Regenerated polyamide resin composition

Abstract

The present invention pertains to a regenerated polyamide resin composition obtained by melt-kneading a polyamide resin (a) or a polyamide resin composition (A) containing the polyamide resin (a) as a main component and a polyamide-based resin waste (B), the polyamide-based resin waste (B) containing a polyamide resin (b1) and a thermoplastic resin (b2) other than the polyamide resin, the thermoplastic resin (b2) other than the polyamide resin is more than 0% by mass and 2.00% by mass or less in 100% by mass of the polyamide-based resin waste (B), and the polyamide-based resin waste (B) is contained in an amount of 2% by mass or more and less than 50% by mass in 100% by mass of the regenerated polyamide resin composition. The regenerated polyamide resin composition according to the present invention is capable of contributing to SDGs (Sodium Dodecyl Goals), which is a sustainable development target.

Description

Technical Field

[0001] The present invention relates to a recycled polyamide resin composition. Background Art

[0002] In recent years, with the advancement of SDGs (Sustainable Development Goals), there is a demand to reduce plastic waste.

[0003] For example, if fishing nets are left in the wild, they may become entangled in fish, birds and other creatures, or pollute the ocean as microplastics. In addition, even if they are properly disposed of, they can lead to an increase in plastic waste.

[0004] Fishnets are often made of a composition containing polyamide resin as a main component. Patent Document 1 discloses a method for recycling fishnets, which is used to obtain high-quality recycled pellets, and includes cutting, crushing, and pelletizing fishnets.

[0005] Patent Document 2 discloses that, in a regenerated polyamide for molding obtained by mixing polyamide monofilament waste fibers with a polyamide resin composition, the polyamide resin composition is obtained by mixing a polyamide resin having a lower mass average molecular weight than the waste fibers with glass fibers.

[0006] Furthermore, Patent Document 3 describes that a recycled thermoplastic is stabilized by blending it with at least one compound that reacts with a carbonyl group and an antioxidant in combination.

[0007] [Prior art literature]

[0008] [Patent Document]

[0009] Patent Document 1: Japanese Patent No. 6935963

[0010] Patent Document 2: Japanese Patent Application Publication No. 2004-18614

[0011] Patent Document 3: Japanese Patent Application No. 2022-518047 Summary of the invention

[0012] Problem that the invention aims to solve

[0013] Even if the scrap composition is a polyamide-based composition, it usually contains other unexpected components such as thermoplastic resins and colorants. It is believed that the physical properties of the recycled resin composition will change depending on its composition, and the composition of the scrap composition will have an impact. In addition, it is believed that the proportion of the scrap composition contained in the recycled resin composition will also affect the physical properties of the recycled resin composition. However, Patent Documents 1 to 3 do not study the composition of the scrap composition or the composition of the recycled resin composition.

[0014] Polyamide resins and compositions thereof are characterized by excellent tensile properties such as tensile strength and tensile modulus. The recycled resin composition is preferably a composition that utilizes a waste composition so as to improve or not impair the tensile properties of the polyamide resin and the composition thereof.

[0015] Furthermore, the recycled resin composition is required to have moldability because it is used as a molded product. In addition, in the monofilament used for mowing ropes, fishing nets, fishing lines, etc., it is desirable to have a certain degree of softness while having mechanical strength.

[0016] Therefore, an object of the present invention is to provide a recycled polyamide resin composition which, even when containing a scrap composition, has an improved tensile modulus compared to a case where no scrap composition is contained and has good moldability.

[0017] Solutions for solving problems

[0018] The present inventors have found that by setting the amount of polyamide-based resin scrap (B) in a recycled polyamide resin composition and the amount of a thermoplastic resin (b2) other than the polyamide resin contained in the polyamide-based resin scrap (B) as an unintended component within specific ranges, a tensile strength and a tensile modulus equivalent to those of a polyamide resin composition not containing scraps can be maintained, and that the composition can be used as a recycled polyamide resin composition, thereby contributing to SDGs (Sustainable Development Goals), thereby completing the present invention.

[0019] The present invention is, for example, the following [1] to

[18] .

[0020] [1] A recycled polyamide resin composition obtained by melt-kneading a polyamide resin (a) or a polyamide resin composition (A) containing the polyamide resin (a) as a main component and polyamide-based resin waste (B);

[0021] The polyamide-based resin scrap (B) comprises a polyamide resin (b1) and a thermoplastic resin (b2) other than the polyamide resin.

[0022] In 100% by mass of the polyamide-based resin scrap (B), the content of the thermoplastic resin (b2) other than the polyamide resin is greater than 0% by mass and is 2.00% by mass or less,

[0023] The polyamide-based resin scrap (B) is contained in 100% by mass of the recycled polyamide resin composition in an amount of 2% by mass or more and less than 50% by mass.

[0024] [2] The recycled polyamide resin composition according to [1], wherein the content of the polyamide resin (b1) is 5 parts by mass or more, based on 100 parts by mass of the total amount of the polyamide resin (a) and the polyamide resin (b1).

[0025] [3] The recycled polyamide resin composition according to [1] or [2], wherein the content of the thermoplastic resin (b2) other than the polyamide resin is 0.05 parts by mass or more, when the total amount of the polyamide resin (a) and the polyamide resin (b1) is 100 parts by mass.

[0026] [4] A recycled polyamide resin composition according to any one of [1] to [3], wherein, when the total amount of the polyamide resin (a) and the polyamide resin (b1) is 100 parts by mass, the content of the polyamide resin (b1) is 5 parts by mass or more, and the content of the thermoplastic resin (b2) other than the polyamide resin is 0.05 parts by mass or more.

[0027] [5] The recycled polyamide resin composition according to any one of [1] to [4], wherein the thermoplastic resin (b2) other than the polyamide resin is at least one selected from the group consisting of polyester resins, polyolefin resins and polyvinyl alcohol.

[0028] [6] The recycled polyamide resin composition according to any one of [1] to [5], wherein the polyamide resin (a) or the polyamide resin composition (A) comprising the polyamide resin (a) as a main component is a polyamide resin composition (A) comprising the polyamide resin (a) as a main component and contains at least one selected from the group consisting of a lubricant and a heat resisting agent.

[0029] [7] The recycled polyamide resin composition according to any one of [1] to [6], wherein the polyamide-based resin scrap (B) contains a colorant.

[0030] [8] The recycled polyamide resin composition according to any one of [1] to [7], wherein the polyamide resin (a) or the polyamide resin composition (A) containing the polyamide resin (a) as a main component comprises at least one selected from the group consisting of polyamide 4, polyamide 46, polyamide 410, polyamide 56, polyamide 510, polyamide 512, polyamide 6, polyamide 66, polyamide 610, polyamide 612, polyamide 1010, polyamide 1012, polyamide 11, polyamide 12, polyamide 6 / 66, polyamide 6 / 12 and polyamide 6 / 66 / 12.

[0031] [9] The recycled polyamide resin composition according to any one of [1] to [8], wherein the polyamide resin (a) or the polyamide resin (a) in the polyamide resin composition (A) containing the polyamide resin (a) as a main component is an aliphatic homopolyamide resin.

[0032]

[10] The recycled polyamide resin composition according to any one of [1] to [8], wherein the polyamide resin (a) or the polyamide resin (a) in the polyamide resin composition (A) containing the polyamide resin (a) as a main component is an aliphatic copolyamide resin.

[0033]

[11] The recycled polyamide resin composition according to any one of [1] to

[10] , wherein the polyamide resin (b1) is an aliphatic homopolyamide resin.

[0034]

[12] The recycled polyamide resin composition according to any one of [1] to

[11] , wherein the polyamide-based resin scrap (B) is monofilament scrap.

[0035]

[13] The recycled polyamide resin composition according to any one of [1] to

[12] , wherein the difference between the melting point and the crystallization temperature (Tm-Tc) measured by a differential scanning calorimeter (DSC) is 10 to 45°C.

[0036]

[14] The recycled polyamide resin composition according to any one of [1] to

[13] , wherein an extractable amount when boiled with pure water for 6 hours is 0.5 to 7.5% by mass.

[0037]

[15] A molded article, which is a molded article of the recycled polyamide resin composition according to any one of [1] to

[14] .

[0038]

[16] The molded article according to

[15] , which is a monofilament.

[0039]

[17] A method for producing a recycled polyamide resin composition, comprising melt-kneading a polyamide resin (a) or a polyamide resin composition (A) comprising the polyamide resin (a) as a main component and polyamide-based resin waste (B), wherein:

[0040] The polyamide-based resin scrap (B) comprises a polyamide resin (b1) and a thermoplastic resin (b2) other than the polyamide resin.

[0041] In 100% by mass of the polyamide-based resin waste (B), the content of thermoplastic resin (b2) other than polyamide resin is greater than 0% by mass and less than 2.00% by mass,

[0042] The polyamide-based resin scrap (B) is contained in 100% by mass of the recycled polyamide resin composition in an amount of 2% by mass or more and less than 50% by mass.

[0043]

[18] The method for producing a recycled polyamide resin composition according to

[17] , comprising the following steps:

[0044] Step 1, crushing the aforementioned polyamide resin waste (B);

[0045] Step 2, which comprises adding the aforementioned polyamide resin (a) or the polyamide resin composition (A) containing the polyamide resin (a) as a main component to the pulverized polyamide-based resin waste (B) obtained in Step 1 and mixing them; and

[0046] Step 3 is to melt-knead the mixture obtained in step 2 to obtain pellets.

[0047] Effects of the Invention

[0048] Even if the recycled polyamide resin composition of the present invention contains the scrap composition, the tensile modulus is improved compared to the case where the scrap composition is not contained, and the moldability is good. DETAILED DESCRIPTION

[0049] The present invention relates to a recycled polyamide resin composition, which is obtained by melt-kneading a polyamide resin (a) or a polyamide resin composition (A) containing the polyamide resin (a) as a main component and polyamide-based resin waste (B), and

[0050] The polyamide-based resin scrap (B) comprises a polyamide resin (b1) and a thermoplastic resin (b2) other than the polyamide resin.

[0051] In 100% by mass of the polyamide-based resin scrap (B), the content of the thermoplastic resin (b2) other than the polyamide resin is greater than 0% by mass and less than 2.00% by mass,

[0052] The polyamide-based resin scrap (B) is contained in 100% by mass of the recycled polyamide resin composition in an amount of 2% by mass or more and less than 50% by mass.

[0053] <<Polyamide resin (a) or polyamide resin composition (A) containing polyamide resin (a) as a main component>>

[0054] The recycled polyamide resin composition comprises: a polyamide resin (a) or a polyamide resin composition (A) comprising the polyamide resin (a) as a main component.

[0055] The polyamide resin (a) is not particularly limited, and examples thereof include aliphatic homopolyamide resins and aliphatic copolyamide resins.

[0056] (Aliphatic homopolyamide resin (a-1))

[0057] Aliphatic homopolyamide resin is a polyamide resin formed of one structural unit derived from an aliphatic monomer. Aliphatic homopolyamide resin may be formed of at least one of a lactam and an aminocarboxylic acid, or may be formed of a combination of a diamine and a dicarboxylic acid. Here, for the combination of a diamine and a dicarboxylic acid, the combination of a diamine and a dicarboxylic acid is regarded as one monomer. Aliphatic also includes alicyclic.

[0058] The number of carbon atoms of the lactam is preferably 4 to 12, more preferably 5 to 12. The number of carbon atoms of the aminocarboxylic acid is preferably 4 to 12, more preferably 5 to 12. The number of carbon atoms of the diamine is preferably 2 to 20, more preferably 4 to 12. The number of carbon atoms of the dicarboxylic acid is preferably 2 to 20, more preferably 6 to 12.

[0059] Examples of lactams include ε-caprolactam, enantholactam, undecanolactam, laurolactam, 2-pyrrolidone (γ-butyrolactam), 2-piperidone, and laurolactam (ω-lauryl lactam). Among these, one selected from the group consisting of ε-caprolactam, undecanolactam, and laurolactam is preferred from the viewpoint of polymerization productivity.

[0060] Examples of the aminocarboxylic acid include 6-aminohexanoic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid.

[0061] Examples of the diamine include aliphatic diamines such as ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, tridecanediamine, tetradecanediamine, pentadecanediamine, hexadecanediamine, heptadecanediamine, octadecanediamine, nonadecanediamine, eicosanediamine, 2-methyl-1,8-octanediamine, and 2,2,4 / 2,4,4-trimethylhexamethylenediamine; and 1,3 - / 1,4-cyclohexanediamine, bis(4-aminocyclohexyl)methane, bis(4-aminocyclohexyl)propane, bis(3-methyl-4-aminocyclohexyl)methane, (3-methyl-4-aminocyclohexyl)propane, 1,3- / 1,4-bisaminomethylcyclohexane, 5-amino-2,2,4-trimethyl-1-cyclopentanemethylamine, 5-amino-1,3,3-trimethylcyclohexanemethylamine, bis(aminopropyl)piperazine, bis(aminoethyl)piperazine, norbornane dimethylenediamine and other alicyclic diamines, etc.

[0062] Examples of the dicarboxylic acid include aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, octadecanedioic acid, and eicosanedioic acid; and alicyclic dicarboxylic acids such as 1,3- / 1,4-cyclohexanedicarboxylic acid, dicyclohexanemethane-4,4'-dicarboxylic acid, and norbornanedicarboxylic acid.

[0063] Specific examples of the aliphatic polyamide resin include polybutyrolactam (polyamide 4), polyvalerolactam (polyamide 5), polycaprolactam (polyamide 6), polyheptanoyl lactam (polyamide 7), polyundecalactam (polyamide 11), polylauryllactam (polyamide 12), polyhexamethylene adipamide (polyamide 66), polybutylene adipamide (polyamide 46), polybutylene azelaamide (polyamide 49), polybutylene sebacate (polyamide 410), polybutylene dodecanamide (polyamide 412), polypentamethylene adipamide (polyamide 56), polypentamethylene azelaamide (polyamide 59), polypentamethylene sebacate (polyamide 510), polypentamethylene dodecanamide (polyamide 512), polyhexamethylene azelaamide (polyamide 512), and polypentamethylene adipamide (polyamide 56). The aliphatic homopolyamide resins include polyamide 69), polyhexamethylenediamine sebacamide (polyamide 610), polyhexamethylenediamine dodecane diamide (polyamide 612), polynonanediamine adipamide (polyamide 96), polynonanediamine azelaamide (polyamide 99), polynonanediamine sebacamide (polyamide 910), polynonanediamine dodecane diamide (polyamide 912), polydecanediamine adipamide (polyamide 106), polydecanediamine azelaamide (polyamide 109), polydecanediamine sebacamide (polyamide 1010), polydecanediamine dodecane diamide (polyamide 1012), polydodecanediamine adipamide (polyamide 126), polydodecanediamine azelaamide (polyamide 129), polydodecanediamine sebacamide (polyamide 1210), and polydodecanediamine dodecane diamide (polyamide 1212). These aliphatic homopolyamide resins may be used alone or as a mixture of two or more.

[0064] Among these aliphatic homopolyamide resins, polyamide 6, polyamide 66, polyamide 610, polyamide 612, polyamide 11, and polyamide 12 are preferred from the viewpoint of compatibility with polyamide-based resin scraps, polyamide 6 and polyamide 66 are more preferred, and polyamide 6 is further preferred.

[0065] The relative viscosity of the aliphatic homopolyamide resin measured at 25°C by dissolving 1 g of the polyamide resin in 100 ml of 96% concentrated sulfuric acid in accordance with JIS K6920-2 is preferably 2.0 or more, more preferably 2.3 to 5.0, and further preferably 3.0 to 4.5 from the viewpoint of the moldability of the polyamide resin composition.

[0066] When the aliphatic homopolyamide resin includes two or more polyamide resins having different relative viscosities, the relative viscosity of the aliphatic homopolyamide resin is preferably measured as described above. When the relative viscosities of the individual polyamide resins and their mixing ratios are known, the average value calculated by adding the values ​​obtained by multiplying the mixing ratios of the individual relative viscosities can be used as the relative viscosity of the aliphatic homopolyamide resin. In the present invention, when the aliphatic homopolyamide resin includes two or more polyamide resins, the measured value is adopted.

[0067] (Aliphatic copolyamide resin (a-2))

[0068] Aliphatic copolyamide resin is a polyamide resin formed by structural units derived from two or more aliphatic monomers. Aliphatic copolyamide resin is a copolymer of monomers selected from the group consisting of a combination of diamine and dicarboxylic acid, lactam and aminocarboxylic acid. Here, for the combination of diamine and dicarboxylic acid, the combination of one diamine and one dicarboxylic acid is regarded as one monomer.

[0069] Examples of the diamine include the same diamines as those exemplified as the raw materials of the aliphatic homopolyamide resin.

[0070] Examples of the dicarboxylic acid include the same ones as exemplified as the raw materials of the aliphatic homopolyamide resin.

[0071] Examples of the lactam include the same ones as exemplified as the raw materials of the aliphatic homopolyamide resin.

[0072] Examples of the aminocarboxylic acid include the same ones as exemplified as the raw materials of the aliphatic homopolyamide resin.

[0073] Specific examples of the aliphatic copolyamide resins include caprolactam / hexamethylenediaminoadipic acid copolymer (polyamide 6 / 66), caprolactam / hexamethylenediaminoazelaic acid copolymer (polyamide 6 / 69), caprolactam / hexamethylenediaminosebacic acid copolymer (polyamide 6 / 610), caprolactam / hexamethylenediaminoundecanedicarboxylic acid copolymer (polyamide 6 / 611), caprolactam / hexamethylenediaminododecanedicarboxylic acid copolymer (polyamide 6 / 612), caprolactam / aminoundecanoic acid copolymer (polyamide 6 / 11), caprolactam / hexamethylenediaminododecanedicarboxylic acid copolymer (polyamide 6 / 613), caprolactam / aminoundecanoic acid copolymer (polyamide 6 / 14), caprolactam / hexamethylenediaminododecanedicarboxylic acid copolymer (polyamide 6 / 15), caprolactam / hexamethylenediaminododecanedicarboxylic acid copolymer (polyamide 6 / 16), caprolactam / hexamethylenediaminododecanedicarboxylic acid copolymer (polyamide 6 / 17), caprolactam / hexamethylenediaminododecanedicarboxylic acid copolymer (polyamide 6 / 18), caprolactam / hexamethylenediaminododecanedicarboxylic acid copolymer (polyamide 6 / 19), caprolactam / hexamethylenediaminododecanedicarboxylic acid copolymer (polyamide 6 / 1 The present invention relates to aliphatic copolyamides such as caprolactam / lauryllactam copolymer (polyamide 6 / 12), caprolactam / hexamethylenediaminoadipic acid / lauryllactam copolymer (polyamide 6 / 66 / 12), caprolactam / hexamethylenediaminoadipic acid / hexamethylenediaminosebacic acid copolymer (polyamide 6 / 66 / 610), caprolactam / hexamethylenediaminoadipic acid / hexamethylenediaminododecanedicarboxylic acid copolymer (polyamide 6 / 66 / 612), and caprolactam / hexamethylenediaminoadipic acid / aminoundecanoic acid copolymer (polyamide 6 / 66 / 11). These aliphatic copolyamides may be used alone or as a mixture of two or more.

[0074] Among these aliphatic copolyamide resins, polyamide 6 / 66, polyamide 6 / 12, and polyamide 6 / 66 / 12 are preferred, polyamide 6 / 66 and polyamide 6 / 66 / 12 are more preferred, and polyamide 6 / 66 is further preferred.

[0075] The relative viscosity of the aliphatic copolyamide resin measured at 25°C by dissolving 1 g of the polyamide resin in 100 ml of 96% concentrated sulfuric acid in accordance with JIS K6920-2 is preferably 2.0 to 5.0, more preferably 2.3 to 5.0, and even more preferably 3.0 to 4.5 from the viewpoint of the moldability of the polyamide resin composition.

[0076] When the aliphatic copolyamide resin contains two or more polyamide resins having different relative viscosities, the relative viscosity can be determined by the same method as described in the section of the aliphatic homopolyamide resin.

[0077] The polyamide resin (a) preferably contains at least one selected from the group consisting of polyamide 4, polyamide 46, polyamide 410, polyamide 56, polyamide 510, polyamide 512, polyamide 6, polyamide 66, polyamide 610, polyamide 612, polyamide 1010, polyamide 1012, polyamide 11, polyamide 12, polyamide 6 / 66, polyamide 6 / 12 and polyamide 6 / 66 / 12 from the viewpoint of compatibility with polyamide-based resin scraps, and more preferably contains at least one selected from the group consisting of polyamide 6, polyamide 6 / 66 and polyamide 6 / 66 / 12 from the viewpoint of further improving the tensile modulus.

[0078] In addition to aliphatic homopolyamide resins and aliphatic copolymers, polyamide resins (a) may also include aromatic polyamide resins. Aromatic polyamide resins refer to polyamide resins containing at least one structural unit derived from aromatic monomer components, which may be a homopolymer or a copolymer. In polyamide resins (a), aromatic polyamide resins are preferably less than 5% by mass, more preferably less than 1% by mass, and further preferably 0% by mass. That is, polyamide resins (a) are further preferably formed by aliphatic polyamide resins.

[0079] (Manufacture of polyamide resin)

[0080] As the manufacturing device of polyamide resin (a), known polyamide manufacturing devices can be listed, such as intermittent reactor, single reactor or multi-reactor continuous reactor, tubular continuous reactor, single screw type mixing extruder, twin screw type mixing extruder and other mixing reaction extruders. As the polymerization method, known methods such as melt polymerization, solution polymerization, solid phase polymerization are used, and polymerization can be repeated under normal pressure, reduced pressure, and pressurized operation. These polymerization methods can be used alone or in appropriate combination.

[0081] The polyamide resin is produced by polymerizing or copolymerizing the above-mentioned polyamide raw materials by known methods such as melt polymerization, solution polymerization and solid phase polymerization. In order to promote polymerization, it is preferable to appropriately add a catalyst or the like at any stage during polymerization or at any stage during melt kneading after polymerization.

[0082] The relative viscosity of the polyamide resin (a), measured at 25°C in accordance with JIS K6920-2 by dissolving 1 g of the polyamide resin in 100 ml of 96% concentrated sulfuric acid, is preferably 2.0 to 5.0, more preferably 2.3 to 5.0, and further preferably 3.0 to 4.5, from the viewpoint of the moldability of the polyamide resin composition.

[0083] The polyamide resin (a) is preferably a mixture of polyamide resins of the same type having different relative viscosities, and is also preferably a mixture of polyamide resins of the same type having different terminal amino group concentrations.

[0084] The terminal amino group concentration of the polyamide resin (a) is preferably 2.0×10 -5 eq / g or more, more preferably 2.8×10 -5 The range of eq / g is above 10.0×10 -5 eq / g or less, more preferably 9.8×10 -5 eq / g or less.

[0085] The terminal carboxyl group concentration of the polyamide resin (a) is preferably 7.5×10 -5 eq / g or less, more preferably 6.5×10 -5 The range of eq / g or less is preferably 2.0×10 -5 eq / g or more, more preferably 2.5×10 -5 eq / g or above.

[0086] When the polyamide resin (a) contains two or more polyamide resins having different terminal amino group concentrations, the terminal amino group concentration in the polyamide resin is preferably measured by the above-mentioned neutralization titration. When the terminal amino group concentrations of the respective polyamide resins and their mixing ratios are known, the terminal amino group concentration of the polyamide resin can also be calculated as the average value obtained by adding the values ​​obtained by multiplying the terminal amino group concentrations by their mixing ratios. In the present invention, when two or more types are contained, the neutralization titration value is adopted.

[0087] When the polyamide resin (a) includes two or more polyamide resins having different terminal carboxyl group concentrations, the calculation is performed in the same manner.

[0088] The terminal amino group concentration and the terminal carboxyl group concentration can be adjusted to the above range by adjusting the molecular weight of the polyamide resin, adjusting the terminal of the polyamide resin with a compound such as dicarboxylic acid, diamine, carboxylic acid, or amine.

[0089] When the component (A) is a polyamide resin composition containing the polyamide resin (a) as a main component (hereinafter also referred to as a "polyamide resin composition"), the following is performed.

[0090] It should be noted that “polyamide resin (a) as the main component” means that the polyamide resin (a) is contained in the largest amount by mass among all the components of the polyamide resin composition, and means that 100 mass % of the polyamide resin composition (A) contains preferably 95.00 mass % or more, more preferably 97.00 mass % or more of the polyamide resin (a).

[0091] The polyamide resin composition may contain a thermoplastic resin other than the polyamide resin within a range not impairing the object of the present invention, but preferably does not contain the thermoplastic resin.

[0092] The polyamide resin composition may contain, as optional components, dyes, pigments, fibrous reinforcements, particulate reinforcements, plasticizers, antioxidants, light stabilizers, heat-resistant agents, foaming agents, weathering agents, crystallization accelerators, crystallization nucleating agents, antistatic agents, mold release agents, lubricants, additives, flame retardants, flame retardant aids, colorants and other functional agents, etc. Among these, it is preferred to contain at least one selected from the group consisting of lubricants and heat-resistant agents.

[0093] <Heat-resistant agent>

[0094] As the heat-resistant agent, an organic or inorganic heat-resistant agent can be used according to the purpose, and these may be used alone or in combination of two or more.

[0095] The heat-resisting agent is a component that suppresses thermal oxidation and thermal aging of the polyamide resin, and in terms of its purpose, it also includes substances called antioxidants.

[0096] ((Organic heat-resistant agent))

[0097] Examples of the organic heat-resistant agent include phenolic compounds, phosphorus compounds, sulfur compounds, nitrogen compounds, etc. These may be used alone or in combination of two or more.

[0098] (Phenol compounds)

[0099] As the phenolic compound, hindered phenolic compounds are preferably listed. In this specification, hindered phenol refers to a compound having a substituent at the ortho position (hereinafter also referred to as "o position") of the hydroxyl group of phenol. As the substituent at the o position, there is no particular limitation, and alkyl, alkoxy, amino, halogen, etc. can be listed. Among these, alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, and tert-butyl are preferred, and bulky isopropyl, sec-butyl, isobutyl, and tert-butyl are more preferred, and tert-butyl is most preferred. In addition, the o position preferably has a substituent at both o positions of phenol relative to the hydroxyl group.

[0100] Specific examples of hindered phenols having a tert-butyl group at the o-position include N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid), pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, ethylenebis(oxyethylene)bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate], and 3,9-bis[2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane. These may be used alone or in combination of two or more. Commercially available products of these heat-resistant agents include "Irganox 245", "Irganox 1010" (BASF), and "Sumilizer GA-80" (Sumitomo Chemical Co., Ltd.). These may be used alone or in combination of two or more.

[0101] (Phosphorus compounds)

[0102] As the phosphorus compound, a hindered phenol phosphite compound or a hindered phenol hypophosphite compound is preferred, and a hindered phenol phosphite compound having a tert-butyl group at the o-position or a hindered phenol hypophosphite compound having a tert-butyl group at the o-position is more preferred, and a hindered phenol phosphite compound having a tert-butyl group at the o-position is further preferred. As for the hindered phenol phosphite compound having a tert-butyl group at the o-position, specifically, tris(2,4-di-tert-butylphenyl)phosphite and bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite can be listed. As for the hindered phenol hypophosphite compound having a tert-butyl group at the o-position, specifically, a reaction product of biphenyl with p,p,p',p'-tetrakis(2,4-di-tert-butylphenoxy)-4,4-biphenyldiphosphine as the main component, phosphorus trichloride and 2,4-di-tert-butylphenol can be listed. Commercially available products of these heat-resistant agents include "Irgafos 168" (BASF) and "hostanox P-EPQ" (Clariant Chemicals). These may be used alone or in combination of two or more.

[0103] (Sulfur compounds)

[0104] Examples of the sulfur-based compound include distearyl 3,3-thiodipropionate, pentaerythritol tetra(3-laurylthiopropionate), and didodecyl(3,3′-thiodipropionate). These may be used alone or in combination of two or more.

[0105] (Nitrogen compounds)

[0106] Examples of the nitrogen compound include melamine, melamine cyanurate, benzoguanamine, dimethylol urea, and cyanuric acid. These may be used alone or in combination of two or more.

[0107] As the organic heat-resistant agent, from the viewpoint of coloring of the material, phenolic compounds and phosphorus compounds are preferred, and hindered phenolic compounds are more preferred.

[0108] ((Inorganic heat resistant agent))

[0109] The types of inorganic heat-resistant agents as heat-resistant agents are copper compounds and potassium halides. As copper compounds, cuprous iodide, cuprous bromide, cupric bromide, cupric acetate, etc. can be listed. From the perspective of heat resistance and suppression of metal corrosion, cuprous iodide is preferred. For potassium halides, potassium iodide, potassium bromide, potassium chloride, etc. can be listed. From the perspective of heat resistance and long-term stability of inorganic heat-resistant agents, potassium iodide and / or potassium bromide are preferred. These can be used alone or in combination of two or more.

[0110] <Lubricant>

[0111] The lubricant is a substance that contributes to improving the releasability from a mold when molding the resin composition.

[0112] As lubricant, terminal modification of polyalkylene glycol, phosphate or phosphite, higher fatty acid monoester, higher fatty acid or its metal salt, carboxylic acid amide, ethylenebisamide compound, low molecular weight polyethylene, magnesium silicate and substituted benzylidene sorbitol and other compounds can be listed. These can be used alone or in combination of two or more. Among these, preferably higher fatty acid or its metal salt.

[0113] Examples of terminal-modified products of polyalkylene glycol include terminal-modified products of polyethylene glycol and terminal-modified products of polypropylene glycol.

[0114] More specific examples of phosphates and phosphites include aliphatic phosphates and aliphatic phosphites such as di(2-ethylhexyl)phosphate, tridecyl phosphite, tritridecyl phosphite, and tristearyl phosphite, and aromatic phosphites such as triphenyl phosphite and diphenyl monodecyl phosphite.

[0115] Examples of the higher fatty acid monoesters include myristyl myristate, stearyl stearate, behenyl behenate, oleyl oleate, and hexyldecyl myristate.

[0116] Examples of the higher fatty acid include myristic acid, palmitic acid, behenic acid, oleic acid, and arachidic acid.

[0117] Examples of the metal salt of a higher fatty acid include zinc stearate, lithium stearate, calcium stearate, and aluminum palmitate.

[0118] Examples of the carboxylic acid amide include aliphatic monocarboxylic acid amides such as lauric acid amide, palmitic acid amide, oleic acid amide, stearic acid amide, erucic acid amide, behenic acid amide, ricinoleic acid amide, and 12-hydroxystearic acid amide; N-lauryl lauric acid amide, N-palmityl palmitic acid amide, N-oleyl palmitic acid amide, N-oleyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-stearyl erucic acid amide, N-stearyl-12-hydroxystearic acid amide, N-oleyl-12-hydroxystearic acid amide, hydroxymethyl stearic acid amide, and hydroxymethyl behenic acid amide. Amine, 12-hydroxystearic acid monoethanolamide and other N-substituted aliphatic monocarboxylic acid amides, methylene bisstearic acid amide, methylene bislauric acid amide, methylene bis-12-hydroxystearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisoleic acid amide, ethylene bisstearic acid amide, ethylene biserucic acid amide, ethylene bisbehenic acid amide, ethylene bisisostearyl acid amide, ethylene bis-12-hydroxystearic acid amide, butylene bisstearic acid amide, hexamethylene bisoleic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene bis-12-hydroxystearic acid amide Fatty acid amides, N,N'-dioleyl sebacic acid amide, N,N'-dioleyl adipamide, N,N'-distearyl adipamide, N,N'-distearyl sebacic acid amide and other aliphatic carboxylic acid bisamides, N,N'-dicyclohexanecarbonyl-1,4-diaminocyclohexane, 1,4-cyclohexanedicarboxamide, 1,4-cyclohexanedicarboxylic acid diaminocyclohexane, 1,2,3,4-butanetetracarboxylic acid tetracyclohexylamide, N,N'-bis(3-hydroxypropyl)-1,4-cubanedicarboxamide, N,N'-(1,4-cyclohexanediyl)bis(acetamide), tris(methylcyclohexyl)propanetri Alicyclic carboxylic acid amides such as formamide, and aromatic carboxylic acid amides such as 1,4-cyclohexanedicarboxylic acid dianilide, 1,4-cyclohexanedicarboxylic acid dibenzylamide, trimesic acid tris(tert-butylamide), trimesic acid tricyclohexylamide, trimesic acid tris(2-methylcyclohexylamide), trimesic acid tris(4-cyclohexylamide), 2,6-naphthoic acid dicyclohexylamide, N,N'-dibenzylcyclohexane-1,4-dicarboxamide, N,N'-distearylisophthalic acid amide, N,N'-distearylterephthalic acid amide, isophthalenebisstearic acid amide, and isophthalenebis-12-hydroxystearic acid amide.

[0119] Examples of the ethylenebisamide compound include ethylenebisstearylamide and ethylenebispalmitamide.

[0120] Examples of the low molecular weight polyethylene include those having a molecular weight in the range of 500 to 5,000, and those having a molecular weight in the range of 1,000 to 3,000.

[0121] Examples of magnesium silicate include those having an average particle size of 1 to 10 μm.

[0122] Examples of the substituted benzylidene sorbitols include substituted benzylidene sorbitols synthesized by dehydration condensation of sorbitol and substituted benzaldehyde in the presence of an acid catalyst.

[0123] These may be used alone or in combination of two or more.

[0124] The optional additives may be contained in an amount of preferably 0.01 to 1.00% by mass, more preferably 0.05 to 0.50% by mass, based on 100% by mass of the polyamide resin composition (A).

[0125] In 100% by mass of the recycled polyamide resin composition, the content of the polyamide resin (a) or the polyamide resin composition (A) containing the polyamide resin (a) as a main component is preferably greater than 50% by mass and less than 98% by mass, more preferably 70 to 97% by mass, further preferably 80 to 95% by mass, and most preferably 80 to 87% by mass. If the content of the polyamide resin (a) or the polyamide resin composition (A) containing the polyamide resin (a) as a main component in the recycled polyamide resin composition is within the above range, the mass reduction of the molded product manufactured from the recycled polyamide resin composition is reduced.

[0126] <<Polyamide resin waste (B)>>

[0127] The recycled polyamide resin composition contains polyamide-based resin scrap (B).

[0128] The polyamide-based resin scrap (B) contains a polyamide resin (b1) and a thermoplastic resin (b2) other than the polyamide resin, wherein the content of the thermoplastic resin (b2) other than the polyamide resin in 100% by mass of the polyamide-based resin scrap (B) is greater than 0% by mass and is 2.00% by mass or less.

[0129] <Polyamide resin (b1)>

[0130] The polyamide resin (b1) is not particularly limited, and examples thereof include aliphatic homopolyamide resins and aliphatic copolyamide resins. Examples thereof include the same ones as those for the polyamide resin (a).

[0131] From the viewpoint of compatibility with the polyamide resin (a) or the polyamide resin composition (A) containing the polyamide resin (a) as a main component, the polyamide resin (b1) is preferably an aliphatic homopolyamide resin, more preferably polyamide 6 or polyamide 66, and still more preferably polyamide 6.

[0132] The polyamide resin (b1) may contain an aromatic polyamide resin in addition to an aliphatic homopolyamide resin and an aliphatic copolyamide resin. The aromatic polyamide resin in the polyamide resin (b1) is preferably 5% by mass or less, more preferably 1% by mass or less, and even more preferably 0% by mass.

[0133] The polyamide resin (b1) has good moldability if it has the same molecular weight as the polyamide resin (a) of component (A) according to JIS K6920-2. Therefore, the relative viscosity measured at 25°C when 1 g of the polyamide resin is dissolved in 100 ml of 96% concentrated sulfuric acid is preferably 2.0 or more, more preferably 2.3 to 5.0, and even more preferably 2.3 to 4.5.

[0134] The content of the polyamide resin (b1) in 100% by mass of the polyamide resin scrap (B) is preferably 95.00 to 99.80% by mass, more preferably 97.00 to 99.50% by mass, and even more preferably 98.00 to 99.60% by mass. Within the above range, the functions and characteristics of the polyamide resin are not impaired.

[0135] The contents of the polyamide resin (b1) and the thermoplastic resin (b2) other than the polyamide resin as the components in the polyamide-based resin scrap (B) can be analyzed by a known method such as nuclear magnetic resonance analysis, IR (infrared spectroscopy), or liquid chromatography.

[0136] <Thermoplastic resin other than polyamide resin (b2)>

[0137] Examples of thermoplastic resins (b2) other than polyamide resins include polyester resins, polyolefin resins, polyvinyl alcohol, polystyrene resins, polyether resins, poly(meth)acrylate resins, polycarbonate resins, cellulose resins, polyimide resins, thermoplastic polyurethane resins, polyamide elastomers, polyurethane elastomers, polyester elastomers, and the like. Among these, from the perspective of compatibility with the polyamide resin, preferably at least one selected from the group consisting of polyester resins, polyolefin resins, polyvinyl alcohol, polyamide elastomers, polystyrene resins, and poly(meth)acrylate resins is preferred, more preferably at least one selected from the group consisting of polyester resins, polyolefin resins, and polyvinyl alcohol is more preferred, and still more preferably a polyester resin is preferred.

[0138] Examples of the polyester resin include polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), poly(ethylene terephthalate / ethylene isophthalate) copolymer (PET / PEI), polytrimethylene terephthalate (PTT), polycyclohexanedimethylene terephthalate (PCT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), polyarylate (PAR), liquid crystal polyester (LCP), polylactic acid (PLA), polyglycolic acid (PGA), etc. Among these, polyethylene terephthalate (PET) is preferred from the viewpoint of heat resistance.

[0139] Examples of polyolefin resins include high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), ultra-high molecular weight polyethylene (UHMWPE), polypropylene (PP), polybutene (PB), polymethylpentene (TPX), ethylene / propylene copolymer (EPR), and ethylene / butene copolymer (EBR).

[0140] The content of the thermoplastic resin (b2) other than the polyamide resin in 100% by mass of the polyamide-based resin scrap (B) is greater than 0% by mass and is 2.00% by mass or less. If the content of the thermoplastic resin (b2) other than the polyamide resin in the polyamide-based resin scrap (B) is outside the above range, the properties of the thermoplastic resin will be greatly manifested, and the properties of the polyamide resin may be impaired. Here, "greater than 0% by mass" means that the case where it is not contained at all is excluded.

[0141] The polyamide resin waste (B) may contain, as optional components, appropriate functional imparting agents such as dyes, pigments, fibrous reinforcements, particulate reinforcements, plasticizers, antioxidants, light stabilizers, heat stabilizers, foaming agents, weathering agents, crystallization accelerators, crystallization nucleating agents, antistatic agents, mold release agents, lubricants, additives, flame retardants, flame retardant aids, and colorants.

[0142] Among these, fishnets often contain colorants such as dyes, pigments, and colorants. Therefore, the polyamide resin scrap (B) preferably contains a colorant. Examples of the colorant include carbon black and the like.

[0143] In 100% by mass of the polyamide resin waste (B), the content of the colorant is preferably 1.00% by mass or less, more preferably greater than 0% by mass and less than 1.00% by mass. If the colorant in the polyamide resin waste (B) is within the above range, the functions and characteristics of the recycled polyamide resin composition will not be impaired. Here, "greater than 0% by mass" means excluding the case where it is completely not contained.

[0144] The content of the colorant in the polyamide resin scrap (B) can be analyzed by a known method such as differential thermal analysis and thermogravimetric analysis.

[0145] Examples of the polyamide resin waste (B) include polyamide resin molded products satisfying the above composition, for example, waste of monofilaments such as fishnets, fishing lines, gut lines, ropes, toothbrushes, combs, cosmetic brushes, industrial brushes, fabrics, chain coils, leads, tortoise shell nets, bird-proof lines, artificial hair, and mowing ropes. Preferably, waste of fishnets and fishing lines that may pollute the marine environment are included, and more preferably, fishnets are included.

[0146] In 100% by mass of the recycled polyamide resin composition, the polyamide-based resin scrap (B) is 2% by mass or more and less than 50% by mass, preferably 2 to 30% by mass, more preferably 5 to 20% by mass, and further preferably 12 to 20% by mass. When the polyamide-based resin scrap (B) in the recycled polyamide resin composition is within the above range, the quality of the molded product manufactured from the recycled polyamide resin is not reduced.

[0147] <<Recycled polyamide resin composition>>

[0148] The recycled polyamide resin composition is obtained by melt-kneading a polyamide resin (a) or a polyamide resin composition (A) containing the polyamide resin (a) as a main component and polyamide-based resin scrap (B).

[0149] The recycled polyamide resin composition is preferably obtained by a production method including the following steps.

[0150] The manufacturing method has the following steps:

[0151] Step 1, crushing the polyamide resin waste (B);

[0152] Step 2, which comprises adding a polyamide resin (a) or a polyamide resin composition (A) containing the polyamide resin (a) as a main component to the pulverized polyamide-based resin waste (B) obtained in Step 1 and mixing them; and

[0153] Step 3 is to melt-knead the mixture obtained in step 2 to obtain pellets.

[0154] These steps may include a washing step, a dehydrating step, a drying step, and the like of the polyamide resin waste (B).

[0155] In addition, when using commercially available pelletized polyamide-based resin scrap (B), step 1 may be omitted.

[0156] Step 1: The polyamide resin waste (B) is pulverized.

[0157] The pulverizing means is not particularly limited as long as it is a known pulverizing means, and examples thereof include jaw crusher, gyratory crusher, cone crusher, impact crusher, roller crusher, autogenous mill, stamping mill, stone mill type pulverizer, pounding machine, large shredder, ring mill, roller mill, shredder, hammer mill, turbine grinder, jet mill, pin mill, centrifugal mill, grinder such as pulverizer, crusher, ROTOPLEX pulverizer, milling machine, Ultra Rotor, etc. The pulverization can be carried out in a wet manner.

[0158] Step 2: To the pulverized polyamide-based resin scrap (B) obtained in Step 1, the polyamide resin (a) or the polyamide resin composition (A) containing the polyamide resin (a) as a main component is added and mixed.

[0159] The mixing means is not particularly limited as long as it is a known mixing means, and examples thereof include a stirrer, a ball mill, etc. The polyamide resin (a) or the polyamide resin composition (A) containing the polyamide resin (a) as a main component may be in the form of pellets.

[0160] Step 3: The mixture obtained in step 2 is melt-kneaded to obtain pellets.

[0161] The melt-kneading means is not particularly limited as long as it is a known melt-kneading means, and examples thereof include a single-screw or twin-screw extruder, a Banbury mixer, a kneader, and a kneading roll.

[0162] For example, when a twin-screw extruder is used, any of the following methods can be used: a method in which all raw materials are blended and then melt-kneaded; a method in which a part of the raw materials are blended and then melt-kneaded and the remaining raw materials are further blended and then melt-kneaded; a method in which a part of the raw materials are blended and then the remaining raw materials are mixed during melt-kneading using a side feeder; and the method in which all raw materials are blended and then melt-kneaded is preferred.

[0163] The melting temperature is not particularly limited as long as it is a temperature equal to or higher than the melting point of each resin, but is preferably 280° C. or lower from the viewpoint of dispersibility of the raw material and suppression of decomposition.

[0164] When at least one step selected from the group consisting of a washing step, a dehydration step, and a drying step is included, the step is usually performed before step 1, but may be performed after step 1. In addition, when the polyamide resin (a) or the polyamide resin composition (A) containing the polyamide resin (a) as a main component is a polyamide resin composition (A), a step of producing the polyamide resin composition (A) may be included before step 2. In addition, a step of melt-kneading the pulverized polyamide-based resin scrap (B) obtained in step 1 to form pellets may be included before step 2.

[0165] As the combination of the polyamide resin (a) and the polyamide resin (b1) in the recycled polyamide resin composition, from the viewpoint of tensile properties, preferably, the combination of the polyamide resin (a) being polyamide 6 and the polyamide resin (b1) being polyamide 6, and the combination of the polyamide resin (a) being polyamide 6 / 66 and the polyamide resin (b1) being polyamide 6 are mentioned. The polyamide resin (a) and the polyamide resin (b1) may be the same type of polyamide resin or different types of polyamide resins, but from the viewpoint of improving the tensile modulus while maintaining the tensile strength, the same type of polyamide resin is preferred.

[0166] When the polyamide resin (a) and the polyamide resin (b1) in the recycled polyamide resin composition are 100 parts by mass, the content of the polyamide resin (b1) (b1×100 / (a+b1)) is preferably 5 parts by mass or more, and more preferably 5 to 20 parts by mass. If the content of the polyamide resin (b1) is within the above range when the total amount of the polyamide resin (a) and the polyamide resin (b1) is 100 parts by mass, the tensile modulus is excellent, and the quality of the molded product manufactured from the recycled polyamide resin is not reduced.

[0167] When the total amount of the polyamide resin (a) and the polyamide resin (b1) in the recycled polyamide resin composition is 100 parts by mass, the content of the thermoplastic resin (b2) other than the polyamide resin (b2×100 / (a+b1)) is preferably 0.05 parts by mass or more, more preferably 0.05 to 0.40 parts by mass, and further preferably 0.05 to 0.20 parts by mass. If the content of the thermoplastic resin (b2) other than the polyamide resin when the total amount of the polyamide resin (a) and the polyamide resin (b1) is 100 parts by mass is within the above range, the tensile modulus is excellent, and the quality of the molded product manufactured from the recycled polyamide resin is not reduced.

[0168] In the recycled polyamide resin composition, in addition to the components (A) and (B), as optional components, dyes, pigments, fibrous reinforcements, particulate reinforcements, plasticizers, antioxidants, light stabilizers, heat stabilizers, foaming agents, weathering agents, crystallization accelerators, crystallization nucleating agents, antistatic agents, mold release agents, lubricants, additives, flame retardants, flame retardant aids, colorants and other functional agents can be appropriately blended.

[0169] The optional additives may be contained in an amount of preferably 0.01 to 1.00% by mass, more preferably 0.05 to 0.50% by mass, based on 100% by mass of the recycled polyamide resin composition.

[0170] The tensile strength of the recycled polyamide resin composition measured by the method described in the examples is preferably 1.0 gf / d or more, more preferably 1.3 gf / d or more, and further preferably 1.6 gf / d or more. If the tensile strength of the recycled polyamide resin composition is within the above range, it becomes a monofilament that is not easily broken when used for fishnets, fishing lines, cutting parts, artificial turf, etc.

[0171] The tensile modulus of the recycled polyamide resin composition measured by the method described in the examples is preferably 6.0 to 12.0 gf / d, more preferably 6.0 to 11.0 gf / d, and further preferably 6.7 to 10.8 gf / d. If the tensile modulus of the recycled polyamide resin composition is within the above range, it becomes a monofilament that can take both hardness and softness into account when used for fishnets, fishing lines, cutting parts, artificial turf, etc.

[0172] The denier of a single yarn is defined as the weight of 9000 m of a single yarn, and the weight of 90 cm of a single yarn is actually measured, and the measured value is multiplied by 10000 times as the denier of a single yarn.

[0173] The difference (Tm-Tc) between the melting point (Tm) and the crystallization temperature (Tc) of the recycled polyamide resin composition is preferably 10 to 45°C, more preferably 20 to 43°C, and further preferably 30 to 41°C. If the difference between the melting point and the crystallization temperature of the recycled polyamide resin composition is within the above range, the recycled polyamide resin composition will be a monofilament that is easy to crystallize and not easily broken when used, and has good formability for fishnets, fishing lines, cut parts, artificial turf, etc. The melting point and the crystallization temperature are values ​​measured by the method described in the examples using a differential scanning calorimeter (DSC).

[0174] The amount of the recycled polyamide resin composition to be extracted is preferably 0.5 to 7.5% by mass, more preferably 1.0 to 7.0% by mass, and still more preferably 2.0 to 6.8% by mass. If the amount of the recycled polyamide resin composition to be extracted is within the above range, the resulting monofilament is flexible and not easily broken when used for fishnets, fishing lines, cutting parts, artificial turf, etc.

[0175] The extraction amount of the regenerated polyamide resin composition can be measured using pellets or monofilament-shaped regenerated polyamide resin compositions as samples. After boiling 10 g of the sample of the regenerated polyamide resin composition with pure water for 6 hours and vacuum drying for 16 hours, the mass of the sample is measured, and the weight loss value is taken as the amount of hot water soluble components (g). Then, the extraction amount (mass %) = hot water soluble components (g) / 10 (g) × 100 can be calculated. The main components contained in the extraction amount are composed of low molecular weight components such as monomers and oligomer components of the resin contained in the polyamide resin composition.

[0176] [Molded articles of recycled polyamide resin composition and their uses]

[0177] The recycled polyamide resin composition can be suitably used for producing molded products such as monofilaments, injection-molded products by injection molding, extrusion-molded products by extrusion molding, blow-molded products by blow molding, and rotational-molded products by rotational molding.

[0178] The method for producing the monofilament is not particularly limited, and a known method for producing the monofilament may be used.

[0179] The method for producing a monofilament preferably includes: a step of producing an unstretched monofilament, a step of obtaining a stretched monofilament by stretching the unstretched monofilament as appropriate, and a step of heat-treating the obtained stretched monofilament. Here, when the method for producing a polyamide monofilament includes a step of producing an unstretched monofilament, the obtained monofilament is an unstretched monofilament. In addition, when the method for producing a polyamide monofilament includes a step of producing an unstretched monofilament, a step of obtaining a stretched monofilament by stretching the unstretched monofilament, and a step of heat-treating the obtained stretched monofilament, the obtained monofilament is a stretched monofilament.

[0180] (Process for producing undrawn monofilament)

[0181] As a method for producing undrawn monofilaments, the following method can be cited: the undrawn monofilaments are produced by melting pellets of a copolyamide resin or a polyamide resin composition by means of an extruder, extruding the pellets from a spinning die nozzle, and cooling the pellets in a coolant bath such as water or trichloroethylene. In this case, the distance from the yarn outlet of the spinning nozzle to the coolant liquid surface is preferably maintained at about 10 to 300 mm.

[0182] The temperature of the extruder is preferably 200°C to 290°C, more preferably 200°C to 280°C.

[0183] The temperature of the extrusion die is preferably 150°C to 260°C, more preferably 170°C to 250°C.

[0184] Furthermore, the temperature of the coolant is preferably 0 to 30°C, more preferably 5 to 20°C.

[0185] (Step of Obtaining a Stretched Monofilament)

[0186] The step of obtaining a drawn monofilament is a step of drawing the undrawn monofilament obtained in the above step. Here, the drawing may be a single-stage drawing or a two-stage drawing.

[0187] The first stage stretching of the first stage stretching and the second stage stretching is preferably carried out in steam or hot water so that the unstretched monofilament reaches a predetermined stretching ratio. The first stage stretching ratio is preferably 2.0 to 4.5 times, more preferably 2.2 to 4.0 times. If the first stage stretching ratio is within the above range, there is a tendency for the tensile strength to be further improved.

[0188] When the first stage stretching is performed in steam, the temperature of the steam is preferably 95 to 120° C., more preferably 100 to 110° C. When the temperature of the steam is within the above range, the knot strength and transparency of the obtained monofilament tend to be further improved.

[0189] When the first stage stretching is performed in hot water, the temperature of the hot water is preferably 50 to 99° C., more preferably 60 to 99° C. When the temperature of the hot water is within the above range, the knot strength and transparency of the obtained monofilament tend to be further improved.

[0190] The second stage stretching of the two-stage stretching is preferably carried out in a gas atmosphere. The second stage stretching ratio is preferably 1.1 to 2.5 times, more preferably 1.2 to 2.0 times. The gas is not particularly limited, and examples thereof include inert gases such as helium, nitrogen, and argon, and air. The temperature of the gas atmosphere in the second stage stretching is preferably 120 to 300° C., more preferably 150 to 240° C. When the temperature of the gas atmosphere in the second stage stretching and the stretching ratio are within the aforementioned ranges, there is a tendency for the knot strength and transparency of the obtained monofilament to be further improved.

[0191] (Step of heat treating the drawn yarn)

[0192] The drawn monofilament obtained by the above process is preferably heat-set. The monofilament drawn in two stages can be heat-set in a gas atmosphere preferably at 140 to 260° C., more preferably at 150 to 190° C., while being relaxed at a relaxation rate of 0 to 15%. In the case of this temperature range, there is a tendency for the knot strength to be further improved.

[0193] Furthermore, the combined draw ratio of the monofilament obtained by the above-mentioned step of drawing the undrawn monofilament and the step of heat-treating the monofilament is preferably the combined draw ratio of the above-mentioned drawn monofilament.

[0194] Monofilament is useful for structures such as filament, multifilament and net used for purposes such as fishery, industry, clothing, medical treatment, artificial turf, cutting parts, 3D printers, etc. Monofilament is preferably used for fishery purposes and artificial turf, and more preferably aquatic materials comprising monofilament. Here, as aquatic materials comprising monofilament, aquatic materials comprising monofilament and needle, fishery components such as colored components (such as dyes) corresponding to the use form can be listed. As specific examples of aquatic materials comprising monofilament, fish lines, fish nets, squid fishing lines, trunk lines of longlines, branch lines, competitive fishing lines, etc. can be listed.

[0195] Examples of the injection molded product, extrusion molded product, blow molded product or rotational molded product include machine parts, stationery, stakes, flower pots, blocks, packaging films, sheets, bottles and containers, and the like.

[0196] [Example]

[0197] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

[0198] The materials used in the examples are as follows.

[0199] Polyamide resin composition (A)

[0200] PA6: Polyamide 6, manufactured by UBE Co., Ltd., relative viscosity 4.0, terminal amino group concentration 3.3×10 -5 eq / g, melting point 218°C, crystallization temperature 171°C, extraction amount 8.0% by mass.

[0201] PA6 / 66: Polyamide 6 / 66, manufactured by UBE Co., Ltd., relative viscosity 4.05, terminal amino group concentration 3.3×10 - 5 eq / g, melting point 190°C, crystallization temperature 132°C.

[0202] Heat-resistant agent: Product name: "Irganox (registered trademark) 245" (hindered phenol-based heat-resistant agent, ethylenebis(oxyethylene)bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate], manufactured by BASF).

[0203] Lubricant: Calcium stearate (St-Ca)

[0204] Polyamide resin scrap (B-1): pellets manufactured by REFINVERSE, Inc. The amount of polyethylene terephthalate was analyzed by nuclear magnetic resonance analysis. The result showed that 99.00% by mass of polyamide 6 and 1.00% by mass of polyethylene terephthalate (PET) were contained in 100% by mass of the polyamide resin scrap (B-1). The melting point was 218° C. and the crystallization temperature was 182° C.

[0205] Polyamide resin waste (B-2): pellets manufactured by REFINVERSE, Inc. The amount of polyethylene terephthalate was analyzed by nuclear magnetic resonance analysis and the amount of carbon black was analyzed by differential thermal-thermogravimetric simultaneous measurement. As a result, 100% by mass of the polyamide resin waste (B-2) contained 98.40% by mass of polyamide 6, 1.00% by mass of polyethylene terephthalate (PET) and 0.60% by mass of carbon black (CB), with a melting point of 220°C and a crystallization temperature of 184°C.

[0206] [Measurement]

[0207] <Relative viscosity>

[0208] This is a value measured at 25°C by dissolving 1 g of polyamide in 100 ml of 96% concentrated sulfuric acid in accordance with JIS K6920-2.

[0209] <Terminal amino group concentration>

[0210] The polyamide resin was dissolved in a mixed solvent of phenol and methanol and the resultant was determined by neutralization titration.

[0211] <Tensile Strength and Tensile Modulus>

[0212] The denier (d) of a single yarn is defined as the weight of 9000 m of a single yarn. The weight of 90 cm of a single yarn is actually measured and the measured value is multiplied by 10000 times as the denier of the single yarn.

[0213] The tensile strength of a single yarn is expressed as the value obtained by dividing the breaking stress (g) by the yarn diameter (denier) when the yarn is stretched using TENSILON RTC-131-A manufactured by ORIENTEC Co., Ltd. at a chuck distance of 200 mm and a stretching speed of 200 mm (unit: gf / d).

[0214] The tensile modulus of a single yarn is expressed as the value obtained by dividing the elastic modulus (g) when stretched using TENSILON RTC-131-A manufactured by ORIENTEC Co., Ltd. at a chuck distance of 200 mm and a stretching speed of 200 mm by the yarn diameter (denier) (unit: gf / d).

[0215] <Melting point (Tm) and crystallization temperature (Tc)>

[0216] The single fibers of each embodiment and comparative example were measured using a differential scanning calorimeter (DSC). The sample was heated to 280°C in an air atmosphere, maintained at this temperature for 5 minutes, and then the temperature was lowered to 0°C at a cooling rate of 20°C / min, and the peak temperature of the exothermic peak at this time was taken as the crystallization temperature. Next, the sample was heated from 0°C to 280°C at a rate of 20°C / min, and the peak temperature of the endothermic peak at this time was taken as the melting peak temperature (melting point). The difference between the melting point and the crystallization temperature (Tm-Tc) was calculated by subtracting each crystallization temperature from each melting point.

[0217] <Extraction amount>

[0218] 10 g of the monofilament (sample A) of the example and comparative example was boiled with pure water for 6 hours. Then, the sample A was vacuum dried for 16 hours, and the mass of the sample A was measured, and the weight loss value was taken as the amount of hot water soluble components (g). The extraction amount (mass %) = the amount of hot water soluble components (g) / 10 (g) × 100 was calculated.

[0219] [Example 1]

[0220] According to the composition shown in Table 1, 99.97% by mass of polyamide 6 and 0.03% by mass of lubricant were mixed to obtain a polyamide resin composition (A-1). Then, 5% by mass of polyamide resin scrap (B-1) and 95% by mass of polyamide resin composition (A-1) were mixed to obtain a recycled polyamide resin composition.

[0221] The obtained recycled polyamide resin composition is used to obtain a stretched monofilament by the following manufacturing method. The unstretched monofilament is manufactured using an extruder (CS-40-26N, screw diameter 40mm L / D27). The barrel of the extruder is divided into the front half C1, the middle part C2, and the rear half C3 for temperature control, and the temperature of each part is set to C1 255°C, C2 265°C, and C3 275°C. In addition, the extrusion die head is divided into the front half D1 and the rear half D2 for temperature control, and the temperature is set to D1 250°C and D2 240°C. The stretching process is carried out with a single-stage stretching, the stretching ratio is set to 2.5 times, the stretching is carried out in hot water and the temperature is set to 95°C to obtain the target stretched monofilament.

[0222] [Examples 2 and 3]

[0223] Except having changed the mixing ratio of the polyamide-based resin scrap (B-1) and the polyamide resin composition (A-1) into the composition shown in Table 1, it carried out similarly to Example 1, and obtained the monofilament.

[0224] [Example 4]

[0225] A monofilament was obtained in the same manner as in Example 1 except that the polyamide resin scrap (B-2) was used in place of the polyamide resin scrap (B-1).

[0226] [Examples 5 and 6]

[0227] Except having changed the mixing ratio of the polyamide-based resin scrap (B-2) and the polyamide resin composition (A-1) into the composition shown in Table 1, it carried out similarly to Example 4, and obtained the monofilament.

[0228] [Comparative Example 1]

[0229] A polyamide resin composition (A-1) was obtained by mixing polyamide 6 at 99.97 mass % and lubricant at 0.03 mass % according to the composition shown in Table 1. The target monofilament was obtained by the same monofilament production method as in Example 1 using the polyamide resin composition (A-1).

[0230] [Example 7]

[0231] According to the composition shown in Table 2, 99.96 mass% of polyamide 6 / 66, 0.03 mass% of lubricant and 0.01 mass% of heat-resistant agent were mixed to obtain a polyamide resin composition (A-2), which was used instead of the polyamide resin composition (A-1), and 5 mass% of polyamide resin scrap (B-1) and 95 mass% of polyamide resin composition (A-2) were mixed to obtain a recycled polyamide resin composition. Monofilaments were obtained in the same manner as in Example 1, except that the above-mentioned procedures were repeated.

[0232] [Examples 8 and 9]

[0233] Except having changed the mixing ratio of the polyamide-based resin scrap (B-1) and the polyamide resin composition (A-2) into the composition shown in Table 2, it carried out similarly to Example 7, and obtained the monofilament.

[0234] [Example 10]

[0235] A monofilament was obtained in the same manner as in Example 7 except that the polyamide resin scrap (B-2) was used in place of the polyamide resin scrap (B-1).

[0236] [Examples 11 and 12]

[0237] Except having changed the mixing ratio of the polyamide-based resin scrap (B-2) and the polyamide resin composition (A-2) into the composition shown in Table 2, it carried out similarly to Example 10, and obtained the monofilament.

[0238] [Comparative Example 2]

[0239] A polyamide resin composition (A-2) was obtained by mixing polyamide 6 / 66 at 99.96 mass %, lubricant at 0.03 mass % and heat-resistant agent at 0.01 mass % according to the composition shown in Table 2. The target monofilament was obtained by the same monofilament production method as in Example 1 using the polyamide resin composition (A-2).

[0240] [Table 1]

[0241]

[0242] [Table 2]

[0243]

[0244] Examples 1 to 6 maintain the same tensile strength as Comparative Example 1 which does not contain polyamide resin waste (B), and the tensile modulus is improved compared with Comparative Example 1. In addition, the more the ratio of polyamide resin waste (B) in the recycled polyamide resin composition increases, the more the tensile modulus increases. Furthermore, by including polyamide resin waste (B), Examples 1 to 6 have a smaller difference between the melting point and the crystallization temperature than Comparative Example 1, and can be said to have excellent formability and easy crystallization. In addition, Examples 1 to 6 contain an extracted amount of low molecular weight components and have flexibility, and can be said to be difficult to break.

[0245] Compared with Comparative Example 2 which does not contain polyamide resin waste (B), Examples 7 to 12 have significantly improved tensile modulus. In addition, the more the ratio of polyamide resin waste (B) in the recycled polyamide resin composition increases, the more the tensile modulus increases. Furthermore, by including polyamide resin waste (B), Examples 7 to 12 have a smaller difference between the melting point and the crystallization temperature than Comparative Example 2, and can be said to have excellent formability and easy crystallization. In addition, Examples 7 to 12 have softness due to the low molecular weight component extracted, and can be said to be difficult to break.

[0246] Thus, the present invention can maintain the same tensile strength as that of a polyamide resin composition not containing waste, and can improve the tensile modulus by setting the content of the polyamide-based resin scrap (B) in the recycled polyamide resin composition and the content of the thermoplastic resin (b2) other than the polyamide resin in the polyamide-based resin scrap (B) to specific ranges.

[0247] Industrial Applicability

[0248] The recycled polyamide resin composition can be suitably used for producing monofilaments, injection-molded products by injection molding, extrusion-molded products by extrusion molding, blow-molded products by blow molding, and rotational-molded products by rotational molding.

Claims

1. A recycled polyamide resin composition, which is obtained by melt-kneading a polyamide resin (a) or a polyamide resin composition (A) containing the polyamide resin (a) as a main component and a polyamide resin waste (B), and The polyamide-based resin scrap (B) comprises a polyamide resin (b1) and a thermoplastic resin (b2) other than the polyamide resin. In 100% by mass of the polyamide-based resin waste (B), the content of the thermoplastic resin (b2) other than the polyamide resin is greater than 0% by mass and is 2.00% by mass or less, The polyamide-based resin scrap (B) is contained in 100% by mass of the recycled polyamide resin composition in an amount of 2% by mass or more and less than 50% by mass.

2. The recycled polyamide resin composition according to claim 1, wherein When the total amount of the polyamide resin (a) and the polyamide resin (b1) is 100 parts by mass, the content of the polyamide resin (b1) is 5 parts by mass or more.

3. The recycled polyamide resin composition according to claim 1, wherein When the total amount of the polyamide resin (a) and the polyamide resin (b1) is 100 parts by mass, the content of the thermoplastic resin (b2) other than the polyamide resin is 0.05 parts by mass or more.

4. The recycled polyamide resin composition according to claim 1, wherein When the total amount of the polyamide resin (a) and the polyamide resin (b1) is 100 parts by mass, the content of the polyamide resin (b1) is 5 parts by mass or more, and the content of the thermoplastic resin (b2) other than the polyamide resin is 0.05 parts by mass or more.

5. The recycled polyamide resin composition according to claim 1, wherein The thermoplastic resin (b2) other than the polyamide resin is at least one selected from the group consisting of polyester resins, polyolefin resins and polyvinyl alcohol.

6. The recycled polyamide resin composition according to claim 1, wherein The polyamide resin (a) or the polyamide resin composition (A) comprising the polyamide resin (a) as a main component is a polyamide resin composition (A) comprising the polyamide resin (a) as a main component and contains at least one selected from the group consisting of a lubricant and a heat-resistant agent.

7. The recycled polyamide resin composition according to claim 1, wherein The polyamide-based resin scrap (B) contains a colorant.

8. The recycled polyamide resin composition according to claim 1, wherein The polyamide resin (a) or the polyamide resin composition (A) containing the polyamide resin (a) as a main component includes at least one selected from the group consisting of polyamide 4, polyamide 46, polyamide 410, polyamide 56, polyamide 510, polyamide 512, polyamide 6, polyamide 66, polyamide 610, polyamide 612, polyamide 1010, polyamide 1012, polyamide 11, polyamide 12, polyamide 6 / 66, polyamide 6 / 12 and polyamide 6 / 66 / 12.

9. The recycled polyamide resin composition according to claim 1, wherein The polyamide resin (a) or the polyamide resin (a) in the polyamide resin composition (A) comprising the polyamide resin (a) as a main component is an aliphatic homopolyamide resin.

10. The recycled polyamide resin composition according to claim 1, wherein The polyamide resin (a) or the polyamide resin (a) in the polyamide resin composition (A) comprising the polyamide resin (a) as a main component is an aliphatic copolyamide resin.

11. The recycled polyamide resin composition according to claim 1, wherein The polyamide resin (b1) is an aliphatic homopolyamide resin.

12. The recycled polyamide resin composition according to claim 1, wherein The polyamide resin waste (B) is monofilament waste.

13. The recycled polyamide resin composition according to claim 1, wherein The difference between the melting point and the crystallization temperature, namely Tm-Tc, measured by differential scanning calorimetry (DSC) is 10 to 45°C.

14. The recycled polyamide resin composition according to claim 1, wherein The extraction amount when boiled with pure water for 6 hours was 0.5 to 7.5% by mass. 15 . A molded article, which is a molded article of the recycled polyamide resin composition according to claim 1 . The molded article according to claim 15 , which is a monofilament.

17. A method for producing a recycled polyamide resin composition, comprising melt-kneading a polyamide resin (a) or a polyamide resin composition (A) comprising the polyamide resin (a) as a main component and polyamide-based resin waste (B), wherein: The polyamide-based resin scrap (B) comprises a polyamide resin (b1) and a thermoplastic resin (b2) other than the polyamide resin. In 100% by mass of the polyamide-based resin waste (B), the content of thermoplastic resin (b2) other than polyamide resin is greater than 0% by mass and is less than 2.00% by mass, The polyamide-based resin scrap (B) is contained in 100% by mass of the recycled polyamide resin composition in an amount of 2% by mass or more and less than 50% by mass.

18. The method for producing a recycled polyamide resin composition according to claim 17, comprising the following steps: Step 1, crushing the polyamide resin waste (B); Step 2, which comprises adding the polyamide resin (a) or the polyamide resin composition (A) containing the polyamide resin (a) as a main component to the pulverized polyamide-based resin waste (B) obtained in Step 1 and mixing; and Step 3 is to melt-knead the mixture obtained in step 2 to obtain pellets.

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