polymerization degree of 5 or less was extracted and quantified, and the result was 0.9 wt%.

[0323] In Example 8 and Comparative Examples 6 and 7, regarding the coloring of the recycled polyamide composition, the value of YI (ASTM E313) was adopted. The specific analysis method is shown below.

[0324] 〈Spectrophotometric colorimeter〉

[0325] Measuring device: SD5000 (Nippon Denshoku Industries Co., Ltd.)

[0326] Light source: D65 / 10

[0327] The values are derived in accordance with ASTM E313

[0328] [Example 8]

[0329] In a 300 mL glass bottle equipped with a magnetic stir bar, 10 g of a polyamide 66 base fabric placed in a polyethylene mesh bag and 100 g of a 20 wt% calcium chloride methanol solution were added. It was placed in a water bath at 60 °C and stirred with a magnetic stirrer for 12 hours while dissolving the polyamide (polyamide 66) contained in the polyamide 66 base fabric to obtain a mixture of a polyamide solution (polyamide 66 solution) and a silicone resin. The mixture of the polyamide solution and the silicone resin was passed through a stainless steel mesh with a mesh size of 1 mm and a stainless steel mesh with a mesh size of 500 μm to remove the silicone resin. The removed silicone resin was returned to the original 300 mL glass bottle, washed with 5 g of a 20 wt% calcium chloride methanol solution, and separated from the polyamide solution (the washed cleaning liquid) again by passing through the stainless steel mesh. All the recovered polyamide solution was transferred to a 1000 mL beaker, and 500 g of methanol was added while stirring to obtain a solid precipitate of polyamide (polyamide 66). The formed solid precipitate was filtered and recovered using a 1 μm membrane filter. The filtered solid precipitate was thoroughly washed with water. The washed solid precipitate was heated and dried in a vacuum dryer at 40 °C to obtain 8.8 g (yield 97.8%) of a regenerated polyamide composition (regenerated polyamide 66 composition).

[0330] For the obtained regenerated polyamide composition, analysis by X-ray fluorescence showed that it contained 400 ppm of silicon atoms and 300 ppm of calcium atoms. In addition, the content of polyamide components with a degree of polymerization of 5 or less was 120 ppm.

[0331] The YI of the obtained regenerated polyamide composition was 6.8.

[0332] [Comparative Example 6]

[0333] Without using a polyethylene mesh bag, regenerated polyamide was obtained in the same manner as in Example 1. The results were 1500 ppm of silicon atoms, 300 ppm of calcium atoms, and a content of polyamide components with a degree of polymerization of 5 or less of 130 ppm.

[0334] The YI of the obtained regenerated polyamide composition was 20.

[0335] [Comparative Example 7]

[0336] In a 300 mL glass bottle containing a magnetic stir bar, 5 g of polyamide 66 base fabric, 143.5 g of dodecane, and 7.5 g of dodecylbenzenesulfonic acid were added, and the mixture was stirred for 12 hours using a magnetic stirrer. After the polyamide 66 base fabric was separated from the silicone, the silicone resin was taken out by lifting it from the upper part. The peeled polyamide base fabric was filtered and recovered through a 1 μm membrane filter. The filtered polyamide base fabric was thoroughly washed with dodecane. The washed polyamide base fabric was heated and dried in a vacuum dryer at 40 °C to obtain 4.3 g (yield 95.5%) of a regenerated polyamide composition (regenerated polyamide 66 composition).

[0337] For the obtained regenerated polyamide composition, analysis by X-ray fluorescence analysis showed that it contained 20,000 ppm of silicon atoms and no calcium atoms were detected. In addition, the content of polyamide components with a polymerization degree of 5 or less was 7,000 ppm.

[0338] Since the obtained regenerated polyamide composition had uneven coloring, it was first melted at 280 °C and then pelletized. The obtained pellets had a YI of 37.5.

[0339] [Example 9]

[0340] 1 kg of process scraps of an airbag composed of 90 wt% of polyamide 6,6 and 10 wt% of silicone resin was cut into squares of about 10 cm on each side and evenly filled into 3 cylindrical containers made of polyethylene mesh with a diameter of 10 cm, a height of 10 cm, and a mesh size of 5 mm. Then, 12 kg of methanol (manufactured by Wako Pure Chemical Industries, Ltd.) and 3 kg of anhydrous calcium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) were charged into a 20 L separable flask and mixed using a mechanical stirrer to prepare a 20 wt% calcium chloride methanol solution. The cylindrical containers filled with the process scraps of the airbag were immersed and stirred at 60 °C for 24 hours to dissolve the polyamide. After dissolution, the silicone resin as an inclusion was separated into the cylindrical containers. The obtained polyamide solution passed through a polyethylene mesh with a mesh size of 500 μm by its own weight to remove a small amount of the inadvertently remaining silicone resin, and then was dropped into 30 kg of methanol to precipitate a solid. After separating the precipitated solid by pressure filtration, it was mixed with 20 kg of water and subjected to reduced-pressure filtration for washing. After repeating the washing with water 5 times, it was dried under reduced pressure at 80 °C to recover 800 g of polyamide.

[0341] [Example 10]

[0342] 50 kg of the process scrap of an airbag composed of 90 wt% of polyamide 6,6 and 10 wt% of silicone resin was cut into squares of about 20 cm on a side and evenly filled into 20 cylindrical containers made of polyethylene mesh with a diameter of 20 cm, a height of 20 cm, and a mesh size of 5 mm. Next, 480 kg of methanol (manufactured by Wako Pure Chemical Industries, Ltd.) and 120 kg of anhydrous calcium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) were charged into a 1 m 3 glass-lined reaction kettle, and mixed by a stirring blade to prepare a 20 wt% calcium chloride methanol solution. The cylindrical containers filled with the process scrap of the airbag were immersed and stirred at 60 °C for 24 hours to dissolve the polyamide. After dissolution, the silicone resin as an inclusion was separated into the cylindrical containers. The obtained polyamide solution was pressure-filtered using a polyethylene filter with a mesh size of 10 μm to remove a small amount of the silicone resin that had leaked through. The filterability was good. Next, the filtrate was dropped into 600 kg of methanol to precipitate a solid. After separating the precipitated solid by pressure filtration, it was mixed with 300 kg of water and subjected to vacuum filtration for washing. After repeating the washing with water 5 times, vacuum drying was carried out at 80 °C to recover 40 kg of polyamide.

[0343] [Example 11]

[0344] 50 g of the process scrap of a UD tape composed of 30 wt% of a random copolymer of polyamide 6,6 and polyamide 6I and 70 wt% of carbon fiber was cut into squares of about 5 cm on a side and filled into 1 cylindrical container made of a polyester sieve with a mesh size of 1.5 mm, a diameter of 5 cm, and a height of 5 cm. Next, 400 g of methanol (manufactured by Wako Pure Chemical Industries, Ltd.) and 100 g of anhydrous calcium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) were charged into a separable flask and mixed by a mechanical stirrer to prepare a 20 wt% calcium chloride methanol solution. The cylindrical container filled with the process scrap of the UD tape was immersed and stirred at 60 °C for 24 hours to dissolve the polyamide. After dissolution, the carbon fiber system as an inclusion was separated into the cylindrical containers, and no leakage outside the container was visually observed. The polyamide solution was dropped into 1.5 kg of a mixed solution of 50 wt% methanol and 50 wt% water to precipitate a solid, and the precipitated solid was separated by vacuum filtration. Further, it was mixed with 1 kg of water and subjected to vacuum filtration for washing. After repeating the washing with water 5 times, vacuum drying was carried out at 80 °C to recover 10 g of polyamide.

[0345] [Example 12]

[0346] After cutting 50 g of a tire cord composed of 95 wt% or more of polyamide into lengths of approximately 10 cm, it was filled into a cylindrical container with a diameter of 5 cm and a height of 5 cm made of a polyester screen with a mesh size of 0.5 mm. Next, 400 g of methanol (manufactured by Wako Pure Chemical Industries, Ltd.) and 100 g of anhydrous calcium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) were placed in a separable flask and mixed using a mechanical stirrer to prepare a 20 wt% calcium chloride methanol solution. The cylindrical container filled with the tire cord was immersed and stirred at 60°C for 24 hours to dissolve the polyamide. After dissolution, the inclusions were separated inside the cylindrical container. The obtained polyamide solution was pressure-filtered using a polyethylene filter with a mesh size of 10 μm to remove the omitted inclusions. The filterability was good. Next, the filtrate was dropped into 600 g of methanol to precipitate a solid. After separating the precipitated solid by pressure filtration, it was mixed with 1 kg of water and subjected to vacuum filtration for washing. After repeating the washing with water 5 times, it was dried under reduced pressure at 80°C to recover 45 g of polyamide.

[0347] [Example 13]

[0348] Zinc chloride was used in place of calcium chloride, and otherwise, the same operations as in Example 1 were performed to prepare a polyamide solution from the process scraps of the airbag, and 800 g of polyamide was recovered.

[0349] [Comparative Example 8]

[0350] 1 kg of process scraps of an airbag composed of 90 wt% of polyamide 6,6 and 10 wt% of silicone resin was cut into squares of approximately 10 cm. Next, 12 kg of methanol (manufactured by Wako Pure Chemical Industries, Ltd.) and 3 kg of anhydrous calcium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) were placed in a 20 L separable flask and mixed using a mechanical stirrer to prepare a 20 wt% calcium chloride methanol solution. The cut process scraps of the airbag were immersed and stirred at 60°C for 24 hours to dissolve the polyamide. After dissolution, the silicone resin, which was an inclusion, was finely chopped. Although it was intended to pass through a polyethylene mesh with a mesh size of 5 mm by its own weight, clogging occurred and separation was not possible.

[0351] [Comparative Example 9]

[0352] 1 kg of the process scrap of an airbag composed of 90 wt% of polyamide 6,6 and 10 wt% of silicone resin was cut into squares of about 10 cm on a side and evenly filled into 3 wire mesh cylindrical containers with a diameter of 10 cm, a height of 10 cm, and a mesh size of 5 mm. Next, 12 kg of methanol (manufactured by Wako Pure Chemical Industries, Ltd.) and 3 kg of anhydrous calcium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) were charged into a 20 L separable flask and mixed by a mechanical stirrer to prepare a 20 wt% calcium chloride methanol solution. The process scrap of the airbag was impregnated, and the mechanical stirrer was rotated. As a result, a sound of contact between the wire mesh and the inner wall of the apparatus was generated. Therefore, it was impregnated at 60 °C for 24 hours without stirring. Then, the dissolved polyamide was precipitated by the method described in Example 1, and washed and dried, but 90 g of polyamide was obtained.

[0353] Industrial Applicability

[0354] According to the present invention, a polyamide composition can be provided which can prevent the flow path of a filter or the like of a processing apparatus from being clogged during melt processing such as melt spinning, and can enable the processing apparatus to continuously operate for a long time. In addition, a polyamide fiber capable of improving the quality of an airbag base fabric can be provided.

Claims

1. A polyamide composition, which is a polyamide composition containing a silicon compound, wherein, the content of silicon atoms quantified by X-ray fluorescence analysis is 1000 ppm or less.

2. The polyamide composition according to claim 1, which is a recycled polyamide composition.

3. The polyamide composition according to claim 1 or 2, wherein, the content of silicon atoms quantified by X-ray fluorescence analysis is 30 ppm or more and 1000 ppm or less.

4. The polyamide composition according to claim 1 or 2, wherein, the silicon compound contains an organosilicon compound.

5. The polyamide composition according to claim 1 or 2, wherein, the content of polyamide components with a polymerization degree of 5 or less is 10000 ppm or less.

6. The polyamide composition according to claim 1 or 2, wherein, the polyamide contains polyamide 66.

7. A method for manufacturing a polyamide composition, which includes a step of dissolving polyamide from a polyamide base fabric covered with silicone, and this step is carried out using a container that has a mechanism where the part that rotates due to external power during dissolution does not contact the polyamide base fabric covered with silicone.

8. The manufacturing method according to claim 7, wherein, the dissolution of polyamide is carried out using a metal chloride alcohol solution.

9. A polyamide fiber, wherein, the content of polyamide components with a polymerization degree of 5 or less is 20000 ppm or less, and the content of silicon atoms quantified by X-ray fluorescence analysis is 50 ppm or more and 1000 ppm or less.

10. A polyamide fiber obtained from the polyamide composition according to claim 1, wherein the content of polyamide components with a polymerization degree of 5 or less in the polyamide fiber is 20000 ppm or less, and the content of silicon atoms quantified by X-ray fluorescence analysis is 50 ppm or more and 1000 ppm or less.

11. The polyamide fiber according to claim 9 or 10, in the dynamic viscoelasticity measurement, tanδ does not have a peak in the range of -50°C to +50°C, and tanδ has a peak in the range of +90°C to +130°C, and the peak value of tanδ is 0.1 or more and 0.15 or less.

12. The polyamide fiber according to claim 9 or 10, which is a multifilament having the following physical properties (1) to (7): (1) A total fineness of 150 dtex or more and 2500 dtex or less; (2) A strength of 6.0 cN / dtex or more and 11.0 cN / dtex or less; (3) An elongation at break of 15% or more and 25% or less; (4) A boiling water shrinkage rate of 4.0% or more and 11.0% or less; (5) A finishing agent adhesion rate of 0.5 wt% or more and 1.5 wt% or less; (6) The number of filaments is 30 or more and 400 or less; (7) A 3-month shrinkage decline rate of 12% or less.

13. The polyamide fiber according to claim 9 or 10, wherein, the polyamide fiber contains polyamide 66 fiber.

14. An airbag base fabric, which contains the polyamide fiber according to claim 9 or 10.

15. An airbag, which contains the airbag base fabric according to claim 14.

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