Recycled resin composition, recycled resin molded body, method for producing recycled resin composition, and method for producing recycled resin molded body

Abstract

This recycled resin composition contains a first recycled resin having a melting point of not more than 200°C, a second recycled resin having a melting point of more than 200°C, and a reactive compatibilizer. The mass ratio of the first recycled resin to the second recycled resin is 75:25 to 99:1. The content of the reactive compatibilizer is 0.1-10.0 mass% with respect to the total mass of the recycled resin composition.

Description

Recycled resin composition, recycled resin molded body, method for producing recycled resin composition, and method for producing recycled resin molded body

[0001] The present invention relates to a recycled resin composition, a recycled resin molded body, a method for producing a recycled resin composition, and a method for producing a recycled resin molded body.

[0002] In recent years, in view of environmental problems and the like, interest in resource recycling (reuse) has been increasing. Such resources include resin waste materials and the like.

[0003] Resin waste materials are a mixture of various resins, but it is very difficult to separate and reuse each resin from such resin waste materials. Therefore, it has been considered to use resin waste materials having various resins as recycled resins as they are.

[0004] Patent Document 1 discloses a specific graft polymer obtained by polymerizing an aromatic vinyl and an unsaturated nitrile in the presence of a hydrogenated isoprene copolymer as a compatibilizer used when recycling a styrene-based resin and an olefin-based resin. It is described that when such a compatibilizer is used, the decrease in the impact strength of the recycled product is improved.

[0005] Japanese Patent Application Laid-Open No. 2002-294017

[0006] However, according to the findings of the present inventors, when a compatibilizer as described in Patent Document 1 is used, the molded body obtained from such a resin still has unsatisfactory mechanical strengths such as tensile strength.

[0007] Furthermore, recycled resins contain foreign matter due to the attachment of dirt and other substances. When recycled resin compositions containing such recycled resins are used for molding at high temperatures, problems can arise such as the progression of phase separation between the foreign matter and the resin, the formation of defects at the interface between the foreign matter and the resin, resulting in unstable molding, accelerated degradation of the resin by the foreign matter, or bleeding out onto the surface of the molded product, making it difficult to obtain a molded product of good quality. For this reason, it is desirable that such recycled resin compositions be molded at relatively low temperatures (for example, below 200°C). However, as described in Patent Document 1, recycled resin compositions containing high-melting-point resins (styrene-based resins) present the challenge of difficulty in molding at low temperatures.

[0008] This invention has been made in view of the above circumstances, and aims to provide a recycled resin composition, a recycled resin molded article, a method for producing a recycled resin composition, and a method for producing a recycled resin molded article that have good mechanical strength and excellent moldability at low temperatures.

[0009] One aspect of the present invention relates to the recycled resin compositions described in [1] to [5] below.

[0010] [1] A recycled resin composition comprising: a first recycled resin having a melting point of 200°C or less; a second recycled resin having a melting point exceeding 200°C; and a reactive compatibilizer, wherein the mass ratio of the first recycled resin to the second recycled resin is 75:25 to 99:1, and the content of the reactive compatibilizer is 0.1% by mass or more and 10.0% by mass or less with respect to the total mass of the recycled resin composition.

[0011] [2] The recycled resin composition according to [1], wherein the first recycled resin comprises a polyethylene resin and / or a polypropylene resin, and the second recycled resin comprises a polyester resin and / or a polystyrene resin.

[0012] [3] The recycled resin composition according to [1] or [2], wherein the reactive compatibilizer comprises an ethylene / glycidyl (meth)acrylate copolymer.

[0013] [4] The recycled resin composition according to any one of [1] to [3], wherein the content ratio of structural units derived from glycidyl (meth)acrylate to the total mass of the reactive compatibilizer is 5% by mass or more and 13% by mass or less.

[0014] [5] The recycled resin composition according to any one of [1] to [4], wherein the content ratio of structural units derived from glycidyl (meth)acrylate to the total mass of the reactive compatibilizer is 5% by mass or more and 7% by mass or less.

[0015] One aspect of the present invention relates to recycled resin molded articles as described in [6] to [7] below.

[0016] [6] A recycled resin molded article comprising the recycled resin composition described in any of [1] to [5].

[0017] [7] A recycled resin molded article according to [6], which is in the form of a film with a thickness of 100 μm or less.

[0018] One aspect of the present invention relates to a method for producing the recycled resin composition described in [8] below.

[0019] [8] A method for producing a recycled resin composition, comprising the steps of: preparing a recycled resin mixture containing a first recycled resin having a melting point of 200°C or less and a second recycled resin having a melting point of over 200°C; and melt-kneading the recycled resin mixture and a reactive compatibilizer, wherein the mass ratio of the first recycled resin to the second recycled resin is 75:25 to 99:1, and the content of the reactive compatibilizer is 0.1% by mass or more and 10.0% by mass or less with respect to the total mass of the recycled resin composition.

[0020] One aspect of the present invention relates to a method for manufacturing a recycled resin molded article as described in [9] below.

[0021] [9] A method for manufacturing a recycled resin molded article, comprising melting and molding a recycled resin composition described in any of [1] to [5], wherein the melting temperature when melting and molding is 200°C or less.

[0022] According to the present invention, it is possible to provide a recycled resin composition having good mechanical strength and excellent moldability at low temperatures, a recycled resin molded article, a method for producing a recycled resin composition, and a method for producing a recycled resin molded article.

[0023] One embodiment of the present invention will be described in detail below. However, the present invention is not limited to this embodiment. Furthermore, in this specification, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower limit and upper limit.

[0024] 1. Recycled Resin Composition The recycled resin composition according to this embodiment comprises: a first recycled resin having a melting point of 200°C or less; a second recycled resin having a melting point exceeding 200°C; and a reactive compatibilizer, wherein the mass ratio of the first recycled resin to the second recycled resin is 75:25 to 99:1, and the content of the reactive compatibilizer is 0.1% by mass or more and 10.0% by mass or less with respect to the total mass of the recycled resin composition.

[0025] Such recycled resin compositions possess good mechanical strength and excellent moldability at low temperatures. The reason for this is not entirely clear, but it is thought to be as follows.

[0026] As mentioned above, it is extremely difficult to completely separate and reuse each resin from resin waste. When resin waste is used as recycled resin, it generally contains both a first recycled resin with a melting point of 200°C or less and a second recycled resin with a melting point of over 200°C. However, the first and second recycled resins often have low compatibility, and phase separation is likely to occur between them, leading to defects at the interface between each recycled resin. As a result, the mechanical strength of such resin mixtures tends to decrease.

[0027] Furthermore, in the process of manufacturing the molded product, the physical properties of the first recycled resin and the second recycled resin differ when heated. Generally, the physical properties of resins change significantly depending on whether the temperature is above or below the melting point. When melt molding is performed at relatively low temperatures (for example, below 200°C), the molding temperature is often set to a temperature above the melting point of the first recycled resin and below the melting point of the second recycled resin. As a result, the difference in physical properties (e.g., elastic modulus, elongation at break) between the first recycled resin and the second recycled resin at the molding temperature becomes significantly large. Consequently, when stress is applied during the molding process, for example, when the product is stretched in the winding direction during transport, stress tends to concentrate near the interface between the different resins, leading to defects such as holes in the molded product and a deterioration in moldability.

[0028] Recycled resins may have carboxyl groups or other reactive groups due to oxidative degradation, for example. Furthermore, depending on the type of resin (e.g., polyester resin, polyamide resin), they may contain reactive groups such as carboxyl groups, amino groups, and hydroxyl groups. Therefore, if a predetermined amount of reactive compatibilizer is used, for example, if the reactive compatibilizer is a copolymer having a block that reacts with at least one of the first recycled resin and the second recycled resin, and a block that has high affinity with the other block, the reactive compatibilizer can contribute to improving the compatibility between the first recycled resin and the second recycled resin. Also, for example, if the reactive compatibilizer is a compound having multiple reactive groups, crosslinking the resins together can reduce the mobility of each resin at the molding temperature, suppressing the progression of aggregation between the resins and making phase separation less likely. In addition, by adjusting the ratio of the first recycled resin and the second recycled resin to a predetermined ratio, the reactive compatibilizer can act effectively, making it less likely for defects to occur at the interface between the different resins, resulting in a significant increase in mechanical strength.

[0029] Similarly, by adjusting the ratio to a predetermined level so that the proportion of the second recycled resin does not become too high, and by using a predetermined proportion of reactive compatibilizer, it is possible to appropriately adjust the viscosity of the composition at the molding temperature and improve the uniformity of the composition's physical properties. Therefore, it is thought that the moldability when molding at relatively low temperatures will be improved.

[0030] 1-1. First recycled resin with a melting point of 200°C or less The first recycled resin is not particularly limited as long as it is a resin with a melting point of 200°C or less, and may be a single type of resin or a combination of two or more types of resins.

[0031] The melting point of the resin in this application is the value measured in accordance with JIS K 7122:2012.

[0032] Examples of recycled resins include: polyolefin resins such as polyethylene resins and polypropylene resins; functional group-containing polyolefin resins such as ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-alkyl acrylate copolymer, ethylene-alkyl methacrylate copolymer, maleic acid-modified polyethylene, and maleic acid-modified polypropylene; thermoplastic polyester resins such as polybutylene succinate and polylactic acid aliphatic polyester resins; and polyvinyl chloride resins such as polyvinyl chloride and polyvinylidene chloride.

[0033] Among these, the first recycled resin preferably contains a polyolefin resin, more preferably a polyethylene resin and / or a polypropylene resin, and even more preferably a polyethylene resin. Using such a resin makes it easier to improve the processability at low temperatures, and when made into a film, it is easier to obtain good flexibility and mechanical strength.

[0034] Polyolefin resins are resins whose main component is olefin-derived structural units. In this application, a polyolefin resin is a resin in which the amount of olefin-derived structural units relative to the total structural units constituting the polyolefin resin is 50% by mass or more. A polyolefin resin may be a homopolymer of one olefin, a copolymer of two or more olefins, or a copolymer of one or more olefins and one or more other monomers (monomers other than olefins). The amount of olefin-derived structural units in the polyolefin resin is preferably 75% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more.

[0035] Examples of olefins include ethylene and α-olefins having 3 to 10 carbon atoms. Specific examples of olefins include ethylene, propylene, 1-butene, isobutylene, 1-pentene, 3-methyl-1-butene, 1-hexene, 3,4-dimethyl-1-butene, 1-heptene, 3-methyl-1-hexene, and 1-octene. Polyolefin resins may contain only one of these constituent units, or two or more.

[0036] Other examples of monomers used in polyolefin resins include diene monomers such as 1,4-hexadiene, 1,6-octadiene, 5-methyl-1,4-hexadiene, 3,7-dimethyl-1,6-octadiene, dicyclopentadiene (DCPD), ethylidene norbornene (ENB), norbornadiene, and 5-vinyl-2-norbornene; acid (or acid anhydride) modified olefins such as maleic anhydride modified olefins; and (meth)acrylates such as methyl (meth)acrylate. Polyolefin resins may contain only one of these constituent units, or two or more.

[0037] In this specification, "polypropylene resin" refers to a resin having 50% by mass or more of propylene-derived structural units, and includes propylene homopolymers and copolymers of propylene and other monomers (propylene copolymers). Propylene homopolymers include isotactic, syndiotactic, atactic, hemiisotactic, and linear or branched polypropylenes exhibiting various stereoregularities. Note that the stereoregularity of propylene is １３ It can be identified by C-NMR, etc. Furthermore, the propylene copolymer may be a random copolymer or a block copolymer. Furthermore, the propylene copolymer may be a binary copolymer of propylene and other monomers, or a polypolymer of propylene and two or more other monomers. Examples of preferred copolymer components (other monomers) include ethylene, α-olefins with 4 or more carbon atoms, tetrafluoroethylene, vinyl acetate, etc. In this embodiment, the polypropylene resin is preferably a propylene homopolymer or a propylene copolymer in which the constituent units derived from other monomers are less than 5% by mass.

[0038] In this specification, "polyethylene resin" refers to a resin having 50% by mass or more of ethylene-derived structural units, and includes ethylene homopolymers and copolymers of ethylene and other monomers (ethylene copolymers). Examples of ethylene homopolymers include high-density polyethylene (HDPE), low-density polyethylene (LDPE), medium-density polyethylene, and linear low-density polyethylene (LLDPE). Furthermore, the ethylene copolymer may be a binary copolymer of ethylene and other monomers, or a polypolymer of ethylene and two or more other monomers. Examples of preferred copolymer components (other monomers) include vinyl acetate and α-olefins having 3 or more carbon atoms. In this embodiment, the polyethylene resin is preferably an ethylene homopolymer or an ethylene copolymer having less than 5% by mass of structural units derived from other monomers.

[0039] The mass ratio of the first recycled resin to the second recycled resin is 75:25 to 99:1, preferably 80:20 to 99:1, more preferably 85:15 to 99:1, and even more preferably 90:10 to 99:1. As described above, when the amount of the first recycled resin is greater than 75:25, defects in the composition are less likely to occur, mechanical strength tends to increase, and the amount of the second recycled resin, which has a high melting point, does not become too large, thus improving moldability at low temperatures. In addition, when formed into a film, it is easier to obtain a good appearance and good flexibility. Furthermore, when the amount of the first recycled resin is less than 99:1, the proportion of the second recycled resin, which tends to have higher mechanical strength than the first recycled resin, increases, so in the presence of a reactive compatibilizer, mechanical strength tends to increase.

[0040] The content of the first recycled resin in the recycled resin composition is not particularly limited, but from the same viewpoint as above, it is preferable that it is 75% by mass or more and 98% by mass or less of the total mass of the recycled resin composition.

[0041] 1-2. Second recycled resin with a melting point exceeding 200°C The second recycled resin is not particularly limited as long as it is a resin with a melting point exceeding 200°C, and may be a single type of resin or a combination of two or more types of resins.

[0042] Examples of recycled resins include: polyamide resins such as nylon-6, nylon-6,6, nylon-6,10, and nylon-6,12; polyester resins such as aromatic polyester resins such as polyethylene terephthalate and its copolymers, polyethylene naphthalate, and polybutylene terephthalate; polycarbonate resins such as aromatic polycarbonate and aliphatic polycarbonate; polystyrene resins such as atactic polystyrene, syndiotactic polystyrene, acrylonitrile-styrene (AS) copolymer, and acrylonitrile-butadiene-styrene (ABS) copolymer; polyphenylene sulfide; and polyether resins such as polyethersulfone, polyetherketone, and polyetheretherketone.

[0043] The second recycled resin preferably contains a polyamide-based resin, a polyester-based resin, or a polycarbonate-based resin, and more preferably contains a polyester-based resin. Since these resins may have reactive groups such as carboxy groups, their reactivity with a reactive compatibilizer is likely to increase. In particular, these recycled resins have been repeatedly melted and heated, foreign substances promote the deterioration of the resin, and hydrolysis or the like occurs in some structures, so they are more likely to react with the reactive compatibilizer than virgin materials. Also, from the viewpoint of being likely to enhance compatibility with the first recycled resin having a relatively low polarity, an embodiment containing a relatively low-polarity polystyrene-based resin is also preferably used. From the above viewpoints, an embodiment in which the second recycled resin contains polyester and / or a polystyrene-based resin is also preferably used.

[0044] The content of the second recycled resin in the recycled resin composition is not particularly limited, but from the same viewpoint as above, it is preferably 0.5% by mass or more and 25% by mass or less based on the total mass of the recycled resin composition.

[0045] 1-3. Reactive compatibilizer The reactive compatibilizer is not particularly limited as long as it contains a reactive site and compatibilizes the first recycled resin and the second recycled resin.

[0046] Examples of the reactive site contained in the reactive compatibilizer include a double bond site, a carboxy group or carboxylic anhydride site, an epoxy group, or an oxazoline site.

[0047] Examples of the reactive compatibilizer containing an epoxy group include ethylene / glycidyl (meth)acrylate copolymer and the like. Examples of commercially available products of the reactive compatibilizer containing an epoxy group include Bondfast 2C, Bondfast E, Bondfast 30C, Bondfast CG5001, Bondfast 2B, Bondfast 7B, Bondfast 7L, Bondfast 7M (manufactured by Sumitomo Chemical Co., Ltd., "Bondfast" is a registered trademark of the company), Modiper A4100, Modiper A4300, Modiper A4400, Modiper CL430-G (manufactured by NOF Corporation, "Modiper" is a registered trademark of the company), and the like. In the present application, "(meth)acrylate" may be an acrylate compound, a methacrylate compound, or a mixture thereof.

[0048] The ethylene / glycidyl (meth)acrylate copolymer may be any copolymer having a structural unit derived from ethylene and a structural unit derived from glycidyl (meth)acrylate. For example, it includes ethylene / glycidyl (meth)acrylate / vinyl alcohol copolymer, ethylene / glycidyl (meth)acrylate / (meth)acrylate copolymer, ethylene / glycidyl (meth)acrylate / acrylonitrile / styrene copolymer, ethylene / glycidyl (meth)acrylate / methyl (meth)acrylate copolymer, ethylene / glycidyl (meth)acrylate / styrene copolymer, and the like.

[0049] Examples of the reactive compatibilizer containing a carboxy group or a carboxylic anhydride moiety include styrene / maleic anhydride copolymer, methyl (meth)acrylate / maleic anhydride copolymer, maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, ethylene / maleic anhydride / ethyl (meth)acrylate, and the like. Examples of commercially available products of the reactive compatibilizer containing a carboxy group or a carboxylic anhydride moiety include Lexparl ET (manufactured by Nippon Polyethylene Co., Ltd., "Lexparl" is a registered trademark of the company), and the like.

[0050] Examples of reactive compatibilizers containing an oxazoline moiety include mixtures of bisoxazoline and styrene / maleic anhydride copolymer, mixtures of bisoxazoline and maleic anhydride-modified polyethylene, mixtures of bisoxazoline and maleic anhydride-modified polypropylene, or polymers containing an oxazoline moiety in their side chains (for example, the Epocross series: manufactured by Nippon Shokubai Co., Ltd., "Epocross" is a registered trademark of the company).

[0051] Among these, from the viewpoint of reacting with carboxyl groups, hydroxyl groups, etc., contained in the recycled resin, the reactive site in the reactive compatibilizer is preferably a carboxyl group or carboxylic acid anhydride site, an epoxy group, a carbodiimide group, or an oxazoline site, and more preferably an epoxy group. Similarly, the reactive compatibilizer preferably contains an ethylene / glycidyl (meth)acrylate copolymer, and more preferably the ethylene / glycidyl (meth)acrylate copolymer is 50% by mass or more, even more preferably 75% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 99% by mass or more, and most preferably only the ethylene / glycidyl (meth)acrylate copolymer is present, relative to the total mass of the reactive compatibilizer. With this configuration, when the first recycled resin contains a low-polarity resin (for example, a polyolefin resin such as polyethylene resin or polypropylene resin), the compatibility between the first recycled resin and the second recycled resin tends to increase.

[0052] Furthermore, from a similar viewpoint, it is preferable that the ethylene / glycidyl (meth)acrylate copolymer contained in the reactive compatibilizer is a copolymer having substantially only structural units derived from ethylene and structural units derived from glycidyl (meth)acrylate. In this application, "having substantially only structural units derived from ethylene and structural units derived from glycidyl (meth)acrylate" means that the amount of structural units other than those derived from ethylene and glycidyl (meth)acrylate is 1% by mass or less, preferably 0.1% by mass or less, and more preferably none.

[0053] When the reactive compatibilizer contains an ethylene / glycidyl (meth)acrylate copolymer, or when it contains a polymer having structural units derived from glycidyl (meth)acrylate, the content ratio of structural units derived from glycidyl (meth)acrylate is preferably 5% by mass or more and 13% by mass or less, and more preferably 5% by mass or more and 7% by mass or less, relative to the total mass of the reactive compatibilizer. When the content ratio is 5% by mass or more, it reacts more easily with recycled resin, making it easier to obtain compatibilization ability and improving mechanical strength and moldability at low temperatures. When the content ratio is 13% by mass or less, the reactivity does not become too high, making it less likely to become hard and brittle, and making it easier to obtain moldability at low temperatures and a good appearance.

[0054] The content of the reactive compatibilizer is preferably 0.1% by mass or more and 10.0% by mass or less, and more preferably 0.5% by mass or more and 5.0% by mass or less, based on the total mass of the recycled resin composition. If the content of the reactive compatibilizer is above the lower limit, it reacts more easily with the recycled resin, making it easier to obtain compatibilization ability and improving mechanical strength and moldability at low temperatures. If the content of the reactive compatibilizer is below the upper limit, the reactivity does not become too high, making it less likely to become hard and brittle, and improving moldability at low temperatures and making it easier to obtain a good appearance.

[0055] 1-4. Other Components The recycled resin composition according to this embodiment may further contain other components not mentioned above, to the extent that they do not impair the purpose and effects of this embodiment. Examples of other components include lubricants, inorganic powders, plasticizers, colorants, antioxidants, flame retardants, foaming agents, flow regulators, etc. These other components may be originally contained in the resin waste material that serves as the raw material for the recycled resin, or they may be added during the manufacture of the recycled resin composition.

[0056] Examples of lubricants include fatty acid-based lubricants such as stearic acid, hydroxystearic acid, complex stearic acid, and oleic acid; aliphatic alcohol-based lubricants; aliphatic amide-based lubricants such as stearamide, oxystearamide, oleylamide, erucylamide, ricinolamide, behenamide, methylolamide, methylenebisstearoamide, methylenebisstearobehenamide, bisamic acid (a higher fatty acid), and complex amides; aliphatic ester-based lubricants such as n-butyl stearate, methyl hydroxystearate, polyhydric alcohol fatty acid esters, saturated fatty acid esters, and ester waxes; and fatty acid metal soap-based lubricants, such as zinc stearate and magnesium stearate. Examples of commercially available lubricants include Aamide AP-1 (manufactured by Mitsubishi Chemical Corporation).

[0057] The recycled resin composition according to this embodiment preferably contains a lubricant. As described above, the lubricant has hydrophobic parts such as long-chain alkyl groups and hydrophilic parts such as carboxyl groups, improving the fluidity of the resin so that it can be efficiently kneaded and uniformly dispersed. For example, even if the recycled resin contains dirt or impurities, it is thought that the compatibility with the resin can be improved. As a result, defects are less likely to occur at the interface between the dirt or impurities and the resin, and the suitability for molding at low temperatures is likely to be improved. In addition, in tensile strength measurement, which is a general test method for mechanical strength, stress is applied to the molded body and the maximum stress when the stress is applied until it breaks is defined as the tensile strength. Therefore, if defects occur at the interface between the dirt or impurities and the resin, the elongation at break tends to be small and the tensile strength tends to be low. Therefore, by including a lubricant, defects are reduced and the mechanical strength becomes relatively uniform within the composition, so it is thought that mechanical strength such as elongation at break and tensile strength can be improved in particular. In addition, since the lubricant can also act as a surfactant, a smooth appearance is more easily obtained when it is made into a film. From this viewpoint, the lubricant is preferably stearate amide.

[0058] When the recycled resin composition contains a lubricant, the lubricant content is preferably 0.05% by mass or more and 0.50% by mass or less, relative to the total mass of the recycled resin composition. This range makes it easier to obtain the above-mentioned effects.

[0059] Inorganic powders are powders composed of inorganic substances. The type of inorganic substance can be selected according to the application of the resin composition. Examples of inorganic substances include calcium, magnesium, aluminum, titanium, iron, zinc, silicon, barium, molybdenum, sodium, and potassium carbonates, silicates, phosphates, borates, oxides, sulfates, or hydrates thereof. Inorganic carbon compounds are also included as examples of inorganic substances.

[0060] Specific examples of inorganic substances include calcium carbonate, magnesium carbonate, zinc oxide, titanium dioxide, silica, alumina, clay (e.g., talc and kaolin), aluminum hydroxide, magnesium hydroxide, aluminum silicate, magnesium silicate, calcium silicate, aluminum sulfate, magnesium sulfate, calcium sulfate, magnesium phosphate, barium sulfate, silica sand, carbon black, zeolite, molybdenum, diatomaceous earth, sericite, shirasu, calcium sulfite, sodium sulfate, potassium titanate, bentonite, wollastonite, dolomite, and graphite. These may be synthesized or derived from natural minerals. Inorganic powders may contain only one or more of these substances.

[0061] Examples of plasticizers include triethyl citrate, acetyl triethyl citrate, dibutyl phthalate, diaryl phthalate, dimethyl phthalate, diethyl phthalate, dioctyl phthalate, di(2-ethylhexyl) phthalate, di-2-methoxyethyl phthalate, dibutyl tartrate, o-benzoyl benzoate, diacetin, and epoxidized soybean oil. The resin composition may contain one of these individually or two or more.

[0062] The colorant may be any known organic pigment, inorganic pigment, or dye. Specific examples of colorants include organic pigments such as azo, anthraquinone, phthalocyanine, quinacridone, isoindolinone, diosadin, perinone, quinophthalone, and perylene pigments; and inorganic pigments such as ultramarine, titanium yellow, and chromium oxide. The resin composition may contain one of these individually or two or more.

[0063] Examples of antioxidants include phosphorus-based antioxidants, phenol-based antioxidants, and pentaerythritol-based antioxidants. The resin composition may contain one or more of these. Phosphorus-based antioxidants, more specifically phosphorus-based antioxidants such as phosphite esters and phosphate esters, are preferred. Examples of phosphite esters include triesters, diesters, and monoesters of phosphite such as triphenyl phosphite, trisnonylphenyl phosphite, and tris(2,4-di-t-butylphenyl) phosphite.

[0064] Examples of phosphate esters include trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, tris(nonylphenyl) phosphate, and 2-ethylphenyldiphenyl phosphate.

[0065] Examples of phenolic antioxidants include α-tocopherol, butylhydroxytoluene, cinapyl alcohol, vitamin E, n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2-t-butyl-6-(3'-t-butyl-5'-methyl-2'-hydroxybenzyl)-4-methylphenyl acrylate, 2,6-di-t-butyl-4-(N,N-dimethylaminomethyl)phenol, 3,5-di-t-butyl-4-hydroxybenzylphosphonate diethyl ester, and tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxymethyl]methane.

[0066] The flame retardant is not particularly limited, but for example, halogenated flame retardants or non-phosphorus halogenated flame retardants such as phosphorus-based flame retardants or metal hydrates can be used. The resin composition may contain one of these alone or two or more of them.

[0067] Examples of halogenated flame retardants include halogenated bisphenol compounds such as halogenated bisphenylalkanes, halogenated bisphenyl ethers, halogenated bisphenyl thioethers, and halogenated bisphenylsulfones, as well as bisphenol-bis(alkyl ether) compounds such as brominated bisphenol A, brominated bisphenol S, chlorinated bisphenol A, and chlorinated bisphenol S. Examples of phosphorus-based flame retardants include aluminum tris(diethylphosphinate), bisphenol A bis(diphenyl phosphate), triarylisopropyl phosphate, cresyldi 2,6-xylenyl phosphate, and aromatic condensed phosphate esters. Examples of metal hydrates include aluminum trihydrate, magnesium dihydrate, or combinations thereof.

[0068] Furthermore, flame retardants and flame retardant additives may be combined. Examples of flame retardant additives include antimony oxides such as antimony trioxide and antimony pentoxide, and other known flame retardant additives.

[0069] The blowing agent is not particularly limited as long as it is a compound capable of generating bubbles when mixed with or injected under pressure into a composition that is in a molten state in a melting kneader. Examples of blowing agents include those that change phase from solid to gas to generate bubbles, those that change phase from liquid to gas to generate bubbles, those that decompose from solid or liquid to generate gas, or gas itself.

[0070] Examples of blowing agents include aliphatic hydrocarbons such as propane, butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclobutane, cyclopentane, and cyclohexane; halogenated hydrocarbons such as chlorodifluoromethane, difluoromethane, trifluoromethane, trichlorofluoromethane, dichloromethane, dichlorofluoromethane, dichlorodifluoromethane, chloromethane, chloroethane, dichlorotrifluoroethane, dichloropentafluoroethane, tetrafluoroethane, difluoroethane, pentafluoroethane, trifluoroethane, dichlorotetrafluoroethane, trichlorotrifluoroethane, tetrachlorodifluoroethane, and perfluorocyclobutane; pyrolytic compounds such as azodicarbonamide, N,N'-dinitropentamethylenetetramine, 4,4'-oxybisbenzenesulfonylhydrazide, carbon dioxide, and sodium hydrocarbons; inorganic gases such as nitrogen and air; and water.

[0071] The foaming agent may contain the active ingredient of the foaming agent together with the carrier resin. Examples of carrier resins include crystalline olefin resins such as crystalline propylene. Examples of active ingredients include bicarbonates. Of these, bicarbonates are preferred. Preferably, the foaming agent concentrate contains crystalline polypropylene resin as the carrier resin and bicarbonate as a thermal decomposition type foaming agent.

[0072] Known fluidity modifiers can also be used. Examples of fluidity modifiers include peroxides such as dialkyl peroxides, for example, 1,4-bis[(t-butylperoxy)isopropyl]benzene. Depending on the type of thermoplastic resin used, these peroxides can also act as crosslinking agents. In particular, if the thermoplastic resin (polyolefin resin) has constituent units derived from dienes, the dienes may be crosslinked with the peroxide.

[0073] Examples of antistatic agents include fatty acid diethanolamides such as lauryl diethanolamide and stearyl diethanolamide; and hydroxyl group-containing compounds, including alcoholamine compounds. Alcoholamines, such as monoethanolamine, diethanolamine, and triethanolamine, are particularly preferred. Two or more antistatic agents can also be used in combination. These antistatic agents may be supported on calcium silicate or calcium carbonate. Furthermore, a range of 8 to 22 carbon atoms in the acyl group of fatty acid diethanolamides is preferred from the viewpoint of exhibiting sufficient antistatic effect.

[0074] The total amount of other components in the resin composition is not particularly limited, but can be, for example, 5% by mass or less relative to the total amount of the resin composition.

[0075] 1-5. Shape of the Recycled Resin Composition The shape of the resin composition according to this embodiment is not particularly limited and can be any shape, such as particulate, pelletized, or lumpy. If the resin composition is pelletized, the shape of the pellet is not particularly limited and can be cylindrical, spherical, ellipsoidal, or any other shape. The size is also not particularly limited and can be appropriately selected according to the shape. For example, in the case of spherical pellets, the diameter may be 1 to 10 mm. In the case of ellipsoidal pellets, the major axis may be about 1 to 10 mm and the aspect ratio may be about 0.1 to 1.0. In the case of cylindrical pellets, the diameter may be about 1 to 10 mm and the height may be about 1 to 10 mm.

[0076] 2. Method for Manufacturing a Recycled Resin Composition The method for manufacturing a recycled resin composition according to this embodiment comprises the steps of: preparing a recycled resin mixture containing a first recycled resin having a melting point of 200°C or less and a second recycled resin having a melting point exceeding 200°C; and mixing the recycled resin mixture with a reactive compatibilizer, wherein the mass ratio of the first recycled resin to the second recycled resin is 75:25 to 99:1, and the content of the reactive compatibilizer is 0.1% by mass or more and 10.0% by mass or less with respect to the total mass of the recycled resin composition.

[0077] The step of preparing a recycled resin mixture containing a first recycled resin and a second recycled resin may be replaced with the preparation of a mixture containing the recycled resin mixture. The mixture containing the recycled resin mixture may be prepared by sorting the resin waste materials so that the mass ratio of the first recycled resin to the second recycled resin is a predetermined ratio, or by adjusting the mixing ratio of each resin waste material.

[0078] The resin waste used in the above preparation process may be pre-crushed into chips (several centimeters to several millimeters in diameter) using a crusher or the like to facilitate melting and processing, or it may be pelletized using known methods.

[0079] Furthermore, known methods can be used to adjust the above ratio. For example, the resin waste material may be sorted by visual inspection, by specific gravity, by electrostatic charge, or by X-ray or light absorption.

[0080] The method for mixing the recycled resin mixture and the reactive compatibilizer is not particularly limited, but may be, for example, by melt kneading. All components may be mixed before melt kneading, or some components may be melt kneaded first and the remaining components kneaded afterward. The apparatus for melt kneading is not particularly limited, and general extruders, kneaders, Banbury mixers, etc., can be used. In particular, from the viewpoint of obtaining a resin composition with a uniform composition, kneading with a twin-screw kneader is preferable.

[0081] 3. Recycled Resin Molded Body The recycled resin molded body according to this embodiment is molded using the above-mentioned recycled resin composition by a known method.

[0082] The shape and application of the recycled resin molded article are not particularly limited and can be used in films, sheets, containers (such as food containers), daily necessities, automotive parts, electrical and electronic components, and various consumables. For example, the molded article obtained from the recycled resin composition according to this embodiment is suitable as a film-like molded article because it is easy to obtain a good appearance.

[0083] Furthermore, from the viewpoint of easily obtaining the above-mentioned good appearance, it is preferable to use a thin film-like molded body. The thickness of the molded body is preferably 100 μm or less, and more preferably 15 μm or more and 100 μm or less. If it is 15 μm or more, sufficient strength can be ensured when molding the molded body, and moldability can be improved. If it is 100 μm or less, the weight of the molded body can be reduced, the amount of material used can be reduced, and it becomes easier to obtain a good appearance.

[0084] 4. Method for manufacturing recycled resin molded articles The molded articles according to this embodiment are molded using the above resin composition by a known method, but may also be molded by melting.

[0085] The molding method is not particularly limited and may include any of the following: inflation molding, extrusion molding, injection molding, foam injection molding, injection compression molding, blow molding, press molding, calendering, vacuum forming, etc., but inflation molding is preferably used.

[0086] When molding a molded product by melting it, the melting temperature is preferably above the melting point of the first recycled resin used (for example, 150°C or higher in the case of polyethylene-based resins) and below 200°C. By setting these conditions, the formation of defects due to foreign matter such as dirt and impurities contained in the recycled resin mixture is suppressed, the moldability is improved, foreign matter is less likely to bleed out onto the surface of the molded product, and a molded product of good quality is more likely to be obtained.

[0087] The present invention will be described in detail based on examples, but the present invention is not limited to these examples.

[0088] 1. Preparation of Materials The following materials were used to prepare the resin compositions for each example and comparative example.

[0089] 1-1. First recycled resins with a melting point of 200°C or less: Recycled LLDPE (manufactured by Asei Shoji Co., Ltd., MFR 1.37 g / 10 min [190°C, 2.16 kg]) and Recycled HDPE (manufactured by Chiyo Environmental Resources Co., Ltd., MFR 0.45 g / 10 min [190°C, 2.16 kg]).

[0090] 1-2. Recycled PET: A second type of recycled resin with a melting point exceeding 200°C

[0091] 1-3. Reactive Compatibilizers ・BF-2C: Bondfast 2C (a copolymer of ethylene and glycidyl methacrylate, with a glycidyl methacrylate content of 6% by mass) ・BF-E: Bondfast E (a copolymer of ethylene and glycidyl methacrylate, with a glycidyl methacrylate content of 12% by mass) ・BF-CG5001: Bondfast CG5001 (a copolymer of ethylene and glycidyl methacrylate, with a glycidyl methacrylate content of 19% by mass) ・BF-7M: Bondfast 7M (a copolymer of ethylene, glycidyl methacrylate, and methyl acrylate, with a glycidyl methacrylate content of 6% by mass and a methyl acrylate content of 27% by mass) (All of the above are manufactured by Sumitomo Chemical Co., Ltd., and "Bondfast" is a registered trademark of the company.)

[0092] 1-4. Other ingredients / lubricants: Aamide AP-1 (manufactured by Mitsubishi Chemical Corporation) - Antioxidant 1 (phenol-based antioxidant, manufactured by ADEKA Corporation) - Antioxidant 2 (phosphite-based antioxidant, manufactured by ADEKA Corporation)

[0093] 1-5. Virgin resin, virgin LLDPE, and virgin PET used in the reference examples.

[0094] 2. Preparation of Recycled Resin Compositions [Examples 1-14, Comparative Examples 1-17, Reference Examples 1-3] (Preparation of Recycled Resin Composition Pellets) Each component was placed in the mass ratios shown in Tables 1-5 into a Parker HK-25D co-rotating twin-screw compounding extruder (φ25 mm, L / D = 41), melt-kneaded at a cylinder temperature of 280°C, and then extruded into strands. After the extruded resin composition was cooled, it was cut to obtain resin composition pellets.

[0095] 3. Evaluation The pellets obtained from Examples 1 to 14, Comparative Examples 1 to 17, and Reference Examples 1 to 3 described above were evaluated as follows.

[0096] 3-1. Moldability at Low Temperatures Each pellet was molded (30 μm thick) using an inflation film extrusion line (60 mm circular die, 1.2 mm die gap, 30 mm screw diameter, L / D ratio = 30). The film was processed with a BUR (blow-up ratio) of 2.5. In the extruder, the temperature in each section was set to 180°C to 200°C, and the rotation speed was maintained at 20 rpm. The moldability at this time was evaluated according to the following criteria. A score of B or higher was considered acceptable.

[0097] (Judgment Criteria) A: No defects occur for a long period of time from the time of extrusion from the die until the completion of molding, and stable continuous molding is possible. B: No defects occur for a reasonable period of time from the time of extrusion from the die until the completion of molding, and there are virtually no problems with continuous molding. C: Holes or other defects occur from the time of extrusion from the die until the completion of molding, making stable continuous molding impossible. D: After extrusion from the die, the molding was extremely unstable and impossible.

[0098] 3-2. Tensile Strength Each film obtained in the above moldability test was subjected to a tensile test in accordance with JIS K 7161-1:2014, and the maximum stress was defined as the tensile strength. For comparative examples that received a C or D rating in the moldability evaluation at low temperatures, the films were evaluated after raising the temperature of each section of the extruder to a moldable temperature.

[0099] 3-3. Appearance The appearance of each film obtained in the above moldability test was evaluated using the film of Reference Example 1 as a reference. For comparative examples that received a C or D rating in the moldability evaluation at low temperatures, the evaluation was performed on films that were molded by raising the temperature of each section of the extruder to a moldable temperature.

[0100] (Evaluation Criteria) A: Appearance is equivalent to that of Reference Example 1. B: Appearance is slightly inferior to that of Reference Example 1 (no problems in actual use). C: Appearance is significantly inferior to that of Reference Example 1.

[0101] 3-4. Evaluation Results The evaluation results for Examples 1-14, Comparative Examples 1-17, and Reference Examples 1-3 are shown in Tables 1-5.

[0102]

[0103]

[0104]

[0105]

[0106]

[0107] As shown in Tables 1 to 5, when the first recycled resin, the second recycled resin, and the reactive compatibilizer are included in predetermined ratios (comparison between examples and comparative examples), excellent mechanical strength (tensile strength) and moldability at low temperatures (below 200°C) are obtained, and a good appearance is also obtained as a molded article.

[0108] This application claims priority under Japanese Patent Application No. 2024-223996, filed on 19 December 2024. All contents described in the specification and drawings of said application are incorporated herein by reference.

[0109] According to the present invention, a recycled resin composition having good mechanical strength and excellent moldability at low temperatures, a recycled resin molded article, and a method for producing a recycled resin composition can be provided using a recycled resin composition comprising a first recycled resin and a second recycled resin. Therefore, even when the first recycled resin and the second recycled resin cannot be completely separated from the resin waste material, for example, the recycled resin can be effectively utilized.

Claims

1. A recycled resin composition comprising: a first recycled resin having a melting point of 200°C or less; a second recycled resin having a melting point exceeding 200°C; and a reactive compatibilizer, wherein the mass ratio of the first recycled resin to the second recycled resin is 75:25 to 99:1, and the content of the reactive compatibilizer is 0.1% by mass or more and 10.0% by mass or less with respect to the total mass of the recycled resin composition.

2. The recycled resin composition according to claim 1, wherein the first recycled resin comprises a polyethylene resin and / or a polypropylene resin, and the second recycled resin comprises a polyester resin and / or a polystyrene resin.

3. The recycled resin composition according to claim 1, wherein the reactive compatibilizer comprises an ethylene / glycidyl (meth)acrylate copolymer.

4. The recycled resin composition according to claim 3, wherein the content ratio of structural units derived from glycidyl (meth)acrylate to the total mass of the reactive compatibilizer is 5% by mass or more and 13% by mass or less.

5. The recycled resin composition according to claim 4, wherein the content ratio of structural units derived from glycidyl (meth)acrylate to the total mass of the reactive compatibilizer is 5% by mass or more and 7% by mass or less.

6. A recycled resin molded article comprising the recycled resin composition described in any one of claims 1 to 5.

7. The recycled resin molded article according to claim 6, which is in the form of a film with a thickness of 100 μm or less.

8. A method for producing a recycled resin composition, comprising the steps of: preparing a recycled resin mixture containing a first recycled resin having a melting point of 200°C or less and a second recycled resin having a melting point exceeding 200°C; and melt-kneading the recycled resin mixture and a reactive compatibilizer, wherein the mass ratio of the first recycled resin to the second recycled resin is 75:25 to 99:1, and the content of the reactive compatibilizer is 0.1% by mass or more and 10.0% by mass or less with respect to the total mass of the recycled resin composition.

9. A method for producing a recycled resin molded article, comprising melting and molding a recycled resin composition according to any one of claims 1 to 5, wherein the melting temperature during the melting and molding process is 200°C or lower.

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