Resin separation method

Abstract

To provide a method for separating polyester and polyamide from a resin composition containing multiple resins, for example, a resin composition containing at least thermoplastic resin.SOLUTION: There is provided a method for separating resin B1 and resin P from a resin composition, comprising: step 1: a mixing step of mixing a resin composition containing a thermoplastic resin A1, a polyamide resin B1, and a polyester resin P with a thermoplastic resin A2 and a component C; and step 2: a separation step in which filtration treatment of a mixture obtained in the step 1 is performed at a temperature range above a melting point of resin A1 and below a melting point of a mixture of resin P or the like to separate resin B1 and resin P from the mixture obtained in the step 1.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for separating polyester and polyamide from a resin composition containing multiple resins. [Background technology]

[0002] Many packaging materials are made from thermoplastic composites and / or laminates and are molded into, for example, bottle containers and refill pouches. These materials are sometimes composed of completely different types of resin films for functional reasons. Therefore, when packaging materials made from these materials are recovered and recycled, the resulting resins contain polymers that are incompatible with the main polymer. For example, polyethylene resins recovered from recycled pouches contain unmelted polyamide resins and PET, and polyamide resins and PET form heterogeneous blends, significantly reducing the formability of the resulting film compared to virgin polyethylene. In particular, unmelted polyamide resins and PET resins are incompatible with polyethylene resins, and their large size significantly impacts formability.

[0003] Therefore, methods for separating a specific resin that is not required for recycling from a resin composition containing multiple resins include the methods described in Patent Documents 1 and 2, for example. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2022-230331 [Patent Document 2] U.S. Patent Application Publication No. 2021 / 114335 Summary of the Invention [Problem to be solved by the invention]

[0005] Although Patent Documents 1 and 2 describe methods for separating a target thermoplastic resin (resin for recycling) from a mixture of thermoplastic resins, a method for separating a highly pure resin for recycling is desired.

[0006] The present invention relates to a method for separating polyester and polyamide from a resin composition containing multiple resins, for example, a resin composition containing at least a thermoplastic resin. [Means for solving the problem]

[0007] The present invention relates to the following [1] to [3]. [1] Step 1: A mixing step of mixing a resin composition containing a thermoplastic resin A1, a polyamide resin B1, and a polyester resin P with a thermoplastic resin A2 and a component C; and Step 2: A separation step in which the mixture obtained in Step 1 is filtered at a temperature range equal to or higher than the melting point of Resin A1 and equal to or lower than the melting point of the mixture of Resin P, Resin B1, and Component C, to separate Resin B1 and Resin P from the mixture obtained in Step 1. A method for separating resin B1 and resin P from a resin composition containing resin A1, resin B1, and resin P, comprising: Resin A2 is a resin having a melt viscosity higher than that of Resin A1, Component C is a compound that increases the contact angle of resin A1 with a mixture of component C and resin P compared to the contact angle of resin A1 with resin P. A method for separating resin B1 and resin P. [2] Step 1 is a step of mixing a resin composition containing resin A1, resin B1, and resin P with resin A2, polyamide resin B2, and component C, Step 2 is a step of filtering the mixture obtained in Step 1 at a temperature range of not less than the melting point of Resin A1 and not more than the melting point of the mixture of Resin P, Resin B1, Resin B2, and Component C, thereby separating Resin B1, Resin B2, and Resin P from the mixture obtained in Step 1; Resin B2 is a resin whose melt viscosity when mixed with component C is higher than the melt viscosity when mixed with resin B1 and component C. The method for separating resin B1 and resin P according to [1] above. [3] Step 3: A resin composition containing a thermoplastic resin A1 and a polyester resin P, (1) Mixing polyamide resin B2 and component C, or (2) Mixing thermoplastic resin A2, resin B2 and component C a mixing step, and Step 4: A separation step in which the mixture obtained in Step 3 is filtered at a temperature range of not less than the melting point of Resin A1 and not more than the melting point of the mixture of Resin P, Resin B2, and Component C, to separate Resin B2 and Resin P from the mixture obtained in Step 3. A method for separating resin P from a resin composition containing resin A1 and resin P, comprising: Resin A2 is a resin having a melt viscosity higher than that of Resin A1, Component C is a compound that increases the contact angle of resin A1 with a mixture of component C and resin P compared to the contact angle of resin A1 with resin P. Method for separating resin P. [Effects of the Invention]

[0008] According to the method of the present invention, polyester and polyamide can be separated from a resin composition containing multiple resins, for example, a resin composition containing at least a thermoplastic resin. DETAILED DESCRIPTION OF THE INVENTION

[0009] According to the method of the present invention, polyester and polyamide can be separated from a resin composition containing multiple resins, for example, a resin composition containing at least a thermoplastic resin, and therefore it is possible to recover the polyester and polyamide with high purity, thereby enabling efficient reuse of the polyester and polyamide.

[0010] The separation method of the present invention comprises: A mixing step of mixing a resin composition containing a thermoplastic resin with component C and the like (hereinafter referred to as "additives"); A separation step in which the mixture obtained in the mixing step is filtered to separate the target resin from the resin composition. Includes.

[0011] [Various components in the present invention] The thermoplastic resin in the present invention is not particularly limited, and examples thereof include polyolefin resin, vinyl chloride resin, styrene resin, vinyl ether resin, polyvinyl alcohol resin, polycarbonate resin, polysulfone resin, etc. As the thermoplastic resin in the present invention, a polyolefin resin, which is generally used as a main raw material for packaging materials and is in high demand for recycling, is preferred, a polyethylene resin or a polypropylene resin is more preferred, and among polyolefin resins, a polyethylene resin having a relatively low melting point is even more preferred, a low-density polyethylene is even more preferred, and a linear low-density polyethylene is even more preferred.

[0012] From the viewpoint of productivity of the separation process, the melting point of resin A1 is preferably 80°C or higher, more preferably 90°C or higher, and even more preferably 100°C or higher, and from the viewpoint of the melting point difference with resin B, it is preferably 200°C or lower, more preferably 180°C or lower, even more preferably 160°C or lower, and even more preferably 140°C or lower. Resin A1 may be one type or a mixture of two or more types. When resin A1 is two or more types of resin, the melting point of resin A1 is the melting point of the highest resin among those resins. Resin A1 preferably has a melting point lower than the melting point of the mixture of resin B1 and resin P, from the viewpoint of improving the efficiency of separating resin B1 and resin P during filtering.

[0013] The content of resin A1 in the resin mixture to be subjected to filtration, for example, the mixture obtained in step 1, is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, even more preferably 60% by mass or more, and even more preferably 75% by mass or more, from the viewpoint of improving the yield of the separation step and the purity of the thermoplastic resin after separation, and is preferably 99% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less, from the viewpoint of ease of separation.

[0014] Resin A2 is a thermoplastic resin having a melt viscosity higher than that of Resin A1. The melt viscosity of the thermoplastic resin is measured by the method described in the Examples below. In the present invention, "having a higher melt viscosity" means that the difference in melt viscosity (at the same temperature) between the resins being compared is preferably 10 mPa·s or more, more preferably 50 mPa·s or more, even more preferably 100 mPa·s or more, and even more preferably 150 mPa·s or more.

[0015] Resin A2 is preferably the same type of thermoplastic resin as resin A1, from the viewpoint of improving the efficiency of separation of resin B1 and resin P during filter treatment. Here, the term "same type of thermoplastic resin" means, for example, that when one is polyethylene, the other is also polyethylene, and when one is polypropylene, the other is also polypropylene; however, when one is polyethylene and the other is polypropylene, this does not fall under the category of "same type of thermoplastic resin."

[0016] The content of resin A1 in the resin mixture to be subjected to filtration, for example, the mixture obtained in step 1, is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, even more preferably 60% by mass or more, and even more preferably 75% by mass or more, from the viewpoint of improving the yield of the separation step and the purity of the thermoplastic resin after separation, and is preferably 99% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less, from the viewpoint of ease of separation.

[0017] The polyamide resin in the present invention is a polymer compound having an amide bond, and is a polycondensation product of a carboxylic acid component and an amine component. A specific example of the polyamide resin is nylon 6.

[0018] The melt viscosity of the polyamide resin B1 used in the present invention at 240°C is preferably 140 mPa·s or more, more preferably 150 mPa·s or more, even more preferably 160 mPa·s or more, even more preferably 170 mPa·s or more, and even more preferably more than 180 mPa·s, and is preferably 500 mPa·s or less, more preferably 400 mPa·s or less, and even more preferably 350 mPa·s or less.

[0019] Resin B2 is a polyamide resin. When resin B2 is used in step 1, a preferred resin B2 is one in which the melt viscosity of a mixture of resin B2 and component C is higher than the melt viscosity of a mixture of resin B1 and component C, and a more preferred resin B2 is a resin with a number average molecular weight lower than that of resin B1. Here, unless otherwise specified in this specification, a mixture of resin B1 and component C is a mixture in which both components are equal in mass, and a mixture of resin B2 and component C is also a mixture in which both components are equal in mass.

[0020] In the present invention, "having a higher melt viscosity" means that the difference in melt viscosity (at the same temperature) between the compared resins is preferably 10 mPa s or more, more preferably 50 mPa s or more, even more preferably 100 mPa s or more, and even more preferably 150 mPa s or more. Here, the mixing ratio of component C in the mixture of resin B1 and component C, and the mixing ratio of component C in the mixture of resin B2 and component C, are both preferably 0.001 part by mass or more, more preferably 0.005 part by mass or more, even more preferably 0.01 part by mass or more, and preferably 0.25 part by mass or less, more preferably 0.11 part by mass or less, per part by mass of the mixture.

[0021] Resin B2 has a melt viscosity at 240°C of preferably 140 mPa·s or more, more preferably 150 mPa·s or more, even more preferably 160 mPa·s or more, even more preferably 170 mPa·s or more, and even more preferably more than 180 mPa·s, and the melt viscosity is preferably 500 mPa·s or less, more preferably 400 mPa·s or less, and even more preferably 350 mPa·s or less.

[0022] A preferred combination of Resin B1 and Resin B2 in the present invention is Examples of the combination include a combination in which Resin B1 is Nylon 6 1022B and Resin B2 is Nylon 6 1013B, a combination in which Resin B1 is Nylon 6 1022B and Resin B2 is Nylon 6 1013A, and a combination in which Resin B1 is Nylon 6 1022B and Resin B2 is Nylon 6 SF1018A.

[0023] Examples of the polyester resin P in the present invention include polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polybutylene naphthalate (PBN).

[0024] The melting point of resin P is preferably 200° C. or higher, more preferably 210° C. or higher, and even more preferably 220° C. or higher, from the viewpoint of the difference in melting point from resin A1, and is preferably 300° C. or lower, more preferably 290° C. or lower, and even more preferably 280° C. or lower, from the viewpoint of suppressing deterioration of the thermoplastic resin during the mixing step and filter treatment. When resin P is composed of two or more resins, it is preferable that each of the resins has the above melting point.

[0025] The content of resin P in the resin mixture to be subjected to filtration is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more from the viewpoint of easy separation, and is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 25% by mass or less from the viewpoint of improving the yield of the separation process and the purity of the thermoplastic resin after separation.

[0026] Component C in the present invention is a compound that increases the contact angle of resin A1 with a mixture of component C and resin P to be greater than the contact angle of resin A1 with resin P.

[0027] If the contact angle of resin A1 with resin P is CA1 and the contact angle of resin A1 with the mixture of component C and resin P is CA2, the greater the difference between CA1 and CA2, the greater the difference in interfacial tension and the greater the effect of coarsening the particles of resin P. From this perspective, the difference between CA1 and CA2 is preferably 1° or more, more preferably 3° or more, even more preferably 5° or more, and is preferably 30° or less, more preferably 28° or less, even more preferably 25° or less.

[0028] In this specification, the contact angle of resin A1 with resin P and the contact angle of resin A1 with a mixture of component C and resin P are measured by dropping resin A1 onto resin P molded into a sheet or onto a mixture of component C and resin P molded into a sheet. Specifically, the measurement is performed by the method described in the Examples below. The mixture of component C and resin P is a mixture in which the two components are uniformly mixed in a molten state and then solidified, and includes a mixture containing a reactant formed by partial reaction of the two components and a reactant formed by complete reaction of the two components.

[0029] Component C is preferably a compound having a functional group capable of reacting with resin P. Examples of such a functional group include an epoxy group, a carbodiimide group, an oxazoline group, and an acid anhydride group. Of these, from the viewpoint of separating resin P, an epoxy group or a carbodiimide group is preferred, and an epoxy group is more preferred.

[0030] As the compound having these functional groups, from the viewpoint of separating the resin P, a compound containing an epoxy group or a compound containing a carbodiimide group is preferred, a glycidyl methacrylate copolymer, a mono- or dicarbodiimide compound, or a polycarbodiimide compound is more preferred, a glycidyl methacrylate copolymer, a monocarbodiimide compound, or an aromatic polycarbodiimide compound is more preferred, and a glycidyl methacrylate copolymer is even more preferred.

[0031] Examples of compounds having an epoxy group include copolymers of glycidyl methacrylate such as poly(styrene-methyl methacrylate-glycidyl methacrylate) and poly(styrene-glycidyl methacrylate).

[0032] Compounds having such epoxy groups are commercially available, and examples thereof include JONCRYL (registered trademark) ADR4370S, JONCRYL ADR4368CS, JONCRYL ADR4368F, JONCRYL ADR4300S, and JONCRYL ADR4468 (all manufactured by BASF), and ARUFON (registered trademark) UG4035, ARUFON UG4040, and ARUFON UG4070 (all manufactured by Toagosei Co., Ltd.).

[0033] Examples of compounds having a carbodiimide group include diisopropylcarbodiimide, dioctyldecylcarbodiimide, dicyclohexylcarbodiimide, diphenylcarbodiimide, di-2,6-dimethylphenylcarbodiimide, di-2,6-diisopropylphenylcarbodiimide, N-toluyl-N'-phenylcarbodiimide, di-p-nitrophenylcarbodiimide, di-p-aminophenylcarbodiimide, di-p-hydroxyphenylcarbodiimide, di-p-chlorophenylcarbodiimide, di-p-methoxyphenylcarbodiimide, di-3,4-dichlorophenylcarbodiimide, di-2,5-dichlorophenylcarbodiimide, di-o-chlorophenylcarbodiimide, p-phenylene-bis-di-o-toluylcarbodiimide, p-phenylene-bis-dicyclohexylcarbodiimide, p-phenylene-bis mono- or dicarbodiimide compounds such as ethylene-bis-diphenylcarbodiimide, di-p-chlorophenylcarbodiimide, and ethylene-bis-diphenylcarbodiimide; and polycarbodiimide compounds such as poly(4,4'-diphenylmethanecarbodiimide), poly(3,5'-dimethyl-4,4'-biphenylmethanecarbodiimide), poly(p-phenylenecarbodiimide), poly(m-phenylenecarbodiimide), poly(3,5'-dimethyl-4,4'-diphenylmethanecarbodiimide), poly(naphthylenecarbodiimide), poly(1,3-diisopropylphenylenecarbodiimide), poly(1-methyl-3,5-diisopropylphenylenecarbodiimide), poly(1,3,5-triethylphenylenecarbodiimide), poly(triisopropylphenylenecarbodiimide), and poly(4,4'-dicyclohexylmethanecarbodiimide).

[0034] Component C is preferably a compound that has low compatibility with resin A1, and more preferably a compound that does not react with resin A1. For example, when resin A1 is a polyolefin resin, a compound that does not have a polyolefin chain is preferred.

[0035] When component C is a polymer compound, the weight average molecular weight is preferably 100 or more, more preferably 1000 or more, even more preferably 3000 or more, from the viewpoint of increasing the contact angle of resin A1 with the mixture of component C and resin P and efficiently separating resin P, and is preferably 100,000 or less, more preferably 20,000 or less, even more preferably 10,000 or less.

[0036] From the viewpoint of increasing the contact angle of resin A1A with the mixture of component C and resin P and efficiently separating resin P, the functional group equivalent weight of component C is preferably 10 g / mol or more, more preferably 100 g / mol or more, even more preferably 200 g / mol or more, and is preferably 5000 g / mol or less, more preferably 1000 g / mol or less, even more preferably 800 g / mol or less, even more preferably 600 g / mol or less, even more preferably 400 g / mol or less.

[0037] The preferred content of component C in the mixture to be subjected to filtering is as follows: The preferred content of component C in the mixture obtained in step 1 is preferably 0.1 mass% or more, more preferably 0.2 mass% or more, even more preferably 0.5 mass% or more, from the viewpoint of increasing the contact angle of resin A1 with the mixture of component C and resin P and efficiently separating resin P, and is preferably 10 mass% or less, more preferably 5 mass% or less, even more preferably 2 mass% or less.

[0038] The preferred content of component C in the mixture obtained in step 3 is preferably 0.1 mass% or more, more preferably 0.2 mass% or more, even more preferably 0.5 mass% or more, from the viewpoint of increasing the contact angle of resin A1 with the mixture of component C and resin P and efficiently separating resin P, and is preferably 10 mass% or less, more preferably 5 mass% or less, even more preferably 2 mass% or less.

[0039] The resin composition in step 1 or step 3 may contain resins other than resin A1, resin B1, and resin P, such as thermosetting resins, laminating agents, inorganic substances such as aluminum, alumina oxide, and silicon oxide, printing inks, pigments, and other components.

[0040] In step 1, the total content of resin A1, resin B1 and resin P in the resin composition is preferably 80 mass% or more, more preferably 90 mass% or more, even more preferably 95 mass% or more, even more preferably 98 mass% or more, and even more preferably 100 mass%. In step 3, the total content of resin A1 and resin P in the resin composition is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 100% by mass.

[0041] Other ingredients referred to here include plasticizers; nucleating agents; fillers (inorganic fillers, organic fillers); hydrolysis inhibitors; flame retardants; antioxidants; lubricants such as hydrocarbon waxes and anionic surfactants; UV absorbers; antistatic agents; anti-fogging agents; light stabilizers; pigments; mildew inhibitors; antibacterial agents; foaming agents; surfactants; polysaccharides such as starches, alginic acid, and cellulose fibers; natural proteins such as gelatin, glue, and casein; inorganic compounds such as tannins, zeolites, ceramics, and metal powders; fragrances; flow adjusters; leveling agents; conductive agents; UV dispersants; and deodorizers.

[0042] Specific examples of the resin composition of the present invention include used refill pouches, food retort pouches, detergent bottles, etc. These can be collected and appropriately washed, dried, crushed, etc., and then suitably used in step 1 or step 3.

[0043] [Mixing process] The mixing step in the present invention may be the following step 1 or step 3, depending on the components constituting the resin composition and the components constituting the additives. Step 1: A mixing step of mixing a resin composition containing a thermoplastic resin A1, a polyamide resin B1, and a polyester resin P with a thermoplastic resin A2 and a component C.

[0044] Step 3: A resin composition containing a thermoplastic resin A1 and a polyester resin P, (1) Mixing polyamide resin B2 and component C, or (2) Mixing thermoplastic resin A2, resin B2 and component C Mixing process.

[0045] The additives used in step 1 include those containing resin A2 and component C, and those containing polyamide resin B2 may also be used.

[0046] The additives in step 3 include: (1) comprising polyamide resin B2 and component C, or (2) Thermoplastic resin A2, resin B2, and component C Examples include:

[0047] In the mixing step, it is believed that mixing the resin composition with the additives shifts the equilibrium state of the polyamide resin B1 and the polyester resin P in the resin composition, or the polyester resin P in the resin composition, from dispersion to aggregation.

[0048] The content of Resin A1 in the resin composition in Step 1 is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, from the viewpoint of improving processability and subsequent separability. From the same viewpoint, it is preferably 100% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less.

[0049] The content of Resin A1 in the resin composition in Step 3 is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, from the viewpoint of improving processability and subsequent separability, and from the same viewpoint, is preferably 100% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less.

[0050] The content of component C in the additive in step 1 is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more, from the viewpoint of improving processability and subsequent separability. From the same viewpoint, it is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less.

[0051] The content of component C in the additive in step 3 is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more, from the viewpoint of improving processability and subsequent separability. From the same viewpoint, it is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less.

[0052] The mixing ratio of the resin composition and the additive in the mixing step is, from the viewpoint of improving separability, preferably 0.01 parts by mass or more of the resin composition per 1 part by mass of the additive, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more; on the other hand, from the same viewpoint, preferably 500 parts by mass or less of the resin composition per 1 part by mass of the additive, more preferably 350 parts by mass or less, and even more preferably 200 parts by mass or less.

[0053] The mixing (kneading) temperature in the mixing step is preferably a temperature at which all of the resins to be mixed melt, from the viewpoints of improving the yield of the separation step and the purity of the resins to be separated after separation. Preferably, the temperature ranges from the melting point of the resin with the lowest melting point in the resulting mixture to the melting point of the resin with the highest melting point in the resulting mixture. Specific examples of temperature conditions include preferably 110°C or higher, more preferably 120°C or higher, even more preferably 150°C or higher, even more preferably 180°C or higher, even more preferably 200°C or higher, even more preferably 210°C or higher, even more preferably 220°C or higher, even more preferably 230°C or higher, even more preferably 240°C or higher, even more preferably 250°C or higher, even more preferably 260°C or higher, even more preferably 270°C or higher, and preferably 350°C or lower, more preferably 340°C or lower, even more preferably 300°C or lower, even more preferably 290°C or lower, and even more preferably 280°C or lower.

[0054] The duration of the mixing step is not particularly limited, but from the viewpoint of improving the yield of the separation step and the purity of the resin to be separated after separation, the duration during which the resin composition is within the above-mentioned kneading temperature range is preferably 10 seconds or more, more preferably 30 seconds or more, even more preferably 50 seconds or more, and even more preferably 1 minute or more, and is preferably 5 minutes or less, more preferably 4 minutes or less.

[0055] In the mixing step, a continuous kneader such as a single-screw or twin-screw kneader or an open-roll type kneader can be used. Use of such a continuous kneader is preferred because it allows the mixing step and the separation step to be carried out as a series of steps.

[0056] After the mixing step, if the resin composition is at a temperature suitable for filtering, it may be subjected to filtering as is. Alternatively, after the mixing step (after kneading is stopped), the resin composition may be isothermally maintained and then cooled to a predetermined temperature before being subjected to filtering, or the set kneading temperature may be lowered midway, and the resin composition may be kneaded until the temperature drops to the predetermined temperature before being subjected to filtering. The former is preferred from the viewpoint of separating the resin to be separated with higher purity, and the latter is preferred from the viewpoint of work efficiency.

[0057] [Separation process] The separation step in the present invention differs depending on the mixing step. When the mixing step is step 1, step 2 is added, and when the mixing step is step 3, step 4 is added.

[0058] The separation step involves filtering. The filtration can be carried out, for example, by placing a filter between the kneader and the die, but can also be carried out continuously using an apparatus equipped with a filter screen changer. Examples of apparatuses equipped with a screen changer that can perform continuous treatment include a plate type using a metal mesh, a backflush type that performs backwashing, and a laser filter type that uses a flat or drum-shaped metal filter and a scraper.

[0059] The filter is selected appropriately depending on the particle size of resin B1 and resin P, with a mesh size large enough to prevent the passage of these. For example, from the viewpoint of separation efficiency, the mesh size is preferably 80 μm or larger, more preferably 100 μm or larger. From the viewpoint of the purity of the thermoplastic resin obtained by passing through the filter, the mesh size is preferably 1000 μm or smaller, more preferably 600 μm or smaller. By such a filtering process, the resin to be separated does not pass through the filter and remains, while the thermoplastic resin passes through the filter, so that the resin to be separated can be separated from the mixture.

[0060] In the case of Step 2, the preferred lower limit temperature for the temperature range during the filtering process is the melting point of Resin A1. Meanwhile, the preferred upper limit temperature is "the melting point of the mixture of Resin P, Resin B1, and Component C," where the melting point of the mixture of these three components is the lowest melting point among the three. Furthermore, the more preferred upper limit temperature for the filtering process in this case is "the lowest melting point of Resin P and Resin B1."

[0061] When resin A2, polyamide resin B2, and component C are used as additives in step 1, the lower limit of the temperature range for the filtering process in step 2 is the melting point of resin A1, and the upper limit is the melting point of the four-component mixture of resin P, resin B1, resin B2, and component C. Furthermore, a more preferred upper limit of the temperature for the filtering process in this case is the lowest of the melting points of resin P, resin B1, and resin B2.

[0062] From the viewpoint of improving productivity and separability, the lower limit temperature is preferably the melting point of resin A1 + 10°C or more, more preferably the melting point of resin A1 + 20°C or more, and even more preferably the melting point of resin A1 + 30°C or more.

[0063] With regard to the upper limit temperature, from the viewpoint of improving productivity and separability, it is preferably the melting point of the mixture −10° C. or less, more preferably the melting point of the mixture −20° C. or less, and even more preferably the melting point of the mixture −30° C. or less.

[0064] Specific examples of temperature conditions are preferably 130°C or higher, more preferably 140°C or higher, and even more preferably 150°C or higher, and preferably 245°C or lower, more preferably 235°C or lower, and more preferably 225°C or lower.

[0065] The lower limit of the temperature range during the filtering process in step 4 is the melting point of resin A1, and the upper limit is the melting point of the mixture of resin P, resin B2, and component C. Furthermore, a more preferable upper limit of the temperature during the filtering process in this case is the lowest melting point of resin P and resin B2.

[0066] From the viewpoint of improving productivity and separability, the lower limit temperature is preferably the melting point of resin A1 + 10°C or more, more preferably the melting point of resin A1 + 20°C or more, and even more preferably the melting point of resin A1 + 30°C or more.

[0067] With regard to the upper limit temperature, from the viewpoint of improving productivity and separability, it is preferably the melting point of the mixture −10° C. or less, more preferably the melting point of the mixture −20° C. or less, and even more preferably the melting point of the mixture −30° C. or less.

[0068] Specific examples of temperature conditions are preferably 130°C or higher, more preferably 140°C or higher, and even more preferably 150°C or higher, and preferably 245°C or lower, more preferably 235°C or lower, and more preferably 225°C or lower.

[0069] The separation method of the present invention allows efficient separation of polyamide resins and polyester resins from resin compositions. Meanwhile, the resin components that pass through the filter contain highly purified thermoplastic resins, so that the thermoplastic resins, polyamide resins, and / or polyester resins can be reused by appropriately molding the resin components according to the purpose and application using known methods. Examples of molded products include films, sheets, fibers, filaments, and injection-molded products.

[0070] The content of the thermoplastic resin in the resin component that has passed through the filter is, for example, 85% by mass or more, for example, 92% by mass or more, for example, 95% by mass or more.

[0071] It should be noted that a certain degree of separation effect can be achieved even if the resin composition in step 1 does not contain the polyester resin P. An example of this embodiment is the following method. Step 1': mixing a resin composition containing resin A1 and polyamide resin B1 with resin A2 and component C; and Step 2: A step of filtering the mixture obtained in Step 1' at a temperature range equal to or higher than the melting point of Resin A1 and equal to or lower than the melting point of the mixture of Resin B1 and Component C to separate Resin B1 from the mixture obtained in Step 1. A method for separating resin B1 from a resin composition containing resin A1 and resin B1, comprising: Resin A1 is a thermoplastic resin having a lower melting point than Resin B1, Resin A2 is a thermoplastic resin having a melt viscosity higher than that of Resin A1, Component C is a compound that increases the contact angle of resin A1 with a mixture of component C and resin B1 compared to the contact angle of resin A1 with resin B1. Method for isolating resin B1. [Example]

[0072] The present invention will be specifically described below with reference to examples. Note that these examples are merely illustrative of the present invention and are not intended to limit the scope of the invention in any way. Unless otherwise specified, "parts" in the examples are parts by mass, and "%" is mass%. The physical properties of resins and the like were measured by the following methods.

[0073] [Melting points of various resins, etc.] Using a differential scanning calorimeter (PerkinElmer, DSC8500), 10 mg of sample is weighed into a standard aluminum pan and heated from 25°C to 280°C at a rate of 15°C / min, with the peak top of the endothermic peak being taken as the melting point.

[0074] [Crystallization temperature of various resins, etc.] Using a differential scanning calorimeter (DSC8500, manufactured by PerkinElmer), 10 mg of sample is weighed into a standard aluminum pan and cooled from 280°C to 15°C at a rate of 15°C / min. The peak top of the exothermic peak is taken as the crystallization temperature.

[0075] [Contact angle] (1) Contact angle 1: Contact angle of thermoplastic resin to polyester resin The thermoplastic resin to be measured is dropped onto a polyester resin formed into a sheet, and the contact angle of the thermoplastic resin with the polyester resin is measured as follows. The polyester resin and the thermoplastic resin are the same as those used in the examples.

[0076] (a) Sheet preparation 20 g of dry polyester resin was sandwiched between a 200 mm x 200 mm x 0.4 mm metal spacer and a metal plate in a press molding machine (manufactured by Toyo Seiki Seisakusho Co., Ltd.), heated to 270°C in an autopress, and melt-compressed at 0.5 MPa for 2 minutes, then at 20 MPa for 2 minutes. It was then immediately transferred to a hand press and held at 20 MPa and 150°C for 10 minutes to crystallize. After crystallization, it was cooled at 15°C and 0.5 MPa for 1 minute and molded into a sheet. (b) Contact angle measurement The thermoplastic resin to be measured is dropped onto the obtained sheet in a chamber set at 230°C, and the contact angle is photographed using a shell-equipped temperature variable contact angle meter (KYOWA, DMC-3). The contact angle after contact with the droplet is measured at measurement intervals of 1 minute, and the point at which the contact angle reaches equilibrium is the endpoint. The contact angle is determined from the photographed image using the θ / 2 method. The measurement is performed twice, and the average value is calculated.

[0077] (2) Contact angle 2: Contact angle of thermoplastic resin to a mixture of component C and polyester resin The polyester resin (PET) and component C shown in the table below were mixed in the mass ratio shown in the table below, and the mixture was melt-kneaded using a twin-screw kneader (manufactured by The Japan Steel Works, Ltd., TEX28V (screw diameter 28 mm, L / D = 42)) at a discharge rate of 1.5 kg / h, a rotation speed of 70 r / min, and 270°C, and then allowed to cool to obtain a mixture of component C and polyester resin. Using the obtained mixture, a sheet of the mixture is prepared in the same manner as in Contact Angle 1 above, and the contact angle of the thermoplastic resin with respect to the mixture of Component C and polyester resin is measured.

[0078] (3) Contact angle 3: Contact angle of thermoplastic resin to polyamide resin The thermoplastic resin to be measured is dropped onto a polyamide resin formed into a sheet, and the contact angle of the thermoplastic resin with the polyamide resin is measured. (a) Sheet preparation 20 g of dry polyamide resin was sandwiched between a 200 mm x 200 mm x 0.4 mm metal spacer and a metal plate in a press molding machine (manufactured by Toyo Seiki Seisakusho Co., Ltd.), heated to 240°C in an autopress, and melt-compressed at 0.5 MPa for 2 minutes, then at 20 MPa for 2 minutes. It was then immediately transferred to a hand press and held at 20 MPa and 80°C for 2 minutes to crystallize. After crystallization, it was cooled at 15°C and 0.5 MPa for 1 minute and molded into a sheet. (b) Contact angle measurement Using the obtained sheet, the contact angle of the thermoplastic resin to the polyamide resin is measured in the same manner as in the contact angle 1 above.

[0079] (4) Contact angle 4: Contact angle of thermoplastic resin to a mixture of component C and polyamide resin The polyamide resin (Ny6) and component C shown in Table 6 are mixed in the mass ratio shown in Table 6, and a mixture of the polyamide resin and component C is obtained in the same manner as in the case of contact angle 2 above. Using the obtained mixture, a sheet of the mixture is prepared in the same manner as in Contact angle 3 above, and the contact angle of the thermoplastic resin with respect to the mixture of component C and polyamide resin is measured.

[0080] [Melt Viscosity] Using a capillary rheometer (Toyo Seiki Seisakusho, Capillograph 1D PMD-C1) and a capillary with a length of 10 mm and a diameter of 1 mm, the rheometer was operated at a rate of 10 mm / min (1.22E+02 s -1 The melt viscosity is measured at a shear rate of 1 / 3000 of the melt viscosity at 230°C for resins A1 and A2, 240°C for resins B1, B2 and their mixtures with component C, and 270°C for resin P. In the case of a mixture of two or more resin components, the melt viscosity of the mixture is used.

[0081] [Evaluation of filter processing] The purity and purity increase rate of the thermoplastic resin after the filter treatment are measured by the following method.

[0082] [Purity of thermoplastic resin after filtering] The solid matter that passed through the filter was immersed in hexafluoro-2-propanol at room temperature for 1 hour to elute the components that dissolve in this solvent. The purity of the thermoplastic resin after filtering was calculated from the change in mass before and after this elution process using the following formula. The "thermoplastic resin" here refers to the "total of both Resin A1 and Resin A2." Purity after filtration (%) = Mass of solids after elution (g) / Mass of solids before elution (g) × 100

[0083] [Purity increase rate] The purity increase rate of the thermoplastic resin is calculated using the following formula: Here, "thermoplastic resin" refers to "the total of both resin A1 and resin A2." Increase in purity (%)=[Purity of thermoplastic resin after filtering (%)−Purity of thermoplastic resin in resin composition immediately before being supplied to step 1 (%)] / [Purity of thermoplastic resin in resin composition after filtering (%)]×100 Here, the "purity of the thermoplastic resin in the resin composition immediately before being supplied to step 1" can be measured by the same method as the above-mentioned "purity of the thermoplastic resin after filtering." Alternatively, when the composition of the thermoplastic resin in the resin composition is known, the value calculated from the content may be used as the purity.

[0084] Example 1 (combination of step 1 and step 2) [Mixing process] Taking into account the collected refill pouches, a resin composition was prepared with the composition shown in Table 1. Specifically, 40 parts by mass of polyethylene (20201J) as resin A1, 9.7 parts by mass of nylon 6 (1022B) as resin B1, and 9.7 parts by mass of polyethylene terephthalate (MA-2103) as resin P were mixed together to prepare a resin composition. To this resin composition, 40 parts by mass of polyethylene (2006H) of resin A2 shown in Table 1 and 0.6 parts by mass of component C (ADR 4468) were added as additives and mixed.

[0085] The mixture was then fed into a twin-screw extruder (TEX28V (screw diameter 28 mm, L / D = 42) manufactured by The Japan Steel Works, Ltd.). A die was installed at the discharge section of this twin-screw extruder, and a metal mesh with 80 mesh openings was further installed as a filter between the discharge section and the die. For reinforcement, three metal meshes of 60 mesh / 80 mesh / 60 mesh were installed in a stacked order.

[0086] The temperature settings of the twin-screw kneader were as follows: If the total length of the kneading section of the twin-screw kneader is L, the set temperature from the upstream of the twin-screw kneader to the first half end (i.e., a point 1 / 2L long from the upstream of the twin-screw kneader) was 270°C, the set temperature from the first half end to the middle end of the twin-screw kneader (i.e., a point 2 / 3L long from the upstream of the twin-screw kneader) was 220°C, and the set temperature from the middle end to the discharge section was 190°C. That is, the temperature in step 1 was 270°C to 190°C, and the temperature during the filtering process was 190°C. The twin-screw kneader was operated at a discharge rate of 1.5 kg / h and a rotation speed of 70 r / min to melt and knead the mixture. The residence time of the mixture in the twin-screw kneader was 480 seconds.

[0087] [Separation process] The mixture was fed and the twin-screw kneader was operated, followed by filtration. In the following Examples, Comparative Examples, and Reference Examples, if the metal mesh became clogged and the resin pressure in the kneader exceeded 5 MPa before 2 minutes had elapsed since the start of the separation process, the filter process was stopped at that point, and the resin composition separated from the start of separation until the end of separation and the components that could not pass through the filter were evaluated. On the other hand, if clogging did not occur within 2 minutes after the start of the separation process and the resin pressure inside the kneader did not exceed 5 MPa, the components that could not pass through the resin composition filter separated from the start of separation until 2 minutes after the start of separation were evaluated. When the components that could not pass through the filter in Example 1 were confirmed, they were found to be Resin B1 and Resin P. In this way, Resin B1 and Resin P could be separated from the resin composition containing Resin A1, Resin B1, and Resin P.

[0088] Examples 2 to 11 (combination of step 1 and step 2), Reference Example 1 and Comparative Examples 1 to 11 [Mixing process] Resin compositions were prepared based on the collected refill pouches, with the compositions shown in Tables 1, 2, and 3. The components shown in Tables 1, 2, and 3 were added as additives to these resin compositions and mixed.

[0089] Next, the settings of the twin-screw kneader were set to the same as in Example 1, and the mixture was melt-kneaded.

[0090] [Separation process] The mixture was fed and the twin-screw kneader was operated, followed by filtration.

[0091] The composition, processing conditions, and evaluation results are shown in the table below. Note that the amounts of each component are rounded off before being listed in the tables, so the total of the compositions in each table may not add up to 100% by mass.

[0092] Furthermore, in each table: "Melting point* of the mixture" means the melting point of the mixture of resin P, resin B1 and component C, the melting point of the mixture of resin P, resin B1, resin B2 and component C, or Melting point of the mixture of resin P, resin B2 and component C In each table, the melting point of resin P, which has the highest melting point in each mixture, is listed.

[0093] Furthermore, in each table, "difference in contact angle**" means The difference between the contact angle of resin A1 with the mixture of component C and resin P and the contact angle of resin A1 with resin P, or The difference between the contact angle of resin A1 to the mixture of component C and resin B1 and the contact angle of resin A1 to resin B1 Therefore, if the value of "contact angle difference**" is a positive number, it means that the component corresponds to component C.

[0094] [Table 1-A]

[0095] [Table 1-B]

[0096] [Table 2]

[0097] [Table 3-A]

[0098] [Table 3-B]

[0099] [Table 3-C]

[0100] In each example, the components that could not pass through the filter were identified as resin B1 and resin P, and in Reference Example 1, the components that could not pass through the filter were identified as resin P. In this way, resin B1 and resin P could be separated from the resin composition containing resin A1, resin B1, and resin P, and resin P could be separated from the resin composition containing resin A1 and resin P. Furthermore, it was found that the separation method including steps 1 and 2 of the present invention improved the purity of the thermoplastic resin in the resin that passed through the filter.

[0101] Example 18 (Combination of Steps 3 and 4) [Mixing process] Resin compositions were prepared for the collected refill pouches, as shown in Table 4. Specifically, 80 parts by mass of polyethylene (SP0510) as resin A1 and 9.7 parts by mass of polyethylene terephthalate (MA-2103) as resin P were mixed together to prepare the resin composition. To this resin composition, 9.5 parts by mass of resin B2 (nylon 6, 1013B) and 0.8 parts by mass of component C (ADR 4468) shown in Table 4 were added as additives and mixed.

[0102] Next, the settings of the twin-screw kneader were set to the same as in Example 1, and the mixture was melt-kneaded.

[0103] [Separation process] The mixture was fed and the twin-screw kneader was operated, followed by filtration. In Example 18, the components that could not pass through the filter were identified as resin B2 and resin P. In this way, resin P could be separated from the resin composition containing resin A1 and resin P.

[0104] Examples 13 to 17 (combination of step 3 and step 4), 19 to 21 and Comparative Examples 12 to 14 [Mixing process] Resin compositions were prepared with the compositions shown in Tables 4 and 5, assuming the use of collected refill pouches. Each of the components shown in Tables 4 and 5 was added as an additive to this resin composition and mixed.

[0105] Next, the settings of the twin-screw kneader were set to the same as in Example 1, and the mixture was melt-kneaded.

[0106] [Separation process] The mixture was fed and the twin-screw kneader was operated, followed by filtration.

[0107] [Table 4-A]

[0108] [Table 4-B]

[0109] [Table 5]

[0110] In each example, the components that could not pass through the filter were confirmed to be Resin B2 and Resin P. In this way, Resin P could be separated from the resin composition containing Resin A1 and Resin P. Furthermore, it was found that the separation method including steps 3 and 4 of the present invention improved the purity of polyethylene in the resin that passed through the filter.

[0111] Reference Example 2 (Combination of Step 1' and Step 2) [Mixing process] Resin compositions were prepared for the collected refill pouches, as shown in Table 6. Specifically, 72 parts by mass of polyethylene (SP0510) as resin A1 and 9.7 parts by mass of nylon 6 (1022B) as resin B1 were mixed together to prepare the resin composition. To this resin composition, 18 parts by mass of resin A2 (polyethylene, 2006H) and 0.3 parts by mass of component C (ADR 4468) shown in Table 6 were added as additives and mixed.

[0112] Next, the settings of the twin-screw kneader were set to the same as in Example 1, and the mixture was melt-kneaded.

[0113] [Separation process] The mixture was fed and the twin-screw kneader was operated, followed by filtration. In Example 22, the component that could not pass through the filter was identified as resin B1. In this way, resin B1 could be separated from the resin composition containing resin A1 and resin B1.

[0114] Comparative Example 15 [Mixing process] A resin composition was prepared by mixing 90 parts by mass of polyethylene (SP0510) as resin A1 and 9.7 parts by mass of nylon 6 (1022B) as resin B1.

[0115] Next, the resin composition was melt-kneaded using the same settings as in Example 1 on the twin-screw kneader without adding any additives.

[0116] [Separation process] The mixture was fed and the twin-screw kneader was operated, followed by filtration.

[0117] [Table 6]

[0118] The component that could not pass through the filter in Reference Example 2 was identified and found to be Resin B1. In this way, Resin B1 was separated from the resin composition containing Resin A1 and Resin B1. Furthermore, it was found that the separation method including steps 1' and 2 improved the purity of polyethylene in the resin that passed through the filter.

[0119] Details of the various components used in the examples are as follows: Resin A1 20201J: LLDPE Neo-Zex 20201J, polyethylene manufactured by Prime Polymer, melting point: 111°C, melt viscosity: 214 Pa·s SP2020: LLDPE Evolue SP2020 polyethylene manufactured by Prime Polymer, melting point: 112°C, melt viscosity: 884 Pa·s SP0510: LLDPE Evolue SP0510 polyethylene manufactured by Prime Polymer, melting point: 120°C, melt viscosity: 601 Pa·s 2110JH: HDPE Hizex 2110JH, polyethylene manufactured by Prime Polymer Co., Ltd., melting point: 129°C, melt viscosity: 68 Pa·s F113G: Polypropylene manufactured by Prime Polymer, PP F113G, melting point: 163°C, melt viscosity: 421 Pa·s F-730NV: Polypropylene manufactured by Prime Polymer, PP F-730NV, melting point: 140°C, melt viscosity: 200 Pa·s

[0120] Resin A2 2006H: LLDPE Neo-Zex 2006H, polyethylene manufactured by Prime Polymer Co., Ltd., melting point: 115°C, melt viscosity: 1055 Pa·s SP4020: LLDPE Evolue SP4020 polyethylene manufactured by Prime Polymer, melting point: 120°C, melt viscosity: 1042 Pa·s E111G: Polypropylene manufactured by Prime Polymer, PP E111G, melting point: 162°C, melt viscosity: 982 Pa·s E222: Polypropylene manufactured by Prime Polymer, PP E222, melting point: 146°C, melt viscosity: 586 Pa·s

[0121] Resin B1 1022B: Nylon 6 manufactured by Ube Industries, Ny6 1022B, melting point: 225°C, melt viscosity: 1150 Pa·s, melt viscosity in mixture with component C: 4579 Pa·s

[0122] Resin B2 1013B: Nylon 6 manufactured by Ube Industries, Ny6 1013B, melting point: 225°C, melt viscosity: 281 Pa·s, melt viscosity in mixture with component C: 4827 Pa·s 1013A: Nylon 6 manufactured by Ube Industries, Ny6 1013A, melting point: 225°C, melt viscosity: 220 Pa·s, melt viscosity in mixture with component C: 8284 Pa·s SF1018A: Nylon 6 manufactured by Ube Industries, Ny6 SF1018A, melting point: 225°C, melt viscosity: 663 Pa·s, melt viscosity in mixture with component C: 5683 Pa·s

[0123] Component C ADR4468: Chain extender manufactured by BASF, Joncryl ADR4468

[0124] Resin P MA-2103: Unitika polyethylene terephthalate, PET MA-2103, melting point: 255°C, melt viscosity: 112 Pa·s [Industrial Applicability]

[0125] The method of the present invention can separate and remove resins other than thermoplastic resins from packaging materials such as bottle containers and refill pouches used in various fields, including daily necessities such as shampoos, detergents, and cosmetics, and foods, and therefore the method of the present invention can be suitably used in the field of recycling thermoplastic resins.

Claims

1. Step 1: A mixing step of mixing a resin composition containing a thermoplastic resin A1, a polyamide resin B1, and a polyester resin P with a thermoplastic resin A2 and a component C; and Step 2: A separation step in which the mixture obtained in Step 1 is filtered at a temperature range of not less than the melting point of Resin A1 and not more than the melting point of the mixture of Resin P, Resin B1, and Component C to separate Resin B1 and Resin P from the mixture obtained in Step 1. A method for separating resin B1 and resin P from a resin composition containing resin A1, resin B1, and resin P, comprising: Resin A2 is a resin having a melt viscosity higher than that of Resin A1, Component C is a compound that increases the contact angle of resin A1 with a mixture of component C and resin P to be greater than the contact angle of resin A1 with resin P. A method for separating resin B1 and resin P.

2. Step 1 is a step of mixing a resin composition containing resin A1, resin B1, and resin P with resin A2, polyamide resin B2, and component C, Step 2 is a step of filtering the mixture obtained in Step 1 at a temperature range equal to or higher than the melting point of Resin A1 and equal to or lower than the melting point of the mixture of Resin P, Resin B1, Resin B2, and Component C, thereby separating Resin B1, Resin B2, and Resin P from the mixture obtained in Step 1; Resin B2 is a resin whose melt viscosity when mixed with component C is higher than the melt viscosity when mixed with resin B1 and component C.

2. The method for separating resin B1 and resin P according to claim 1.

3. Step 3: A resin composition containing a thermoplastic resin A1 and a polyester resin P, (1) Mixing polyamide resin B2 and component C, or (2) Mix thermoplastic resin A2, resin B2, and component C. a mixing step, and Step 4: A separation step in which the mixture obtained in Step 3 is filtered at a temperature range of not less than the melting point of Resin A1 and not more than the melting point of the mixture of Resin P, Resin B2, and Component C, to separate Resin B2 and Resin P from the mixture obtained in Step 3. A method for separating resin P from a resin composition containing resin A1 and resin P, comprising: Resin A2 is a resin having a melt viscosity higher than that of Resin A1, Component C is a compound that increases the contact angle of resin A1 with a mixture of component C and resin P to be greater than the contact angle of resin A1 with resin P. A method for separating resin P.

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