Resin composition, molded article, sheet, film, regrind layer, multilayer structure, and methods for producing multilayer structure and molded article

Abstract

To provide a resin composition excellent in thermal stability.SOLUTION: The resin composition comprises a polypropylene resin (A) containing carbon-14, an ethylene-vinyl alcohol copolymer (B), and an acid-modified polyolefin resin (C). The ethylene-vinyl alcohol copolymer (B) contains an ethylene-vinyl alcohol copolymer (B1) and an ethylene-vinyl alcohol copolymer (B2) having different ratios of ethylene structural unit, and a difference in the content ratio of the ethylene structural unit between the ethylene-vinyl alcohol copolymer (B1) and the ethylene-vinyl alcohol copolymer (B2) is 4 mol% or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition, and also to a molded article, sheet, film, regrind layer, multilayer structure, and method for producing the multilayer structure and molded article, each containing the resin composition. [Background technology]

[0002] Conventionally, ethylene-vinyl alcohol copolymers (hereinafter sometimes referred to as "EVOH resins") have been mainly used as food packaging materials due to their excellent gas barrier properties and transparency. Sheets, films, etc. used as food packaging materials can be produced using the EVOH resins alone, but they are often blended with other thermoplastic resins to improve physical properties, or multilayer structures in which layers made of polyolefin resins or the like are laminated to impart other functions.

[0003] For example, in order to improve the gas barrier properties of molded articles against oxygen and water vapor, a resin composition has been proposed in which a resin primarily composed of polypropylene resin and EVOH resin contains maleic acid-modified polypropylene as a compatibilizer (see Patent Document 1 below). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2021 / 193318 Summary of the Invention [Problem to be solved by the invention]

[0005] According to the investigations of the present inventors, it has been found that although the resin composition disclosed in Patent Document 1 prevents a decrease in mechanical strength and prevents discoloration even when the recovered materials are reused as a resin composition, the thermal stability of the resin composition itself is still insufficient.

[0006] Under these circumstances, an object of the present invention is to provide a resin composition having excellent thermal stability. [Means for solving the problem]

[0007] In view of these circumstances, the present inventors have conducted extensive research and have found that a resin composition with excellent thermal stability can be obtained by using a (biomass-derived) polypropylene resin containing 14 carbon atoms instead of the conventional petroleum-derived polypropylene resin.

[0008] That is, the present invention has the following aspects. [1] A polypropylene resin (A) containing 14 carbon atoms, an ethylene-vinyl alcohol copolymer (B), and an acid-modified polyolefin resin (C), a resin composition, wherein the ethylene-vinyl alcohol copolymer (B) comprises an ethylene-vinyl alcohol copolymer (B1) and an ethylene-vinyl alcohol copolymer (B2) having different proportions of ethylene structural units, and the difference in the content of ethylene structural units between the ethylene-vinyl alcohol copolymer (B1) and the ethylene-vinyl alcohol copolymer (B2) is 4 mol % or more; [2] The resin composition according to [1], wherein the polypropylene resin (A) containing 14 carbon atoms comprises a bio-polypropylene resin. [3] The resin composition according to [1] or [2], wherein the following resin composition [α] is excluded from the resin composition: Resin composition [α] comprising: a polypropylene resin (A) containing 14 carbon atoms; an ethylene-vinyl alcohol copolymer (B); an acid-modified polyolefin resin (C); an aliphatic carboxylic acid (D) having 3 or more carbon atoms; and an aliphatic carboxylic acid metal salt (E) which is a metal salt of the aliphatic carboxylic acid (D), wherein the ethylene-vinyl alcohol copolymer (B) comprises an ethylene-vinyl alcohol copolymer (B1) and an ethylene-vinyl alcohol copolymer (B2) which differ in the proportion of ethylene structural units, and wherein the difference in the proportion of ethylene structural units between the ethylene-vinyl alcohol copolymer (B1) and the ethylene-vinyl alcohol copolymer (B2) is 4 mol % or more; and the metal species of the aliphatic carboxylic acid metal salt (E) is at least one element selected from the d-block elements of Period 4 of the Long Periodic Table. [4] The resin composition according to any one of [1] to [3], wherein the polypropylene resin (A) containing 14 carbon atoms is a homopolypropylene. [5] The resin composition according to any one of [1] to [4], wherein the polypropylene resin (A) containing 14 carbon atoms contains a linear aliphatic hydrocarbon having 10 to 24 carbon atoms. [6] The resin composition according to any one of [1] to [5], comprising at least an ethylene-vinyl alcohol copolymer (B1) having an ethylene structural unit content of 20 to 34 mol % and an ethylene-vinyl alcohol copolymer (B2) having an ethylene structural unit content of 35 to 60 mol %. [7] The resin composition according to any one of [1] to [6], wherein the ethylene-vinyl alcohol copolymer (B) contains 20 to 60 mol % of ethylene structural units. [8] The resin composition according to any one of [1] to [7], wherein the content of the ethylene-vinyl alcohol copolymer (B) is 0.01 to 15.0 mass % based on the total mass of the resin composition. [9] The resin composition according to any one of [1] to [8], wherein the content of the polypropylene resin (A) containing 14 carbon atoms is 10% by mass or more and 99% by mass or less based on the total resin composition.

[10] The resin composition according to any one of [1] to [9], wherein the content of the acid-modified polyolefin resin (C) is 0.1% by mass or more and 20% by mass or less based on the total mass of the resin composition.

[11] A sheet comprising the resin composition according to any one of [1] to

[10] .

[12] A film comprising the resin composition according to any one of [1] to

[10] .

[13] A regrind layer comprising the resin composition according to any one of [1] to

[10] .

[14] A multilayer structure comprising a regrind layer according to

[13] .

[15] The multilayer structure according to

[14] , further comprising a layer containing a polyolefin resin.

[16] The multilayer structure according to

[14] , further comprising an adhesive resin layer.

[17] The multilayer structure according to

[14] , further comprising a layer containing an ethylene-vinyl alcohol copolymer different from the regrind layer.

[18] A molded article obtained by molding the multilayer structure according to

[14] .

[19] A method for producing a multilayer structure, comprising a step of co-extruding the resin composition according to any one of [1] to

[10] .

[20] A method for producing a molded article, comprising the step of molding the multilayer structure according to

[14] . [Effects of the Invention]

[0009] The resin composition of the present invention has excellent thermal stability. Furthermore, molded articles, sheets, films, regrind layers, and multilayer structures containing the resin composition of the present invention also have excellent thermal stability. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described below based on examples of embodiments for carrying out the present invention, but the present invention is not limited to the embodiments described below.

[0011] In this specification, "x and / or y (x and y are optional configurations)" means at least one of x and y, and can mean three possibilities: x only, y only, or x and y. In this specification, when the expression "X to Y" (X and Y are any numbers) is used, unless otherwise specified, it means "X or more and Y or less," as well as "preferably more than X" or "preferably less than Y." In this specification, when it is expressed as "X or more" (X is any number) or "Y or less" (Y is any number), it also means "preferably more than X" or "preferably less than Y." In the present specification, when numerical ranges are described in stages, the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of another numerical range. In addition, in the numerical ranges described in this specification, the upper or lower limit of the numerical range can also be replaced with the values ​​shown in the examples. In this specification, the term "layer" also includes relatively thin layers such as "film," "tape," and "sheet."

[0012] A resin composition according to one embodiment of the present invention (hereinafter referred to as "the resin composition") contains a polypropylene resin (A) containing 14 carbon atoms, an EVOH resin (B), and an acid-modified polyolefin resin (C), and the EVOH resin (B) contains two or more types of EVOH resins having different ethylene structural unit content ratios.

[0013] From the viewpoint of thermal stability, it is preferable that the present resin composition does not contain the following resin composition [α]. Resin composition [α] comprising: a polypropylene resin (A) containing 14 carbon atoms; an ethylene-vinyl alcohol copolymer (B); an acid-modified polyolefin resin (C); an aliphatic carboxylic acid (D) having 3 or more carbon atoms; and an aliphatic carboxylic acid metal salt (E) which is a metal salt of the aliphatic carboxylic acid (D), wherein the ethylene-vinyl alcohol copolymer (B) comprises an ethylene-vinyl alcohol copolymer (B1) and an ethylene-vinyl alcohol copolymer (B2) which differ in the proportion of ethylene structural units, and wherein the difference in the proportion of ethylene structural units between the ethylene-vinyl alcohol copolymer (B1) and the ethylene-vinyl alcohol copolymer (B2) is 4 mol % or more; and the metal species of the aliphatic carboxylic acid metal salt (E) is at least one element selected from the d-block elements of Period 4 of the Long Periodic Table. Each component will be described below.

[0014] <Polypropylene resin containing carbon 14 (A)> The carbon-14-containing polypropylene resin (A) used in the present resin composition refers to a polypropylene resin obtained by chemical or biological synthesis using renewable biomass resources as raw materials. Carbon-14-containing polypropylene resin (A) has the advantage that, even when incinerated, it does not increase the carbon dioxide concentration in the atmosphere due to the carbon-neutrality of biomass.

[0015] The polypropylene resin (A) containing 14 carbon atoms is preferably a biopolypropylene resin derived from biopropanol obtained from plant raw materials, i.e., the polypropylene resin (A) containing 14 carbon atoms is preferably a plant-derived polypropylene resin.

[0016] In addition, plant (biomass resource) derived polypropylene resin and petroleum derived polypropylene resin do not differ in physical properties such as molecular weight and mechanical properties. Therefore, to distinguish between them, the bio-based content is generally used. The bio-based content refers to the carbon content of petroleum derived polypropylene resin. 14Since it does not contain C (radioactive carbon 14, half-life 5730 years), 14 The concentration of carbon-14 is measured by accelerator mass spectrometry and used as an index of the content of plant-derived bio-polypropylene resin. Therefore, if a film is made using plant-derived polypropylene resin, measuring the bio-based content of that film will result in a bio-based content that corresponds to the content of plant-derived polypropylene resin. In other words, polypropylene resin (A) containing carbon-14 is radioactive 14 C).

[0017] The biobased content can be determined, for example, by heating and stirring the resin composition in a water / methanol mixed solvent to dissolve the polypropylene resin, and then measuring the carbon-14( 14 The C) content can be determined by measuring it using the following method. The sample to be measured is burned to generate carbon dioxide, which is then purified in a vacuum line and reduced with hydrogen using iron as a catalyst to generate graphite. This graphite is then analyzed using a tandem accelerator-based 14 Attach it to the C-AMS dedicated device (manufactured by NEC) 14 Counting C, 13 The concentration of C ( 13 C / 12 C). 14 The concentration of C ( 14 C / 12 C) is measured, and the carbon content of the sample is compared to the standard modern carbon. 14 The C concentration ratio is calculated and the biobased content is determined in accordance with ASTM D6866.

[0018] The carbon-14 content of the carbon-14-containing polypropylene resin (A) is not particularly limited, but is usually 1.0 × 10 -14 or more, 1.0 × 10 -13 The upper limit is usually 1.2 × 10 -12 The range of the carbon-14 content in the polypropylene resin (A) containing carbon-14 is usually 1.0 × 10 -14 Over 1.2 x 10 -12 The following are examples.

[0019] This resin composition contains polypropylene resin (A) containing 14 carbon atoms in a resin composition containing EVOH resin (B), and therefore has superior thermal stability compared to resin compositions containing conventional petroleum-derived polypropylene resins.

[0020] The mechanism is thought to be as follows. It is known that petroleum-derived polypropylene resins are easily oxidized by heat, generating hydroperoxides and undergoing degradation reactions such as molecular weight reduction. One method for suppressing such thermal degradation is to add a hindered phenol or other antioxidant to improve the thermal stability of polypropylene. However, because the antioxidant easily interacts with the EVOH resin, the effect of improving thermal stability is not fully exerted, and particularly when a large amount is added, the discoloration prevention effect of the antioxidant tends to decrease and the mechanical properties tend to deteriorate. In such a resin composition containing polypropylene resin and EVOH resin as essential components, the use of polypropylene resin (A) containing carbon-14 strengthens the bond energy due to the primary isotope effect. As a result, it is presumed that the decomposition of polypropylene resin (A) containing carbon-14 itself is slowed down, and thermal stability is improved. Furthermore, since thermal stability can be improved without affecting EVOH resin (B), it is presumed that an excellent thermal stability improving effect is achieved.

[0021] The carbon-14 containing polypropylene resin (A) used in the present resin composition typically has a biobased content of 1 to 99%, preferably 5 to 95%, more preferably 10 to 90%, even more preferably 20 to 80%, and particularly preferably 30 to 70%. By setting the biobased content of the carbon-14 containing polypropylene resin (A) within the above range, a resin composition with better thermal stability can be obtained.

[0022] The type of "polypropylene resin" in the polypropylene resin (A) containing 14 carbon atoms is not particularly limited, and may be a homopolypropylene or a copolymer of propylene and a small amount of a comonomer. The copolymer may be in the form of a block copolymer or a random copolymer. For example, a copolymer consisting of propylene and less than 50% by mass of another α-olefin monomer, or a copolymer consisting of 3% or less by mass of a non-olefin monomer having a functional group can be used.

[0023] Examples of the other α-olefin monomers include ethylene, α-olefins having 4 to 20 carbon atoms, such as 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, and 3-methyl Examples of the alkyl esters include 4-methyl-1-butene, 4-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 9-methyl-1-decene, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene, etc. These may be used alone or in combination of two or more.

[0024] Examples of the non-olefin monomer include styrene monomers, diene monomers, cyclic monomers, oxygen atom-containing monomers, etc. These may be used alone or in combination of two or more.

[0025] Examples of the styrene monomer include styrene, 4-methylstyrene, and 4-dimethylaminostyrene.

[0026] Examples of the diene monomer include 1,3-butadiene, 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 1,4-octadiene, 1,5-octadiene, 1,6-octadiene, 1,7-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, 7-methyl-1,6-octadiene, 4-ethylidene-8-methyl-1,7-nonadiene, 4,8-dimethyl-1,4,8-decatriene (DMDT), dicyclopentadiene, cyclohexadiene, and dicyclooctadiene.

[0027] Examples of the cyclic monomer include methylenenorbornene, 5-vinylnorbornene, 5-ethylidene-2-norbornene, 5-isopropylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene, 2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-2,2-norbornadiene, and cyclopentene.

[0028] Examples of the oxygen atom-containing monomer include hexenol, hexenoic acid, and methyl octenoate.

[0029] The other α-olefin monomers and non-olefin monomers may be derived from renewable biomass resources or petroleum. When using those derived from renewable biomass resources, the bio-based content of the final product can be further increased. When using those derived from petroleum, a wide variety of them are available, so by using them in production, the physical properties of the polypropylene resin (A) containing 14 carbon atoms can be easily adjusted.

[0030] As described above, the polypropylene resin (A) containing 14 carbon atoms is obtained by homopolymerization of propylene or copolymerization of propylene with a comonomer, and the polymerization or copolymerization can be carried out in accordance with a conventional method using a metallocene catalyst or a Ziegler-Natta catalyst. Of these, it is preferable to use a metallocene catalyst.

[0031] The polypropylene resin (A) containing 14 carbon atoms may be used alone or in combination of two or more kinds. Among these, homopolypropylene derived from biopropylene, or ethylene-propylene block copolymer, ethylene-propylene random copolymer, or impact copolymer derived from biopropylene are preferred in terms of moldability, handling, and thermal stability, and homopolypropylene is particularly preferred.

[0032] The polypropylene resin (A) containing 14 carbon atoms may also contain a linear aliphatic hydrocarbon having 10 or more and 24 or less carbon atoms. When the carbon-14 containing polypropylene resin (A) contains linear aliphatic hydrocarbons having 10 to 24 carbon atoms, the content is typically 20% by mass or less relative to the total carbon-14 containing polypropylene resin (A). The lower limit is 0% by mass. The range of the content is typically 0% by mass or more and 20% by mass or less. When the linear aliphatic hydrocarbons are at most the upper limit, the effects of the present invention tend to be more effectively achieved.

[0033] The melt flow rate (MFR) (230°C, 2160 g load) of the polypropylene resin (A) containing 14 carbon atoms is usually 0.1 to 100 g / 10 min, preferably 0.5 to 80 g / 10 min, more preferably 1 to 60 g / 10 min, even more preferably 1.5 to 40 g / 10 min, and particularly preferably 2 to 20 g / 10 min. When the MFR is equal to or less than the upper limit, excellent film-forming properties tend to be obtained, and when the MFR is equal to or greater than the lower limit, the viscosity does not become too high and melt extrudability tends to be good.

[0034] Examples of commercially available polypropylene resins (A) containing carbon-14 that are preferably used in this embodiment include HP640J manufactured by Lyondellbasell.

[0035] The content ratio of the polypropylene resin (A) containing carbon-14 is usually 10% by mass or more, preferably 30% by mass or more, more preferably 50% by mass or more, still more preferably 70% by mass or more, and particularly preferably 80% by mass or more, based on the entire resin composition. The upper limit is 99% by mass, preferably 95% by mass. The range of such a content ratio is usually 10% by mass or more and 99% by mass or less, etc. By setting the content ratio of the polypropylene resin (A) containing carbon-14 within the above range, a resin composition with more excellent thermal stability can be obtained.

[0036] <EVOH resin (B)> The EVOH resin (B) used in this embodiment includes EVOH resin (B1) and EVOH resin (B2) with different ethylene structural unit content ratios, and the difference in the ethylene structural unit content ratio between EVOH resin (B1) and EVOH resin (B2) is 4 mol% or more. EVOH resin is usually a resin obtained by saponifying an ethylene-vinyl ester copolymer, which is a copolymer of ethylene and a vinyl ester monomer, and is a water-insoluble thermoplastic resin.

[0037] It is essential that the resin composition contains two or more types of EVOH resins with different ethylene structural unit content ratios. By including two or more types of EVOH resins with different ethylene structural unit content ratios, the EVOH resin having the ethylene structural unit with a lower content ratio of ethylene structural units contributes to excellent gas barrier properties, and the EVOH resin having the ethylene structural unit with a higher content ratio contributes to excellent moldability and mechanical properties. As a result, it becomes possible to achieve both gas barrier properties, moldability, and mechanical properties of the obtained resin composition, multilayer structure, and molded body.

[0038] The polymerization of ethylene and vinyl ester monomers can be carried out by any known polymerization method, such as solution polymerization, suspension polymerization, or emulsion polymerization, and solution polymerization using methanol as a solvent is generally used. The resulting ethylene-vinyl ester copolymer can also be saponified by a known method.

[0039] The EVOH resin produced in this manner is mainly composed of structural units derived from ethylene and vinyl alcohol structural units, and usually contains a small amount of vinyl ester structural units that remain unsaponified.

[0040] Vinyl acetate is typically used as the vinyl ester monomer because of its commercial availability and the efficiency of impurity removal during production. Examples of vinyl ester monomers other than vinyl acetate include aliphatic vinyl esters such as vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, and vinyl versatate, and aromatic vinyl esters such as vinyl benzoate. Aliphatic vinyl esters having typically 3 to 20 carbon atoms, preferably 4 to 10 carbon atoms, and particularly preferably 4 to 7 carbon atoms, can be used. These can be used alone or in combination of two or more.

[0041] The EVOH resin (B) may further contain structural units derived from the comonomers shown below within a range that does not impair the effects of the present invention (for example, 10 mol % or less of the EVOH resin). Examples of the comonomer include olefins such as propylene, 1-butene, and isobutene; hydroxyl group-containing α-olefins such as 3-butene-1-ol, 3-butene-1,2-diol, 4-pentene-1-ol, and 5-hexene-1,2-diol, and derivatives thereof such as esters and acylation products; hydroxyalkylvinylidenes such as 2-methylenepropane-1,3-diol and 3-methylenepentane-1,5-diol; 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2-methylenepropane, and 1,3-dibutyryloxy. hydroxyalkylvinylidene diacetates such as 2-methylenepropane; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, (anhydrous) phthalic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, or their salts or mono- or di-alkyl esters in which the alkyl group has 1 to 18 carbon atoms; acrylamide, N-alkylacrylamide in which the alkyl group has 1 to 18 carbon atoms, N,N-dimethylacrylamide, 2-acrylamidopropanesulfonic acid or its salts, acrylamidopropyldimethylamine or its acid salts or its quaternary salts, etc. Acrylamides; methacrylamide, N-alkylmethacrylamides in which the alkyl group has 1 to 18 carbon atoms, N,N-dimethylmethacrylamide, 2-methacrylamidopropanesulfonic acid or its salt, methacrylamidepropyldimethylamine or its acid salt or its quaternary salt; N-vinylamides such as N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide; vinyl cyanides such as acrylonitrile and methacrylonitrile; alkyl vinyl ethers in which the alkyl group has 1 to 18 carbon atoms, hydrochlorides vinyl ethers such as alkoxyalkyl vinyl ether and alkoxyalkyl vinyl ether; halogenated vinyl compounds such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride and vinyl bromide; vinyl silanes such as trimethoxyvinylsilane; halogenated allyl compounds such as allyl acetate and allyl chloride; allyl alcohols such as allyl alcohol and dimethoxyallyl alcohol; and comonomers such as trimethyl-(3-acrylamido-3-dimethylpropyl)-ammonium chloride and acrylamido-2-methylpropanesulfonic acid.These may be used alone or in combination of two or more.

[0042] Among these, hydroxyl group-containing α-olefins are preferred, and 3-butene-1,2-diol, 5-hexene-1,2-diol, and 2-methylenepropane-1,3-diol are particularly preferred. When the hydroxyl group-containing α-olefins are copolymerized, the resulting EVOH resin has primary hydroxyl groups in the side chains. Such EVOH resins having primary hydroxyl groups in the side chains, particularly EVOH resins having a 1,2-diol structure in the side chain, are preferred because they maintain gas barrier properties while exhibiting good secondary moldability.

[0043] In the case of an EVOH resin having a primary hydroxyl group in the side chain, the content of structural units derived from a monomer having the primary hydroxyl group is usually 0.1 to 20 mol %, preferably 0.5 to 15 mol %, and particularly preferably 1 to 10 mol %.

[0044] Furthermore, the EVOH resin used in this embodiment may be a "post-modified" EVOH resin such as urethanized, acetalized, cyanoethylated, or oxyalkylenated.

[0045] When the post-modified EVOH resin is used, the modification rate is usually 10 mol% or less, and preferably 4 mol% or less. When the modification rate of the EVOH resin is the upper limit or less, thermal degradation is suppressed and the long-run property tends to be excellent.

[0046] As described above, the EVOH resin (B) contains two or more EVOH resins having different ethylene structural unit content ratios. The number of EVOH resins having different ethylene structural unit content ratios is usually 2 to 4, preferably 2 to 3, and particularly preferably 2. When the number of types is within the above range, productivity and economy tend to be good.

[0047] The number of different EVOH resins with different content ratios of ethylene structural units contained in an EVOH resin can be determined from the number of peaks measured using a differential scanning calorimeter (DSC) described below. The content of each ethylene structural unit in the EVOH resin (B) can be determined, for example, by measuring the melting peak temperature and comparing it with the melting peak temperature of an EVOH resin having a known content of ethylene structural units. From the above, by measuring the melting peak temperature and the number of melting peaks of the EVOH resin, the content ratio of the ethylene structural unit of each of the two or more types of EVOH resin contained in EVOH resin (B) can be calculated. Furthermore, the melting peak temperature and the number of melting peaks of the EVOH resin (B) were measured, and these results and the 1 By combining this with the results of the content ratio of ethylene structural units obtained by H-NMR measurement and analyzing them, it is possible to calculate the blending ratio of each EVOH resin having a different content ratio of ethylene structural units. The melting peak temperature refers to the peak temperature measured using DSC when the temperature is increased from -50°C to 230°C at 10°C / min, decreased from 230°C to -50°C at 10°C / min, and then increased again from -50°C to 230°C at 10°C / min.

[0048] The EVOH resin (B) includes at least an EVOH resin (B1) and an EVOH resin (B2) having different ethylene structural unit contents.

[0049] The difference in the content of ethylene structural units between the EVOH resin (B1) and the EVOH resin (B2) in the EVOH resin (B) is 4 mol% or more, preferably 5 to 30 mol%, more preferably 6 to 25 mol%, and even more preferably 7 to 20 mol%. When the difference in the content ratio of such ethylene structural units is equal to or greater than the lower limit, uneven thickness and cracks tend to be less likely to occur during molding of the multilayer container, and when it is equal to or less than the upper limit, there is a tendency for the gas barrier properties to be reduced and for the appearance to be good.

[0050] From the viewpoints of gas barrier properties and container moldability, it is preferable that the content of ethylene structural units in the EVOH resin (B2) is higher than the content of ethylene structural units in the EVOH resin (B1).

[0051] From the viewpoints of gas barrier properties and container moldability, it is preferable that the EVOH resin (B1) is an EVOH resin having the smallest content of ethylene structural units among the EVOH resins (B), and that the EVOH resin (B2) is an EVOH resin having the highest content of ethylene structural units among the EVOH resins (B).

[0052] The ethylene content in the EVOH resin (B) can be controlled by the ethylene pressure when copolymerizing the vinyl ester monomer with ethylene, and is 20 to 60 mol%, preferably 23 to 55 mol%, and particularly preferably 25 to 50 mol%. When the ethylene content is equal to or less than the upper limit, the resin tends to have excellent gas barrier properties, and when the ethylene content is equal to or more than the lower limit, the resin tends to have good gas barrier properties and melt moldability under high humidity conditions.

[0053] The content of ethylene structural units in the EVOH resin (B1) is usually 20 to 34 mol%, preferably 20 to 32 mol%, more preferably 22 to 30 mol%, and even more preferably 25 to 30 mol%. When the content of ethylene structural units is at least the lower limit, secondary processability and flexibility tend to be excellent, and when it is at most the upper limit, gas barrier properties tend to be good.

[0054] The content of ethylene structural units in the EVOH resin (B2) is usually 35 to 60 mol%, preferably 35 to 55 mol%, more preferably 35 to 50 mol%, and even more preferably 38 to 48 mol%. When the content of ethylene structural units is at least the lower limit, secondary processability and flexibility tend to be excellent, and when it is at most the upper limit, gas barrier properties tend to be good.

[0055] In this specification, the content of the ethylene structural unit in the EVOH resin or resin composition is usually 1 It is measured by H-NMR measurement. For example, 1 H-NMR measurement is performed using DMSO-d6 as the measurement solvent at a measurement temperature of 50°C.

[0056] The degree of saponification of the vinyl ester component in the EVOH resin (B) can be controlled by the amount, temperature, time, etc. of the saponification catalyst (usually an alkaline catalyst such as sodium hydroxide) used when saponifying the ethylene-vinyl ester copolymer, and is usually 90 to 100 mol%, preferably 95 to 100 mol%, particularly preferably 99 to 100 mol%. If the degree of saponification is too low, the gas barrier properties, thermal stability, moisture resistance, etc. tend to decrease.

[0057] The saponification degree of the EVOH resin (B1) is usually 90 to 100 mol%, preferably 95 to 100 mol%, more preferably 99 to 100 mol%, and particularly preferably 99.5 to 100 mol%. When the saponification degree is within the above range, the gas barrier property, thermal stability, moisture resistance, etc. tend to be good.

[0058] The saponification degree of the EVOH resin (B2) is usually 90 to 99.7 mol%, preferably 93 to 99.5 mol%, and more preferably 95 to 99 mol%. When the saponification degree is equal to or greater than the lower limit, the gas barrier properties, thermal stability, moisture resistance, etc. tend to be good, and when it is equal to or less than the upper limit, the secondary processability and flexibility tend to be good.

[0059] In this specification, the saponification degree of the EVOH resin is usually 1 It is measured by H-NMR measurement. For example, 1 H-NMR measurement is performed using DMSO-d6 as the measurement solvent at a measurement temperature of 50°C.

[0060] The melt flow rate (MFR) of the EVOH resin (B) (210°C, 2160 g load) is usually 0.5 to 100 g / 10 min, preferably 1 to 50 g / 10 min, more preferably 2 to 35 g / 10 min, and even more preferably 3 to 25 g / 10 min. When the MFR is equal to or less than the upper limit, the film-forming property tends to be excellent, and when the MFR is equal to or more than the lower limit, the viscosity does not become too high and the melt extrudability tends to be good. The MFR is an index of the degree of polymerization of the EVOH resin, and can be adjusted by the amount of polymerization initiator and the amount of solvent used when copolymerizing ethylene and vinyl ester monomers.

[0061] The melt flow rate (MFR) (210°C, load 2160 g) of the EVOH resin (B1) is usually 1 to 100 g / 10 min, preferably 2 to 50 g / 10 min, and particularly preferably 3 to 10 g / 10 min. When the MFR is equal to or less than the upper limit, the mechanical strength of the molded product tends to be excellent, and when the MFR is equal to or more than the lower limit, the extrusion processability tends to be good.

[0062] The melt flow rate (MFR) (210°C, load 2160 g) of the EVOH resin (B2) is usually 1 to 100 g / 10 min, preferably 2 to 50 g / 10 min, and particularly preferably 3 to 30 g / 10 min. When the MFR is equal to or less than the upper limit, the mechanical strength of the molded product tends to be excellent, and when the MFR is equal to or more than the lower limit, the extrusion processability tends to be good.

[0063] In the combination of EVOH resin (B1) and EVOH resin (B2), it is preferable to adjust the molecular weight of each EVOH resin so that the difference (ΔMFR) in MFR (210°C, load 2160 g) is 5 g / 10 min or less, more preferably 1.5 g / 10 min or less, so that the flow properties of the resins during melt molding are similar. In this specification, MFR can be determined by measuring the rate at which a sample flows through an orifice with a length of 8 mm and a hole diameter of 2.095 mm under conditions of a temperature of 210°C and a load of 2160 g using an automatic melt flow rate tester (manufactured by Toyo Seiki Co., Ltd.).

[0064] The density of the EVOH resin (B) is 0.8 to 2.55 g / cm for both the EVOH resin (B1) and the EVOH resin (B2). 3 When the density of the EVOH resin (B) is within the above range, stable extrusion molding tends to be possible. In this specification, the density can be measured based on JIS Z8807.

[0065] The mass content ratio (B1 / B2) of the EVOH resin (B1) to the EVOH resin (B2) is usually 99 / 1 to 30 / 70, preferably 95 / 5 to 30 / 70, more preferably 90 / 10 to 40 / 60, and particularly preferably 85 / 15 to 50 / 50. When the content ratio of the EVOH resin (B1) is equal to or higher than the lower limit, the gas barrier property tends to be excellent, and when it is equal to or lower than the upper limit, uneven thickness and cracks tend to be less likely to occur during molding of the multilayer container.

[0066] The content of the EVOH resin (B) in the resin composition is not particularly limited, but is preferably 0.01 to 15.0 mass%, more preferably 0.05 to 13.0 mass%, even more preferably 0.1 to 9.9 mass%, particularly preferably 1.0 to 7.0 mass%, and most preferably 2.0 to 5.0 mass%, based on the total mass of the resin composition. When the value is within the above range, the effects of the present invention tend to be more effectively obtained.

[0067] In the resin composition, the mass ratio of the carbon-14 containing polypropylene resin (A) to the EVOH resin (B) [(A) / (B)] is usually 10 / 90 to 99 / 1, preferably 30 / 70 to 98 / 2, more preferably 50 / 50 to 97 / 3, even more preferably 70 / 30 to 95 / 5, and particularly preferably 80 / 20 to 94 / 6. When the mass ratio of the carbon-14 containing polypropylene resin (A) to the EVOH resin (B) is within the above range, a resin composition with better thermal stability can be obtained.

[0068] In addition, in the present resin composition, the proportion of the total content of the EVOH resin (B) and the polypropylene resin (A) containing 14 carbon atoms in the entire resin composition is not particularly limited, but is usually 70 mass% or more, preferably 75 mass% or more, and more preferably 80 mass% or more.

[0069] <Acid-modified polyolefin resin (C)> Examples of the acid-modified polyolefin resin (C) include graft-modified polyolefin resins obtained by graft-modifying polyolefin resins with acids, and olefin copolymers obtained by copolymerizing olefins with acids. These may be used alone or in combination of two or more. Among them, modified polyolefins graft-modified with unsaturated carboxylic acids and / or their derivatives are preferred. From the viewpoint of achieving better compatibility with the polypropylene resin (A) containing 14 carbon atoms, the acid-modified polyolefin resin (C) is preferably a polypropylene resin obtained by acid modification. That is, the acid-modified polyolefin resin (C) is preferably an acid-modified polypropylene, and preferably an acid-modified polypropylene obtained by modifying the same type of polypropylene resin as the polypropylene resin (A) containing 14 carbon atoms. The acid-modified polyolefin resin (C) is preferably an acid-modified polypropylene resin.

[0070] Examples of unsaturated carboxylic acids used to modify the acid-modified polyolefin resin (C) include acrylic acid, methacrylic acid, fumaric acid, itaconic acid, and maleic acid, and examples of derivatives thereof include acid anhydrides such as maleic anhydride and itaconic anhydride. Of these, maleic anhydride is most suitable.

[0071] Furthermore, from the viewpoint of more effectively obtaining the effects of the present invention, the acid-modified polyolefin resin (C) is preferably an acid-modified ethylene-α-olefin copolymer obtained by acid-modifying a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, more preferably an acid-modified ethylene-α-olefin copolymer obtained by acid-modifying a copolymer of ethylene and an α-olefin having 3 to 10 carbon atoms, even more preferably an acid-modified ethylene-α-olefin copolymer obtained by acid-modifying a copolymer of ethylene and an α-olefin having 2 to 8 carbon atoms, particularly preferably an acid-modified ethylene-butene copolymer, and especially preferably a maleic anhydride-modified ethylene-butene copolymer.

[0072] The acid-modified polyolefin resin (C) has a melt flow rate (MFR: 190°C, load 2160 g) of 0.01 to 15 g / 10 min, preferably 0.5 to 10 g / 10 min. When the MFR of the acid-modified polyolefin resin (C) is within the above range, the viscosity of the acid-modified polyolefin resin (C) and the polypropylene resin (A) are well balanced. As a result, the dispersibility of the EVOH resin (B) tends to be further improved.

[0073] The density of the acid-modified polyolefin resin (C) is 0.855 to 0.955 g / cm 3 When the density of the acid-modified polyolefin resin (C) is within the above range, stable extrusion molding tends to be possible.

[0074] The amount of unsaturated carboxylic acid and / or its derivative contained in the acid-modified polyolefin resin (C) is not particularly limited, but is preferably 0.001 to 20 mass %, more preferably 0.01 to 10 mass %, even more preferably 0.1 to 5 mass %, and particularly preferably 0.5 to 3 mass % of the acid-modified polyolefin resin (C). If the amount of unsaturated carboxylic acid and / or its derivative in the acid-modified polyolefin resin (C) is within the above range, the dispersibility of the EVOH resin (B) in the resin composition tends to be further improved.

[0075] The acid-modified polyolefin resin (C) may be used alone, or it is preferable to mix two or more types of resins that are different in type and physical properties before modification.

[0076] The content of the acid-modified polyolefin resin (C) in the resin composition is usually 0.1% by mass or more and 20% by mass or less, preferably 1% by mass or more and 15% by mass or less, more preferably 2% by mass or more and 13% by mass or less, even more preferably 3% by mass or more and 10% by mass or less, and particularly preferably 4% by mass or more and 9% by mass or less, based on the total mass of the resin composition. When the value is within the above range, the effects of the present invention tend to be more effectively obtained.

[0077] <Other ingredients> The resin composition may contain other resins (e.g., petroleum-derived polypropylene resins, other types of resins) and optional additives (hereinafter referred to as "other components") other than the polypropylene resin (A) containing 14 carbon atoms, the EVOH resin (B), and the acid-modified polyolefin resin (C) depending on the purpose, as long as the effects of the present invention are not significantly impaired. The other components may be used alone or in any combination and ratio of two or more.

[0078] Examples of the additives include antioxidants, ultraviolet absorbers, plasticizers, lubricants, fillers, and antistatic agents.

[0079] When the resin composition contains the "other components," the total content of these components is generally 30% by mass or less, preferably 20% by mass or less, and more preferably 10% by mass or less, relative to the resin composition. The lower limit is generally 0% by mass. The content is generally 0 to 30% by mass, etc.

[0080] <Method of manufacturing resin composition> The resin composition can be produced by mixing the essential components, namely, the carbon-14-containing polypropylene resin (A), the EVOH resin (B), and the acid-modified polyolefin resin (C), as well as the other components as needed. Examples of the mixing method include known methods such as a dry blending method, a melt mixing method in which a compound is obtained using a single-screw extruder or a twin-screw extruder, a solution mixing method, and an impregnation method, and these methods can be used in any combination. The carbon-14-containing polypropylene resin (A), EVOH resin (B), and acid-modified polyolefin resin (C) can be recycled resins obtained by pulverizing scraps of multilayer structures containing a carbon-14-containing polypropylene resin layer, an EVOH resin layer, and an acid-modified polyolefin resin layer.

[0081] The resin composition obtained in this manner is less likely to decompose under high temperature heating and has excellent thermal stability compared to conventional resin compositions obtained by combining EVOH resin and petroleum-derived polypropylene resin.

[0082] The biobased content of the resin composition is usually 0.01 to 99%, preferably 0.1 to 90%, more preferably 1 to 80%, even more preferably 1 to 70%, and particularly preferably 10 to 60%. By setting the biobased content of the resin composition within the above range, a resin composition with better thermal stability can be obtained.

[0083] The content of carbon-14 in the resin composition is not particularly limited, but the ratio of carbon-14 to the total carbon in the resin composition is usually 1.0 × 10 -16 or more, 1.0 × 10 -14The upper limit is usually 1.2 × 10 -12 is.

[0084] The melt flow rate (MFR) (210°C, 2160g load) of the present resin composition is usually 0.1 to 100g / 10min, preferably 0.5 to 90g / 10min, and more preferably 2 to 80g / 10min.

[0085] The water content of the present resin composition is usually 0.01 to 0.5% by mass, preferably 0.02 to 0.35% by mass, and more preferably 0.05 to 0.3% by mass.

[0086] The water content of the resin composition is measured and calculated by the following method. The mass (W1) of the resin composition before drying is weighed on an electronic balance, dried in a hot air dryer at 150°C for 5 hours, and then cooled in a desiccator for 30 minutes, after which the mass (W2) is weighed and calculated using the following formula. Moisture content (mass%)=[(W1-W2) / W1]×100

[0087] The present resin composition is prepared as a resin composition in various forms, such as pellets or powder, and is provided as a material for various molded articles and multilayer structures. As described above, the present resin composition has excellent thermal stability, so molded articles using the present resin composition or multilayer structures having layers using the present resin composition are of excellent quality. In particular, in this embodiment, when the present resin composition is provided as a material for melt molding, the effects of the present invention tend to be more efficiently obtained, which is preferable.

[0088] [Molded body] A molded article according to one embodiment of the present invention (hereinafter referred to as the "present molded article") is obtained by molding the present resin composition.

[0089] Examples of the shape of the present molded article include films, sheets, tapes, cups, trays, tubes, bottles, containers, pipes, filaments, irregular cross-section extrusions, various irregularly shaped articles, etc. That is, the present resin composition can be suitably used as any of films, sheets, tapes, cups, trays, tubes, bottles, containers, pipes, filaments, irregular cross-section extrusions, various irregularly shaped articles, etc.

[0090] The resin composition may be molded by any method that is generally applicable to resin compositions, such as extrusion molding, blow molding, injection molding, and thermoforming.

[0091] [Multilayer structure] A multilayer structure according to one embodiment of the present invention (hereinafter referred to as "the present multilayer structure") has at least one layer containing the present resin composition. The present multilayer structure can be further strengthened or endowed with other functions by being laminated with another substrate (hereinafter referred to as "substrate resin") whose main component is a thermoplastic resin other than the present resin composition. In this specification, the term "main component" refers to the component that accounts for the largest amount in the target, and typically accounts for preferably 50% by mass or more of the target, more preferably 60% by mass or more, even more preferably 70% by mass or more, particularly preferably 80% by mass or more, and especially preferably 90% by mass or more, or even 100% by mass. The range of the content is, for example, 50 to 100% by mass.

[0092] Examples of the base resin include polyethylene resins such as linear low-density polyethylene, low-density polyethylene, very low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene (block and random) copolymers, and ethylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers; polypropylene resins such as polypropylene resins and propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers; (unmodified) polyolefin resins such as polybutene, polypentene, and polycyclic olefin resins (polymers having a cyclic olefin structure in at least one of the main chain and the side chain); and resins obtained by converting these polyolefins into unsaturated carboxylic acids. Examples of the polyolefin resin include polyolefin resins in the broad sense, which include modified olefin resins such as unsaturated carboxylic acid-modified polyolefin resins graft-modified with carboxylic acid or its ester, ionomers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers, polyester resins, polyamide resins (including copolymerized polyamides), polyvinyl chloride, polyvinylidene chloride, acrylic resins, polystyrene resins, vinyl ester resins, polyester elastomers, polyurethane elastomers, polystyrene elastomers, halogenated polyolefins such as chlorinated polyethylene and chlorinated polypropylene, and aromatic or aliphatic polyketones.

[0093] Of these, polyamide resins, polyolefin resins, polyester resins, and polystyrene resins are preferred from the viewpoint of economy and productivity, and more preferred are polyolefin resins such as polyethylene resins, polypropylene resins, polycyclic olefin resins, and unsaturated carboxylic acid-modified polyolefin resins thereof.

[0094] The layer structure of the present multilayer structure can be any combination, such as a / b, b / a / b, a / b / a, a1 / a2 / b, a / b1 / b2, b2 / b1 / a / b1 / b2, or b2 / b1 / a / b1 / a / b1 / b2, where a (a1, a2, ...) represents the resin composition layer and b (b1, b2, ...) represents the base resin layer. It is also possible to provide a recycled layer containing a mixture of the present resin composition and the base resin, obtained by remelting and molding end portions or defective products generated during the manufacturing process of the multilayer structure. The total number of layers in the multilayer structure is usually 2 to 15, preferably 3 to 10. In the above layer structure, an adhesive resin layer containing an adhesive resin may be interposed between each layer, if necessary.

[0095] Known adhesive resins can be used, and may be selected appropriately depending on the type of thermoplastic resin used in the base resin layer "b." Representative examples include carboxyl-containing modified polyolefin polymers obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin resin through an addition reaction, a graft reaction, or the like. Examples of the carboxyl-containing modified polyolefin polymers include maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, maleic anhydride-grafted ethylene-propylene (block and random) copolymers, maleic anhydride-grafted ethylene-ethyl acrylate copolymers, maleic anhydride-grafted ethylene-vinyl acetate copolymers, maleic anhydride-grafted polycyclic olefin resins, and maleic anhydride-grafted polyolefin resins. One or a mixture of two or more selected from these can be used.

[0096] In the present multilayer structure, when an adhesive resin layer is used between the resin composition layer and the base resin layer, since the adhesive resin layers are located on both sides of the resin composition layer, it is preferable to use an adhesive resin with excellent hydrophobicity.

[0097] The base resin and adhesive resin may contain conventionally known plasticizers, fillers, clay (montmorillonite, etc.), colorants, antioxidants, antistatic agents, lubricants, core materials, antiblocking agents, waxes, etc., within a range that does not impair the spirit of the present invention (for example, 30% by mass or less, preferably 10% by mass or less, based on the total mass of the resin).

[0098] The resin composition and the substrate resin can be laminated (including through an adhesive resin layer) by a known method. Examples include a method of melt-extrusion laminating the substrate resin onto a film, sheet, etc. of the resin composition, a method of melt-extrusion laminating the resin composition onto a substrate resin layer, a method of co-extruding the resin composition and the substrate resin, a method of dry-laminating the resin composition layer and the substrate resin layer using a known adhesive such as an organic titanium compound, an isocyanate compound, a polyester compound, or a polyurethane compound, and a method of applying a solution of the resin composition onto the substrate resin and then removing the solvent. Among these, the method of co-extruding the resin composition and the substrate resin is preferred from the standpoints of cost and the environment.

[0099] The multilayer structure is subjected to a (heat) stretching treatment as necessary. The stretching treatment may be either uniaxial stretching or biaxial stretching, and in the case of biaxial stretching, it may be simultaneous stretching or sequential stretching. Furthermore, the stretching method may be a roll stretching method, tenter stretching method, tubular stretching method, stretch-blow method, vacuum pressure forming, or the like, whichever provides a higher stretch ratio. The stretching temperature is a temperature near the melting point of the multilayer structure, and is usually selected from the range of 40 to 170°C, preferably about 60 to 160°C. If the stretching temperature is too low, the stretchability will be poor, and if it is too high, it will be difficult to maintain a stable stretched state.

[0100] For the purpose of imparting dimensional stability, heat setting may be performed after stretching. Heat setting can be performed by known means, for example, by heat treating the stretched film while maintaining it in a tensile state, typically at 80 to 180°C, preferably 100 to 165°C, for typically 2 to 600 seconds. When the multilayer stretched film obtained from the present resin composition is used as a shrink film, heat shrinkability can be imparted by not performing the heat setting described above, but by performing a treatment such as cooling and setting the stretched film by applying cold air.

[0101] In some cases, the multilayer structure can be used to produce cup- or tray-shaped multilayer containers. In this case, a drawing method is typically used, specifically vacuum forming, pressure forming, vacuum-pressure forming, plug-assisted vacuum-pressure forming, etc. Furthermore, blow molding is used to produce tube- or bottle-shaped multilayer containers (laminate structure) from a multilayer parison (a hollow tubular preform before blowing). Specific examples include extrusion blow molding (two-head, mold-moving, parison-shift, rotary, accumulator, horizontal parison, etc.), cold parison blow molding, injection blow molding, and biaxial stretch blow molding (extrusion-type cold parison biaxial stretch blow molding, injection-type cold parison biaxial stretch blow molding, injection-molding in-line biaxial stretch blow molding, etc.). The resulting laminate may be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or melt coating treatment, bag making, deep drawing, box processing, tube processing, splitting processing, etc. as required.

[0102] The thickness of the multilayer structure (including the stretched one), as well as the thickness of the resin composition layer, substrate resin layer, and adhesive resin layer that make up the multilayer structure, cannot be generalized depending on the layer configuration, type of substrate resin, type of adhesive resin, intended use, packaging form, required physical properties, etc., but the thickness of the multilayer structure (including the stretched one) is usually 10 to 5,000 μm, preferably 30 to 3,000 μm, and particularly preferably 50 to 2,000 μm. The resin composition layer is usually 1 to 500 μm, preferably 3 to 300 μm, and particularly preferably 5 to 200 μm. The substrate resin layer is usually 5 to 3,000 μm, preferably 10 to 2,000 μm, and particularly preferably 20 to 1,000 μm. The adhesive resin layer is usually 0.5 to 250 μm, preferably 1 to 150 μm, and particularly preferably 3 to 100 μm.

[0103] Furthermore, the thickness ratio of the resin composition layer to the base resin layer in the multilayer structure (resin composition layer / base resin layer), when there are multiple layers, is typically 1 / 99 to 50 / 50, preferably 5 / 95 to 45 / 55, and particularly preferably 10 / 90 to 40 / 60, and when there are multiple layers, the thickness ratio of the resin composition layer to the adhesive resin layer (resin composition layer / adhesive resin layer), when there are multiple layers, is typically 10 / 90 to 99 / 1, preferably 20 / 80 to 95 / 5, and particularly preferably 50 / 50 to 90 / 10, and when there are multiple layers, the thickness ratio of the resin composition layer to the adhesive resin layer in the multilayer structure (resin composition layer / adhesive resin layer), when there are multiple layers, is typically 10 / 90 to 99 / 1, preferably 20 / 80 to 95 / 5, and particularly preferably 50 / 50 to 90 / 10, and when there are multiple layers, the thickness ratio of the resin composition layer to the adhesive resin layer is typically 10 / 90 to 99 / 1, preferably 20 / 80 to 95 / 5, and particularly preferably 50 / 50 to 90 / 10.

[0104] In the multilayer structure, the layer containing the resin composition is preferably a layer (regrind layer) formed using the resin composition (=recycled resin composition) containing a polypropylene resin layer containing 14 carbon atoms, an EVOH resin layer containing two or more EVOH resins with different ethylene structural unit content ratios, and an acid-modified polyolefin resin layer. Such a multilayer structure having a regrind layer will be described below.

[0105] The recycled materials of the multilayer structure containing a polypropylene resin layer containing 14 carbon atoms, an EVOH resin layer containing two or more EVOH resins with different ethylene structural unit content ratios, and an acid-modified polyolefin resin layer used to obtain the regrind layer are scraps, unnecessary parts such as edges, and defective products collected during the production process, or waste after the molded body has been used for various purposes.These recycled materials can be reused to prepare the present resin composition, which can be used to obtain the regrind layer.

[0106] To obtain the regrind layer, for example, the recycled material (a composition containing a carbon-14 polypropylene resin (A), an EVOH resin layer containing two or more EVOH resins with different ethylene structural unit content ratios, and an acid-modified polyolefin resin (C)) is appropriately combined with other optional components, and, if necessary, additional carbon-14 polypropylene resin (A), an EVOH resin layer containing two or more EVOH resins with different ethylene structural unit content ratios, and an acid-modified polyolefin resin (C) are added. By uniformly mixing these components, the present resin composition, which is a recycled resin composition, is obtained. The present resin composition is then melt-molded and co-extruded to obtain the present multilayer structure having a regrind layer.

[0107] In order to re-submit the recovered multilayer structure comprising the polypropylene resin layer containing 14 carbon atoms, the EVOH resin layer containing two or more EVOH resins having different ethylene structural unit content ratios, and the acid-modified polyolefin resin layer to melt molding using an extruder or the like, it is preferable to pulverize the recovered material. The recovered material can be pulverized using a known pulverizer. The shape and particle size of the pulverized product, as measured, for example, in accordance with the "5.3 Apparent Density" test method of JIS-K6891, are typically 0.25 to 0.85 g / mL, preferably 0.3 to 0.7 g / mL, and particularly preferably 0.35 to 0.6 g / mL. When the apparent density is equal to or greater than the lower limit, the dispersion of the EVOH resin in the regrind layer is improved, and the resulting regrind layer of the molded article tends to have excellent melt-moldability and mechanical properties. When the apparent density is equal to or less than the upper limit, feeding in the extruder is stabilized, and the melt-moldability of the regrind layer of the molded article tends to be improved.

[0108] The apparent density can be controlled by adjusting the shape of the crushing blade of the crusher, the number of revolutions of the crushing blade, the crushing processing speed, the size of the openings of the mesh used, and the like.

[0109] The multilayer structure having a regrind layer is generally preferably a multilayer structure that further includes, in addition to the regrind layer, a layer containing a polyolefin resin, an adhesive layer, and an EVOH resin layer, where the EVOH resin layer refers to a layer containing an EVOH resin different from the regrind layer.

[0110] The thickness of each layer of a regrind layer-containing multilayer structure cannot be generalized depending on the layer configuration, type of polyolefin resin, intended use, container form, required physical properties, etc., but the regrind layer is usually 5 to 5,000 μm, preferably 30 to 1,000 μm. The EVOH resin layer is usually 5 to 500 μm, preferably 10 to 200 μm. The polyolefin resin layer is usually 5 to 5,000 μm, preferably 30 to 1,000 μm. In this case, if an adhesive resin layer is present, the adhesive resin layer is usually 5 to 400 μm, preferably 10 to 150 μm.

[0111] The thickness ratio of the regrind layer to the polyolefin resin layer is usually 1 / 5 to 10 / 1, and preferably 1 / 2 to 5 / 1. The thickness ratio of the regrind layer to the EVOH resin layer is usually 1 / 1 to 100 / 1, and preferably 5 / 1 to 20 / 1.

[0112] The regrind layer-containing multilayer structure can be used to obtain, for example, cup- or tray-shaped multilayer containers by the same method as used to mold the multilayer structure.

[0113] The films, sheets, and bags made of the stretched films obtained as described above, and containers such as cups, trays, tubes, and bottles are useful as various packaging materials and containers for general foods, as well as seasonings such as mayonnaise and dressings, fermented foods such as miso, oily foods such as salad oil, beverages, cosmetics, pharmaceuticals, and the like. [Example]

[0114] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. In the examples, "parts" and "%" are by mass. Prior to the examples, the following ingredients were prepared:

[0115] [Polypropylene resin (A)] Polypropylene resin containing carbon-14 (A1): Homopolypropylene resin containing carbon-14 (LyondellBasell, HP640J), MFR (230°C, load 2160g) 3.2g / 10min, biomass content 40% or more, carbon-14 content 0.4ppt or more Petroleum-derived polypropylene resin (A'1): Polypropylene resin (manufactured by Japan Polypropylene Co., Ltd., FY6), MFR (230°C, load 2160g) 2.4g / 10min

[0116] [EVOH resin (B)] EVOH resin (B1-1): Ethylene structural unit content 29 mol%, MFR (230°C, load 2160 g) 3.8 g / 10 min, density 1.21 g / cm3 , Saponification degree 99.9 mol% EVOH resin (B2-1): Ethylene structural unit content 44 mol%, MFR (230°C, load 2160 g) 3.5 g / 10 min, density 1.14 g / cm 3 , Saponification degree 99.9 mol%

[0117] [Acid-modified polyolefin resin (C)] Acid-modified polyolefin resin (C1): Maleic acid graft-modified polyolefin resin (manufactured by Mitsubishi Chemical Corporation, Modic (registered trademark) P674V), MFR (230°C, load 2160 g) 3.4 g / 10 min, density 0.890 g / cm 3

[0118] Example 1 85.1% of a polypropylene resin (A1) containing carbon 14, 7.92% of an EVOH resin (B1-1), 1.98% of an EVOH resin (B2-1), and 5% of an acid-modified polyolefin resin (C1) were dry-blended together, and then fed into a twin-screw kneader at a rate of 12 kg / hour using a mass feeder. The resulting mixture was then strand-cut using a drum pelletizer to prepare a pelletized resin composition. The kneading conditions were as follows: [Mixing conditions] Twin-screw extruder: diameter 20 mm, L / D=48 (Toshiba Machine Co., Ltd.) ·Extruder setting temperature: C1 / C2 / C3 / C4 / C5 / C6 / H=100 / 180 / 210 / 210 / 230 / 230 / 230 Screw rotation speed: 460 rpm Take-up speed: 21.0 m / min

[0119] <Example 2 and Comparative Examples 1 to 5> Resin compositions of Example 2 and Comparative Examples 1 to 5 were prepared in the same manner as in Example 1, except that the types and amounts of each component were changed as shown in Table 1 below.

[0120] The following thermal stability evaluation was carried out using the obtained resin compositions of Examples 1 and 2 and Comparative Examples 1 to 5. The results are also shown in Table 1 below.

[0121] [Evaluation of thermal stability] [YI increase rate] The pellet-shaped resin compositions of Examples 1 and 2 and Comparative Examples 1 to 5 were pulverized at 650 rpm in a pulverizer (SKR16-240, manufactured by Sometani Sangyo Co., Ltd.) to obtain pulverized products of 1 to 5 mm square. The obtained pulverized material was filled into a cylinder having an inner diameter of 32 mm and a height of 30 mm, and the YI value before heating was measured in a state where the pulverized material was completely leveled using a spectrocolorimeter (manufactured by Nippon Denshoku Industries Co., Ltd.). The pulverized material was then heated in an oven under air at 100°C for 7 days, after which the YI value after heating was measured in the same manner. The ratio of the YI value after heating to the YI value before heating (YI increase rate) was calculated. A larger value indicates that the resin composition was more yellow after heating, which means that the thermal stability was poor.

[0122] [Table 1]

[0123] The results in Table 1 show that the resin compositions of Examples 1 and 2, which used the carbon-14 containing polypropylene resin (A1), had improved thermal stability compared to the resin compositions of Comparative Examples 1 and 2, which used the petroleum-derived polypropylene resin (A'1) corresponding to each Example. The reason for this is presumed to be that the carbon-14 containing polypropylene resin has stronger bond energy due to the primary isotope effect, which slows decomposition and improves thermal stability. Furthermore, the resin composition of Example 1, which contains a carbon-14 polypropylene resin (A1) and two or more EVOH resins with different ethylene structural unit content ratios, exhibits improved thermal stability compared to the resin composition of Comparative Example 3, which uses a carbon-14 polypropylene resin (A1) and only one EVOH resin. Similarly, the resin composition of Example 2, which contains a carbon-14 polypropylene resin (A1) and two or more EVOH resins with different ethylene structural unit content ratios, exhibits improved thermal stability compared to the resin compositions of Comparative Examples 4 and 5, which use a carbon-14 polypropylene resin (A1) and only one EVOH resin. This is presumably because the use of two or more EVOH resins with different ethylene structural unit content ratios allows radicals generated by thermal degradation to react preferentially with the EVOH resin with a higher ethylene structural unit content, thereby reducing radical reactions with the EVOH resin with a lower ethylene structural unit content. Therefore, it is presumed that the improved thermal stability of the EVOH resin with a lower ethylene structural unit content results in improved thermal stability compared to an EVOH resin with a single ethylene structural unit. Furthermore, Comparative Examples 1 and 2 are resin compositions in which the petroleum-derived polypropylene resin (A'1) was used instead of Comparative Examples 3 and 4, but it can be seen that neither of them has particularly superior thermal stability compared to Comparative Examples 3 and 4. Therefore, it can be seen that the thermal stability is significantly improved by using a resin composition containing a polypropylene resin (A1) containing 14 carbon atoms and two or more EVOH resins with different ethylene structural unit content ratios. The molded articles, sheets, films, regrind layers, and multilayer structures containing the resin compositions of Examples 1 and 2 also have excellent thermal stability. Furthermore, a multilayer structure having a regrind layer, a layer containing a polyolefin resin, an adhesive resin layer, and a layer containing an EVOH resin, and a molded article obtained by molding such a multilayer structure also have excellent thermal stability. [Industrial Applicability]

[0124] The present resin composition can have higher thermal stability than resin compositions using petroleum-derived polypropylene resins. Therefore, molded articles made from the present resin composition and multilayer structures having a layer containing the present resin composition are useful as materials for various packaging containers.

Claims

1. The composition contains a polypropylene resin (A) containing 14 carbon atoms, an ethylene-vinyl alcohol copolymer (B), and an acid-modified polyolefin resin (C), The ethylene-vinyl alcohol copolymer (B) comprises an ethylene-vinyl alcohol copolymer (B1) and an ethylene-vinyl alcohol copolymer (B2) having different proportions of ethylene structural units, and the difference in the content of ethylene structural units between the ethylene-vinyl alcohol copolymer (B1) and the ethylene-vinyl alcohol copolymer (B2) is 4 mol % or more.

2. The resin composition according to claim 1, wherein the carbon-14 containing polypropylene resin (A) comprises a bio-polypropylene resin.

3. The resin composition according to claim 1 or 2, wherein the following resin composition [α] is excluded from the resin composition: Resin composition [α] comprises a polypropylene resin (A) containing 14 carbon atoms, an ethylene-vinyl alcohol copolymer (B), an acid-modified polyolefin resin (C), an aliphatic carboxylic acid (D) having 3 or more carbon atoms, and an aliphatic carboxylic acid metal salt (E) which is a metal salt of the aliphatic carboxylic acid (D), wherein the ethylene-vinyl alcohol copolymer (B) comprises an ethylene-vinyl alcohol copolymer (B1) and an ethylene-vinyl alcohol copolymer (B2) which differ in the proportion of ethylene structural units, and the difference in the proportion of ethylene structural units between the ethylene-vinyl alcohol copolymer (B1) and the ethylene-vinyl alcohol copolymer (B2) is 4 mol % or more, and the metal species of the aliphatic carboxylic acid metal salt (E) is at least one element selected from the group consisting of elements belonging to the d block of Period 4 of the Long Form Periodic Table.

4. The resin composition according to claim 1 or 2, wherein the polypropylene resin (A) containing 14 carbon atoms is a homopolypropylene.

5. The resin composition according to claim 1 or 2, wherein the carbon-14 containing polypropylene resin (A) contains a linear aliphatic hydrocarbon having 10 to 24 carbon atoms.

6. The resin composition according to claim 1 or 2, comprising at least an ethylene-vinyl alcohol copolymer (B1) having an ethylene structural unit content of 20 to 34 mol% and an ethylene-vinyl alcohol copolymer (B2) having an ethylene structural unit content of 35 to 60 mol%.

7. 3. The resin composition according to claim 1, wherein the ethylene-vinyl alcohol copolymer (B) has an ethylene structural unit content of 20 to 60 mol %.

8. The resin composition according to claim 1 or 2, wherein the content of the ethylene-vinyl alcohol copolymer (B) is 0.01 to 15.0 mass% with respect to the entire resin composition.

9. The resin composition according to claim 1 or 2, wherein the content of the polypropylene resin (A) containing carbon-14 is 10% by mass or more and 99% by mass or less with respect to the entire resin composition.

10. The resin composition according to claim 1 or 2, wherein the content of the acid-modified polyolefin resin (C) is 0.1 mass % or more and 20 mass % or less with respect to the entire resin composition.

11. A sheet comprising the resin composition according to claim 1 or 2.

12. A film comprising the resin composition according to claim 1 or 2.

13. A regrind layer comprising the resin composition according to claim 1 or 2.

14. A multi-layer structure comprising the regrind layer of claim 13.

15. 15. The multilayer structure of claim 14, further comprising a layer comprising a polyolefin resin.

16. The multilayer structure of claim 14, further comprising an adhesive resin layer.

17. 15. The multilayer structure of claim 14, further comprising a layer comprising an ethylene-vinyl alcohol copolymer different from the regrind layer.

18. A molded article obtained by molding the multilayer structure according to claim 14.

19. A method for producing a multilayer structure, comprising a step of co-extruding the resin composition according to claim 1 or 2.

20. A method for producing a molded article, comprising the step of molding the multilayer structure according to claim 14.

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