JP5110704B2 - Regeneration method of aliphatic polyamide from aliphatic polyamide fiber base fabric composite - Google Patents

Description

  The present invention relates to an aliphatic polyamide in which an aliphatic polyamide fiber base fabric is coated with another synthetic resin by coating or the like, or an aliphatic polyamide fiber base fabric is mixed with other synthetic resins as impurities. The present invention relates to a method of regenerating aliphatic polyamide as a valuable material such as resin pellets and resin chips from a fiber base fabric composite, in particular, an aliphatic polyamide fiber base composite as waste.

  2. Description of the Related Art Conventionally, a sheet-like material obtained by coating a fiber base fabric with a synthetic resin by a coating method, an extrusion method, a calendar method, a dipping method, or the like has been widely applied to various products. Aliphatic polyamide fibers are one of the typical ones used as such fiber base fabrics.

  There are various products in which an aliphatic polyamide fiber is used as a base fabric and a synthetic resin is coated by coating or the like, such as an automobile air bag. Automobile air bags have been initially developed with various materials, but recently, woven fabrics of aliphatic polyamide fibers have been used as the base fabrics, and in particular, those based on nylon 66 woven fabrics are being unified. This is because the excellent toughness and heat resistance of the nylon 66 woven fabric have been recognized as optimal as an air bag material.

  In order to ensure the safety of drivers and the like, such automobile air bags tend to be installed in all recent new cars. However, in such an air bag, many scraps are generated as waste in the manufacturing process, and it has been a problem to recycle such waste. Moreover, since it is predicted that a large amount of used airbags will be generated in the future, the treatment will be a major issue in the future.

  Such waste recycling is not limited to automobile airbags, but is also required for other products coated with synthetic resin by coating with aliphatic polyamide fibers as a base fabric. Is Rukoto. Such recycling of products based on aliphatic polyamide fibers can be effectively achieved by reusing aliphatic polyamide as a resin.

  When reusing aliphatic polyamide as a resin from products based on aliphatic polyamide fibers, it may be possible to remove contaminants of synthetic resin that has been coated with a coating by hand, for example. There is a problem that it becomes very high and is difficult to put into practical use. It is also conceivable to separate the coated synthetic resin and the aliphatic polyamide fiber by melting, but the aliphatic polyamide fiber is inherently difficult to dissolve with a chemical or the like, and the coated synthetic resin, etc. Since these foreign substances are firmly fixed to the base fabric of the aliphatic polyamide fiber, it was practically impossible to separate them by a method such as melting.

  For this reason, for example, a patent application such as the following Patent Document 1 has been filed as a technique for recycling wastes of products based on aliphatic polyamide fibers. The invention according to Patent Document 1 relates to a method for producing recycled pellets. In the method for producing recycled pellets, the edge material and waste material of the airbag fabric are pulverized into small pieces, and the small pieces are melt-kneaded into pellets. A method for producing reclaimed pellets, comprising using a cutting machine comprising a concave movable blade and a fixed flat blade when pulverizing into the small pieces.

  The invention according to Patent Document 1 is merely an improvement of the means for pulverizing the edge material and waste material of the airbag base fabric into small pieces, and does not focus on melting and kneading after making small pieces. Absent.

  However, since the aliphatic polyamide fiber is essentially difficult to dissolve as described above, even if the base fabric of the aliphatic polyamide fiber coated with the synthetic resin contaminant is fragmented, it is actually melt-kneaded. Thus, it is difficult to separate only the aliphatic polyamide and pelletize it as a resin.

JP 2003-191239 A

  The present invention has been made to solve the above-described problems, and does not involve complicated operations, and does not require much cost, and coats the base fabric of aliphatic polyamide fiber with another synthetic resin or the like. Etc., or an aliphatic polyamide fiber base fabric composite in which other synthetic resin or the like is mixed into the base fabric of aliphatic polyamide fiber as a contaminant, especially an aliphatic polyamide fiber base fabric composite that is a waste product Accordingly, an object of the present invention is to provide a recycling method capable of very easily and reliably performing an operation of recycling and reusing aliphatic polyamide as valuable materials such as resin pellets and resin chips.

  As a result of diligent research to solve such problems, the present inventors have found that when dissolving an aliphatic polyamide, it can be dissolved only in a limited solvent, such as a high-concentration formic acid or an alcohol solution of calcium chloride. In particular, the calcium chloride alcohol solution uses a calcium chloride alcohol solution, focusing on the fact that it is easier to separate and extract because the working environment is milder than formic acid and the soluble substances are limited. Thus, it was found that the aliphatic polyamide fiber base fabric, the synthetic resin or impurities coated on the base fabric, and the mixed synthetic resin can be separated to obtain only the aliphatic polyamide. It came to complete.

That is, the present invention provides a fat in which at least one of silicone and polyethylene is contained as a contaminant on an aliphatic polyamide fiber base fabric by an extract prepared by dissolving calcium chloride with an alkyl alcohol having 1 to 4 carbon atoms. The present invention provides a method for regenerating an aliphatic polyamide, which comprises extracting and regenerating only an aliphatic polyamide from an aromatic polyamide fiber base fabric composite.

The present invention is a method for extracting and regenerating only an aliphatic polyamide from an aliphatic polyamide fiber base fabric composite by an extract prepared by dissolving calcium chloride with an alkyl alcohol having 1 to 4 carbon atoms as described above. Therefore, at least one of silicone and polyethylene, which is a synthetic resin coated on an aliphatic polyamide fiber base fabric or mixed as a contaminant, and the aliphatic polyamide constituting the base fabric, as described above Due to the difference in solubility in the extract, only the aliphatic polyamide can be extracted and easily separated from the synthetic resin that has been coated or mixed as a contaminant, and the operation to regenerate the aliphatic polyamide as a resin is easy. And there is an effect that it can be performed reliably.

  As a result, it is possible to reuse the aliphatic polyamide that is the fiber base fabric and the other synthetic resin that is a foreign substance, and it is possible to save these petroleum resources.

  Furthermore, as in the above-described conventional technique, a technique for fragmenting an aliphatic polyamide fiber base fabric composite coated with a synthetic resin, an aliphatic polyamide fiber base fabric, and a coated synthetic resin Compared with the technique of separating the materials by manual work, the work is easy, workability is remarkably improved, and the processing cost can be remarkably reduced.

  Furthermore, there is less possibility that wastes of aliphatic polyamide fiber base fabric composites with poor biodegradability that are generated in large quantities will be left as they are, and there will be no need for treatment by combustion or the like, which will contribute to environmental conservation. effective.

The method of reproducing aliphatic polyamide of the present invention, as described above, the extract prepared by dissolving calcium chloride in an alkyl alcohol having 1 to 4 carbon atoms, at least silicone and polyethylene based fabric aliphatic polyamide fibers one extracts only aliphatic polyamides from aliphatic polyamide fiber base fabric composite which is provided as a contaminant, a reproduction method of an aliphatic polyamide to be reproduced. The contaminants of at least one of silicone and polyethylene are provided by a coating process such as coating.

As a solvent for extracting only the aliphatic polyamide, an extract prepared by dissolving calcium chloride with an alkyl alcohol having 1 to 4 carbon atoms as described above is used. As the alkyl alcohol having 1 to 4 carbon atoms, methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, etc. can be used, but the solubility is good. In particular, it is desirable to use methanol or ethanol for reasons such as.
As calcium chloride, both hydrates and anhydrides can be used, and as hydrates are generally commercially available and easy to obtain, as shown in the embodiments and examples described below, It is desirable to use a dihydrate for reasons such as showing excellent solubility in aliphatic polyamides.
In addition to such dihydrate, calcium chloride is also known to take the form of monohydrate, tetrahydrate, hexahydrate and the like. It is also possible to use hydrates, hexahydrates and the like. However, since it is not easily available as a raw material like dihydrate, calcium chloride anhydride is dissolved in an alcohol solution having 1 to 4 carbon alcohols such as methanol and ethanol. It is also possible to add an equivalent calculated amount of water to make an aliphatic polyamide extract.
That is, in the present invention, “an extract prepared by dissolving calcium chloride with an alkyl alcohol having 1 to 4 carbon atoms” means an anhydrous calcium chloride or hydrate containing only an alkyl alcohol having 1 to 4 carbon atoms. In addition to a dissolved alcohol solution, calcium chloride anhydride is dissolved with an alkyl alcohol having 1 to 4 carbon atoms, and a calculated amount of water corresponding to various hydrates, or equivalent to such hydrates. Although it is not a calculated amount, it means to include a solution prepared by adding a predetermined amount of water capable of suitably dissolving calcium chloride.
In the present invention, “dissolving calcium chloride with an alkyl alcohol having 1 to 4 carbon atoms” does not require that calcium chloride is completely dissolved, but increases the solubility of aliphatic polyamide. For this purpose, it is desirable that calcium chloride is dissolved in the alcohol as much as possible so that the calcium chloride does not crystallize. In this sense, it is desirable to use a calcium chloride hydrate or a saturated alkyl alcohol saturated solution having 1 to 4 carbon atoms, particularly a saturated methanol solution or a saturated ethanol solution. It is desirable to use a saturated saturated methanol solution.

  The means for extracting the aliphatic polyamide is not particularly limited. For example, the above-mentioned aliphatic polyamide fiber base fabric composite is added to an extract prepared by dissolving calcium chloride with an alkyl alcohol having 1 to 4 carbon atoms. A means for immersing the body is employed. In this case, for example, the extraction liquid as described above is stored in advance in an immersion tank, and the aliphatic polyamide fiber base fabric composite is added to the immersion tank. However, it is also possible to extract the aliphatic polyamide by means other than immersion.

  Furthermore, when using such an immersion tank, it is desirable to stir the said extract in the immersion tank, after adding an aliphatic polyamide fiber base fabric composite in the immersion tank. By stirring, the extraction efficiency of the aliphatic polyamide with respect to the above extract can be improved.

Furthermore, at least one of silicone and polyethylene is used as the synthetic resin that is coated on the aliphatic polyamide fiber base fabric or mixed as a contaminant .

  For example, in the case of an aliphatic polyamide fiber base fabric composite applied to an automobile airbag, a silicone resin or polyethylene film is laminated by coating or the like, so that the silicone or polyethylene is separated from the aliphatic polyamide and The group polyamide is extracted and regenerated. In particular, silicone and polyethylene do not dissolve in the above extract prepared by dissolving calcium chloride with an alkyl alcohol having 1 to 4 carbon atoms. Therefore, extraction and regeneration by separating from aliphatic polyamide are more effective. It can be suitably performed.

  Furthermore, the application to which the present invention is applied is not questioned, and it can be applied to wastes of various products composed of an aliphatic polyamide fiber base fabric composite in addition to the above-described automobile airbag. is there.

  The present invention is mainly applied to the waste of various products composed of the aliphatic polyamide fiber base fabric composite as described above, but the aliphatic polyamide fiber base other than the waste is used. It is also possible to apply to fabric composites.

  Hereinafter, a more specific embodiment of the present invention will be described with reference to FIG. In the embodiment of FIG. 1, a calcium chloride dihydrate saturated methanol solution is used as a solution for extracting the aliphatic polyamide.

  First, as shown in FIG. 1, calcium chloride dihydrate and methanol are supplied to a mixing tank 1 in which calcium chloride dihydrate and methanol are mixed. In the mixing tank 1, the calcium chloride dihydrate in methanol is stirred by the stirring blade 2. As a result, calcium chloride dihydrate is gradually dissolved in methanol, and calcium chloride dihydrate saturated methanol is obtained after a certain period of time.

  Thus, calcium chloride dihydrate that cannot be completely dissolved in the saturated solution is separated as a cake (solid) as shown in FIG. 1 and supplied to the mixing tank 1. Reused as a hydrate.

  The solution separated from the cake is supplied to the immersion tank 3. An aliphatic polyamide fiber base fabric composite composing an air bag is added to the dipping tank 3 and dipped in the calcium chloride dihydrate saturated methanol solution. Then, the aliphatic polyamide fiber base fabric composite in the calcium chloride dihydrate saturated methanol solution is stirred by the stirring blade 4 in the immersion tank 3.

  At this time, the aliphatic polyamide fibers constituting the composite fabric are gradually dissolved in calcium chloride dihydrate saturated methanol, and the aliphatic polyamide is extracted into calcium chloride dihydrate saturated methanol. It becomes.

On the other hand, since the silicone resin and polyethylene film laminated on the surface of the aliphatic polyamide fiber base fabric by coating or the like do not dissolve in calcium chloride dihydrate saturated methanol, the aliphatic polyamide constituting the base fabric and It will be suitably separated.
The silicone resin and polyethylene film, which are the impurities separated in this way, can be reused as recycled products.

  Water or methanol is added to a calcium chloride dihydrate saturated methanol solution that dissolves the aliphatic polyamide separated from impurities. By adding water or methanol in this manner, an aliphatic polyamide precipitate is obtained. This precipitate is pulverized by drying or the like to obtain an aliphatic polyamide powder, that is, a so-called nylon chip. And it will be reused as a nylon tip.

  The calcium chloride dihydrate saturated methanol separated from the aliphatic polyamide is returned to the mixing tank 1 and reused.

  As described above, in the present embodiment, the aliphatic polyamide fiber base fabric composite constituting the automotive airbag in which the silicone resin and the polyethylene film are laminated on the aliphatic polyamide fiber base fabric by coating or the like, calcium chloride Only the aliphatic polyamide that constitutes the base fabric of the composite is chlorinated without dissolving the silicone resin and polyethylene film laminated by coating etc. as a contaminant of the composite by immersing in dihydrate saturated methanol. Since it can be extracted by dissolving in calcium dihydrate saturated methanol and separated from silicone resin and polyethylene film, aliphatic polyamide and silicone resin and polyethylene film can be regenerated and reused separately It becomes possible.

  In addition, calcium chloride dihydrate separated as a solid substance in the middle of the process is returned to the mixing tank 1, and calcium chloride.2 water separated from aliphatic polyamide and foreign silicone resin and polyethylene film. Since the saturated Japanese methanol solution is also returned to the mixing tank 1, the chemical used for extracting the aliphatic polyamide is not discharged out of the system. Can be provided.

Examples of the present invention will be described below.
Example 1
In this example, an aliphatic polyamide fiber is dissolved in an extract prepared by adding a predetermined amount of water to a saturated solution of calcium chloride and a solution saturated with methanol or ethanol. Its solubility was tested.

That is, anhydrous calcium chloride was dissolved in methanol to prepare saturated methanol solutions having three concentrations of 3.9M, 4.3M, and 4.7M. The three concentrations 3.9M, 4.3M, and 4.7M in this case represent the molar molar concentration of calcium chloride with respect to methanol. Further, water was added to such three kinds of saturated methanol solutions to prepare an extract. As shown in Table 1, when the molar concentration of calcium chloride with respect to methanol is 4.7 M, the addition rate of water at that time is 17.0% by volume of water and 34.0% of the total amount of the extract. When water is added to the saturated methanol solution so that the volume%, 51.0 volume%, and 68.0 volume% respectively, and the volume molar concentration of calcium chloride with respect to methanol is 3.9 M, the total amount of the extract is reduced. On the other hand, water is added to a saturated methanol solution so that water becomes 14.0% by volume, 28.0% by volume, 42.0% by volume, and 56.0% by volume, respectively, and the volume molar concentration of calcium chloride with respect to methanol. Is 4.3M, saturated methanol solution so that the water is 15.5% by volume, 31.0% by volume, 47.0% by volume, and 62.0% by volume with respect to the total amount of the extract. Add water to . Thus, what added water so that it might become 4 types of different addition rates to the saturated methanol solution of 3 types of density | concentration was prepared as an extract which dissolves an aliphatic polyamide fiber.
Therefore, a total of 15 types of extract solutions are prepared including a saturated methanol solution having three types of concentrations to which water is not added. Aliphatic polyamide fibers were added to these 15 types of extracts and stirred.
Based on the difference in the volume molar concentration of calcium chloride with respect to methanol among the three types of saturated methanol solutions, the rate of addition of water to each of the three types of saturated methanol solutions is also different. This is because the calculated amount of water to be added is different when it is assumed that calcium chloride dissolved in a saturated methanol solution having a concentration of 1 is a hydrate.
That is, in this test example, anhydrous calcium chloride was used as a sample, but dihydrate, tetrahydrate, hexahydrate, and octahydrate were also assumed assuming that a hydrate was used. A calculated amount of water corresponding to the product is added. Therefore, 2 times, 4 times, 6 times, and 8 times mol of water are added to 1 mol of calcium chloride, respectively, so if the volume molar concentration of calcium chloride with respect to methanol is different, This is also because the addition rate of is different.
In addition, as mentioned above, dihydrate, tetrahydrate, and hexahydrate exist as calcium chloride hydrate, but octahydrate does not exist. Further, when a calculated amount of water corresponding to octahydrate is added, the saturated methanol solution is considerably diluted, so that it is assumed that the solubility of the aliphatic polyamide fiber also decreases. Therefore, it seems that there is not much profit to conduct a test to add water equivalent to octahydrate.
However, in this test example, when water is added to a calcium chloride saturated methanol solution as well as adding a calculated amount of water assuming that calcium hydrate is used as described above, It is important to confirm how the solubility of the aliphatic polyamide fiber changes depending on the amount of water added. In that sense, when water equivalent to the non-existing octahydrate is added. We are also testing.
Also, without assuming a hydrate, an arbitrary amount (for example, 1.5 times mol or 3 times mol) of water other than 2 times mol, 4 times mol, 6 times mol or the like is added to the saturated methanol solution. It is of course possible to prepare it as an extract.

  A saturated methanol solution having a concentration of 3.9M and 4.3M, and an extract obtained by adding 2 times mol, 4 times mol, 6 times mol, and 8 times mol of water to 1 mol of calcium chloride, respectively. Is stirred at 60 ° C., a saturated methanol solution having a concentration of 4.7 M, and 2 times mol, 4 times mol, 6 times mol and 8 times mol of water with respect to 1 mol of calcium chloride, respectively. The added extract was tested by changing the temperature during stirring to 60 ° C. and 23 ° C. (room temperature). Stirring was carried out at these temperatures, and when completely dissolved, aliphatic polyamide fibers were further added and stirred. This operation was repeated until the dissolution was stopped, and the solubility was measured.

Meanwhile, anhydrous calcium chloride was dissolved in ethanol to prepare a saturated ethanol solution having a concentration of 4.57M. Furthermore, water was added to this saturated ethanol solution to prepare an extract. As shown in Table 2, the water addition rate at that time is 17.0% by volume, 34.0% by volume, 51.0% by volume, and 68.0% by volume of water with respect to the total amount of the extract. It was prepared as follows. Therefore, a total of five types of extracts are prepared including a saturated ethanol solution to which water is not added.
Then, aliphatic polyamide fibers were added to these five types of extracts and stirred. The temperature at the time of stirring was changed to 60 ° C. and 23 ° C. (room temperature), and the test was performed. Stirring was carried out at these temperatures, and when completely dissolved, aliphatic polyamide fibers were further added and stirred. This operation was repeated until the dissolution was stopped, and the solubility was measured.

  The test results when using a saturated methanol solution are shown in Table 1, and the test results when using a saturated ethanol solution are shown in Table 2. In Tables 1 and 2, the water addition rate is% by volume, and the solubility of the aliphatic polyamide fiber is% by mass.

  As is apparent from Table 1, when a saturated methanol solution is used and the volume molar concentration of calcium chloride with respect to methanol is 4.7M and 4.3M, the total amount of water in the extract is 17.0 vol. % (15.5% by volume), that is, when water was added twice as much as 1 mol of calcium chloride, the highest solubility was obtained. On the other hand, when the volume molar concentration of calcium chloride with respect to methanol was 3.9 M, the result that the solubility was highest when water was not added was obtained. Moreover, the solubility improved as the volume molar concentration of calcium chloride in methanol was increased. Furthermore, it was found that the solubility was higher when stirring at 60 ° C. than when stirring at normal temperature (23 ° C.).

  On the other hand, when using a saturated ethanol solution, as is clear from Table 2, the water in the total amount of the extract is 33.0% by volume (4 times mol), 50.0% by volume (6 times mol). When water was added so as to be, that is, when 4 times mol and 6 times mol of water were added with respect to 1 mol of calcium chloride, the result that the solubility was high was obtained. Further, as in the case of saturated methanol, it was found that the solubility was higher when stirring at 60 ° C. than when stirring at normal temperature (23 ° C.).

(Example 2)
1kg of aliphatic polyamide woven fabric with polyethylene coating on both sides including polyethylene film as a narrow object is immersed in 5 liters of calcium chloride dihydrate saturated methanol solution and stirred at room temperature to completely complete the aliphatic polyamide woven fabric portion Dissolved in.

  The resulting viscous solution was filtered through a fine stainless mesh to remove the silicone and polyethylene film. A large excess of water was added to the aliphatic polyamide solution to precipitate the aliphatic polyamide. The precipitate obtained by filtration and filtration was dried under reduced pressure at 100 ° C. to obtain an aliphatic polyamide powder. This aliphatic polyamide powder was immediately placed on an extruder, heated and melted, extruded into air, and cut into a so-called nylon chip. In order to precipitate the aliphatic polyamide, alcohol (preferably methanol) can be added instead of a large excess of water.

(Example 3)
150 g of aliphatic polyamide woven fabric with polyethylene coating on both sides including polyethylene film as a narrow object is immersed in 5 liters of calcium chloride dihydrate saturated methanol solution and stirred at room temperature to complete the aliphatic polyamide woven fabric part Dissolved in.

  The resulting viscous solution was filtered through a fine stainless mesh to remove the silicone and polyethylene film. A large excess of water was added to the aliphatic polyamide solution to precipitate the aliphatic polyamide. The precipitate obtained by filtration and collection was analyzed by FT-IR and confirmed to be an aliphatic polyamide. In order to precipitate the aliphatic polyamide, alcohol (preferably methanol) can be added instead of a large excess of water.

Example 4
Add 4.5 liters of calcium chloride dihydrate saturated methanol solution and 22.5 g of aliphatic polyamide woven fabric cut to 1 × 1 cm to a cylindrical stirring tank with a volume of about 6.6 liters, and use three propeller blades. And stirred at 500 rpm for 24 hours. The insoluble part was filtered off, and a large excess of water was added to the filtrate to precipitate the aliphatic polyamide. The precipitate was separated with a PTFE filter and dried under reduced pressure at 100 ° C. to obtain an aliphatic polyamide powder.

  The filtrate was distilled to recover methanol and reused for preparing calcium chloride dihydrate saturated methanol solution. In addition, calcium chloride dihydrate precipitated during the distillation was filtered and dried, and then reused for preparing a calcium chloride dihydrate saturated methanol solution. In order to precipitate the aliphatic polyamide, alcohol (preferably methanol) can be added instead of a large excess of water.

The flowchart which shows the process of the regeneration method of the aliphatic polyamide of one Embodiment.

Claims (4)

An aliphatic polyamide fiber group in which at least one of silicone and polyethylene is included as a contaminant on an aliphatic polyamide fiber base fabric by an extract prepared by dissolving calcium chloride with an alkyl alcohol having 1 to 4 carbon atoms. A method for regenerating aliphatic polyamide, wherein only the aliphatic polyamide is extracted from the fabric composite and regenerated. By using an extract prepared by dissolving calcium chloride with an alkyl alcohol having 1 to 4 carbon atoms, fat is removed from the aliphatic polyamide fiber base fabric composite in which silicone and polyethylene are contained as impurities on the base fabric of the aliphatic polyamide fiber. A method for regenerating an aliphatic polyamide, wherein only the aliphatic polyamide is extracted and regenerated. The aliphatic group according to claim 1 or 2, wherein only the aliphatic polyamide is extracted by immersing the aliphatic polyamide fiber base fabric composite in an extract prepared by dissolving calcium chloride with an alkyl alcohol having 1 to 4 carbon atoms. Polyamide regeneration method. The method for regenerating an aliphatic polyamide according to any one of claims 1 to 3 , wherein the alkyl alcohol having 1 to 4 carbon atoms is methanol or ethanol.

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