Polyolefin-based resin composition

Abstract

To provide a resin composition containing a post-consumer recycled (PCR) polyolefin reduced in an aldehyde-derived odor.SOLUTION: A polyolefin-based resin composition comprises a post-consumer recycled (PCR) polyolefin and an aldehyde scavenger. The aldehyde scavenger is an aminooxyalkyl group-supporting carrier in which a specific compound having an aminooxyalkyl group and a carrier are bonded to each other through a chemical bond. The aminooxyalkyl group-supporting carrier has one or more structures selected from the structures represented by the following formulae (2) to (4).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to a polyolefin resin composition having reduced odor derived from aldehydes. [Background technology]

[0002] In recent years, environmental pollution caused by plastics has become a problem, and material recycling of plastic products has been promoted.

[0003] Plastic recycling can be divided into two types, "post-consumer recycling (PCR)" and "post-industrial recycling (PIR)," depending on the raw materials and source of separation. Post-consumer recycling (PCR) refers to the collection and recycling of used products in the market, while post-industrial recycling (PIR) refers to the recycling and reuse of materials generated during the manufacturing process of products before they are released on the market.

[0004] The process of reusing waste plastics to obtain molded products generally includes washing, dehydrating, crushing, re-pelletizing, and molding the recovered waste plastics.

[0005] Here, waste plastics used in post-consumer recycling (PCR) contain a wide variety of substances other than the main components, and these impurities often remain even after the cleaning process. For this reason, molded products using recycled plastic materials as raw materials not only have an unpleasant odor due to aldehydes and other substances derived from the impurities, making them difficult to use, but also have the problem of reduced moldability.

[0006] Under these circumstances, the removal of impurities contained in waste plastics has been investigated to date.

[0007] For example, a method has been proposed in which an acid acceptor such as magnesium oxide or hydrotalcite is added to waste plastics containing polyvinyl chloride resin, such as waste plastic containers and packaging and other general plastic product waste, to suppress the generation of hydrochloric acid (see, for example, Patent Document 1).

[0008] In addition, a recycled resin container with less odor has been proposed in which an adsorbent such as zeolite is added to a multilayer plastic container containing a recycled resin layer from polyolefin-based packaging containers, thereby adsorbing hydrocarbon volatile matter generated by thermal deterioration (see, for example, Patent Document 2).

[0009] However, the method described in Patent Document 1 is a method for suppressing hydrochloric acid, and the method described in Patent Document 2 is a method for reducing odors by adsorption of hydrocarbon volatiles, but no consideration is given to reducing aldehydes. In addition, resin molding is generally performed by heating to 200°C or higher, and in this case, existing aldehyde scavengers may be deactivated. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Patent No. 4828836 [Patent Document 2] JP 1995-33172 A Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been made in view of the above background art, and an object of the present invention is to provide a polyolefin resin composition in which the odor derived from aldehyde is reduced. [Means for solving the problem]

[0012] Means of Solving the Problems The present inventors have conducted intensive research to solve the above problems and have found that a polyolefin resin composition containing a specific aldehyde scavenger can solve the above problems, thereby completing the present invention.

[0013] That is, the present disclosure includes the following embodiments.

[0014] [1] A post-consumer recycled (PCR) polyolefin and an aldehyde scavenger, The aldehyde scavenger is an aminooxyalkyl group-bearing carrier in which a compound represented by the following formula (1) is chemically bonded to the carrier, The polyolefin resin composition, wherein the aminooxyalkyl group-supported carrier has one or more structures selected from the structures represented by the following formulas (2) to (4):

[0015] [ka]

[0016] [ka]

[0017] [In the above formulas (1) to (4), R represents an alkyl group having 1 to 4 carbon atoms, X represents an alkoxy group having 1 to 4 carbon atoms, m represents an integer of 0 to 2, m' represents an integer of 0 to 1, and n represents an integer of 1 to 12. When m is 0 or 1, or m' is 0, multiple Xs may be the same or different, and when m is 2, multiple Rs may be the same or different.] [2] The polyolefin resin composition according to the above [1], wherein the polyolefin in the post-consumer recycled (PCR) polyolefin is polyethylene.

[0018] [3] The polyolefin resin composition according to the above [1] or [2], wherein in the formulae (1), (2a) to (2c), R is a methyl group, and each X is independently a methoxy group, an ethoxy group, or an isopropoxy group.

[0019] [4] The polyolefin resin composition according to any one of the above [1] to [3], wherein the support is silica gel, alumina, zeolite, magnesia, titania, zirconia, ceria, diatomaceous earth, activated carbon, cellulose, or hydroxyapatite.

[0020] [5] The polyolefin resin composition according to the above [4], wherein the carrier is silica gel.

[0021] [6] The polyolefin resin composition according to the above [1] or [2], wherein the content of the aldehyde scavenger is 0.01 mass % or more and 10 mass % or less, based on the total amount of the polyolefin resin composition.

[0022] [7] The polyolefin resin composition according to any one of [1] to [6] above, wherein the post-consumer recycled (PCR) polyolefin contains an aldehyde.

[0023] [8] The polyolefin resin composition according to the above [7], wherein the aldehyde contained in the post-consumer recycled (PCR) polyolefin is acetaldehyde and / or butyraldehyde.

[0024] In this disclosure, polyolefins that have been used in the market and are subjected to post-consumer recycling (PCR) are referred to as "post-consumer recycled (PCR) polyolefins." Effect of the Invention

[0025] Molded articles obtained by molding the polyolefin resin composition of the present disclosure have less aldehyde odor compared to conventional molded articles derived from post-consumer recycled (PCR) polyolefins, and can therefore be used for daily necessities, industrial parts, office supplies, chemical products, etc. As a result, the reuse of post-consumer recycled (PCR) polyethylene is promoted, thereby reducing the environmental load. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] In the present disclosure, the polyolefin-based resin composition includes a post-consumer recycled (PCR) polyolefin and an aldehyde scavenger.

[0027] The polyolefin in the post-consumer recycled (PCR) polyolefin is not particularly limited, but examples thereof include homopolymers or copolymers of α-olefins having 2 to 12 carbon atoms, such as ethylene, propylene, and 1-butene, and copolymers of ethylene and vinyl esters and / or acrylic esters, etc., and specific examples thereof include ethylene homopolymers such as high-pressure low-density polyethylene and high-density polyethylene, ethylene-1-butene copolymers, ethylene-1-hexene copolymers, ethylene-1-octene copolymers, ethylene-4-methyl-1-pentene copolymers, ethylene-vinyl acetate copolymers, ethylene-acrylic ester copolymers, ethylene-methacrylic ester copolymers, propylene homopolymers, propylene-ethylene copolymers, propylene-1-butene copolymers, poly-1-butene, poly-1-hexene, poly-4-methyl-1-pentene, etc. Among these, polyethylene is preferred.

[0028] The post-consumer recycled (PCR) polyolefins are not particularly limited, but examples thereof include polyolefins used as automobile and railway seats or chairs, sofas, sheets, gloves, container lids, bottles, cups, trays, tubes, etc.

[0029] The post-consumer recycled (PCR) polyolefin means a polyolefin recovered for reuse of waste. Since it has been once discarded, the polyolefin may include attachments and other waste-derived substances mixed in during the disposal and recovery process. Here, attachments of the polyolefin include sweat and sebum from humans and animals after use and odorous components derived therefrom, and examples of the odorous components include organic acids, aldehydes, ketones, ammonia, and the like. Examples of organic acids include acetic acid, butyric acid, isovaleric acid, and the like, examples of aldehydes include acetaldehyde, butylaldehyde, 2-nonenal, and the like, and examples of ketones include 2,3-butanedione, and the like.

[0030] The post-consumer recycled (PCR) polyolefin may be one which has been subjected to a process of crushing a molded article and a process of washing the molded article with water or the like.

[0031] In the present disclosure, the aldehyde scavenger is an aminooxyalkyl group-supported carrier in which a compound represented by the following formula (1) is chemically bonded to the carrier, and the aminooxyalkyl group-supported carrier has one or more structures among the structures represented by the following formulas (2) to (4).

[0032] [ka]

[0033] [ka]

[0034] [In the above formulas (1) to (4), R represents an alkyl group having 1 to 4 carbon atoms, X represents an alkoxy group having 1 to 4 carbon atoms, m represents an integer of 0 to 2, m' represents an integer of 0 to 1, and n represents an integer of 1 to 12. When m is 0 or 1, or m' is 0, multiple Xs may be the same or different, and when m is 2, multiple Rs may be the same or different.] An example of the aldehyde scavenger is one obtained by chemically modifying a support with a compound represented by the above formula (1) (hereinafter also referred to as a "silane coupling agent") (hereinafter also referred to as a "silane coupling reaction").

[0035] In the above formulas (1), (2a) to (2c), R represents an alkyl group having 1 to 4 carbon atoms, and X represents an alkoxy group having 1 to 4 carbon atoms.

[0036] Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a 2-methylpropyl group, a 1-methylpropyl group, and a tert-butyl group.

[0037] Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a 2-methylpropyloxy group, a 1-methylpropyloxy group, and a tert-butoxy group.

[0038] In terms of efficiency of the silane coupling reaction, R is preferably a methyl group, X is preferably a methoxy group, an ethoxy group, or an isopropoxy group, m is preferably an integer of 0 to 1, m' is preferably 0, and n is preferably an integer of 3 to 9. Multiple Xs may be the same or different.

[0039] The silane coupling agent represented by the above formula (1) may be a commercially available product, but it can also be synthesized according to the methods described in Organic Preparations and Procedures International, 1994, Vol. 26, pp. 111-113, JP-A-7-233132, and Tetrahedron Letters, 2005, Vol. 46, pp. 7973-7975.

[0040] In the aminooxyalkyl group-supported carrier, a part or all of the aminooxyalkyl group may be in the form of a chemically acceptable salt with an inorganic acid or an organic acid. The type of salt is not particularly limited, but examples thereof include: Inorganic acid salts such as hydrochlorides, hydrobromides, perchlorates, silicates, tetrafluoroborates, hexafluorophosphates, sulfates, nitrates, and phosphates; Organic acid salts such as acetates, citrates, fumarates, maleates, trifluoromethanesulfonates, trifluoroacetates, benzoates, and p-toluenesulfonates; Among them, inorganic acid salts are preferred in terms of being inexpensive, and hydrochlorides are more preferred.

[0041] The amount of aminooxyalkyl group supported on the carrier can be adjusted as desired depending on the purpose and is not particularly limited, but it is preferable that the amount of aminooxyalkyl group is in the range of 0.01 mmol / g or more and 10 mmol / g or less relative to the mass of the carrier.

[0042] In the present disclosure, the carrier on which the aminooxyalkyl group is supported may be any carrier that is insoluble in water, and is not particularly limited. For example, Polymer carriers such as styrene-based polymers such as polystyrene and cross-linked polystyrene, polyolefins such as polyethylene and polypropylene, poly(halogenated olefins) such as polyvinyl chloride and polytetrafluoroethylene, nitrile-based polymers such as polyacrylonitrile, (meth)acrylic polymers such as polymethyl methacrylate and polyethyl acrylate, and high molecular weight polysaccharides such as cellulose, agarose, and dextran; Inorganic carriers such as silica gel, alumina, zeolite, magnesia, titania, zirconia, ceria, diatomaceous earth, activated carbon, cellulose, and hydroxyapatite; As the carrier to be mixed with the silane coupling agent, an inorganic carrier is preferable, and silica gel is more preferable, in terms of efficiency of the silane coupling reaction.

[0043] The shape of the carrier is not particularly limited, but examples thereof include shapes generally used as separation substrates, such as spherical (e.g., spherical particles, etc.), granular, fibrous, granular, monolithic column, hollow fiber, and membrane (e.g., flat membrane, etc.), and among these, spherical, membrane, granular, granular, or fibrous carriers are preferred. Spherical, granular, or granular carriers are particularly preferred because the volume of use can be freely set when used in a column method or batch method. The particle size of the spherical, granular, or granular carrier is usually in the range of 0.1 μm to 10 mm in average particle size, but is preferably 0.1 μm to 100 μm in terms of good dispersibility in liquid.

[0044] The carrier may be porous or non-porous. The average pore size of the porous carrier is usually 0.1 nm to 1 μm, but is preferably in the range of 0.1 nm to 300 nm in terms of the aldehyde capture rate.

[0045] The content of the above-mentioned aminooxyalkyl group-supported carrier is preferably 0.01% by mass or more and 10% by mass or less based on the total amount of the polyethylene resin composition. If the content of the aminooxyalkyl group-supported carrier is less than 0.01% by mass, the effect of reducing aldehyde may be insufficient. On the other hand, if the content of the aminooxyalkyl group-supported carrier is more than 10% by mass, the resin physical properties such as tensile strength may be impaired.

[0046] The polyolefin resin composition may contain, within the scope of the invention, a thermoplastic resin other than post-consumer recycled (PCR) polyethylene, an antistatic agent, a light stabilizer, an ultraviolet absorber, a nucleating agent, a lubricant, an antioxidant, an antiblocking agent, a flow improver, a release agent, a colorant, an inorganic neutralizing agent, a hydrochloric acid absorber, a filler conductive agent, a chain extender, a hydrolysis inhibitor, and the like.

[0047] The polyolefin resin composition can be suitably used as a raw material for molded articles.

[0048] The molded articles obtained by molding the polyolefin resin composition are useful as daily necessities, industrial parts, office supplies, chemical supplies, and the like.

[0049] Next, a method for producing the polyolefin resin composition will be described.

[0050] The method for producing the polyolefin resin composition is not particularly limited as long as it can disperse each component, but it can be produced, for example, by using a commonly used resin kneading device, such as a single screw extruder, a twin screw extruder, a multi-screw extruder, a Banbury mixer, a pressure kneader, a rotating roll, an internal mixer, etc. EXAMPLES

[0051] The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these.

[0052] In the examples and comparative examples, the post-consumer recycled (PCR) polyolefin, aldehyde scavenger, and antioxidant shown below were used.

[0053] Post-consumer recycled (PCR) polyolefin: Post-consumer recycled (PCR) polyethylene, a fibrous molded product obtained from Taiseki Sangyo Co., Ltd. Since the amount of aldehyde released varies depending on the production lot, they are referred to as Lot A, Lot B, and Lot C, respectively.

[0054] Aldehyde scavenger A: the aminooxyalkyl group-supported carrier obtained in Synthesis Example 1, Aldehyde scavenger B: Kesmon NS-750 manufactured by Toagosei Co., Ltd. Aldehyde scavenger C: Adipic dihydrazide (Tokyo Chemical Industry Co., Ltd.) Antioxidant: Sumitomo Chemical's Sumilizer GP, phosphite type.

[0055] Synthesis Example 1 After mixing 19.94 g of silica gel (NIPGEL BY-400, manufactured by Tosoh Silica Corporation) and 173.4 g of toluene, a mixture of 8.08 g of the silane coupling agent represented by chemical formula (1') and 43.35 g of toluene was added dropwise under a nitrogen stream and stirred at 25°C for 120 hours.

[0056] [ka]

[0057] The reaction solution obtained was filtered, and the residue was dried at 120°C for 4 hours using a hot air dryer (Advantec, DRJ433DA) to obtain a support supported by chemical bonds carrying aminooxyalkyl groups (hereinafter referred to as "support carrying aminooxyalkyl groups"). Elemental analysis of the support carrying aminooxyalkyl groups revealed that the aminooxyalkyl group content was 1.4 mmol / g relative to the support mass.

[0058] Example 1 A post-consumer recycled (PCR) polyolefin pulverized with a rotary cutter, an aldehyde scavenger, and an antioxidant were mixed in advance in a tumbler in the ratio shown in Table 1, and melt-kneaded at a temperature of 210°C and a discharge rate of 20 kg using a twin-screw extruder (TEX25αIII manufactured by Japan Steel Works, Ltd.) to obtain resin composition pellets. A compression molded sheet having a thickness of 2 mm was produced from the obtained pellets at a temperature of 200°C using a compression molding machine (Shinto AWFA-50 double-acting hydraulic two-stage molding machine manufactured by Shinto Metal Industries Co., Ltd.).

[0059] The obtained compression molded sheet was cut into a square shape with a side length of 50 mm to prepare a test piece, and this test piece was sealed in a 2 L sampling bag together with 1 L of nitrogen gas. This sampling bag was heated at 65 ° C. for 2 hours using a hot air dryer (Advantec, DRJ433DA), and then the gas in the Tedlar bag was adsorbed on a cartridge carrying 2,4-dinitrophenylhydrazine (DNPH) (Fujifilm Wako Pure Chemical, Presep-C DNPH). This cartridge was treated with acetonitrile to elute the DNPH-aldehyde condensate. The eluate was then used to quantify the acetaldehyde and butyraldehyde volatilized from the test piece using a liquid chromatograph (Shimadzu, LC-2030C Plus). The results are shown in Table 1.

[0060] Examples 2 to 7, Comparative Examples 1 to 6 A compression molded sheet was obtained in the same manner as in Example 1, except that the ingredients and their amounts were changed to those shown in Table 1, and the amount of aldehyde volatilized was quantified. The results are shown in Tables 1 and 2.

[0061] As shown in Tables 1 and 2, the polyolefin resin compositions of Examples 1 to 7 were found to have a smaller amount of aldehyde volatilization than the polyolefin resin compositions of Comparative Examples 1 and 2, which did not contain an aldehyde scavenger, and the polyolefin resin compositions of Comparative Examples 3 to 6, which contained an existing aldehyde scavenger.

[0062] [Table 1]

[0063] [Table 2]

[0064] Example 8 A compression molded sheet was obtained in the same manner as in Example 1, except that post-consumer recycled (PCR) polyolefin Lot C was used instead of Lot A, and the aldehyde scavenger and antioxidant were mixed in the ratios shown in Table 3. The amount of aldehyde volatilized was quantified. The results are shown in Table 3.

[0065] [Table 3]

[0066] Example 9 The aldehyde scavenger A was heated in advance in an electric furnace (manufactured by Yamato Scientific Co., Ltd., FO810) for 30 minutes at 200°C, but the same procedure as in Example 8 was used to obtain a compression molded sheet, and the amount of aldehyde volatilized was quantified. The results are also shown in Table 3.

[0067] Example 10, Comparative Examples 7 to 10 A compression-molded sheet was obtained in the same manner as in Example 8, except that the ingredients, the amounts of ingredients, and the preheating conditions for the aldehyde scavenger were changed to those shown in Table 3, and the amount of aldehyde volatilized was quantified. The results are also shown in Table 3.

[0068] As shown in Table 3, the polyolefin resin compositions of Examples 9 and 10, which contained preheat-treated scavenger A, had the same amount of aldehyde volatilization as the polyolefin resin composition of Example 8, which contained non-preheat-treated scavenger A, and the amount of aldehyde volatilization was significantly reduced compared to Comparative Example 7, in which no scavenger was added.

[0069] On the other hand, when existing scavengers were preheated and blended into a polyolefin resin composition, an increase in the amount of aldehyde volatilized was observed (see Comparative Examples 9 and 10), suggesting that the scavengers were deteriorated by the preheat treatment.

[0070] These results demonstrate that the aldehyde scavenger contained in the polyolefin resin composition of the present disclosure maintains its aldehyde scavenging effect even when exposed to high temperatures of 200 to 230°C (simulating the heating temperature during resin molding), and has higher heat resistance than existing scavengers.

Claims

1. a post-consumer recycled (PCR) polyolefin and an aldehyde scavenger; The aldehyde scavenger is an aminooxyalkyl group-bearing carrier in which a compound represented by the following formula (1) is chemically bonded to the carrier, The aminooxyalkyl group-supported carrier has one or more structures represented by the following formulas (2) to (4): 【Chemistry 1】 【Chemistry 2】 [In the above formulas (1) to (4), R represents an alkyl group having 1 to 4 carbon atoms, X represents an alkoxy group having 1 to 4 carbon atoms, m represents an integer of 0 to 2, m' represents an integer of 0 to 1, and n represents an integer of 1 to 12. When m is 0 or 1, or m' is 0, multiple Xs may be the same or different, and when m is 2, multiple Rs may be the same or different.]

2. The polyolefin resin composition according to claim 1, wherein the polyolefin in the post-consumer recycled (PCR) polyolefin is polyethylene.

3. The polyolefin resin composition according to claim 1, wherein in formulas (1), (2a) to (2c), R is a methyl group, and each X is independently a methoxy group, an ethoxy group, or an isopropoxy group.

4. 3. The polyolefin resin composition according to claim 1, wherein the support is silica gel, alumina, zeolite, magnesia, titania, zirconia, ceria, diatomaceous earth, activated carbon, cellulose, or hydroxyapatite.

5. The polyolefin resin composition according to claim 4, wherein the carrier is silica gel.

6. The polyolefin resin composition according to claim 1 or 2, wherein the content of the aldehyde scavenger is from 0.01% by mass to 10% by mass, based on the total amount of the polyolefin resin composition.

7. The polyolefin resin composition according to claim 1 or 2, wherein the post-consumer recycled (PCR) polyolefin comprises an aldehyde.

8. The polyolefin resin composition according to claim 7, wherein the aldehyde contained in the post-consumer recycled (PCR) polyolefin is acetaldehyde and / or butyraldehyde.

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