Resin composition containing compatibilizing material, and recycled film

Abstract

This resin composition contains: a resin for a compatibilizing material, the resin containing an ethylene-(meth)acrylate copolymer (P) that has 70-99 mol% of structural units derived from ethylene, 0.99-29.99 mol% of structural units derived from a (meth)acryloyloxy-group-containing compound, and 0.001-5 mol% of structural units derived from an unsaturated dicarboxylic anhydride, and has a melt flow rate of 0.01-1000 g / 10 min when measured at 190°C under a load of 2.16 kg; a polyolefin containing 3-60 mass% of a carboxylic-acid- or carboxylic-anhydride-modified polyolefin; and a polymer that does not correspond to either the resin or the polyolefin. As a result, a material for enhancing the recyclability of polyamide-containing plastic films is provided.

Description

Resin composition containing compatibilizer and recycled film

[0001] The present invention relates to a resin composition containing a compatibilizer and a recycled film.

[0002] Resins such as polyethylene, polyester, and polyamide are easily moldable and have various characteristics, making them widely used as a variety of household and industrial materials. In particular, polyolefins such as polyethylene and ethylene-α-olefin copolymers allow for precise control of their physical properties through the design of comonomer combinations or modification with compounds having functional groups, and are therefore widely used as materials for resin molded products (Patent Documents 1 and 2).

[0003] Resins generally melt when heated and can be easily molded into desired shapes. This property allows them to be used in applications such as packaging when stretched into thin films. Furthermore, because it is possible to combine the properties of each resin, such as gloss, rigidity, heat sealability, and tearability, various resins can be mixed or layered to create films with a wide variety of properties based on their material composition.

[0004] Resin-based products have become so closely intertwined with our daily lives that it is difficult to eliminate their use. However, with the recent rise in environmental awareness, there is a demand for resin-based molded products to have recyclability. Resins are mostly carbon atoms, and from the perspective of carbon neutrality, recyclable resins are extremely important industrially (Patent Document 3). It is particularly important to be able to utilize packaging materials, which are mass-produced and consumed, as recycled film. Commercially available resin products are often required to have diverse physical properties, so they often contain multiple components, and there is a demand for the development of a recycling method for such molded products (Patent Document 4).

[0005] Japanese Patent Publication No. 8-509772 Japanese Patent Publication No. 2018-119101 Japanese Patent Publication No. 2002-201292 Japanese Patent Publication No. 2018-502743 Japanese Patent Publication No. 2023-142138

[0006] Polymer Analysis Handbook, edited by the Japan Society for Analytical Chemistry and the Polymer Analysis Research Forum, Asakura Publishing, 2008, p. 402)

[0007] Plastic film is recycled by reusing products collected from the market and by recycling scraps generated during the manufacturing process of molded products. However, plastic films often contain two or more resins or other materials, such as adhesives and printing paints, which can adversely affect recyclability depending on the mixed substances. For example, ethylene-vinyl alcohol copolymer (EVOH), which has gas barrier properties, and polyamide, which has excellent gloss, strength, and pinhole resistance, are useful materials for packaging films. However, the presence of EVOH or polyamide can cause the film to whiten upon reuse. Especially in applications requiring transparency, multilayer films containing these resins present recyclability challenges. Furthermore, packaging films can tear when opened, but with conventional recycled films, the tear direction can be inconsistent due to changes in physical properties during the recycling process. While recycling techniques, such as technologies for separating resins from other components such as additives, have been developed, complete separation is difficult to achieve, and there is always a demand for highly recyclable resins. In light of this background, the objective of the present invention is to provide a material that improves the recyclability of plastic films, particularly those containing polyamide.

[0008] The present inventors have found that the above-mentioned problems can be solved by designing a compatibilizer. Specifically, they have found that using an ethylene-(meth)acrylate copolymer as a compatibilizer resin makes it possible to obtain a resin composition with high recyclability. A compatibilizer is an additive for blending different materials together. The present inventors have found that designing a compatibilizer makes it possible to achieve high homogenization of resin compositions for films and provide recycled materials with excellent physical properties, and have completed the present invention.

[0009] That is, the present invention relates to a resin for a compatibilizer and a resin composition specified by the following items. [1] A resin composition obtained by kneading 0.1 to 35 mass% of a compatibilizer resin (A) containing an ethylene-(meth)acrylate copolymer (P) having 70 to 99 mol% of structural units derived from ethylene, 0.99 to 29.99 mol% of structural units derived from a (meth)acryloyloxy group-containing compound, and 0.001 to 5 mol% of structural units derived from an unsaturated dicarboxylic acid anhydride, and having a melt flow rate of 0.01 to 1,000 g / 10 min measured under conditions of a temperature of 190°C and a load of 2.16 kg; 94.9 to 20 mass% of a polyolefin (B); and 5.0 to 79 mass% of a polymer (C) that does not fall under either (A) or (B), wherein (B) contains 3 to 60 mass% of a carboxylic acid or carboxylic acid anhydride-modified polyolefin (b1), when the total amount of (B) is 100 mass%. [2] The resin composition according to [1], wherein the (meth)acryloyloxy group-containing compound is an alkyl (meth)acrylate and / or an alkoxyalkyl (meth)acrylate having an alkoxyalkyl group. [3] The resin composition according to [1] or [2], wherein the (C) is one or more selected from the group consisting of polyamide, polyester, and ethylene-vinyl alcohol copolymer (EVOH). [4] A resin composition obtained by kneading 35 to 0.1 mass% of the compatibilizer resin (A) according to [1], 65 to 99.9 mass% of molding scrap (D) containing 50 to 95 mass% of a polyolefin and 50 to 5 mass% of one or more selected from the group consisting of polyamide, polyester, and EVOH, and optionally 0 to 95 parts by mass of a polyolefin (B') not derived from the molding scrap, per 100 parts by mass of the total of the compatibilizer resin and the molding scrap. [5] The resin composition according to [4], wherein the Elmendorf tear strength in the machine direction (MD) of the film is 5 to 200 N / mm, as measured at a temperature of 23°C and a humidity of 50% in accordance with JIS K7128-2. [6] The resin composition according to [4] or [5], wherein the haze measured using a 70 μm-thick film in accordance with JIS-K7136-2000 is 1 to 40%.[7] A compatibilizer resin containing an ethylene-(meth)acrylate copolymer (P) having 70 to 99 mol% of structural units derived from ethylene, 0.99 to 29.99 mol% of structural units derived from a (meth)acryloyloxy group-containing compound, and 0.001 to 5 mol% of structural units derived from an unsaturated dicarboxylic acid anhydride, and having a melt flow rate of 0.01 to 1,000 g / 10 min measured under conditions of a temperature of 190°C and a load of 2.16 kg. [8] A recycled film molded using the resin composition described in any of [4] to [6] above. [9] A multilayer film comprising at least a layer (I) made of the resin composition described in any of [4] to [6] above, and a layer (II) made of one or more polymers selected from the group consisting of polyamide, polyester, and ethylene-vinyl alcohol copolymer (EVOH).

[10] A method for producing a recycled film, comprising a step of melt-kneading 0.1 to 35 mass% of the compatibilizer resin (A) according to the above item [1], 94.9 to 20 mass% of a polyolefin (B) containing 3 to 60 mass% of a carboxylic acid or carboxylic anhydride-modified polyolefin (b1), and 5.0 to 79 mass% of a polymer (C) that does not fall under either of the above items (A) or (B).

[0010] According to the present invention, it is possible to obtain a resin for a compatibilizer and a resin composition that can be used as a recycled raw material for a polymer film without causing problems such as deterioration in transparency and tearability.

[0011] Copolymer of ethylene, methyl acrylate and maleic anhydride １ 1 is an example of a H-NMR spectrum for quantifying each structural unit contained in an olefin copolymer. １ 1 is an example of a H-NMR spectrum.

[0012] The resin composition of the present invention will be described in detail below for each item. In this specification, "(meth)acrylic acid" means acrylic acid or methacrylic acid. In addition, in this specification, the term "to" indicating a numerical range is used to mean that the numerical values ​​before and after it are included as the lower limit and upper limit.

[0013] (1) Compatibilizer Resin The copolymer used in the compatibilizer resin of the present invention is an ethylene-(meth)acrylate copolymer (P) having 70 to 99 mol% of structural units derived from ethylene, 0.99 to 29.99 mol% of structural units derived from a (meth)acryloyloxy group-containing compound, and 0.001 to 5 mol% of structural units derived from an unsaturated dicarboxylic acid anhydride, and having a melt flow rate of 0.01 to 1,000 g / 10 min measured under conditions of a temperature of 190°C and a load of 2.16 kg. As the ethylene, ethylene derived from petroleum sources or non-petroleum sources such as plant sources can be used.

[0014] The (meth)acryloyloxy group-containing compound is H ２ C=CHC(=O)O- or H ２ C=C(CH ３ The (meth)acryloyloxy group-containing compound has polarity based on the ester bond (-C(=O)O-), and therefore imparts polarity to the copolymer, giving the copolymer affinity with polar resins such as polyamide. Such compounds are represented by the formula H ２ C=C(R ２ ) C(=O)O-R １ Examples of the esters of (meth)acrylic acid (i.e., (meth)acrylates) include those which can be represented by the following formula:

[0015] The above formula H ２ C=C(R ２ ) C(=O)O-R １ In this case, R １ is a hydrocarbon group which may have a substituent. The hydrocarbon group is a linear, branched or cyclic hydrocarbon group having 1 to 20 carbon atoms, preferably 1 to 8 carbon atoms, and may have a structure in which a linear or branched hydrocarbon portion and a cyclic hydrocarbon portion are combined. In addition, one or more positions on the carbon chain of the hydrocarbon group may be an oxygen atom, a carbonyl group (C═O), a sulfur atom or —NR ３ - group (where R ３ is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms). Examples of the substituent that the hydrocarbon group has include a halogen atom, a hydroxy group, a carboxyl group, an isocyanato group, and —NR ３２ Examples of such groups include alkyl groups having 1 to 6 carbon atoms, alkyl groups having 1 to 6 carbon atoms, aryl groups having 6 to 14 carbon atoms, aryloxy groups having 6 to 14 carbon atoms, heterocyclic groups having 2 to 10 carbon atoms, trialkylsilyl groups, and trialkylsilyloxy groups. The positions at which the hydrocarbon group is substituted with these groups are not particularly limited, and the hydrocarbon group may be substituted with the same or different multiple substituents at two or more positions. R ２ is a hydrogen atom or a methyl group.

[0016] As the (meth)acrylate, at least one of an alkyl(meth)acrylate having an alkyl group having 1 to 8 carbon atoms and an alkoxyalkyl(meth)acrylate having an alkoxyalkyl group having 2 to 8 carbon atoms, which may have a substituent, can be used, and these can be used alone or in combination. Here, (meth)acrylate refers to acrylate or methacrylate.

[0017] Examples of alkyl (meth)acrylates that can be used include (meth)acrylates having a chain alkyl group such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and n-octyl (meth)acrylate, and (meth)acrylates having an alicyclic alkyl group such as cyclopentyl (meth)acrylate and cyclohexyl (meth)acrylate. Examples of substituted alkyl (meth)acrylates include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxy-3-chloropropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-(dimethylamino)ethyl (meth)acrylate, 2-(diethylamino)ethyl (meth)acrylate, glycidyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, 2-(trimethylsilyloxy)ethyl (meth)acrylate, 2-isocyanatoethyl (meth)acrylate, and tetrahydrofurfuryl (meth)acrylate. Examples of compounds in which a portion of the alkyl group is interrupted by a group containing a heteroatom include mono(2-acryloyloxyethyl) succinate and 2,2,6,6-pentamethyl-4-piperidyl (meth)acrylate. Because the acrylate structure exhibits affinity with polar resins, there are no particular limitations on the choice of monomer as long as the compound is one of these.

[0018] Examples of alkoxyalkyl (meth)acrylates that can be used include methoxymethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, n-butoxyethyl (meth)acrylate, ethoxypropyl (meth)acrylate, methoxyethoxyethyl (meth)acrylate, and ethoxyethoxyethyl (meth)acrylate. Alkoxyalkyl (meth)acrylates may have a structure in which an alkoxyalkyl group is further substituted with one or more alkoxy groups. Examples of such compounds include diethylene glycol monomethyl ether (meth)acrylate, polytetramethylene glycol monomethyl ether (meth)acrylate, and polytetraethylene glycol monomethyl ether (meth)acrylate.

[0019] The unsaturated dicarboxylic acid anhydride is a compound having one or more radically polymerizable unsaturated bonds and one or more acid anhydride groups in the molecule. Examples thereof include maleic anhydride, citraconic anhydride, itaconic anhydride, 2,3-dimethylmaleic anhydride, 2-(2-carboxyethyl)-3-methylmaleic anhydride, 3,4,5,6-tetrahydrophthalic anhydride, phenylmaleic anhydride, 2,3-diphenylmaleic anhydride, allylsuccinic anhydride, (2-methyl-2-propenyl)succinic anhydride, 2-buten-1-ylsuccinic anhydride, cis-4-cyclohexene-1,2-dicarboxylic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, and bicyclo[2.2.2]oct-5-ene-2,3-dicarboxylic anhydride. Preferably, maleic anhydride, itaconic anhydride, and citraconic anhydride are used. These may be used alone or in combination of two or more. Acid anhydrides have affinity with polar resins and are thought to improve dispersibility by reacting with polar groups. Therefore, the copolymer (P) of the present invention containing an unsaturated dicarboxylic acid anhydride as a constituent unit is particularly useful for improving compatibility with polyamides.

[0020] In addition to the above-mentioned monomers, the copolymer (P) used in the present invention can also contain, if necessary, other copolymerizable monomers within the range that does not impair its properties, such as vinyl compounds such as styrene, vinyltoluene, α-methylstyrene, vinylnaphthalene, acrylonitrile, methacrylonitrile, acetone acrylamide, vinyl chloride, vinylidene chloride, vinyl fluoride, chloroethyl vinyl ether, hydroxyethyl vinyl ether, and hydroxybutyl vinyl ether; diene compounds such as isoprene, pentadiene, and butadiene; and α-olefins such as propylene, 1-butene, 1-hexene, and 1-octene. α-olefins have the structural formula: CH ２ = CHR １ is an α-olefin having 3 to 20 carbon atoms, represented by (R １ is a hydrocarbon group having 1 to 18 carbon atoms, which may have a linear structure or may be branched.) The number of carbon atoms in the α-olefin is more preferably 3 to 12. Specific examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 3-methyl-1-butene, and 4-methyl-1-pentene.

[0021] The method for producing the copolymer (P) is not particularly limited, and polymerization methods such as solution polymerization and high-pressure polymerization can be used as appropriate. Generally, it can be produced using high-pressure low-density polyethylene production equipment and related technology. For example, it is produced by high-pressure polymerization at a polymerization pressure of 70 to 350 MPa, preferably 100 to 250 MPa, and a polymerization temperature of 100 to 300°C, preferably 150 to 270°C. If the polymerization pressure is less than 70 MPa, the molecular weight of the polymer decreases, resulting in poor moldability and poor resin physical properties of the resin composition. Since the physical properties of the copolymer (P) may affect the physical properties of molded articles such as films obtained from the composition with recycled resins, it is preferable to use a production method set within the above range. On the other hand, if the pressure exceeds 350 MPa, it simply increases production costs and is essentially meaningless. Furthermore, if the polymerization temperature is less than 100°C, the polymerization reaction is unstable, resulting in a low conversion rate to the copolymer, which is economically problematic. On the other hand, if the polymerization temperature exceeds 300°C, the molecular weight of the copolymer decreases and there is a risk of a runaway reaction.

[0022] Since dicarboxylic acid anhydrides have poor polymerization stability, a high degree of homogenization within the reactor is necessary. If necessary, multiple reactors can be connected in series or parallel to perform multi-stage polymerization. Furthermore, by dividing the reactor into multiple zones, more precise temperature control is possible. The polymerization reaction rate can be adjusted by adjusting the temperature of the ethylene used for polymerization; the greater the temperature difference between the polymerization temperature and the ethylene, the higher the polymerization reaction rate.

[0023] The polymerization reaction is carried out in the presence of at least one free radical polymerization initiator. The free radical polymerization initiator used in the radical polymerization is selected from compounds that generate free radicals, and examples thereof include oxygen, dialkyl peroxides such as di-tert-butyl peroxide, tert-butylcumyl peroxide, and dicumyl peroxide, diacyl peroxides such as acetyl peroxide, isobutyl peroxide, and octanoyl peroxide, peroxydicarbonates such as diisopropyl peroxydicarbonate and di(2-ethylhexylperoxy)dicarbonate, tert-butylperoxyisobutyrate, and tert-butyl peroxyisobutyrate. Examples of the peroxyester include methyl peroxy neodecanate, tert-butyl peroxy pivalate, and tert-butyl peroxy laurate; ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide; peroxy ketals such as 1,1-bis-tert-butylperoxycyclohexane and 2,2-bis-tert-butylperoxyoctane; hydroperoxides such as tert-butyl hydroperoxide and cumene hydroperoxide; and azo compounds such as 2,2-azobisisobutyronitrile.

[0024] The copolymer (P) used in the present invention contains 70 to 99 mol% of ethylene-derived structural units, 0.99 to 29.99 mol% of (meth)acryloyloxy group-containing compound-derived structural units, and 0.001 to 5 mol% of unsaturated dicarboxylic acid anhydride-derived structural units. Furthermore, some of the unsaturated dicarboxylic acid anhydride-derived structural units may be ring-opened with water, provided that the effects of the present invention are not impaired. Here, the content of the unsaturated dicarboxylic acid generated by ring-opening is calculated assuming that it is a structural unit derived from the unsaturated dicarboxylic acid anhydride.

[0025] The proportion of the structural units derived from ethylene in the copolymer (P) is 70 to 99 mol%, preferably 80 to 99 mol%, and more preferably 85 to 99 mol%, when the total of the structural units of ethylene, the (meth)acryloyloxy group-containing compound, and the unsaturated dicarboxylic acid anhydride is taken as 100 mol%.

[0026] The proportion of the structural units derived from the (meth)acryloyloxy group-containing compound in the copolymer (P) is 0.99 to 29.99 mol%, preferably 0.99 to 20 mol%, and more preferably 0.99 to 15 mol%, when the total of the structural units of ethylene, the (meth)acryloyloxy group-containing compound, and the unsaturated dicarboxylic acid anhydride is taken as 100 mol%. If the proportion of the (meth)acryloyloxy group-containing compound is low, transparency and flexibility may be impaired, while if the proportion of the (meth)acryloyloxy group-containing compound is high, it may be difficult to homogenize with polyethylene, resulting in a poor appearance.

[0027] The proportion of structural units derived from unsaturated dicarboxylic acid anhydrides in copolymer (P) is 0.001 to 5 mol%, or may be 0.001 to 2 mol%, or 0.01 to 1 mol%, or may be 0.01 to 0.8 mol%, when the sum of the structural units of ethylene, the (meth)acryloyloxy group-containing compound, and the unsaturated dicarboxylic acid anhydride is taken as 100 mol%. A low proportion of unsaturated dicarboxylic acid anhydride may result in reduced affinity with polar resins, making it difficult to achieve sufficient effectiveness as a compatibilizer. On the other hand, a low proportion of unsaturated dicarboxylic acid anhydride is preferable because it reduces the viscosity of copolymer (P) and improves compatibility. Furthermore, a high proportion of unsaturated dicarboxylic acid anhydride may not increase the molecular weight of copolymer (P), making it difficult to obtain a film with high tear strength. Furthermore, a high proportion of unsaturated dicarboxylic acid anhydride may cause gel formation during molding, preventing the production of a transparent film. Furthermore, as long as the effects of the present invention are not impaired, some of the structural units derived from unsaturated dicarboxylic acids may be ring-opened by water.

[0028] By setting the ratio of these monomers in the copolymer (P) within the above range, it is possible to contain moieties with high affinity for polar resins and non-polar resins in appropriate proportions, thereby improving compatibility with other resins. The ratio of each monomer can be controlled by adjusting the amount of each monomer used in the polymerization reaction, particularly the amount of the (meth)acryloyloxy group-containing compound and the unsaturated dicarboxylic acid anhydride. Here, the polar resin refers to a resin having a heteroatom (oxygen, nitrogen, sulfur, etc.), specifically polyamide or polyester. The non-polar resin refers to a resin not having a heteroatom (oxygen, nitrogen, sulfur, etc.), specifically polyethylene or polypropylene.

[0029] The amount of structural units derived from a (meth)acryloyloxy group-containing compound or an unsaturated dicarboxylic acid anhydride in a copolymer can be quantified by nuclear magnetic resonance spectroscopy (NMR). Non-Patent Document 1 describes an analytical method for ethylene-acrylic acid ester copolymers, and those skilled in the art can quantify the comonomer content according to this method. However, in a terpolymer of an olefin, a (meth)acryloyloxy group-containing compound, and maleic anhydride or its derivative, as in the present invention, carbonyl groups are present in both the acrylic acid ester and the maleic anhydride (derivative), and the peaks used for quantification are observed in close proximity, which often leads to ambiguity in the integration of signal areas and makes quantification difficult. Therefore, in the present invention, according to the method described in Patent Document 5, maleic anhydride (derivative) is first reacted with an amine compound to convert the maleic anhydride moiety into an amide or imide, and this is used as a measurement sample for NMR measurement to quantify the content of the (meth)acryloyloxy group-containing compound and the content of maleic anhydride or its derivative. As a specific example, a method of converting maleic anhydride, an unsaturated dicarboxylic acid anhydride, into an amide or imid and then quantifying it by NMR will be described.

[0030] The solvent used for solution NMR measurement is not limited as long as it can dissolve the amide or imide form of the olefin copolymer. However, it is preferable to use a solvent that has a chemical shift at a position that does not overlap with the signal derived from the proton of the amine compound. Furthermore, if the compound does not emit a signal at a position that overlaps with the chemical shift of the main chain portion of the polymer, the accuracy of quantification will be improved. Examples of such solvents include chloroform (near δ = 7.26 ppm), dichloromethane (near δ = 5.32 ppm), tetrachloroethane (near δ = 5.96 ppm), and diethyl ether (near δ = 3.34 ppm). Chloroform or tetrachloroethane, which produce a single signal at a position that does not overlap with the olefin copolymer, are more preferred as the measurement solvent. The measurement solvent used in this method may be a deuterated version (heavy solvent) of the above solvent.

[0031] １ The method for measuring H-NMR is known to those skilled in the art. Those skilled in the art can appropriately set the apparatus, method, and measurement conditions normally used in NMR measurement of polymers. An example of a specific method will be described in the Examples, but the method of the present invention is not limited thereto. The amount of comonomer is calculated by １ It can be calculated from the ratio of the integrated intensities of each signal in H-NMR. The specific calculation method varies depending on the amine compound used and the olefin-based copolymer of interest, but the proportion of comonomer can be quantified by identifying (i) the signal of hydrogen possessed by the polymer main chain, (ii) the signal of hydrogen possessed by the portion to which the ester group of the acrylic ester is bonded or the signal of hydrogen possessed by the alkyl group of the ester group, and (iii) the signal of hydrogen possessed by the amide or imide portion derived from the amine compound and calculating their integrated ratios. These signals (i) to (iii) appear at positions that can be separated from each other, enabling highly accurate quantification.

[0032] To better understand this method, a specific example is provided. Figure 1 shows a typical copolymer of ethylene, methyl acrylate, and maleic anhydride. １ ​The H-NMR spectrum is shown as an example. The chemical formula below shows the correspondence between the NMR signals and the chemical structure. (*The letters attached to each carbon correspond to the letters indicating the NMR chemical shift positions in the figure.)

[0033] In an olefin copolymer obtained by polymerizing an olefin, an acrylic acid ester or methacrylic acid ester, and maleic anhydride or its derivative, the signal (e) of maleic anhydride at 2.50 to 2.68 ppm is detected at the tail of the signal (b) of methyl acrylate at 2.17 to 2.68 ppm, and the two cannot be sufficiently separated. The amount of maleic anhydride is often designed to be lower than the amount of acrylic acid ester, and when the difference between the amounts of methyl acrylate and maleic anhydride in the olefin copolymer is large, the signal (e) of maleic anhydride may be buried in the signal (b) of methyl acrylate and may not be detected.

[0034] By reacting the olefin copolymer (measurement sample) with an amine compound to convert the maleic anhydride moiety to an amide or imide, the signal that appeared at 2.50 to 2.68 ppm can be shifted to a different location. The structure below shows the imide formed by reacting the maleic anhydride moiety with 1-(3-aminopropyl)imidazole.

[0035] After this reaction, the terpolymer １ The H-NMR spectrum is shown in Figure 2. The signals h and i of the imide-formed maleic anhydride moiety appear independently at 7.0 to 7.6 ppm, making integration easy. Meanwhile, the signal of methyl acrylate remains unchanged and is detected at 2.50 to 2.68 ppm. This method allows the NMR signals originating from the maleic acid moiety to be detected independently, enabling the accurate quantification of the maleic acid content of olefin copolymers.

[0036] The melt flow rate (MFR) (190°C, 2.16 kg load) of the copolymer (P) used in the present invention is 0.01 to 1000 g / 10 min, preferably 0.1 to 600 g / 10 min, and more preferably 0.1 to 100 g / 10 min. If the resin's MFR is less than 0.01 g / 10 min, it will be difficult to mix with other components and will not perform as a compatibilizer. Similarly, if it exceeds 1000 g / 10 min, it will be difficult to mix with other components and will not perform as a compatibilizer. The MFR of the copolymer (P) is a value measured in accordance with JIS K7210:2014 under conditions of 190°C and 2.16 kg load.

[0037] The compatibilizer resin of the present invention contains the copolymer (P), but may also contain other known resins used as compatibilizers to form a compatibilizer resin composition, provided that the effects of the present invention are not impaired. When other compatibilizers are contained, the content of the copolymer (P) in the compatibilizer resin composition is preferably in the range of 1 to 50% by mass, more preferably 1 to 35% by mass, based on the total composition.

[0038] (2) Resin Composition One aspect of the present invention is a resin composition comprising the above-mentioned compatibilizer resin (A), polyolefin (B), and polymer (C) which does not fall under either the above-mentioned compatibilizer resin or polyolefin.

[0039] The amount of the compatibilizer resin (A) contained in the resin composition is preferably 0.1 to 35% by mass relative to the total resin composition. A content of 0.1% by mass or more allows the compatibilizer to fully function, while a content of 35% by mass or less allows the film's properties to be maintained without significantly affecting the properties of other resins. Furthermore, by increasing the content of the compatibilizer resin, a film with higher transparency can be formed, and by reducing the content of the compatibilizer resin, tearability can be easily maintained. While the amount of the compatibilizer resin can be appropriately set depending on the required properties, it is more preferably in the range of 1 to 30% by mass, and even more preferably in the range of 5 to 20% by mass.

[0040] Examples of polyolefins (B) that can be mixed into the resin composition include copolymers of ethylene and an α-olefin, copolymers of ethylene and an olefin such as norbornene, ethylene polymers, or copolymers thereof modified with a carboxylic acid or a carboxylic anhydride such as maleic anhydride (but different from the copolymer (P)). These can be selected appropriately depending on the molding application, and may be one or more types. Preferred examples include polyethylene, polypropylene, and copolymers of ethylene and an α-olefin. Polyolefin (B) preferably contains a carboxylic acid or carboxylic anhydride-modified polyolefin (b1). There are no particular restrictions on (b1) as long as it is modified with a carboxylic acid or a carboxylic anhydride, and the modification method and the amount of carboxylic acid groups introduced by modification can be varied as desired. Preferred examples include graft-modified polyolefins. When the total amount of (B) is taken as 100% by mass, (b1) preferably accounts for 3 to 60% by mass, more preferably 5 to 55% by mass, and even more preferably 10 to 40% by mass.

[0041] The amount of polyolefin (B) in the resin composition can be appropriately set within the range of 20 to 94.9% by mass relative to 100% by mass of the total of (A) to (C), preferably 40 to 90% by mass, more preferably 50 to 80% by mass.

[0042] The polymer (C) that can be mixed into the resin composition and does not fall under either (A) or (B) above is not particularly limited as long as it is a polymer that can be used as a raw material for resin films, and a polymer having a functional group in the main chain or side chain can be used. Examples of the functional group include a functional group having a heteroatom selected from the group consisting of oxygen, nitrogen, and sulfur, and in the case of a side chain, an aromatic ring or a halogen atom. Specific examples of (C) include polyamide, polyester, ethylene-vinyl alcohol copolymer (EVOH), polystyrene, polyurethane, acrylic resin, and polyphenylene ether. Among these, polyamide, polyester, and ethylene-vinyl alcohol copolymer (EVOH) are preferred. These resins may be produced from bio-derived monomers. Using such resins further reduces the environmental impact and produces more desirable recycled products. Examples of polyamides that can be mixed into the resin composition include at least one lactam selected from the group consisting of ε-caprolactam, enantholactam, and lauryllactam; at least one aminocarboxylic acid selected from the group consisting of 6-aminocaproic acid, 7-aminoheptanoic acid, 8-aminooctanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid; 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,5-hexanediamine, 1,9-nonanediamine, 1,11-undecanediamine, 1,12-dodecanediamine; and α,ω-diaminopolypropylene. Preferred are polymers of at least one diamine selected from the group consisting of propylene glycol, m- or p-phenylenediamine, and / or at least one dicarboxylic acid selected from the group consisting of adipic acid, sebacic acid, dodecanedioic acid, glutaric acid, terephthalic acid, and isophthalic acid. Specific examples include polycapramide (6-nylon), polyhexamethylene adipamide (6,6-nylon), polyhexamethylene sebacamide (6,10-nylon), polyundecaneamide (11-nylon), poly-ω-aminoheptanoic acid (7-nylon), and poly-ω-aminononanoic acid (9-nylon).

[0043] Polyesters that can be mixed into the resin composition include aromatic ring-containing polyesters and aliphatic polyesters. Examples of aromatic ring-containing polyesters include polyalkylene (C2-24) terephthalates such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); polyalkylene (C2-24) isophthalates such as polyethylene isophthalate and polybutylene isophthalate; and poly-p-phenylene esters such as poly-p-phenylene malonate, poly-p-phenylene adipate, and poly-p-phenylene terephthalate. Examples of aliphatic polyesters include polybutylene adipate, polyethylene adipate, poly-ε-caprolactone, and polylactic acid.

[0044] The ethylene-vinyl alcohol copolymer (EVOH) that can be mixed into the resin composition is not particularly limited in terms of its physical properties such as molecular weight, ethylene content, density, etc. Any EVOH can be used. These polyamides, polyesters, and EVOH are known and commonly used, and commercially available products can be purchased and used as needed.

[0045] The amount of the polymer not corresponding to either (A) or (B) in the resin composition can be set appropriately depending on the application and target of molding within a range of 5.0 to 79% by mass relative to 100% by mass of the total of (A) to (C). A preferred range is 5 to 75% by mass, more preferably 10 to 70% by mass, even more preferably 15 to 50% by mass, and even more preferably 20 to 40% by mass. When the resin composition contains two or more types of polyamide, polyester, and EVOH, the ratio of each of these can be in any range.

[0046] Another aspect of the present invention relates to a resin composition obtained by kneading the above-mentioned compatibilizer resin with scrap molded products. When molding films or other products using resins, scrap materials other than the necessary parts are generated. While such scrap materials during molding and recycled molded products are recycled, their physical properties may change due to factors such as being melted at least once in the extruder during molding. In particular, in the case of multilayer films, which use multiple materials and may contain adhesive resins used to bond these resins, changes in physical properties are a concern. By using the above-mentioned compatibilizer resin, the present invention maintains high levels of transparency and tear resistance even before recycling, thereby improving recyclability.

[0047] The molding scrap (D) is not particularly limited as long as it is a resin composition derived from an article that has been subjected to a molding operation at least once and then recovered. It can include both scraps generated during the manufacturing process of molded articles and products that have been distributed as finished products and then recovered as recycled goods. Both scraps and recycled goods may include products that have been recycled more than once. It is preferable that at least a portion of the polyethylene resin and / or polyamide in the molding scrap (D) is derived from the molding scrap (D). Specifically, a mixture containing (d1) a polyolefin and (d2) one or more selected from the group consisting of polyamide, polyester, and EVOH is used. The quantitative ratio of (d1) to (d2) varies depending on the type of molded article from which the recovered molding scrap (D) is derived. For example, it can be 50 to 95% by mass of (d1) a polyolefin and 5 to 50% by mass of (d2) one or more selected from the group consisting of polyamide, polyester, and EVOH. When the molding scrap contains two or more types of polyamide, polyester, and EVOH, the ratio of each of these may be in any range.

[0048] The resin composition containing the recycled resin may be a resin composition obtained by kneading the above-mentioned molding scrap (D) with a compatibilizer. The mixing ratio of the molding scrap (D) to the compatibilizer may be, for example, 65 to 99.9 mass% of the molding scrap and 35 to 0.1 mass% of the compatibilizer, where the total of the molding scrap (D) and the compatibilizer is 100 mass%.

[0049] Furthermore, polyolefin (virgin material) not derived from molding scraps can be mixed into the resin composition and used. When polyolefin not derived from molding scraps is used, it can be used in an amount of more than 0% by mass to 95% by mass, where the total of the molding scraps and the compatibilizer is 100% by mass.

[0050] The method for producing the resin composition of the present invention is not particularly limited, and the resin composition can be produced by a method known per se. That is, the resin composition can be produced by melt-kneading the above-mentioned components in an appropriate device so as to have a composition appropriate for the intended use of the resin composition.

[0051] Each component can be blended in any form as needed and depending on its physical properties, for example, as a solid, a solution in which the component is dissolved in a solvent, or a slurry in which the component is dispersed in a solvent.

[0052] Examples of melt kneaders include those commonly used in the production of resin compositions, such as single-screw extruders, twin-screw extruders, conical extruders, straight extruders, Banbury mixers, roll mixers, Henschel mixers, Brabender plastographs, kneaders, and co-kneaders.

[0053] In melt-kneading, it is preferable to select a kneading method that can achieve good dispersion of each component, and it is usually preferable to use a single-screw extruder, twin-screw extruder, conical extruder, or Brabender Plastograph. When kneading using these devices, the blend of each component may be kneaded simultaneously, or each component may be kneaded separately.

[0054] The resin composition of the present invention can be molded into molded articles for various uses by various known methods. Examples of molding methods include injection molding (including gas injection molding), injection compression molding (press injection), extrusion molding, blow molding, calendar molding, inflation molding, uniaxially stretched film molding, biaxially stretched film molding, etc. Among these, extrusion molding and inflation molding are more preferred.

[0055] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. Measurement and evaluation of physical properties in the examples and comparative examples were carried out by the methods shown below.

[0056] [ １ H-NMR Measurement] [Sample Preparation] 200 mg of the sample obtained from each experimental example and deuterated tetrachloroethane (TCE-d ２ 2.4 ml of the solution was placed in an NMR sample tube with an inner diameter of 10 mm and dissolved uniformly in a block heater at 150°C. [Measurement conditions] １ H-NMR measurement conditions Apparatus: AV400 model manufactured by Bruker Japan Probe: 10 mmφ cryoprobe Sample temperature: 120°C Pulse angle: 4.5° Pulse interval: 2 seconds Number of accumulations: 512 Chemical shift: The proton signal of deuterated tetrachloroethane was set to 5.96 ppm, and the chemical shifts of signals due to other protons were set to this as the reference.

[0057] [Method for calculating the molar ratio of constituent units] １ The molar ratio of the constituent units was calculated from the signals at 3.3 to 4.0 ppm and 7.0 to 7.6 ppm in the H-NMR spectrum using the following formula: Maleic anhydride (MAH) content (mol %) = I ＭＡＨ × 100 / (I Ｅ +I ＭＡ +I ＭＡＨ ) Methyl acrylate (MA) content (mol%) = I ＭＡ × 100 / (I Ｅ +I ＭＡ +I ＭＡＨ ) where I ＭＡＨ , I ＭＡ , I Ｅ are the quantities shown in the following formulas: ＭＡＨ =I ７．０～７．６ / 2 I ＭＡ = (I ３．３～４．０ -I ＭＡＨ ×2) / 3 I Ｅ = (I ０．０～５．５ -I ＭＡＨ x8-I ＭＡIn the above formula, I represents the integrated intensity, and the subscript of I represents the range of the chemical shift. For example, I ０．０～５．５ indicates the integrated intensity of the signal detected between 0.0 ppm and 5.5 ppm. The properties of the resin compositions in the examples and comparative examples were measured as follows.

[0058] (1) Elmendorf tear strength Based on JIS K7128-2, the Elmendorf tear strength was evaluated using the following device. The measurement direction was the value in the horizontal direction (MD) relative to the machine direction of the film. Device: Digital Elmendorf tear tester, Model SA (manufactured by Toyo Seiki Seisakusho, Ltd.) Measurement environment: Temperature 23°C, humidity 50%

[0059] (2) Haze (%) Using a film having a thickness of 70 μm, the haze was measured in accordance with JIS-K7136-2000, and the transparency was evaluated based on the measured value.

[0060] <Polymerization of Ethylene-(Meth)acrylate Copolymer (P)> (Polymerization Example 1) A 5 L autoclave equipped with a stirrer (high-pressure low-density polyethylene plant equipment) was used, and feedstock (monomer composition) at the reactor inlet was continuously injected into the reactor so that the composition was 99.2 mol % ethylene, 0.69 mol % methyl acrylate, and 0.061 mol % maleic anhydride. Di-(2-ethylhexylperoxy)dicarbonate was continuously injected thereto as a reaction initiator, and polymerization was carried out while maintaining the polymerization pressure at 160 MPa and the polymerization temperature at 195°C. The composition of the obtained copolymer P1 is shown in Table 1.

[0061] (Polymerization Examples 2 and 3) In Polymerization Examples 2 and 3, polymerization was carried out under the conditions of the feed material composition, polymerization pressure, and polymerization temperature shown in Table 1 to obtain copolymers P2 and P3 shown in Table 1. The content was determined by NMR. The polymerization conditions in Polymerization Examples 1 to 3 and the physical properties of the polymers P1 to P3 are summarized in Table 1.

[0062]

[0063] Example 1 Novatec LL UF843 manufactured by Japan Polyethylene Co., Ltd. as polyolefin, Amilan CM1017 manufactured by Toray Industries, Inc. as polyamide, Modic M522 manufactured by Mitsubishi Chemical Corporation as adhesive resin, and ethylene-(meth)acrylate copolymer (P1) as compatibilizer were mixed in a ratio (mass ratio) of 48:28:19:5 and kneaded using a twin-screw kneader at a temperature of 240°C to obtain a resin composition. Pellets of the obtained resin composition were dried at 80°C for 48 hours and extruded using a film molding machine to obtain a film with a thickness of 70 μm.

[0064] Examples 2 to 5 The amount of ethylene-(meth)acrylate copolymer (P1) was changed to 9 mass%, 13 mass%, 23 mass%, and 31 mass%, respectively, and the other resins were used in the proportions shown in Table 2. The same procedures as in Example 1 were carried out to obtain each resin composition and a film having a thickness of 70 μm as shown in Table 2.

[0065] Examples 6 to 10 The same procedures as in Examples 1 to 5 were conducted except that the ethylene-(meth)acrylate copolymer (P) was changed from P1 to P2, and each resin composition and a film having a thickness of 70 μm were obtained as shown in Table 2.

[0066] Example 11 The same procedure as in Example 4 was conducted except that the ethylene-(meth)acrylate copolymer (P) was changed from P1 to P3, to obtain a resin composition and a film having a thickness of 70 μm as shown in Table 2.

[0067] As a comparative example, film molding was attempted in the same manner as in Examples 1 to 11, except that the polyethylene resin, polyamide, and adhesive resin were used in the proportions shown in Table 2. The results of each example and comparative example, as well as various physical properties of the film, are shown in Table 3 below.

[0068]

[0069]

[0070] In the comparative example in which no compatibilizer was used, it was not possible to obtain a uniform film in the first place, but by using the compatibilizer resin of the present invention in combination, it was possible to form a transparent and uniform film.

[0071] The present invention provides a resin for use as a compatibilizer that can provide a resin composition that maintains mechanical properties, transparency, etc. even after recycling and has excellent recyclability. Because the resin composition using the compatibilizer resin of the present invention has excellent recyclability, it can be used as a resin for various molded products that can be recycled, particularly multilayer films.

Claims

1. A resin composition obtained by kneading 0.1 to 35 mass% of a compatibilizer resin (A) containing an ethylene-(meth)acrylate copolymer (P) having 70 to 99 mol% of structural units derived from ethylene, 0.99 to 29.99 mol% of structural units derived from a (meth)acryloyloxy group-containing compound, and 0.001 to 5 mol% of structural units derived from an unsaturated dicarboxylic acid anhydride, and having a melt flow rate of 0.01 to 1,000 g / 10 min measured under conditions of a temperature of 190°C and a load of 2.16 kg; 94.9 to 20 mass% of a polyolefin (B); and 5 to 79 mass% of a polymer (C) that does not fall under either (A) or (B), wherein (B) contains 3 to 60 mass% of a carboxylic acid or carboxylic acid anhydride-modified polyolefin (b1), when the total amount of (B) is 100 mass%.

2. The resin composition according to claim 1, wherein the (meth)acryloyloxy group-containing compound is an alkyl (meth)acrylate and / or an alkoxyalkyl (meth)acrylate having an alkoxyalkyl group.

3. The resin composition according to claim 1, wherein (C) is at least one member selected from the group consisting of polyamide, polyester, and ethylene-vinyl alcohol copolymer (EVOH).

4. A resin composition obtained by kneading together 35-0.1 mass% of the compatibilizer resin (A) according to claim 1, 65-99.9 mass% of molding scrap (D) containing 50-95 mass% of polyolefin and 50-5 mass% of one or more members selected from the group consisting of polyamide, polyester and EVOH, and optionally 0-95 mass parts of polyolefin (B') not derived from molding scrap, per 100 mass parts of the total of the compatibilizer resin and the molding scrap.

5. The resin composition according to claim 4, wherein the Elmendorf tear strength in the machine direction (MD) of the film is 5 to 200 N / mm, measured according to JIS K7128-2 at a temperature of 23°C and a humidity of 50%.

6. The resin composition according to claim 4, which has a haze of 1 to 40% as measured using a 70 μm thick film in accordance with JIS-K7136-2000.

7. A compatibilizer resin comprising an ethylene-(meth)acrylate copolymer (P) having 70 to 99 mol% of structural units derived from ethylene, 0.99 to 29.99 mol% of structural units derived from a (meth)acryloyloxy group-containing compound, and 0.001 to 5 mol% of structural units derived from an unsaturated dicarboxylic acid anhydride, and having a melt flow rate of 0.01 to 1,000 g / 10 min measured under conditions of a temperature of 190°C and a load of 2.16 kg.

8. A recycled film formed using the resin composition according to claim 4.

9. A multilayer film comprising at least a layer (I) made of the resin composition according to claim 4 and a layer (II) made of one or more polymers selected from the group consisting of polyamide, polyester, and ethylene-vinyl alcohol copolymer (EVOH).

10. A method for producing a recycled film, comprising a step of melt-kneading 0.1 to 35 mass% of the compatibilizer resin (A) according to claim 1, 94.9 to 20 mass% of a polyolefin (B) containing 3 to 60 mass% of a carboxylic acid or carboxylic anhydride modified polyolefin (b1), and 5.0 to 79 mass% of a polymer (C) that does not fall under either (A) or (B).

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