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 a polyamide resin (a) as a main component, a polyamide-based resin waste (B), and a fibrous reinforcing filler (C), the polyamide resin waste (B) contains a polyamide resin (b1) and a thermoplastic resin (b2) other than the polyamide resin, and the content of the polyamide resin (b1) is 11.0 parts by mass or more when the sum 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 0.13 parts by mass or more when the sum of the polyamide resin (a) and the polyamide resin (b1) is taken as 100 parts by mass, and the content of the thermoplastic resin (b2) other than the polyamide resin is 0.13 parts by mass or more in 100% by mass of the regenerated polyamide resin composition. The polyamide resin composition contains 0-80.0 mass% of the polyamide resin (a) or a polyamide resin composition (A) containing the polyamide resin (a) as a main component and 5.0-70.0 mass% of the fibrous reinforcing filler (C). 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 mechanical properties such as tensile properties, flexural properties, and impact resistance. It is desirable to form a composition utilizing a waste composition so as to improve or not impair the mechanical properties of the polyamide resins and compositions thereof.

[0015] Therefore, an object of the present invention is to provide a recycled polyamide resin composition having excellent tensile strength, tensile modulus, flexural strength, flexural modulus, and impact resistance.

[0016] Solutions for solving problems

[0017] The present inventors have found that by setting the ratio of the polyamide resin (b1) in the polyamide-based resin scraps (B) to the total polyamide resin in the recycled polyamide resin composition and the ratio of the thermoplastic resin (b2) other than the polyamide resin as an unintended component contained in the polyamide-based resin scraps (B) to the total polyamide resin to specific ranges, the mechanical properties of the polyamide resin composition not containing scraps can be improved or not impaired, 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.

[0018] The present invention includes, for example, the following [1] to

[12] .

[0019] [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, polyamide-based resin waste (B) and a fibrous reinforcing filler (C);

[0020] The polyamide-based resin scrap (B) comprises a polyamide resin (b1) and a thermoplastic resin (b2) other than the polyamide resin.

[0021] 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 11.0 parts by mass or more.

[0022] 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 0.13 parts by mass or more.

[0023] The recycled polyamide resin composition contains 0 to 80.0% by mass of the polyamide resin (a) or the polyamide resin composition (A) containing the polyamide resin (a) as a main component and 5.0 to 70.0% by mass of the fibrous reinforcing filler (C) in 100% by mass.

[0024] [2] The recycled polyamide resin composition according to [1], wherein 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 in 100% by mass of the polyamide-based resin scrap (B).

[0025] [3] The recycled polyamide resin composition according to [1] or [2], wherein the recycled polyamide resin composition contains 5.0 to 90.0% by mass of polyamide-based resin scrap (B) in 100% by mass of the recycled polyamide resin composition.

[0026] [4] The recycled polyamide resin composition according to any one of [1] to [3], 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.

[0027] [5] A recycled polyamide resin composition according to any one of [1] to [4], 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.

[0028] [6] The recycled polyamide resin composition according to any one of [1] to [5], wherein the polyamide-based resin scrap (B) contains a colorant.

[0029] [7] The recycled polyamide resin composition according to any one of [1] to [6], wherein the polyamide resin (a) or the polyamide resin composition (A) comprising 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.

[0030] [8] The recycled polyamide resin composition according to any one of [1] to [7], wherein the polyamide resin (b1) is an aliphatic homopolyamide resin.

[0031] [9] The recycled polyamide resin composition according to any one of [1] to [8], wherein the polyamide-based resin scrap (B) is monofilament scrap.

[0032]

[10] A molded article, which is a molded article of the recycled polyamide resin composition according to any one of [1] to [9].

[0033]

[11] A method for producing a recycled polyamide resin composition, comprising melt-kneading the polyamide resin (a) or the polyamide resin composition (A) comprising the polyamide resin (a) as a main component, polyamide resin waste (B) and a fibrous reinforcing filler (C) to obtain a recycled polyamide resin composition, wherein:

[0034] The polyamide-based resin scrap (B) comprises a polyamide resin (b1) and a thermoplastic resin (b2) other than the polyamide resin.

[0035] 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 11.0 parts by mass or more.

[0036] 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 0.13 parts by mass or more.

[0037] The recycled polyamide resin composition contains 0 to 80.0% by mass of the polyamide resin (a) or the polyamide resin composition (A) containing the polyamide resin (a) as a main component and 5.0 to 70.0% by mass of the fibrous reinforcing filler (C) in 100% by mass of the recycled polyamide resin composition.

[0038]

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

[11] , comprising the following steps:

[0039] Step 1, crushing the polyamide resin waste (B);

[0040] an optional step 2 of adding and mixing 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 the step 1; and

[0041] Step 3 is to add a fibrous reinforcing filler (C) to the pulverized product obtained in step 1 or the mixture obtained in step 2, and melt-knead the mixture to obtain pellets.

[0042] Effects of the Invention

[0043] The recycled polyamide resin composition of the present invention has excellent tensile strength, tensile modulus, flexural strength, flexural modulus and impact resistance. DETAILED DESCRIPTION

[0044] The present invention relates to a recycled polyamide resin composition.

[0045] The invention is obtained by melt-kneading a polyamide resin (a) or a polyamide resin composition (A) containing the polyamide resin (a) as a main component, polyamide resin waste (B) and a fibrous reinforcing filler (C), and

[0046] The polyamide-based resin scrap (B) comprises a polyamide resin (b1) and a thermoplastic resin (b2) other than the polyamide resin.

[0047] 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 11.0 parts by mass or more.

[0048] 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 0.13 parts by mass or more.

[0049] The recycled polyamide resin composition contains 0 to 80.0% by mass of the polyamide resin (a) or the polyamide resin composition (A) containing the polyamide resin (a) as a main component and 5.0 to 70.0% by mass of the fibrous reinforcing filler (C) in 100% by mass.

[0050] <<Polyamide resin (a) or polyamide resin composition (A) containing polyamide resin (a) as a main component>>

[0051] The recycled polyamide resin composition preferably comprises the polyamide resin (a) or a polyamide resin composition (A) comprising the polyamide resin (a) as a main component.

[0052] The polyamide resin (a) is not particularly limited, and examples thereof include aliphatic homopolyamide resins and aliphatic copolyamide resins.

[0053] (Aliphatic homopolyamide resin (a-1))

[0054] 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.

[0055] 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.

[0056] 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.

[0057] Examples of the aminocarboxylic acid include 6-aminohexanoic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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, and 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 respective relative viscosities by their mixing ratios can be used as the relative viscosity of the aliphatic homopolyamide resin. The measured value is adopted in the present invention.

[0064] (Aliphatic copolyamide resin (a-2))

[0065] 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.

[0066] Examples of the diamine include the same diamines as those exemplified as the raw materials of the aliphatic homopolyamide resin.

[0067] Examples of the dicarboxylic acid include the same ones as exemplified as the raw materials of the aliphatic homopolyamide resin.

[0068] Examples of the lactam include the same ones as exemplified as the raw materials of the aliphatic homopolyamide resin.

[0069] Examples of the aminocarboxylic acid include the same ones as exemplified as the raw materials of the aliphatic homopolyamide resin.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] The polyamide resin (a) preferably 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, and preferably comprises a polyamide containing a structural unit derived from ε-caprolactam, a polyamide containing a structural unit derived from 6-aminocaproic acid, The present invention further comprises at least one selected from the group consisting of polyamide 6, polyamide 66, polyamide 610, polyamide 612, polyamide 11, polyamide 12, polyamide 6 / 66, polyamide 6 / 12 and polyamide 6 / 66 / 12. From the viewpoint of improving the tensile modulus, the present invention further comprises at least one selected from the group consisting of polyamide 6, polyamide 6 / 66 and polyamide 6 / 66 / 12. It is particularly preferred that the present invention be composed solely of these resins.

[0075] 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.

[0076] (Manufacture of polyamide resin)

[0077] 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.

[0078] 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.

[0079] 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.

[0080] When the polyamide resin (a) contains two or more polyamide resins having different relative viscosities, the relative viscosity is determined by the same method as described in the section on aliphatic homopolyamide resins.

[0081] 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.

[0082] 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.

[0083] 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 is below 2.0×10 -5 eq / g or more, more preferably 2.5×10 -5 eq / g or above.

[0084] 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 may be calculated as an average value obtained by adding the values ​​obtained by multiplying the terminal amino group concentrations by their mixing ratios. In the present invention, the value based on the neutralization titration is adopted.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] It should be noted that “polyamide resin (a) as a main component” means that the polyamide resin (a) is contained in the largest amount by mass in all the components of the polyamide resin composition, and means that the polyamide resin (a) is contained in 100 mass % of the polyamide resin composition in an amount of preferably 95.00 mass % or more, more preferably 97.00 mass % or more.

[0089] 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.

[0090] The polyamide resin composition may contain, as optional components, dyes, pigments, 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. The polyamide resin composition preferably does not contain fibrous reinforcing fillers.

[0091] <Heat-resistant agent>

[0092] As the heat-resisting agent, organic or inorganic heat-resisting agents can be used according to the purpose, and these can be used alone or in combination of two or more. The heat-resisting agent refers to a component that inhibits thermal oxidation and thermal aging of the polyamide resin, and in terms of its purpose, it also includes substances called antioxidants.

[0093] ((Organic heat-resistant agent))

[0094] 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.

[0095] (Phenol compounds)

[0096] 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.

[0097] 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.

[0098] (Phosphorus compounds)

[0099] 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.

[0100] (Sulfur compounds)

[0101] 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.

[0102] (Nitrogen compounds)

[0103] 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.

[0104] 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.

[0105] ((Inorganic heat resistant agent))

[0106] 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.

[0107] <Lubricant>

[0108] The lubricant is a substance that reduces the viscosity of the resin melt and helps improve the releasability from the metal surface during molding.

[0109] 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.

[0110] Examples of terminal-modified products of polyalkylene glycol include terminal-modified products of polyethylene glycol and terminal-modified products of polypropylene glycol.

[0111] 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.

[0112] Examples of the higher fatty acid monoesters include myristyl myristate, stearyl stearate, behenyl behenate, oleyl oleate, and hexyldecyl myristate.

[0113] Examples of the higher fatty acid include myristic acid, palmitic acid, behenic acid, oleic acid, and arachidic acid.

[0114] Examples of the metal salt of a higher fatty acid include zinc stearate, lithium stearate, calcium stearate, and aluminum palmitate.

[0115] 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-naphthalene dicarboxylic 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.

[0116] Examples of the ethylenebisamide compound include ethylenebisstearylamide and ethylenebispalmitamide.

[0117] 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.

[0118] Examples of magnesium silicate include those having an average particle size of 1 to 10 μm.

[0119] 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.

[0120] These may be used alone or in combination of two or more.

[0121] The optional additives may be contained in an amount of preferably 0.01 to 5.00% by mass, more preferably 0.05 to 2.50% by mass, based on 100% by mass of the polyamide resin composition.

[0122] 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 the main component is 0 to 80.0% by mass, preferably 0 to 65% by mass, preferably 0% by mass or more than 10.0% by mass and less than 80.0% by mass, more preferably 0% by mass or 15.0 to 75.0% by mass, further preferably 0% by mass or 15.0 to 65.0% by mass, particularly preferably 0% by mass or 25.0 to 65.0% by mass. If the polyamide resin (a) or the polyamide resin composition (A) containing the polyamide resin (a) as the 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. 0% by mass means that it is completely free of.

[0123] <<Polyamide resin waste (B)>>

[0124] The recycled polyamide resin composition contains polyamide-based resin scrap (B).

[0125] The polyamide-based resin scrap (B) contains a polyamide resin (b1) and a thermoplastic resin (b2) other than the polyamide resin.

[0126] <Polyamide resin (b1)>

[0127] 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).

[0128] From the viewpoint of compatibility with the aforementioned polyamide resin (a) or the polyamide resin composition (A) comprising the polyamide resin (a) as the main component, the polyamide resin (b1) is preferably an aliphatic homopolyamide resin, more preferably at least one selected from the group consisting of a polyamide containing a structural unit derived from ε-caprolactam, a polyamide containing a structural unit derived from 6-aminocaproic acid, and a polyamide containing a structural unit derived from a monomer of hexamethylenediamine and a dicarboxylic acid, further preferably polyamide 6 and polyamide 66, and particularly preferably polyamide 6.

[0129] 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.

[0130] The polyamide resin (b1) has good moldability if it has the same molecular weight as the polyamide resin (a) of component (A). Therefore, the relative viscosity 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 even more preferably 2.3 to 4.5.

[0131] 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.

[0132] 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.

[0133] <Thermoplastic resin other than polyamide resin (b2)>

[0134] 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.

[0135] 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.

[0136] 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).

[0137] The content of the thermoplastic resin (b2) other than the polyamide resin in 100% by mass of the polyamide-based resin scrap (B) is preferably greater than 0% by mass and less than 2.00% by mass, and more preferably greater than 0% by mass and less than 1.50% by mass. If the content of the thermoplastic resin (b2) other than the polyamide resin in the polyamide-based resin scrap (B) is within the above range, the properties of the thermoplastic resin can be suppressed and the properties of the polyamide resin will not be impaired. Here, "greater than 0% by mass" means that the case where it is completely not contained is excluded.

[0138] The polyamide resin waste (B) may contain, as optional components, appropriate functional imparting agents such as dyes, pigments, 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.

[0139] 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.

[0140] The content of the colorant in 100% by mass of the polyamide resin waste (B) is preferably 1.00% by mass or less, more preferably greater than 0% by mass and less than 1.00% by mass. Here, "greater than 0% by mass" means excluding the case where the colorant is completely not contained. 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.

[0141] 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.

[0142] 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.

[0143] In 100% by mass of the recycled polyamide resin composition, the content of the polyamide-based resin scrap (B) is preferably 5.0 to 90.0% by mass, more preferably 5.0 to 87.5% by mass, further preferably 10.0 to 85.0% by mass, particularly preferably 10.0 to 84.0% by mass, and most preferably 10.0 to 60.0% 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.

[0144] <Fiber-like reinforcing filler (C)>

[0145] The recycled polyamide resin composition contains a fibrous reinforcing filler (C).

[0146] Fibrous means a shape having an average thickness of 1 μm or less and an aspect ratio (ratio of major diameter to minor diameter) of 10 or more. The fibrous reinforcing filler (C) may break during melt kneading with other components. Therefore, the content of the fibrous reinforcing filler (C) in the recycled polyamide resin composition includes materials that no longer meet the definition of "fiber" in this specification due to breakage.

[0147] As the fibrous reinforcing filler, any of an inorganic filler and an organic filler can be used, and glass fiber, carbon fiber, cellulose fiber, aramid fiber, etc. can be listed. Among them, glass fiber is preferred from the perspective that the flexibility of the molded product will not be reduced and the mechanical properties are improved. The fibrous reinforcing filler can be used alone or in combination of two or more.

[0148] The fibrous reinforcing filler can be surface treated with a surface treatment agent. Furthermore, in order to improve workability, it can be bundled or granulated with these surface treatment agents. As the surface treatment agent, various coupling agents such as silane coupling agents, titanium coupling agents, aluminum coupling agents, and zirconium oxide coupling agents can be listed; water glass, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, starch, polyvinyl alcohol, acrylic resin, epoxy resin, phenolic resin, polyvinyl acetate, polyurethane resin, epoxy compound, isocyanate compound, colloidal silica, colloidal alumina, fatty acid, surfactant, etc. The surface treatment agent can be used alone or in combination of two or more.

[0149] The surface treatment agent may be applied to the fibrous reinforcing filler in advance, dried and subjected to surface treatment or bundling treatment, or may be added simultaneously with the fibrous reinforcing filler (C) when preparing the resin composition.

[0150] The fibrous reinforcing filler as a raw material may have an average fiber diameter of 4 to 25 μm. From the viewpoint of dimensional stability and mechanical properties of a molded product formed from the composition, the average fiber diameter is preferably 6 to 23 μm, for example, an average fiber diameter of 10 to 23 μm may be used.

[0151] The fiber length (cut length) of the raw material fibrous reinforcing filler is not particularly limited, and chopped strands of 1 mm to 50 mm can be used. From the viewpoint of productivity, 3 mm to 10 mm is more preferable.

[0152] The thickness, major diameter, minor diameter, average fiber diameter, and glass fiber length (cut length) of the fibrous reinforcing filler can be observed using an optical microscope. The average fiber diameter and glass fiber length (cut length) of the raw material fibrous reinforcing filler may be catalog values.

[0153] In 100% by mass of the recycled polyamide resin composition, the content of the fibrous reinforcing filler (C) is 5.0 to 70.0% by mass, preferably 10.0 to 65.0% by mass, more preferably 15.0 to 62.0% by mass, further preferably 16.0 to 62.0% by mass, and particularly preferably 16.0 to 45.0% by mass. If the content of the fibrous reinforcing filler is within the above range, appropriate mechanical strength can be maintained.

[0154] <<Recycled polyamide resin composition>>

[0155] The recycled polyamide resin composition is obtained by melt-kneading an optional polyamide resin (a) or a polyamide resin composition (A) containing the polyamide resin (a) as a main component, polyamide-based resin scrap (B) and a fibrous reinforcing filler (C).

[0156] The recycled polyamide resin composition is preferably obtained by a production method including the following steps.

[0157] The manufacturing method has the following steps:

[0158] Step 1, crushing the polyamide resin waste (B);

[0159] an optional step 2 of adding and mixing 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 the step 1; and

[0160] Step 3 is to add a fibrous reinforcing filler (C) to the pulverized product obtained in step 1 or the mixture obtained in step 2, and melt-knead the mixture to obtain pellets.

[0161] These steps may include a washing step, a dehydrating step, a drying step, and the like of the polyamide resin waste (B).

[0162] In addition, when using commercially available pelletized polyamide-based resin scrap (B), step 1 may be omitted.

[0163] Step 1: The polyamide resin waste (B) is pulverized.

[0164] 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.

[0165] Step 2: Add and mix 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. Since the polyamide resin composition (A) is an optional component that can be 0% by mass in the recycled polyamide resin composition, when the polyamide resin composition (A) is 0% by mass, the method for producing the recycled polyamide resin composition does not include step 2.

[0166] 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.

[0167] Step 3: A fibrous reinforcing filler (C) is added to the pulverized product obtained in step 1 or the mixture obtained in optional step 2, and melt-kneaded to obtain pellets.

[0168] In step 3, the fibrous reinforcing filler (C) may be added in total at once, or a part of the fibrous reinforcing filler (C) may be added from a top feeder and melt-kneaded with other components, and the remaining part is added from a side feeder and further melt-kneaded. In the latter case, when the total amount of the fibrous reinforcing filler compounded in the recycled polyamide resin composition is 100 parts by mass, the amount of the fibrous reinforcing filler added from the top feeder: the amount of the fibrous reinforcing filler added from the side feeder (mass ratio) is preferably 2:98 to 98:2, more preferably 5:95 to 95:5, and even more preferably 10:90 to 90:10.

[0169] 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.

[0170] 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 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 like.

[0171] 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.

[0172] 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 step of producing the polyamide resin composition 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.

[0173] 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.

[0174] 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 11.0 parts by mass or more, preferably 12.0 parts by mass or more, more preferably 12.0 to 100 parts by mass, further preferably 13.0 to 100 parts by mass, particularly preferably 13.0 to 75.0 parts by mass or 100 parts by mass, and most preferably 13.0 to 70.0 parts by mass or 100 parts by mass. When 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 properties, bending properties and impact resistance are excellent, and the quality of the molded product manufactured from the recycled polyamide resin is not reduced.

[0175] 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 0.13 parts by mass or more, preferably 0.14 parts by mass or more, more preferably 0.15 parts by mass or more, further preferably 0.15 to 0.80 parts by mass or 1.00 to 1.90 parts by mass, particularly preferably greater than 0.15 parts by mass and less than 0.79 parts by mass or 1.00 to 1.40 parts by mass. When the content of the thermoplastic resin (b2) other than the polyamide resin 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 properties, bending properties and impact resistance are excellent, and the quality of the molded product produced from the recycled polyamide resin is not reduced.

[0176] In the recycled polyamide resin composition, in addition to the (A) component, the (B) component, and the (C) component, as optional components, dyes, pigments, 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.

[0177] The optional additives may be contained in an amount of preferably 0.01 to 5.00% by mass, more preferably 0.05 to 2.50% by mass, based on 100% by mass of the recycled polyamide resin composition.

[0178] [Molded articles of recycled polyamide resin composition and their uses]

[0179] The molded product comprising the recycled polyamide resin composition can be obtained as the molded product of desired shape by molding the recycled polyamide resin composition. As molding method, extrusion molding, blow molding, injection molding, rotational molding etc. can be listed. The recycled polyamide resin composition is due to good injection molding property, and therefore can be more preferably used for injection molded products based on injection molding.

[0180] There are no particular limitations on the injection molded products based on injection molding, the extrusion molded products based on extrusion molding, the blow molded products based on blow molding, and the rotational molded products based on rotational molding, and the applications include spoilers, intake pipes, intake manifolds, resonators, fuel tanks, gas tanks, hydraulic oil tanks, fuel filling pipes, fuel delivery pipes, other various hoses (hose), ducts (tube), tanks and other automotive parts, power tool housings, pipes and other mechanical parts, tanks, ducts, hoses, films and other electrical and electronic parts, home and office supplies, building material-related parts, furniture parts and the like.

[0181] In addition, for example, it can be suitably used in driving parts such as gears and belts in the field of vehicles such as automobiles, and sliding parts such as tire sidewalls and belts. As sliding parts, for example, gears, cams, pulleys, bearings, bearing brackets, door checks, timing chain guides, cable and hose support guide devices and other parts aimed at dynamic uses can be further listed.

[0182] Among these, the present invention can be suitably used for automobile parts, sliding parts, or electric and electronic parts.

[0183] [Example]

[0184] 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.

[0185] The materials used in the examples are as follows.

[0186] PA6 in the polyamide resin (a) or the polyamide resin composition (A) containing the polyamide resin (a) as a main component: polyamide 6, manufactured by UBE Co., Ltd., relative viscosity 4.0, terminal amino group concentration 3.3×10 -5 eq / g

[0187] Polyamide resin scrap (B): 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 scrap contained 98.30% by mass of polyamide 6, 1.10% by mass of polyethylene terephthalate, and 0.60% by mass of carbon black.

[0188] Glass fiber: Product name "ECS 03T-249H" (manufactured by Nippon Electric Glass Co., Ltd., diameter 10.5μm, average fiber length 3.5mm)

[0189] [Physical property measurement]

[0190] <Relative viscosity>

[0191] 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.

[0192] <Terminal amino group concentration>

[0193] The polyamide resin was dissolved in a mixed solvent of phenol and methanol and the resultant was determined by neutralization titration.

[0194] In the following, in the evaluation of tensile strength and tensile modulus, flexural strength and flexural modulus, and Charpy impact strength, ⊙ means excellent, ○ means good, △ means fair, and × means poor.

[0195] <Tensile Strength and Tensile Modulus>

[0196] Type A test pieces were prepared in accordance with ISO 294-1, and tensile tests were performed in an atmosphere of 23°C in accordance with ISO 527-1,2.

[0197] The tensile strength was evaluated according to the following criteria.

[0198] ◎:175.0MPa or above

[0199] ○: 150.0MPa or more and less than 175.0MPa

[0200] △: 125.0MPa or more and less than 150.0MPa

[0201] ×: less than 125.0MPa

[0202] The tensile modulus was evaluated according to the following criteria.

[0203] ◎:9.50GPa or above

[0204] ○: 7.00 GPa or more and less than 9.50 GPa

[0205] △: 5.00 GPa or more and less than 7.00 GPa

[0206] ×: less than 5.00 GPa

[0207] <Flexural Strength and Flexural Modulus>

[0208] Type B test pieces were prepared in accordance with ISO 294-1, and a bending test was performed in an atmosphere of 23° C. in accordance with ISO 178.

[0209] The bending strength was evaluated according to the following criteria.

[0210] ◎:260.0MPa or above

[0211] ○: 200.0MPa or more and less than 260.0MPa

[0212] △: 160.0MPa or more and less than 200.0MPa

[0213] ×: less than 160.0MPa

[0214] The flexural modulus was evaluated according to the following criteria.

[0215] ◎:8.50GPa or above

[0216] ○: 6.00 GPa or more and less than 8.50 GPa

[0217] △: 5.00 GPa or more and less than 6.00 GPa

[0218] ×: less than 5.00 GPa

[0219] <Charpy impact strength>

[0220] Type B test pieces were prepared in accordance with ISO 294-1, and V-notch processing was performed in accordance with ISO 179 / 1eA by post-processing. Charpy impact tests were performed at a hammer energy of 1 J and at 23°C.

[0221] The Charpy impact strength was evaluated according to the following criteria.

[0222] ◎:9.5kJ / m 2 above

[0223] ○:7.0kJ / m 2 Above and less than 9.5kJ / m 2

[0224] △: 4.0kJ / m 2 Above and less than 7.0kJ / m 2

[0225] ×: less than 4.0 kJ / m 2

[0226] [Example 1]

[0227] The components shown in Table 1 were mixed so that polyamide 6 accounted for 87.5% by mass and polyamide-based resin scraps accounted for 12.5% ​​by mass, thereby obtaining a mixture of polyamide resin and scraps.

[0228] The obtained mixture of polyamide resin and scrap was melt-kneaded by a ZSK32Mc twin-screw kneader manufactured by Coperion Co., Ltd. while side-feeding glass fiber, thereby preparing pellets of a recycled polyamide resin composition containing 70% by mass of polyamide 6, 10.0% by mass of polyamide resin scrap, and 20.0% by mass of glass fiber. Then, the obtained pellets were injection-molded at a barrel temperature of 290° C. and a mold temperature of 80° C. to prepare various test pieces, and various physical properties were evaluated.

[0229] [Examples 2 to 7, Comparative Example 1]

[0230] A test piece was obtained in the same manner as in Example 1 except that the mixing ratio of polyamide 6, polyamide-based resin scrap and glass fiber in the recycled polyamide resin composition pellets was changed to the composition shown in Table 1.

[0231] [Table 1]

[0232]

[0233] In Examples 1 to 7, the tensile strength, tensile modulus, flexural strength, flexural modulus, and Charpy impact strength were all evaluated as × and contained no component.

[0234] When the total of the polyamide resin (a) and the polyamide resin (b1) was 100 parts by mass, all the evaluations of Comparative Example 1 in which the content of the polyamide resin (b1) was less than 11.0 parts by mass and the content of the thermoplastic resin (b2) other than the polyamide resin was less than 0.13 parts by mass were negative.

[0235] Industrial Applicability

[0236] The recycled polyamide resin composition can be suitably used for production of 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.

[0237] This application claims the priority based on Japanese Patent Application No. 2022-118505 and Japanese Patent Application No. 2023-060954, and all the disclosures of Japanese Patent Application No. 2022-118505 and Japanese Patent Application No. 2023-060954 are incorporated by reference.

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, a polyamide resin waste (B) and a fibrous reinforcing filler (C), and The polyamide-based resin scrap (B) comprises a polyamide resin (b1) and a 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, the content of the polyamide resin (b1) is 11.0 parts by mass or more. 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 0.13 parts by mass or more. The recycled polyamide resin composition contains 0 to 80.0 mass % of the polyamide resin (a) or the polyamide resin composition (A) containing the polyamide resin (a) as a main component and 5.0 to 70.0 mass % of the fibrous reinforcing filler (C) in 100 mass % of the recycled polyamide resin composition.

2. The recycled polyamide resin composition according to claim 1, wherein 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.

3. The recycled polyamide resin composition according to claim 1, wherein The recycled polyamide resin composition contains 5.0 to 90.0% by mass of polyamide-based resin scraps (B) in 100% by mass.

4. 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.

5. 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.

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

7. 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.

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

9. The recycled polyamide resin composition according to claim 1, wherein The polyamide resin waste (B) is monofilament waste. 10 . A molded article, which is a molded article of the recycled polyamide resin composition according to claim 1 .

11. A method for producing a recycled polyamide resin composition, comprising melt-kneading the polyamide resin (a) or the polyamide resin composition (A) comprising the polyamide resin (a) as a main component, polyamide resin waste (B) and fibrous reinforcing filler (C) to obtain a recycled polyamide resin composition, wherein: The polyamide-based resin scrap (B) comprises a polyamide resin (b1) and a 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, the content of the polyamide resin (b1) is 11.0 parts by mass or more. 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 0.13 parts by mass or more. The recycled polyamide resin composition contains 0 to 80.0 mass % of the polyamide resin (a) or the polyamide resin composition (A) containing the polyamide resin (a) as a main component and 5.0 to 70.0 mass % of the fibrous reinforcing filler (C) in 100 mass % of the recycled polyamide resin composition.

12. The method for producing a recycled polyamide resin composition according to claim 11, comprising the following steps: Step 1, crushing the polyamide resin waste (B); an optional step 2 of adding and mixing 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 the step 1; and Step 3 is to add a fibrous reinforcing filler (C) to the pulverized product obtained in step 1 or the mixture obtained in step 2, and melt-knead the mixture to obtain pellets.

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