Method and apparatus of recovering polymer resin, and recycled product

Abstract

To provide a novel recovering method of a polymer resin from an airbag cloth made of the polymer resin, obviating the requirement of using an alkaline aqueous solution for removing a silicone resin, and being easy in operation.SOLUTION: A method of recovering a polymer resin from an airbag cloth made of the polymer resin applied with a silicone resin at least on one surface includes the steps of: immersing the whole airbag cloth in water using an in-water holding member, and heat-processing it at a temperature of 180°C or more and under a saturated steam pressure or more at the temperature while maintaining the in-water immersion using the in-water holding member; and recovering the polymer resin separated from the silicone resin by the heat-processing.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method and device for recovering polymer resin from airbag fabric, and to a recycled product using the recovered polymer resin. [Background technology]

[0002] 2. Description of the Related Art In recent years, attention has been focused on recycling waste materials and the like in order to reduce the burden on the environment. Airbag fabrics are generally made by coating the surface of a base fabric made of polymer resin such as polyamide fabric or polyester fabric as the raw material (yarn) with a silicone resin for the purpose of improving heat resistance, airtightness, flame retardancy, etc. For this reason, when recycling airbag fabrics, particularly when recovering and recycling the polymer resin that constitutes the base fabric, it has been necessary to remove the silicone resin from the base fabric made of polymer resin.

[0003] As a method for recovering polymer resin from airbag fabric, for example, a method is known in which the airbag fabric is treated with an alkaline aqueous solution to remove the silicone resin from the base fabric. Specifically, a method is known in which the airbag fabric is immersed in an alkaline aqueous solution containing a tertiary amine and a surfactant, and then the solution is stirred and allowed to stand to remove the silicone resin (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-180413 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the airbag fabric is treated with an alkaline aqueous solution, the treatment liquid is absorbed into the base fabric made of polymer resin and the layer of silicone resin, so that in order to recover and recycle them, a process of removing the treatment liquid is required, which makes the operation complicated. In addition, the polymer resin constituting the base fabric may be damaged, such as decomposed, by the treatment with the alkaline aqueous solution, so the method does not have a sufficiently high recyclability of the recovered polymer resin. Furthermore, since the treatment with the alkaline aqueous solution uses chemicals such as sodium hydroxide, complicated post-treatment such as waste liquid treatment is required, and environmental load is also a concern.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a new method for recovering polymer resin from a polymer resin airbag fabric, which does not require the use of an alkaline aqueous solution to remove silicone resin, and a simple method for recovering polymer resin with reduced operational complexity. [Means for solving the problem]

[0007] As a result of intensive research into solving the above-mentioned problems, the inventors have found that a method for recovering a polymer resin, which includes the steps of: immersing an entire airbag fabric made of a polymer resin having a silicone resin applied to at least one side thereof in water using a submersible holding member; and, while maintaining the fabric immersed in water using the submersible holding member, heat-treating the fabric at a temperature of 160°C or higher and under a pressure equal to or higher than the saturated water vapor pressure at that temperature; and recovering the polymer resin separated from the silicone resin by the heat treatment, makes it possible to easily recover a polymer resin from an airbag fabric without the need for the use of an alkaline aqueous solution, and has completed the present invention.

[0008] The gist of the present invention is as follows. [1] A method for recovering a polymer resin from a polymer resin airbag fabric having a silicone resin applied to at least one side thereof, comprising the steps of: A step of immersing the entire airbag fabric in water using an underwater holding member, and heat-treating the airbag fabric at a temperature of 160° C. or higher and under a pressure equal to or higher than the saturated water vapor pressure at that temperature while maintaining the airbag fabric immersed in water using the underwater holding member; and and recovering the polymer resin separated from the silicone resin by the heat treatment. [2] The method of recovering silicone resin described in [1], wherein the polymer resin floats on the water surface due to the water current generated by the heat treatment, while the silicone resin is retained in the water by an underwater retention member, thereby separating the polymer resin and the silicone resin. [3] The recovery method described in [1] or [2], wherein the underwater retention member is a filter member, and the entire airbag fabric is retained underwater by restricting the movement of the airbag fabric with the filter member. [4] The recovery method described in [1] or [2], wherein the underwater retention member is a shape retention member that retains the shape of the end of the airbag cloth, and the entire airbag cloth is retained underwater by providing the shape retention member on at least a part of the outer periphery of the airbag cloth. [5] The method for recovering airbags according to any one of [1] to [4], wherein pieces of fabric obtained by cutting or crushing used airbags are used as the airbag fabric. [6] The method for collecting airbag fabric according to any one of [1] to [5], wherein the size of the airbag fabric is 1 mm2 to 2500 cm2. [7] The method for collecting airbag fabric according to any one of [1] to [6], wherein the size of the airbag fabric is within a range of 1 mm to 500 mm in length and 1 mm to 500 mm in width. [8] The method according to any one of [1] to [7], wherein the polymer resin is a polyamide-based resin or a polyester-based resin. [9] The recovery method according to [8], wherein the polyamide-based resin is nylon 66 and the polyester-based resin is polyethylene terephthalate.

[10] The method according to any one of [1] to [9], wherein in the heat treatment step, the treatment temperature is 180° C. to 240° C., and the treatment pressure is 1.0 MPa to 3.6 MPa.

[11] The polymer resin is nylon 66, and in the heat treatment step, the treatment temperature is The recovery method according to [9], wherein the temperature is 180°C to 240°C and the treatment pressure is 1.0 MPa to 3.6 MPa.

[12] The recovery method according to [9], wherein the polymer resin is polyethylene terephthalate, and in the heat treatment step, the treatment temperature is 210°C to 240°C and the treatment pressure is 2.0 MPa to 3.6 MPa.

[13] The method according to any one of [1] to

[12] , further comprising a cooling step after the heat treatment step and before the recovery step.

[14] The recovery method according to [3], wherein the filter member has a plurality of through holes, and the opening area of ​​the through holes is 0.05% to 25% of the area of ​​the airbag fabric.

[15] The method of claim 3 or 14, wherein the filter member is made of metal.

[16] The recovery method described in [4], wherein the shape-retaining member is made of a metal selected from the group consisting of aluminum and stainless steel.

[17] A recycling method comprising at least a part of a raw material being a polyamide-based resin or a polyester-based resin obtained by the recovery method according to any one of [8], [9],

[11] , and

[12] .

[18] A polymer resin recovery device equipped with a high-pressure hot water treatment device, A recovery device having a removable filter member fitted to separate the reaction vessel.

[19] A polyamide resin having a crystal perfection of 95% or more as measured by wide-angle X-ray measurement. Effect of the Invention

[0009] According to the present invention, a new recovery method can be provided in which the use of an alkaline aqueous solution is optional for recovering a polymer resin from a polymer resin airbag fabric. In the recovery method of the present invention, the alkaline aqueous solution is not used or the level of use can be reduced, so damage to the polymer resin caused by the alkaline treatment can be suppressed, and the polymer resin from which the silicone resin has been removed can be recovered using a process with a low environmental impact. In addition, according to the present invention, it is possible to provide a simple polymer resin recovery method in which the complexity of the recovery operation is reduced. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic cross-sectional view showing an example of a high-pressure hot water treatment apparatus according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The method for recovering a polymer resin of the present invention includes the steps of immersing an entire polymer resin airbag fabric having a silicone resin applied to at least one side thereof in water using an underwater holding member, and, while maintaining the fabric immersed in water using the underwater holding member, subjecting the fabric to a heat treatment at a temperature of 160°C or higher and under a pressure equal to or higher than the saturated water vapor pressure at that temperature, and recovering the polymer resin separated from the silicone resin by the heat treatment.

[0012] (Polymer resin airbag fabric) The polymeric resin airbag fabric from which the polymeric resin is recovered by the recovery method of the present invention is an airbag fabric in which silicone resin is applied to at least one side of a base fabric made of polymeric resin. The airbag fabric may be waste material such as scraps generated during the manufacture of airbags and used airbags. When using used airbags, the fabric may be cut into pieces, and the cut pieces may be cut into pieces. It is preferred that the cut or crushed fabric pieces be used as airbag fabric for the heat treatment.

[0013] The polymer resin constituting the base fabric is preferably a polyamide resin or a polyester resin.

[0014] Polyamide resins are polymers having amide bonds in the main chain. Examples of polyamide resins include polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), polytetramethylene adipamide (nylon 46), polyhexamethylene sebacamide (nylon 610), polyhexamethylene dodecamide (nylon 612), polylauryllactam (nylon 12), polyundecane amide (nylon 11), and copolymers and mixtures thereof. For airbag fabrics made of polyamide resins, polycaproamide resin obtained by polycondensation of ε-caprolactam, commonly called nylon 6, and nylon 66 are preferably used in terms of heat resistance and cost, and nylon 66 is particularly preferred. Even when the polyamide resins are recycled after recovery, nylon 6 and nylon 66 are preferred in terms of versatility, and nylon 66 is more preferred.

[0015] The polyester resin is formed by reacting a carboxylic acid component with a hydroxyl group component. Examples of the carboxylic acid component include terephthalic acid, isophthalic acid, adipic acid, sebacic acid, and naphthalenedicarboxylic acid. Examples of the hydroxyl group component include ethylene glycol, 1,4-butanediol, diethylene glycol, neopentyl glycol, and cyclohexanedimethanol. Examples of the polyester resin include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, and copolymerized polyesters obtained by further copolymerizing these polymers with a third component. For the polyester resin airbag fabric, polyethylene terephthalate is preferably used because it can achieve both cost and physical properties such as strength. In addition, even when the polyester resin is recycled after recovery, polyethylene terephthalate is preferable as the polyester resin in terms of versatility.

[0016] The base fabric, which is a polyamide cloth or a polyester cloth, is preferably a woven fabric composed of multifilaments of polyamide fibers or polyester fibers. Examples of the woven fabric include plain weave, twill weave, satin weave, and variations thereof.

[0017] From the viewpoint of recovering polymer resin with higher recyclability, the number of filaments in the multifilament yarn constituting the woven fabric (base fabric) is, for example, preferably 30 to 200, and more preferably 40 to 180. The number of filaments can be determined by counting from a cross-sectional photograph of the multifilament yarn.

[0018] From the viewpoint of recovering polymer resin with high recyclability, the total fineness of the multifilament yarn constituting the woven fabric (base fabric) is, for example, preferably 200 dtex to 1000 dtex, more preferably 250 dtex to 800 dtex. The total fineness of the multifilament yarn can be measured in accordance with JIS L1013 (2010) 8.3.1.

[0019] From the viewpoint of recovering polymer resin with high recyclability, the tensile strength of the multifilament yarn constituting the woven fabric (base fabric) is, for example, preferably 6.0 cN / dtex to 10 cN / dtex, and more preferably 6.5 cN / dtex to 9.5 cN / dtex. The tensile strength of the multifilament yarn can be measured in accordance with JIS L1013 (2010) 8.5.1.

[0020] From the viewpoint of recovering polymer resin with higher recyclability, the weave density of the woven fabric (base fabric) is, for example, preferably 35 threads / 2.54 cm to 80 threads / 2.54 cm in both the warp and weft directions, and more preferably 40 threads / 2.54 cm to 75 threads / 2.54 cm. The weave density can be measured in accordance with JIS L1096 (2010) 8.6.1.

[0021] From the viewpoint of recovering polymer resin with higher recyclability, the cover factor (CF) of the woven fabric (base fabric) is, for example, preferably 1,500 to 2,500, and more preferably 1,700 to 2,300. The cover factor is an index of the covering rate of the woven fabric, and can be calculated by the following formula. CF = (total warp fineness) 0.5 x warp density + (total weft fineness) 0.5 x weft density

[0022] In addition to the polyamide resin or polyester resin, the base fabric may further contain additives such as antioxidants, heat stabilizers, smoothing agents, antistatic agents, thickeners, flame retardants, weather resistance agents, coloring inhibitors, and colorants.

[0023] The polymeric resin airbag fabric has a silicone resin-containing coating resin applied to at least one surface of a base fabric, forming a silicone resin layer.

[0024] The silicone resin is not particularly limited, but specific examples include addition polymerization type silicone rubber, etc. For example, dimethyl silicone rubber, methyl vinyl silicone rubber, methyl phenyl silicone rubber, trimethyl silicone rubber, fluoro silicone rubber, methyl silicone resin, methyl phenyl silicone resin, methyl vinyl silicone resin, epoxy modified silicone resin, acrylic modified silicone resin, polyester modified silicone resin, etc. Among them, addition polymerization type methyl vinyl silicone rubber is preferable.

[0025] The viscosity of the coating resin is preferably 5000 mPa·sec to 40000 mPa·sec, and more preferably 7000 mPa·sec to 38000 mPa·sec. As long as the viscosity is within the above range, the coating resin may be either solvent-based or solventless, but solventless is preferred. In this specification, the viscosity of the coating resin composition containing additives other than the resin, that is, the viscosity of the resin actually applied to the base fabric, is defined as the viscosity of the coating resin.

[0026] The coating resin may contain additives other than silicone resin and solvent. Examples of the additives include reactive curing agents such as platinum catalysts (specifically, platinum black, chloroplatinic acid, alcohol-modified chloroplatinic acid, complexes of chloroplatinic acid with olefins, aldehydes, vinylsiloxanes, or acetylene alcohols, etc.); adhesion aids such as amino-based silane coupling agents, epoxy-modified silane coupling agents, vinyl-based silane coupling agents, chlorine-based silane coupling agents, and mercapto-based silane coupling agents; reinforcing inorganic fillers such as fumed silica and dry silica; non-reinforcing inorganic fillers such as crosslinkable silicones (silicone resins) with adjusted terminal groups, calcium carbonate, calcium silicate, and titanium dioxide; antioxidants; antistatic agents; flame retardants; weather resistance agents; coloring inhibitors; and colorants. When a platinum-based catalyst is contained as a reactive curing agent, the content is preferably 100 ppm to 2000 ppm, and more preferably 150 ppm to 1800 ppm, in terms of the amount of platinum metal per 100 parts by mass of the silicone resin. When a silane coupling agent is contained as an adhesion aid, the content thereof is preferably 0.01 to 3 parts by mass, and more preferably 0.02 to 2 parts by mass, per 100 parts by mass of the silicone resin. When an inorganic filler is contained, the content thereof is preferably 0.1 to 200 parts by mass, and more preferably 0.1 to 100 parts by mass, per 100 parts by mass of the silicone resin.

[0027] The coating resin (i.e., silicone resin) on the base fabric may be applied by a conventionally known application method, such as knife coating, roll coating, reverse coating, gravure coating, gravure reverse coating, kiss coating, etc., and the silicone resin is preferably applied by knife coating.

[0028] The amount of silicone resin applied to the polymer resin airbag fabric is preferably 5 g / m2 to 150 g / m2, more preferably 7 g / m2 or more, even more preferably 10 g / m2 or more, and more preferably 120 g / m2 or less, even more preferably 100 g / m2 or less, and even more preferably 70 g / m2 or less, from the viewpoint of ease of separation of the polymer resin from the silicone resin.

[0029] From the viewpoint of ease of separation of the polymer resin from the silicone resin, the weight ratio of the polymer resin in the polymer resin airbag fabric is preferably 50% by weight to 99% by weight, more preferably 55% by weight or more, even more preferably 60% by weight or more, even more preferably 70% by weight or more, and more preferably 97% by weight or less, even more preferably 95% by weight or less, and even more preferably 93% by weight or less.

[0030] The size of the airbag fabric is preferably 1 mm2 to 2500 cm2 from the viewpoint of ease of retention in water and efficiency of heat treatment. When a filter member described later is used as an underwater retention member during heat treatment, the size of the airbag fabric is more preferably 25 mm2 or more, more preferably 1 cm2 or more, even more preferably 10 cm2 or more, more preferably 1500 cm2 or less, and even more preferably 1000 cm2 or less. When a shape-retaining member described later is used as an underwater retention member during heat treatment, the size of the airbag fabric is more preferably 1 cm2 or more, more preferably 25 cm2 or more, even more preferably 100 cm2 or more, more preferably 2000 cm2 or less, and even more preferably 1500 cm2 or less. From the viewpoints of ease of holding in water and efficiency of heat treatment, the size of the airbag fabric is preferably within the range of 1 mm to 500 mm in length and 1 mm to 500 mm in width, and more preferably within the range of 5 mm to 450 mm in length and 5 mm to 450 mm in width. When the size of the airbag fabric exceeds the above upper limit, it is preferable to cut the airbag fabric into a size within the above range using a known cutting machine or the like before the heat treatment.

[0031] The shape of the airbag fabric is not particularly limited, and may be quadrangular such as rectangular or square, circular, elliptical, or other polygonal or irregular shape, with a quadrangular shape being preferred from the viewpoint of ease of handling.

[0032] (Heat treatment process) The heat treatment is performed using a high-pressure hot water treatment apparatus. The high-pressure hot water treatment apparatus may be a batch type apparatus or a flow type apparatus, but is preferably a batch type apparatus when a shape-retaining member described later is used as the underwater retaining member.

[0033] In the heat treatment process, first, the airbag fabric is placed in the water present in the reaction tank of the high-pressure hot water treatment device using a submersible retaining member so that the entire airbag fabric is immersed in the water. Then, while the submersible retaining member keeps the entire airbag fabric submerged in water, the airbag fabric is heat treated at a temperature of 160°C or higher and under a pressure equal to or higher than the saturated water vapor pressure at that temperature. By performing the heat treatment under the above conditions, the polymer resin constituting the base fabric in the airbag fabric melts. Here, since the silicone resin is kept in the water in the reaction tank by the submersible retaining member, the molten polymer resin is easily detached from the silicone resin. Preferably, the molten polymer resin is separated from the silicone resin by a water flow (e.g., convection) generated during the heat treatment. Although the polymeric resin airbag fabric usually has a higher specific gravity than water, due to the water repellency of the silicone resin, it does not sink in water even when left standing, but rises to the water surface. By using an underwater holding member, the entire polymeric resin airbag fabric can be immersed in water, and the polymeric resin airbag fabric can be prevented from being present on the water surface. On the other hand, the molten polymeric resin detached from the silicone resin flows with the water flow, and for example, rises to the water surface, not only when the polymeric resin has a lower specific gravity than water, but also when the polymeric resin has a higher specific gravity than water. Therefore, it is possible to prevent the polymeric resin once detached from the silicone resin from contacting the polymeric resin airbag fabric and the silicone resin again, and the polymeric resin can be easily recovered by distinguishing them from them.

[0034] The underwater retention member may be any member capable of immersing and retaining the entire airbag fabric in water, and is not preferred if it cannot prevent even a part of the airbag fabric from floating on the water surface. Examples of underwater retention members include filter members and shape retention members.

[0035] The filter member as the underwater holding member has a plurality of through holes of a size that prevents the airbag fabric to be subjected to heat treatment from passing through. By placing the filter member in the reaction tank, the movement of the airbag fabric is restricted by the filter member (i.e., the airbag fabric is prevented from floating to the water surface or flowing out of the reaction tank), and the entire airbag fabric can be held underwater.

[0036] When a water surface is present in the reaction tank during the heat treatment, the filter member is preferably fitted in the reaction tank so as to separate the reaction tank into an upper part where the water surface is present and a lower part where water is present throughout the reaction tank. From the viewpoint of ease of operation, the filter member is preferably provided detachably.

[0037] The size of the filter member may be such that, when the filter member is installed in the reaction vessel, the airbag fabric does not pass through the gap between the inner wall of the reaction vessel and the filter member. For example, the area of ​​the filtration surface including the through-holes is preferably 80% to 100%, more preferably 90% to 100%, and even more preferably 97% to 100% of the cross-sectional area of ​​the reaction vessel at the location where the filter member is installed.

[0038] The thickness of the filter member is not particularly limited. For example, the lower limit of the thickness of the filter member may be set to a thickness that does not cause movement or deformation due to the water flow during heat treatment, and the upper limit of the thickness of the filter member may be set to a thickness that allows the polymer resin melted by heat treatment to easily pass through.

[0039] The size of each through hole in the filter member is preferably such that the water used in the heat treatment and the polymer resin melted by the heat treatment can pass through, but the silicone resin cannot. The size of each through hole in the filter member is, for example, preferably 0.05% to 25% of the area of ​​the airbag cloth, more preferably 0.1% to 20%, and even more preferably 0.1% to 15%. When a plurality of airbag cloths are used, the area of ​​the airbag cloth is the average value of the areas of the airbag cloths used. Specifically, the opening area is preferably 0.05 mm2 to 200 cm2, more preferably 0.1 mm2 to 100 cm2, and even more preferably 0.3 mm2 to 50 cm2. Of the multiple through holes in the filter member, the proportion by number of through holes having an opening area within the above range is preferably 60% to 100%, more preferably 80% to 100%, and even more preferably 90% to 100%.

[0040] The total opening area, which is the sum of the opening areas of the multiple through holes in the filter member, is preferably 30% to 95% of the area of ​​the filtration surface including the through holes of the filter member, more preferably 40% to 93%, and even more preferably 50% to 90%.

[0041] As the material for the filter member, from the viewpoints of heat resistance, pressure resistance, durability, etc., metals such as silicon, aluminum, nickel, tungsten, copper, titanium, and stainless steel are preferred, and aluminum and stainless steel are more preferred.

[0042] Examples of the filter member include metal filters such as metal mesh and punched metal plates.

[0043] The shape-retaining member as an underwater retention member is a member that retains (fixes) the shape of at least the end portion of the airbag cloth. By providing a shape-retaining member on at least a portion of the outer periphery (preferably at least one end) of the airbag cloth, the entire airbag cloth can be retained underwater. Furthermore, by retaining at least one end of the airbag cloth, folding or curling of the airbag cloth can be suppressed, which is also preferable from the viewpoint of heat treatment efficiency. The shape-retaining member may be detachably fixed in the reaction tank using a fixing member such as a hook.

[0044] Examples of the shape-retaining member include an end shape-retaining member that fixes a part of the outer periphery of the airbag fabric, and a frame member that fixes the entire outer periphery of the airbag fabric.

[0045] When an end shape retaining member is used, from the viewpoint of shape retention, it is preferable that the end shape retaining member is provided over a total length of 50% or more of the total length of the end of the airbag fabric, more preferably over a total length of 70% or more, and even more preferably over a total length of 90% or more.

[0046] When a shape-retaining member is used, the total overlapping area of ​​the airbag fabric with the shape-retaining member is preferably 0.1% to 20%, more preferably 0.5% to 15%, and even more preferably 1% to 10%, of the total area of ​​the airbag fabric, from the viewpoints of shape retention and polymer resin recovery rate.

[0047] As the material for the shape-retaining member, from the viewpoints of heat resistance, pressure resistance, durability, etc., metals such as silicon, aluminum, nickel, tungsten, copper, titanium, and stainless steel are preferred, and aluminum and stainless steel are more preferred.

[0048] The shape-retaining member is preferably a metal frame made of a metal such as silicon, aluminum, nickel, tungsten, copper, titanium, or stainless steel, and more preferably an aluminum metal frame or a stainless steel metal frame.

[0049] The heat treatment is carried out while the entire airbag fabric is kept immersed in water by the underwater holding member.

[0050] The treatment temperature in the heat treatment is preferably 160° C. or higher, and may be 170° C. or higher, but from the viewpoint of the polymer resin recovery rate, it is more preferably 185° C. or higher, even more preferably 188° C. or higher, and particularly preferably 190° C. or higher, and from the viewpoint of suppressing deterioration of the polymer resin, it is preferably 250° C. or lower, more preferably 240° C. or lower, even more preferably 235° C. or lower, and even more preferably 230° C. or lower. If the treatment temperature is within the above range, the polymer resin and the silicone resin can be easily separated while suppressing deterioration such as decomposition of the polymer resin.

[0051] The treatment pressure in the heat treatment is equal to or higher than the saturated steam pressure at the treatment temperature, and is preferably 1.0 MPa to 4.0 MPa, more preferably 1.1 MPa or higher, even more preferably 1.2 MPa or higher, more preferably 3.6 MPa or lower, even more preferably 3.3 MPa or lower, even more preferably 3.0 MPa or lower, and even more preferably 2.8 MPa or lower. If the treatment pressure is within the above range, the polymer resin and the silicone resin can be easily separated while suppressing deterioration such as decomposition of the polymer resin. From the viewpoint of easy control of temperature and pressure in the heat treatment, it is also preferable to treat at the saturated steam pressure at the treatment temperature.

[0052] When the polymer resin is nylon 66, from the viewpoint of improving the recovery rate, the treatment temperature is preferably 180°C to 240°C and the treatment pressure is preferably 1.0 MPa to 3.6 MPa. When the polymer resin is polyethylene terephthalate, from the viewpoint of improving the recovery rate, the treatment temperature is preferably 210°C to 240°C and the treatment pressure is preferably 2.0 MPa to 3.6 MPa.

[0053] The treatment time in the heat treatment may be appropriately set depending on the treatment temperature and treatment pressure, but is, for example, preferably 30 seconds to 240 minutes, more preferably 45 seconds or more, even more preferably 1 minute or more, more preferably 180 minutes or less, even more preferably 120 minutes or less, and even more preferably 60 minutes or less. If the treatment time is within the above range, the polymer resin and the silicone resin can be easily separated while suppressing deterioration such as decomposition of the polymer resin.

[0054] From the viewpoint of preventing deterioration of the airbag fabric (particularly the polymer resin), it is preferable to raise the temperature and / or pressure to the treatment temperature and / or treatment pressure in a short time. For example, the pressure is preferably raised from 0.05 MPa to the treatment pressure within 60 minutes, more preferably within 30 minutes, and even more preferably within 20 minutes. The temperature is preferably raised from 80°C to the treatment temperature within 60 minutes, more preferably within 30 minutes, and even more preferably within 20 minutes.

[0055] As a method for performing the heat treatment, for example, a heat-resistant reaction tank containing the airbag fabric held underwater by the underwater holding member may be heated and pressurized using a heating device such as a heater, or high-pressure hot water may be circulated through a heat-resistant reaction tank containing the airbag fabric whose movement is restricted by the underwater holding member using a liquid delivery device such as a pump.

[0056] When water is heated, the heated water rises, generating a water current. The water current releases the polymer resin melted by heat treatment from the submerged holding member and floats on the water surface, while the silicone resin is held in the water by the submerged holding member, resulting in separation of the polymer resin and the silicone resin. When high-pressure hot water is circulated through a reaction tank, the water current caused by the flow releases the polymer resin melted by heat treatment from the submerged holding member and flows out, while the silicone resin is held in the water by the submerged holding member, resulting in separation of the polymer resin and the silicone resin.

[0057] The heat treatment may be carried out while stirring using a known stirring device such as a stirring blade, if necessary. When the heat treatment is carried out while stirring, the stirring is preferably carried out at a rotation speed of 10 to 3000 rpm, more preferably 20 to 2000 rpm. By carrying out the heat treatment while stirring, the separation of the polymer resin and the silicone resin can be further promoted.

[0058] (cooling process) After the heat treatment, the reaction vessel and / or the polymer resin may be cooled by natural cooling or by using a known cooling device. The polymer resin melted by the heat treatment is solidified by cooling, so that the polymer resin separated from the silicone resin can be made into a solid. If it is in a solid state, it is preferable because it is easy to handle. When the method for recovering the polymer resin includes a cooling step, it is preferable to include the step before the recovery step.

[0059] From the viewpoint of suppressing deterioration of the polymer resin, it is preferable to perform the temperature reduction by cooling in a short time. For this reason, it is preferable to perform the cooling by using a known cooling device rather than natural cooling. For example, the temperature reduction from the treatment temperature to 80°C is preferably performed within 60 minutes, more preferably within 30 minutes, and even more preferably within 20 minutes.

[0060] (Recovery process) In the recovery process, the polymer resin separated from the silicone resin by the heat treatment is recovered. As described above, by performing heat treatment while the entire airbag fabric is immersed in water, the polymer resin exists in a state separated from the silicone resin, so that the polymer resin can be easily recovered. If the heat treatment is not performed while the entire airbag fabric is immersed in water, the molten polymer resin may adhere to the silicone resin due to cooling, making the recovery operation complicated.

[0061] The polymer resin can be recovered simply by removing the polymer resin that exists separately from the silicone resin.

[0062] The recovered polymer resin may be appropriately subjected to post-treatment such as washing with a washing liquid such as water or an organic solvent, and drying.

[0063] In the method for recovering polymer resin of the present invention, the airbag fabric is not required to be treated with alkali, and the airbag fabric is kept in water and treated under a specific temperature and pressure, so that the deterioration of the polymer resin due to the alkali treatment can be avoided, and the silicone resin and the polymer resin can be easily separated and recovered without complicated operations. In addition, the recovery method of the present invention has high heat treatment efficiency. Therefore, the recovery method of the present invention can preferably reduce the treatment time required for heat treatment, and can further suppress the deterioration of the polymer resin.

[0064] (polymer resin) The polymer resin recovered by the recovery method of the present invention preferably does not substantially contain silicone resin. Substantially does not contain means that the content of silicone resin in the polymer resin is 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.1% by mass or less. There is no particular lower limit, and it is preferably 0% by mass, and may be 0.01% by mass or more. Polymer resins that do not substantially contain silicone resin have high recyclability. The content of silicone resin contained in the polymer resin can be calculated based on the value obtained by, for example, determining the mass of silicone resin in the polymer resin using a Fourier transform infrared spectrophotometer (FT-IR).

[0065] The higher the recovery rate of the polymer resin, the more preferable, with the upper limit being 100% by weight, and preferably 1% by weight or more, more preferably 5% by weight or more, and even more preferably 7% by weight or more. The recovery rate of the polymer resin is calculated by measuring the weight (B parts by weight) of the polymer resin separated from the silicone resin in the reaction tank after the heat treatment, and using the weight (A parts by weight) of the sample (airbag fabric) before the treatment and the weight ratio (C%) of the polymer resin in the sample before the treatment according to the following formula. Recovery rate (%) = {B / [A×(C / 100)]}×100

[0066] The polymer resin obtained by the recovery method of the present invention is less deteriorated than the polymer resin in the airbag fabric before heat treatment. The degree of deterioration can be confirmed by the viscosity of the polymer resin (e.g., relative viscosity, intrinsic viscosity). Since the viscosity and the molecular weight of the resin are proportional, the higher the viscosity, the higher the molecular weight of the recovered polymer resin, that is, the more the polymer state is maintained. Specifically, when the polymer resin is a polyamide-based resin, if the relative viscosity is 1.3 or more (preferably 1.5 or more, more preferably 1.7 or more, even more preferably 1.9 or more, even more preferably 2.1 or more, and even more preferably 2.3 or more), it can be said that the polyamide-based resin is suitable for material recycling, and when the polymer resin is a polyester-based resin, if the intrinsic viscosity is 0.3 dl / g or more (preferably 0.5 dl / g or more, more preferably 0.7 dl / g or more), it can be said that the polyester-based resin is suitable for material recycling.

[0067] The relative viscosity (RV) of a polymer resin can be calculated by dissolving 0.25 g of the polymer resin in 46 g of 96% sulfuric acid, placing 10 ml of this solution in an Oswald viscosity tube, measuring at 20°C, and using the following formula. RV=T / T0 (RV: relative viscosity, T: drop time of sample solution, T0: drop time of solvent)

[0068] The intrinsic viscosity (η) of a polymer resin can be determined by dissolving 0.1 g of the polymer resin in 25 mL of a mixed solvent of phenol / 1,1,2,2-tetrachloroethane (60 / 40 (weight ratio)) and measuring the viscosity at 30° C. using an Ostwald viscometer.

[0069] In cases where the relative viscosity (RV0) of the polymer resin before heat treatment can be measured, it is preferable that the ratio of RV (relative viscosity of the recovered polymer resin) to RV0 (RV / RV0) is 0.4 or more (preferably 0.5 or more, more preferably 0.6 or more, even more preferably 0.7 or more, and even more preferably 0.8 or more). If the value of RV / RV0 is within the above range, the polymer resin obtained by the recovery method of the present invention is inhibited from deteriorating, and can be said to be a polymer resin that can be suitably used for material recycling. In cases where the intrinsic viscosity (η0) of the polymer resin before heat treatment can be measured, it is preferable that the ratio (η / η0) of η (intrinsic viscosity of the recovered polymer resin) to η0 is 0.3 or more (preferably 0.5 or more, more preferably 0.7 or more). If the value of η / η0 is within the above range, the polymer resin obtained by the recovery method of the present invention is inhibited from deteriorating, and can be said to be a polymer resin that can be suitably used for material recycling.

[0070] Polymer resins that can be suitably used for material recycling can be reused without further treatment such as polymerization, which is advantageous from the standpoint of energy costs and has particularly high recyclability.

[0071] When the polymer resin is a polyamide resin such as polycaproamide (nylon 6) or polyhexamethylene adipamide (nylon 66), the recovery method of the present invention can obtain a polyamide resin with high crystal perfection. The crystal perfection of the polyamide resin is preferably 95% or more, more preferably 97% or more, and may be 100%. The closer the crystal perfection value is to 100%, the higher the crystal perfection is, and the more excellent the stability against heat is. The crystal perfection of the polyamide resin can be determined by the method described in the examples (wide-angle X-ray measurement).

[0072] The use of the polymer resin obtained by the recovery method of the present invention is not particularly limited. For example, it can be reused by decomposing the resin down to monomers and repolymerizing the resulting resin (chemical recycling), or it can be reused by melting the resin and re-pelletizing it without decomposing the resin down to monomers (material recycling). From the viewpoint of energy costs, it is preferable to use the resin for material recycling.

[0073] The polymer resin (preferably a polyamide-based resin or a polyester-based resin) obtained by the recovery method of the present invention can be recycled into recycled products containing the polymer resin as at least a part of the raw material through chemical recycling or material recycling.

[0074] (Collection device) The recovery apparatus of the present invention is an apparatus capable of carrying out the polymer resin recovery method of the present invention described above, and is characterized in that it comprises a high-pressure hot water treatment apparatus, the high-pressure hot water treatment apparatus having a submersible retaining member (in the illustrated example, a removable filter member fitted to separate the reaction tank). The recovery apparatus of the present invention will be described below with reference to the illustrated example as necessary. However, the recovery apparatus of the present invention is not limited to the illustrated example below, and appropriate modifications can be made within the scope of the present invention, and all of these modifications are included in the technical scope of the present invention.

[0075] As shown in the schematic cross-sectional view of FIG. 1, the recovery device includes a high-pressure hot water treatment device 1, which has a submersible holding member, specifically a removable filter member 3 fitted to separate the reaction tank 2. The high-pressure hot water treatment device 1 may also have a lid 21 for closing the reaction tank 2, and may also have a fixing member such as a tightening bolt 22 for fixing the reaction tank 2 and the lid 21. The high-pressure hot water treatment device 1 may also have a heating mechanism 6 such as a heater for heating the reaction tank 2. The high-pressure hot water treatment device 1 may further have a cooling mechanism (e.g., a heat exchanger such as a water jacket), a pressure gauge, a safety valve, a temperature sensor, and / or a stirrer (e.g., a stirring blade), although not shown.

[0076] The filter member 3 has a plurality of through holes. The specific aspects of the size, thickness, material, and through holes of the filter member 3 are as described above.

[0077] The heating mechanism may be installed so as to heat the entire reaction tank 2, or may be installed so as to heat a portion of the reaction tank 2, and from the viewpoint of heating efficiency, it is preferable to install it so as to heat at least the bottom of the reaction tank 2.

[0078] The recovery device of the present invention treats the object to be treated with high-pressure hot water, and in the high-pressure hot water treatment device 1 equipped in the recovery device, the object to be treated, that is, the polymer resin airbag fabric 4 coated with silicone resin, can be held in its entirety in water 5 by the filter member 3. By carrying out the heat treatment, the polymer resin becomes molten and passes through the filter member 3 to accumulate on the water surface. On the other hand, the silicone resin does not pass through the filter member 3 and remains held in the water. Therefore, by using the recovery device, it is possible to separate and recover the airbag fabric 4 into the silicone resin and the polymer resin without complicated operations, and further, it is possible to suppress deterioration of the recovered polymer resin. EXAMPLES

[0079] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples, and it is possible to carry out the present invention by making appropriate modifications within the scope of the above and below-mentioned aims, and all of these modifications are included in the technical scope of the present invention.

[0080] In the following Examples and Comparative Examples, the following polyamide resin airbag fabric 1 was used as the polymer resin airbag fabric.

[0081] (Polyamide resin airbag fabric 1) A plain weave fabric was obtained using polyamide 66 multifilament yarn with an original yarn strength of 8.4 cN / dtex, a total fineness of 470 dtex, and 68 filaments, with a warp density of 46 / 2.54 cm, a weft density of 46 / 2.54 cm, and a cover factor of 1994. One side of the plain weave fabric (base fabric) was coated with an addition polymerization type solventless vinyl methyl silicone resin with a resin viscosity of 14000 mPa·sec and dried at 200°C for 1 minute, to obtain a polyamide resin airbag fabric 1 with a resin coating amount of 25 g / m2. The weight ratio of polyamide resin in the polyamide resin airbag fabric 1 was 87%.

[0082] In the following Examples and Comparative Examples, the polyamide resin, which is a polymer resin recovered from the polyamide resin airbag fabric 1, was evaluated in the following manner.

[0083] (Recovery rate) After the heat treatment, the polyamide resin separated from the silicone resin was collected in the reaction tank. The weight (B parts by weight) of the collected polyamide resin was measured, and the recovery rate was calculated from the weight (A parts by weight) of the sample before the treatment and the weight ratio (C%) of the polyamide resin in the sample before the treatment according to the following formula. Recovery rate (%) = {B / [A×(C / 100)]}×100

[0084] (Relative Viscosity) After the heat treatment, the polyamide resin separated from the silicone resin was collected in the reaction vessel. 0.25 g of the collected polyamide resin was dissolved in 46 g of 96% sulfuric acid, and 10 ml of this solution was placed in an Oswald viscosity tube and measured at 20°C. The relative viscosity was calculated using the following formula: Since the relative viscosity is proportional to the molecular weight of the resin, the higher the relative viscosity, the higher the molecular weight of the recovered polyamide resin, which means that the resin maintains its polymeric state. RV=T / T0 (RV: relative viscosity, T: drop time of sample solution, T0: drop time of solvent)

[0085] (Crystal Perfection) The polyamide resin separated from the silicone resin was collected in the reaction tank after the heat treatment. The collected polyamide resin was subjected to wide-angle X-ray measurement by the transmission method using an X-ray diffractometer (SmartLab) manufactured by Rigaku. CuKa rays were used as the X-ray source, the X-ray output was 45 kV, 200 mA, a 0.3 mm pinhole slit for parallel beams, a 0.1 mmΦ collimator, and a 2D transmission attachment head was used as the sample stage. A two-dimensional semiconductor detector Hypix-3000 manufactured by Rigaku was used as the detector, and a two-dimensional image was obtained with an exposure time of 5 minutes, and the intensity was integrated to obtain a one-dimensional profile. The angles of the diffraction peaks of the (100), (010), and (110) planes of polyamide 66 were used to determine the interplanar spacing d(100) of the (100) plane, and the interplanar spacing d(010) of the (010) plane and the (110) plane. The crystal perfection (CPI) was calculated from the following formula. In the formula below, the denominator value (0.189) is a value based on the calculated value of the interplanar spacing of ideal crystals, and can be found in Spoerer Y, Androsch R, Jehnichen D, Kuehnert I, “Process induced skin-core morphology in injection molded polyamide 66”, Polymers, (2020), 12: 894, etc. In addition, the crystalline perfection of the polyamide resin before heat treatment was 74%. CPI(%)={[(d(100) / d(010))-1] / 0.189}×100

[0086] Example 1 The polyamide resin airbag fabric 1 was cut into 40 mm squares. The cut sample was placed in a reaction tank of a high-pressure hot water treatment device with an internal volume of 500 mL together with 300 mL of water, and heated to 220°C while the cut sample was held in water using a metal filter with a mesh size of 2 mm. The pressure at that time was 2.3 MPa. After heat treatment for 10 minutes, the sample was cooled to room temperature and collected. The evaluation results of the collected sample are shown in Table 1. In Example 1, the recovery rate of the polyamide resin was 48%, and the relative viscosity of the collected polyamide resin was 2.06. Therefore, according to the method of Example 1, the silicone resin and the polyamide resin could be easily separated, and the collected polyamide resin could be obtained in the form of a polymer.

[0087] (Examples 2 to 7) In Examples 2 to 7, samples were recovered in the same manner as in Example 1, except that the conditions were changed as shown in Table 1. The evaluation results of the recovered samples are shown in Table 1. According to the methods of Examples 2 to 7, the silicone resin and the polyamide resin could be easily separated, and further, the recovered polyamide resin could be obtained in the form of a polymer. In Examples 5 and 6, a stirrer (stirring blade) for stirring the inside of the reaction tank was installed, and stirring was performed during the heat treatment.

[0088] (Comparative Examples 1 and 2) In Comparative Examples 1 and 2, samples were collected in the same manner as in Example 1, except that the conditions were changed to those shown in Table 1. The evaluation results of the collected samples are shown in Table 1. In the method of Comparative Example 1, since no underwater holding member was used and the entire sample was not held under water during heat treatment, the polymer resin dissolved by heat treatment adhered to the silicone resin during cooling, and the polymer resin separated from the silicone resin could not be collected. In the method of Comparative Example 2, since the treatment temperature was as low as 170°C, the polymer resin did not melt during heat treatment, and the polymer resin separated from the silicone resin could not be collected.

[0089] [Table 1]

[0090] Example 8 The polyamide resin airbag fabric 1 was cut into 15 cm squares. A metal frame was provided to fix the entire end of the cut sample using aluminum foil. The sample with the metal frame was placed in a reaction tank of a high-pressure hot water treatment device with an internal volume of 500 mL together with 300 mL of water, and the sample was heated to 210°C while being held in water. The pressure at that time was 2.0 MPa. After heat treatment for 10 minutes, the sample was cooled to room temperature and collected. The evaluation results of the collected sample are shown in Table 2. In Example 8, the recovery rate of the polyamide resin was 58%, and the relative viscosity of the collected polyamide resin was 2.40. Therefore, according to the method of Example 8, the silicone resin and the polyamide resin could be easily separated, and the collected polyamide resin could be obtained in the form of a polymer.

[0091] (Examples 9 to 12) In Examples 9 to 12, samples were recovered in the same manner as in Example 8, except that the conditions were changed as shown in Table 2. The evaluation results of the recovered samples are shown in Table 2. According to the methods of Examples 9 to 12, the silicone resin and the polyamide resin could be easily separated, and further, the recovered polyamide resin could be obtained in the form of a polymer.

[0092] Comparative Example 3 In Comparative Example 3, a sample was recovered in the same manner as in Example 8, except that the conditions were changed to those shown in Table 2. The evaluation results of the recovered sample are shown in Table 2. In the method of Comparative Example 3, an underwater holding member was not used, and the treatment temperature was low at 170°C, so that the polymer resin did not melt during the heat treatment, and it was not possible to recover the polymer resin separated from the silicone resin.

[0093] [Table 2]

[0094] From the above, it has been found that by using the polymer resin recovery method and high-pressure hot water treatment device disclosed herein, polymer resin that is suitable for material recycling because it is in a polymer state can be easily recovered from polymer resin airbag fabric. [Explanation of symbols]

[0095] 1. High pressure hot water treatment equipment 2. Reactor 21 Lid 22 Fastening bolt 3 Filter parts 4 Airbag Fabric 5 water 6 Heating mechanism

Claims

1. A method for recovering a polymer resin from a polymer resin airbag fabric having a silicone resin applied to at least one side thereof, comprising the steps of: A step of immersing the entire airbag fabric in water using an underwater holding member, and heat-treating the airbag fabric at a temperature of 160° C. or higher and under a pressure equal to or higher than the saturated water vapor pressure at that temperature while maintaining the airbag fabric immersed in water using the underwater holding member; and and recovering the polymer resin separated from the silicone resin by the heat treatment.

2. The recovery method according to claim 1 , wherein the polymer resin floats on the water surface due to a water current generated by the heat treatment, while the silicone resin is retained in the water by an underwater retention member, thereby separating the polymer resin from the silicone resin.

3. The recovery method according to claim 1 , wherein the underwater retention member is a filter member, and the entire airbag fabric is retained underwater by restricting movement of the airbag fabric with the filter member.

4. The recovery method according to claim 1, wherein the underwater retention member is a shape retention member that retains the shape of the end of the airbag fabric, and the entire airbag fabric is retained underwater by providing the shape retention member on at least a portion of the outer periphery of the airbag fabric.

5. 2. The method according to claim 1, wherein the airbag fabric is made of pieces of fabric obtained by cutting or crushing a used airbag.

6. The method of claim 1, wherein the size of the airbag fabric is between 1 mm2 and 2500 cm2.

7. The recovery method according to claim 1, wherein the size of the airbag fabric is within the range of 1 mm to 500 mm in length and 1 mm to 500 mm in width.

8. The method according to claim 1 , wherein the polymer resin is a polyamide resin or a polyester resin.

9. 9. The method according to claim 8, wherein the polyamide resin is nylon 66 and the polyester resin is polyethylene terephthalate.

10. The method according to claim 1, wherein in the heat treatment step, the treatment temperature is 180°C to 240°C and the treatment pressure is 1.0 MPa to 3.6 MPa.

11. The recovery method according to claim 9, wherein the polymer resin is nylon 66, and in the heat treatment step, the treatment temperature is 180°C to 240°C and the treatment pressure is 1.0 MPa to 3.6 MPa.

12. The recovery method according to claim 9, wherein the polymer resin is polyethylene terephthalate, and in the heat treatment step, the treatment temperature is 210° C. to 240° C. and the treatment pressure is 2.0 MPa to 3.6 MPa.

13. 2. The method of claim 1, further comprising a cooling step after said heat treatment step and before said recovery step.

14. 4. The method according to claim 3, wherein the filter member has a plurality of through holes, and the opening area of ​​the through holes is 0.05% to 25% of the area of ​​the airbag fabric.

15. The method according to claim 3 , wherein the filter member is made of metal.

16. The recovery method according to claim 4 , wherein the shape-retaining member is made of a metal selected from the group consisting of aluminum and stainless steel.

17. A recycled product, comprising, as at least a part of its raw material, a polyamide-based resin or a polyester-based resin obtained by the recovery method according to claim 8.

18. A polymer resin recovery device comprising a high-pressure hot water treatment device, the high-pressure hot water treatment device having a removable filter member fitted so as to separate a reaction tank.

19. A polyamide resin having a degree of crystal perfection of 95% or more as determined by wide-angle X-ray measurement.

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