Resin composition

Abstract

A resin composition for obtaining a molded product which has excellent appearance and in which even when a biopolyethylene resin is used, the occurrence of discoloration, deterioration in pellet shape, and die drool derived from polyethylene resins are inhibited, the composition comprising: a low-density biopolyethylene resin (A); an ethylene-vinyl alcohol copolymer (B) having an ethylene content of 20-60 mol%; and at least one component (C) selected from ethylene-vinyl acetate copolymers, acid-modified macromolecules, and ethylene-vinyl alcohol copolymers having an ethylene content of 70-90 mol%, wherein the low-density biopolyethylene resin (A) is not a straight-chain low-density biopolyethylene resin, and the weight ratio [(A) / (B)] of the component (A) to the component (B) is 10 / 90 to 49 / 51.

Description

Technical Field

[0001] The present invention relates to a resin composition, and more specifically, even when a biopolyethylene-based resin is used, it relates to a resin composition that suppresses the generation of eye droppings and provides a molded article with excellent appearance.

Background Art

[0002] Conventionally, ethylene-vinyl alcohol copolymers have been mainly used as food packaging materials because of their excellent gas barrier properties and transparency. Sheets, films, etc. used as the above food packaging materials can be produced from the ethylene-vinyl alcohol copolymer alone, but usually, in order to impart water resistance, strength, and other functions, they are used as a multilayer structure laminated by melt molding of a polyolefin-based resin or the like through an adhesive layer.

[0003] On the other hand, in recent years, in order to reduce the environmental load, it has been considered to replace a part of the resin used in the above multilayer structure from a petroleum-derived resin to a resin derived from biomass resources such as plants (for example, see Patent Documents 1 to 3).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Disclosure of the Invention

Problems to be Solved by the Invention

[0005] The polyethylene-based resin derived from the biomass resource contains a large amount of low-molecular-weight components as compared with the polyethylene-based resin derived from petroleum. Therefore, when melt-molding a resin composition containing an ethylene-vinyl alcohol copolymer and a polyethylene-based resin derived from a biomass resource, the polyethylene-based resin derived from the biomass resource may be repelled from the resin composition as eye mucus at the discharge port of a kneader or the like. Depending on the type and amount of the polyethylene-based resin derived from the biomass resource used in the resin composition, discoloration and an increase in eye mucus derived from the polyethylene-based resin occur, and the appearance deteriorates, so further improvement is required. Also, when producing pellets from a resin composition, it is usually produced by extruding and cutting the melt-kneaded resin composition into strands. However, when the surface roughness during extrusion is large, cutting becomes difficult and defective-shaped pellets are likely to be produced. Since the above-mentioned defective-shaped pellets cause poor biting during processing and gel generation during film formation due to an increase in fine powder, the pellet shape is important. However, when producing pellets from a resin composition containing a polyethylene-based resin derived from a biomass resource, the surface roughness during extrusion is large and defective-shaped pellets are likely to be produced, so further improvement is required.

Means for Solving the Problems

[0006] As a result of intensive studies in view of the above circumstances, the present inventors have found that the above problems can be solved by blending a specific component with a base polymer containing a low-density biopolyethylene-based resin and an ethylene-vinyl alcohol copolymer having an ethylene content of 20 to 60 mol% in a specific ratio.

[0007] That is, the present invention provides the following [1] and [2]. [1] A resin composition containing a low-density biopolyethylene resin (A), an ethylene-vinyl alcohol copolymer (B) having an ethylene content of 20 to 60 mol%, and at least one component (C) selected from the group consisting of an ethylene-vinyl acetate copolymer, an acid-modified polymer, and an ethylene-vinyl alcohol copolymer having an ethylene content of 70 to 90 mol%, wherein the low-density biopolyethylene resin (A) is a low-density biopolyethylene resin excluding a linear low-density biopolyethylene resin, and the weight ratio [(A) / (B)] of the component (A) to the component (B) is 10 / 90 to 49 / 51. [2] The resin composition according to [1], wherein the content of the component (C) is 0.1 to 20 parts by weight with respect to 100 parts by weight in total of the component (A) and the component (B). [Advantages of the Invention]

[0008] The resin composition of the present invention can suppress deterioration of the pellet shape. Further, it can suppress the occurrence of die lines during molding and can suppress a decrease in appearance such as discoloration of the molded product. [Embodiments for Carrying Out the Invention]

[0009] Hereinafter, embodiments for carrying out the present invention will be specifically described, but the present invention is not limited thereto. In the present invention, the "ethylene-vinyl alcohol copolymer having an ethylene content of 20 to 60 mol%" may be referred to as "EVOH". In the present invention, "x and / or y (x and y are arbitrary configurations or components)" means three combinations: only x, only y, and x and y.

[0010] The resin composition of the present invention is obtained by blending a specific component (C) with a base polymer containing a low-density biopolyethylene resin (A) and EVOH (B) in a specific ratio. Hereinafter, each component will be described.

[0011] [Low-Density Biopolyethylene Resin (A)] The low-density biopolyethylene resin (A) used in the present invention is a low-density biopolyethylene resin (excluding linear low-density biopolyethylene resin (LLDPE, density 0.910 to 0.925 g / cm 3 )) with a density less than 0.925 g / cm 3 .

[0012] The above-mentioned "biopolyethylene resin" means a polyethylene resin obtained by chemically or biologically synthesizing using renewable biomass resources as raw materials. Even when the above biopolyethylene resin is incinerated, it has the characteristic of not increasing the carbon dioxide concentration in the atmosphere due to the carbon neutrality of biomass.

[0013] It is preferable to use plant-derived ethylene derived from bioethanol obtained from plant raw materials for the above biopolyethylene resin. That is, the above biopolyethylene resin is preferably a plant-derived polyethylene resin.

[0014] There is no difference in physical properties such as molecular weight, mechanical properties, and thermal properties between plant (biomass resource)-derived polyethylene resins and petroleum-derived polyethylene resins. Therefore, in order to distinguish between them, the biomass degree is generally used. The above biomass degree means that the carbon of petroleum-derived polyethylene resin does not contain 14 C (radioactive carbon 14, half-life 5730 years). Therefore, the concentration of this 14 C is measured by accelerator mass spectrometry and used as an index of the content ratio of plant-derived biopolyethylene resin. Therefore, for a film using a plant-derived polyethylene resin, when the biomass degree of the film is measured, it becomes the biomass degree corresponding to the content of the plant-derived polyethylene resin. That is, the biopolyethylene resin is characterized by containing radioactive carbon ( 14 C).

[0015] The biomass degree can be measured, for example, by the following method. The sample to be measured is burned to generate carbon dioxide, and the carbon dioxide purified by a vacuum line is reduced with hydrogen using iron as a catalyst to generate graphite. Then, this graphite is mounted on a 14 C-AMS dedicated device (manufactured by NEC Corporation) to 14 count 13 of 13 C, 12 concentration of 14 C ( 14 C / 12 C), 14 and the ratio of the carbon concentration of the sample carbon to the standard modern carbon is calculated from this measured value.

[0016] Examples of the low-density biopolyethylene-based resin (A) include a low-density biopolyethylene homopolymer and a low-density biopolyethylene copolymer obtained by polymerizing ethylene derived from bioethanol. The low-density biopolyethylene copolymer is a copolymer of ethylene and a small amount of comonomer, and is composed of, for example, ethylene and another α-olefin monomer having a weight fraction of less than 50%, or a non-olefin monomer having a functional group with a weight fraction of 3% or less.

[0017] Examples of the other α-olefins include α-olefins having 3 to 20 carbon atoms, such as propylene, 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, 3-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.

[0018] 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 kinds.

[0019] Examples of the styrene monomer include styrene, 4-methylstyrene, 4-dimethylaminostyrene, etc.

[0020] 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, dicyclooctadiene, etc.

[0021] Examples of the cyclic monomer include methylene norbornene, 5-vinyl norbornene, 5-ethylidene-2-norbornene, 5-methylene-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, cyclopentene, etc.

[0022] Examples of the oxygen atom-containing monomer include hexenol, hexenoic acid, methyl octenoate, etc.

[0023] The above-mentioned other α-olefins and non-olefin monomers may be made from renewable biomass resources as raw materials or from petroleum as raw materials. When using those made from renewable biomass resources as raw materials, the biomass degree of the final product can be further increased. Also, when using those made from petroleum as raw materials, since a wide variety of them are available, by using these to manufacture, the physical properties, etc. of the low-density biopolyethylene-based resin (A) can be easily adjusted.

[0024] The low-density biopolyethylene-based resin (A) used in the present invention can be obtained, for example, by homopolymerizing ethylene or copolymerizing ethylene and a comonomer according to a conventional method using a metallocene catalyst or a Ziegler-Natta catalyst. Among them, it is preferable to use a metallocene catalyst.

[0025] The melt flow rate (MFR) (190 °C, load 2160 g) of the above-mentioned low-density biopolyethylene-based resin (A) is usually 0.1 to 50 g / 10 minutes, preferably 0.5 to 30 g / 10 minutes, and particularly preferably 2 to 10 g / 10 minutes. When such MFR is too large, the film-forming property tends to become unstable, and when it is too small, the viscosity becomes too high and melt extrusion tends to be difficult.

[0026] Examples of commercially available products of the low-density biopolyethylene-based resin (A) preferably used in the present invention include SEB853 (manufactured by Braskem), etc. Also, the above-mentioned low-density bioethylene-based resin (A) may be used alone or in combination of two or more.

[0027] <EVOH (B)> The above-mentioned EVOH (B) is usually a resin obtained by saponifying an ethylene-vinyl ester copolymer, which is a copolymer of ethylene and a vinyl ester-based monomer, and is a water-insoluble thermoplastic resin. As the above-mentioned vinyl ester-based monomer, vinyl acetate is generally used from an economic perspective.

[0028] As a polymerization method of ethylene and vinyl ester monomers, any known polymerization method can be used, for example, solution polymerization, suspension polymerization, emulsion polymerization, and generally solution polymerization using methanol as a solvent is used. Saponification of the obtained ethylene-vinyl ester copolymer can also be carried out by a known method.

[0029] The EVOH (B) produced in this way mainly consists of structural units derived from ethylene and vinyl alcohol structural units, and usually contains a small amount of vinyl ester structural units remaining without being saponified.

[0030] As the above vinyl ester monomer, vinyl acetate is typically used from the viewpoints of market availability and impurity treatment efficiency during production. Examples of other vinyl ester monomers other than the above vinyl acetate include aliphatic vinyl esters such as vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, isobutyrate vinyl, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl versatate, and aromatic vinyl esters such as vinyl benzoate. Generally, aliphatic vinyl esters having 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.

[0031] The ethylene content in the above EVOH (B) can be controlled by the pressure of ethylene when copolymerizing the vinyl ester monomer and ethylene, and is 20 to 60 mol%. Preferably it is 25 to 50 mol%, and particularly preferably 25 to 35 mol%. When such a content is too low, the gas barrier property and melt moldability under high humidity tend to decrease. Conversely, when it is too high, the gas barrier property tends to decrease. In addition, such ethylene content can be measured based on ISO14663.

[0032] Also, the saponification degree of the vinyl ester component in EVOH (B) can be controlled by the amount of the saponification catalyst (usually an alkaline catalyst such as sodium hydroxide is used), temperature, time, etc. 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%. When such a saponification degree is too low, the gas barrier property, heat stability, moisture resistance, etc. tend to decrease. The saponification degree of such EVOH (B) can be measured based on JIS K6726 (however, EVOH is used as a solution uniformly dissolved in a water / methanol solvent).

[0033] Also, the melt flow rate (MFR) (210 °C, load 2160 g) of the above EVOH (B) is usually 0.5 to 100 g / 10 min, preferably 1 to 50 g / 10 min, particularly preferably 3 to 35 g / 10 min. When such an MFR is too large, the film-forming property tends to become unstable, and when it is too small, the viscosity becomes too high and melt extrusion tends to be difficult. Such an MFR serves as an index of the degree of polymerization of EVOH and can be adjusted by the amount of the polymerization initiator and the amount of the solvent when copolymerizing ethylene and a vinyl ester monomer.

[0034] Also, EVOH (B) may further contain structural units derived from the following comonomers within a range that does not inhibit the effects of the present invention (for example, 10 mol% or less of EVOH). Examples of the comonomers include olefins such as propylene, 1-butene, and isobutene; hydroxy group-containing α-olefins such as 3-butene-1-ol, 3-butene-1,2-diol, 4-penten-1-ol, and 5-hexene-1,2-diol, and derivatives thereof such as esterified products and acylated products; hydroxyalkyl vinylidenes such as 2-methylenepropane-1,3-diol and 3-methylenepentane-1,5-diol; hydroxyalkyl vinylidene diacetates such as 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2-methylenepropane, and 1,3-dibutyryloxy-2-methylenepropane; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, (anhydrous) phthalic acid, (anhydrous) maleic acid, and (anhydrous) itaconic acid, or salts or mono- or dialkyl esters thereof having 1 to 18 carbon atoms in the alkyl group; acrylamides such as acrylamide, N-alkylacrylamide having 1 to 18 carbon atoms in the alkyl group, N,N-dimethylacrylamide, 2-acrylamidopropanesulfonic acid or a salt thereof, and acrylamidopropyldimethylamine or an acid salt or quaternary salt thereof; methacrylamides such as methacrylamide, N-alkylmethacrylamide having 1 to 18 carbon atoms in the alkyl group, N,N-dimethylmethacrylamide, 2-methacrylamidopropanesulfonic acid or a salt thereof, and methacrylamidopropyldimethylamine or an acid salt or quaternary salt thereof; N-vinylamides such as N-vinylpyrrolidone, N-vinylformamide, and N-vinylacetamide; vinyl cyanides such as acrylonitrile and methacrylonitrile; vinyl ethers such as alkyl vinyl ether, hydroxyalkyl vinyl ether, and alkoxyalkyl vinyl ether having 1 to 18 carbon atoms in the alkyl group; vinyl halide compounds such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, and vinyl bromide; vinyl silanes such as trimethoxyvinylsilane; allyl halide 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 acrylamide-2-methylpropanesulfonic acid.These can be used alone or in combination of two or more.

[0035] In particular, EVOH copolymerized with hydroxy group-containing α-olefins, that is, EVOH having a primary hydroxyl group in the side chain, is preferable in that it has good secondary moldability while maintaining gas barrier properties. Among them, EVOH having a 1,2-diol structure in the side chain is particularly preferable. In particular, in the case of EVOH having a primary hydroxyl group in the side chain, the content of the structural unit derived from the monomer having the primary hydroxyl group is preferably 0.1 to 20 mol%, more preferably 0.5 to 15 mol%, and particularly preferably 1 to 10 mol% of EVOH.

[0036] Further, as the EVOH (B) used in the present invention, those “post-modified” such as urethanation, acetalization, cyanoethylation, oxyalkylation, etc. may be used.

[0037] Furthermore, the EVOH (B) used in the present invention may be a mixture of two or more EVOH (B), for example, those having different saponification degrees, different polymerization degrees, different copolymerization components, etc.

[0038] The weight ratio [(A) / (B)] of the low-density biopolyethylene resin (A) and the above EVOH (B) in the resin composition of the present invention is 10 / 90 to 49 / 51 from the viewpoint of suppressing deterioration of the pellet shape, preferably 20 / 80 to 45 / 55, and particularly preferably 30 / 70 to 40 / 60. If the blending ratio of the low-density biopolyethylene resin (A) is too small, the moldability at low temperatures will decrease. On the other hand, if there is too much low-density biopolyethylene resin (A), the pellet shape will deteriorate.

[0039] The base polymers in the resin composition of the present invention are a low-density biopolyethylene resin (A) and EVOH (B), and the content of the base polymers in the resin composition is usually 60% by weight or more, preferably 70% by weight or more, and particularly preferably 80% by weight or more. Also, the upper limit of the content of the base polymer is usually 99.9% by weight.

[0040] <Component (C)> In the present invention, by blending at least one component (C) selected from the group consisting of an ethylene-vinyl acetate copolymer, an acid-modified polymer, and an ethylene-vinyl alcohol copolymer having an ethylene content of 70 to 90 mol% with the above base polymer, deterioration of the pellet shape can be suppressed, and appearance degradation such as the occurrence of surface roughness during molding and discoloration of the molded product can also be suppressed.

[0041] The content of the above component (C) is preferably 0.1 to 20 parts by weight, more preferably 0.2 to 15 parts by weight, and particularly preferably 0.5 to 10 parts by weight with respect to 100 parts by weight in total of the low-density biopolyethylene-based resin (A) and EVOH (B). By setting the content of component (C) within the above range, deterioration of the pellet shape can be suppressed, and there is a tendency to suppress appearance degradation such as the occurrence of surface roughness during molding and discoloration of the molded product. Further, when the resin composition contains two or more kinds of component (C), the total of all the contents is defined as the content of component (C). Hereinafter, each component (C) will be described in detail.

[0042] 〔Ethylene-vinyl acetate copolymer〕 The above ethylene-vinyl acetate copolymer (hereinafter sometimes referred to as "EVA") is a polymer obtained by copolymerizing ethylene and vinyl acetate. Further, EVA may be modified as necessary.

[0043] The content of vinyl acetate in the above EVA is usually 1 to 60 mol%, preferably 2 to 50 mol%, and particularly preferably 3 to 30 mol%. If the vinyl acetate content is too low, there is a tendency that suppression of surface roughness and improvement of the appearance of the molded product are insufficient. Conversely, if it is too high, since EVA has a low decomposition temperature and acetic acid is generated during decomposition, it may damage the machine. Further, the thermal stability of the resin composition itself tends to decrease.

[0044] The melt flow rate (MFR) (190 °C, load 2160 g) of the above-mentioned EVA is usually 0.1 to 100 g / 10 min, preferably 0.5 to 50 g / 10 min, and particularly preferably 1 to 30 g / 10 min. When the MFR is outside the above range, the compatibility with the base polymer decreases, and the dispersibility tends to decrease during mixing.

[0045] The above-mentioned EVA may be a modified product containing a carboxy group obtained by chemically bonding an unsaturated carboxylic acid or its anhydride by an addition reaction, a graft reaction, or the like within a range not inhibiting the gist of the present invention. Such a modification amount is preferably, for example, 10 mol% or less specifically. Examples of the above-mentioned unsaturated carboxylic acid or its anhydride include ethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, ethacrylic acid, and crotonic acid, ethylenically unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, citraconic acid, maleic acid, monomethyl maleate, and monoethyl maleate, and their anhydrides and half esters. Among them, maleic anhydride is preferred.

[0046] The content of the above-mentioned EVA is preferably 0.1 to 20 parts by weight, more preferably 0.2 to 15 parts by weight, and particularly preferably 0.5 to 10 parts by weight with respect to a total of 100 parts by weight of the low-density biopolyethylene resin (A) and EVOH (B). When the content of EVA is within the above range, the deterioration of the pellet shape can be more suppressed, and the appearance deterioration such as the generation of mold eyes and the discoloration of the molded product during molding can be suppressed. Further, the above-mentioned EVA can be used alone or in combination of two or more kinds of EVAs having different ethylene contents, molecular weights, MFRs, densities, modified groups, and modification amounts thereof.

[0047] 〔Acid-modified polymer〕 An acid-modified polymer is a modified product containing a carboxy group obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polymer by an addition reaction, a graft reaction, or the like.

[0048] Examples of the unsaturated carboxylic acid or its anhydride include ethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, ethacrylic acid, and crotonic acid; ethylenically unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, citraconic acid, maleic acid, monomethyl maleate, and monoethyl maleate, and their anhydrides and half esters. These may be used alone or in combination of two or more.

[0049] Examples of the polymer include polyethylene, polypropylene, polybutene, and copolymers of ethylene and α-olefins having 3 to 20 carbon atoms (ethylene-α-olefin copolymers).

[0050] As the acid-modified polymer used in the present invention, a maleic anhydride-modified polymer is preferred. Hereinafter, these maleic anhydride-modified polymers will be described.

[0051] [Maleic Anhydride-Modified Polymer] In the maleic anhydride-modified polymer, at least one of the main chain and side chain of the polymer is modified with maleic anhydride. However, the maleic anhydride-modified polymer excludes EVA modified with maleic anhydride and ethylene-vinyl alcohol copolymers having an ethylene content of 70 to 90 mol% modified with maleic anhydride.

[0052] Examples of the polymer modified with the maleic anhydride include polyethylene, polypropylene, polybutene, and ethylene-α-olefin copolymers. Among them, from the viewpoint of suppressing the occurrence of eye mucus, ethylene-α-olefin copolymers and polyethylene are preferred, and ethylene-α-olefin copolymers are particularly preferred.

[0053] Examples of the ethylene-α-olefin copolymer include ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-1-hexene copolymer, ethylene-4-methyl-1-pentene copolymer, ethylene-1-octene copolymer, ethylene-1-butene-1-hexene copolymer, ethylene-1-butene-4-methyl-1-pentene copolymer, ethylene-1-butene-1-octene copolymer, and the like. Preferably, they are ethylene-1-butene copolymer, ethylene-1-hexene copolymer, ethylene-1-octene copolymer, ethylene-1-butene-1-hexene copolymer, and ethylene-1-butene-1-octene copolymer.

[0054] The maleic anhydride-modified polymer can be obtained by copolymerizing by replacing a part of the monomers constituting the polymer with maleic anhydride, or by introducing maleic anhydride into a part of the side chain by a graft reaction such as radical addition.

[0055] The acid value of the maleic anhydride-modified polymer is usually 50 mgKOH / g or less, preferably 30 mgKOH / g or less, and particularly preferably 20 mgKOH / g or less. If the acid value is too high, the number of reaction points with the hydroxyl groups in EVOH(B) increases, high molecular weight compounds are generated during the melt-kneading process, the stability during extrusion processing decreases, and it tends to be difficult to obtain a good molded product. The lower limit of the acid value is usually 1 mgKOH / g, and preferably 2 mgKOH / g. The above acid value is measured based on JIS K0070.

[0056] When maleic anhydride-modified polyethylene is used as the maleic anhydride-modified polymer, the melt flow rate (MFR) (190 °C, load 2160 g) is usually 0.01 to 150 g / 10 min, preferably 0.1 to 50 g / 10 min, more preferably 1 to 25 g / 10 min, and even more preferably 3 to 10 g / 10 min. When using a maleic anhydride-modified ethylene-α-olefin copolymer as the maleic anhydride-modified polymer, the melt flow rate (MFR) (230°C, load 2160 g) is usually 0.1 to 150 g / 10 min, preferably 0.5 to 100 g / 10 min, more preferably 1 to 50 g / 10 min, and even more preferably 5 to 35 g / 10 min. If the MFR is outside the above range, the compatibility with the base polymer decreases, and the dispersibility tends to decrease during mixing.

[0057] The content of the maleic anhydride-modified polymer is preferably 0.1 to 20 parts by weight, more preferably 0.2 to 15 parts by weight, and particularly preferably 0.5 to 10 parts by weight, based on 100 parts by weight in total of the low-density biopolyethylene resin (A) and EVOH (B). When the content of the maleic anhydride-modified polymer is within the above range, the deterioration of the pellet shape can be further suppressed, and the appearance deterioration such as the generation of mold fouling and the discoloration of the molded product during molding can also be suppressed. Further, the maleic anhydride-modified polymer may be used alone or in combination of two or more.

[0058] [Ethylene-vinyl alcohol copolymer having an ethylene structural unit content of 70 to 90 mol%] The ethylene-vinyl alcohol copolymer having an ethylene structural unit content of 70 to 90 mol% (hereinafter sometimes referred to as "saponified EVA") is obtained by saponifying the vinyl acetate component of an ethylene-vinyl acetate copolymer having an ethylene content of 70 to 90 mol%, and is different from the above EVA in terms of saponification.

[0059] The above ethylene-vinyl acetate copolymer is produced by any known polymerization method, for example, solution polymerization, suspension polymerization, emulsion polymerization, etc., and the saponification of the above ethylene-vinyl acetate copolymer can also be carried out by a known method. Further, the above saponified EVA may be modified as necessary.

[0060] The ethylene content of the above-mentioned saponified EVA is 70 to 90 mol%, preferably 75 to 90 mol%, particularly preferably 80 to 90 mol%. When the ethylene content is too low, the effects of the present invention (such as suppressing eye mucus) tend to be insufficient.

[0061] In addition, the saponification degree of the above-mentioned saponified EVA is usually 20 mol% or more, further 60 to 100 mol%, particularly preferably 90 to 100 mol%. That is, when the saponification degree is too low, the effects of the present invention (such as suppressing eye mucus) may be insufficient.

[0062] The melt flow rate (MFR) (at 190 °C, load 2160 g) of the above-mentioned saponified EVA is usually 0.5 to 100 g / 10 min, further 1 to 50 g / 10 min, particularly preferably 2 to 30 g / 10 min, which is preferable in terms of excellent dispersibility and excellent effects of the present invention.

[0063] The above-mentioned saponified EVA may be a modified product obtained by chemically bonding an unsaturated carboxylic acid or its anhydride by an addition reaction, a graft reaction, etc. within a range that does not inhibit the gist of the present invention. Such a modification amount is preferably 10 mol% or less, for example. Examples of the unsaturated carboxylic acid or its anhydride include ethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, ethacrylic acid, and crotonic acid, ethylenically unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, citraconic acid, maleic acid, monomethyl maleate, monoethyl maleate, and maleic anhydride, and their anhydrides, half esters, etc. These may be used alone or in combination of two or more. Among them, maleic anhydride is preferable.

[0064] The content of the saponified EVA is preferably 0.1 to 20 parts by weight, more preferably 0.2 to 15 parts by weight, and particularly preferably 0.5 to 10 parts by weight, based on 100 parts by weight in total of the low-density biopolyethylene resin (A) and EVOH (B). When the content of the saponified EVA is within the above range, deterioration of the pellet shape can be further suppressed, and there is a tendency to suppress appearance degradation such as generation of fish eyes during molding and discoloration of the molded product. Further, the above saponified EVA can be used alone or in combination of two or more saponified EVAs having different ethylene contents, saponification degrees, molecular weights, MFRs, densities, modified groups, and modified amounts thereof, etc.

[0065] The resin composition of the present invention contains the above component (C) in the base polymer [low-density biopolyethylene resin (A) + EVOH (B)]. Among them, as the component (C), EVA and acid-modified polymers are preferable, and EVA is more preferable.

[0066] [Other components] The resin composition of the present invention may contain a thermoplastic resin other than the above (A) to (C) (such as petroleum-derived polyethylene) and additives generally added to thermoplastic resins, as long as the effects of the present invention are not inhibited. Examples of the above additives include plasticizers (such as aliphatic polyhydric alcohols such as ethylene glycol, glycerin, and hexanediol), oxygen absorbers, heat stabilizers, light stabilizers, ultraviolet absorbers, colorants, antistatic agents, surfactants (excluding those used as lubricants), antibacterial agents, antiblocking agents, fillers (such as inorganic fillers), etc. These additives can be used alone or in combination of two or more.

[0067] [Manufacture of resin composition] The resin composition of the present invention contains the above (A) to (C), and preferably consists only of the above (A) to (C), or the above (A) to (C) and the other components as required. Further, the low-density biopolyethylene resin (A) and EVOH (B) may be raw materials that have never been used for molding (non-recycled products), or recovered materials such as scraps of the multilayer structure having a layer containing the low-density biopolyethylene resin (A) and EVOH (B) generated during the production of the multilayer structure product described later may be used.

[0068] In some cases, it is also possible to utilize recovered materials of multilayer structures that have been used as various packaging materials. Multilayer structures generally used as packaging materials for foods and the like contain, in addition to the layer composed of the low-density biopolyethylene resin (A) and EVOH (B), an adhesive resin layer and a regrind layer. Therefore, the resin composition of the present invention may contain these adhesive resin layers and regrind layers within a range that does not inhibit the effects of the present invention (for example, 30% by weight or less in the resin composition).

[0069] Hereinafter, the case of using recovered materials of a multilayer structure containing a layer composed of the low-density biopolyethylene resin (A) and EVOH (B) in the method for producing the resin composition of the present invention will be described.

[0070] The recovered materials of the multilayer structure, which are unnecessary parts (scraps) such as scraps and ends generated during the production of the multilayer structure product and recovered as waste, are usually pulverized and then the particle size is adjusted with a sieve or the like as required, and used as a raw material for the resin composition of the present invention.

[0071] When pulverizing the above-mentioned recovered materials, it can be carried out by using a known pulverizer. The apparent density of this pulverized product is usually 0.25 to 0.85 g / mL, more preferably 0.3 to 0.7 g / mL, and particularly preferably 0.35 to 0.6 g / mL. When the apparent density is too small, the dispersion of the low-density biopolyethylene resin (A) in the resin composition layer becomes poor, and the melt moldability and mechanical properties of the resin composition layer of the obtained molded product tend to decrease. When it is too large, the melt moldability of the regrind layer of the obtained molded product tends to decrease due to the occurrence of poor supply in the extruder. The above-mentioned apparent density is a value measured in accordance with the "5.3 Apparent Density" test method of JIS K6891.

[0072] Regarding the above-mentioned apparent density, it can be controlled by arbitrarily adjusting the shape of the pulverizing blade of the pulverizer, the rotation speed of the pulverizing blade, the pulverizing treatment speed, the mesh opening size of the sieve used, etc. Also, the shape and particle size of the pulverized product can be adjusted by known methods.

[0073] When using a pulverized product of a recovered multilayer structure containing a low-density biopolyethylene resin (A) and EVOH (B) (hereinafter referred to as "pulverized product"), the resin composition of the present invention is produced by incorporating component (C) into the above-mentioned pulverized product. Such pulverized products may contain unregenerated low-density biopolyethylene resin (A) and unregenerated EVOH (B) from the viewpoint of productivity.

[0074] Examples of the method for producing the above resin composition include known methods such as the dry blend method, melt kneading method, solution mixing method, and impregnation method.

[0075] Examples of the above dry blend method include (i) a method of dry blending the above-mentioned pulverized product and component (C) using a tumbler or the like. Also, when dry blending, component (C) may be dry blended as it is, or pellets of a thermoplastic resin containing component (C) may be prepared in advance, and these pellets of the thermoplastic resin and the pulverized product may be dry blended.

[0076] Examples of the melt-kneading method include (ii) a method of melt-kneading the dry blend of (i) above, and (iii) a method of adding component (C) to the pulverized product in a molten state and melt-kneading.

[0077] Examples of the solution-kneading method include (iv) a method of preparing a solution using the pulverized product, adding component (C) thereto, performing solid-liquid separation and drying after coagulation molding.

[0078] In the present invention, it is possible to combine the above different methods. Among them, from the viewpoint of productivity, the melt-kneading method is preferable, and the method (ii) is particularly preferable.

[0079] The resin composition of the present invention is not limited to the case where the recovered product of the multilayer structure is used as a raw material as described above, and the unregenerated low-density biopolyethylene resin (A) and EVOH (B) may be used. When using unregenerated products, a resin composition may be prepared by using a generally known method such as a dry blending method, a melt-kneading method, a solution mixing method, etc. so as to have the blending composition of the present invention. The resin composition thus prepared is also included in the present invention.

[0080] The YI [Yellow Index] (ASTM D1925) of the resin composition of the present invention is usually 20 or less, preferably 15 or less, and particularly preferably 10 or less. The YI of the above resin composition is obtained by measuring under the following measurement conditions using a spectrophotometer (CM-3500d, manufactured by Konica Minolta). [Measurement Conditions] · Light source: D65 · CM-A120 white calibration plate · Use CM-A126 petri dish set · Regular reflection measurement SCE · Measurement diameter: φ30 mm

[0081] The biomass content of the resin composition of the present invention is usually 10 to 90% by weight, preferably 15 to 70% by weight, and particularly preferably 20 to 50% by weight. The biomass content of the above resin composition is calculated by the following formula. Biomass content (weight%) = M1 / M2 × 100 In the above formula, M1 is the total weight of the low-density biopolyethylene resin (A) used, and M2 is the total weight of the resin used.

[0082] The melt flow rate (MFR) (210 °C, load 2160 g) of the resin composition of the present invention is usually 0.1 to 50 g / 10 min, preferably 0.5 to 30 g / 10 min, and particularly preferably 2 to 10 g / 10 min.

[0083] The water content of the resin composition of the present invention is usually 0.01 to 0.5% by weight, preferably 0.02 to 0.35% by weight, and particularly preferably 0.05 to 0.3% by weight.

[0084] Note that the water content of the resin composition in the present invention is measured and calculated by the following method. Weigh the weight (W1) of the resin composition before drying with an electronic balance, dry it in a hot air dryer at 150 °C for 5 hours, weigh the weight (W2) after cooling in a desiccator for 30 minutes, and calculate it from the following formula. Water content (weight%) = [(W1 - W2) / W1] × 100

[0085] The resin composition of the present invention is prepared as resin compositions in various forms such as pellets and powders, and provided as a molding material for various molded articles. Particularly in the present invention, when provided as a material for melt molding, the effects of the present invention tend to be obtained more efficiently, which is preferable.

[0086] As the above molded article, it can be put to practical use as a multi-layer structure having a layer formed using the resin composition of the present invention, starting with a single-layer film formed using the resin composition of the present invention.

[0087] [Multi-layer structure] The above-mentioned multilayer structure includes a layer made of the resin composition of the present invention. The layer made of the resin composition of the present invention (hereinafter referred to as "resin composition layer") can be laminated with another base material (hereinafter referred to as "base resin") mainly composed of a thermoplastic resin other than the resin composition of the present invention, so as to further impart strength or other functions.

[0088] Examples of the above-mentioned base resin include polyethylene-based resins such as linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene (block and random) copolymers, ethylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers, polypropylene-based resins such as polypropylene, propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers, polybutene, polypentene, polycyclic olefin-based resins (polymers having a cyclic olefin structure in at least one of the main chain and side chains) and other (unmodified) polyolefin-based resins, and modified olefin-based resins such as unsaturated carboxylic acid-modified polyolefin-based resins obtained by graft-modifying these polyolefins with unsaturated carboxylic acids or their esters, including polyolefin-based resins in a broad sense, ionomers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers, polyester-based resins, polyamide-based resins (including copolymer polyamides), polyvinyl chloride, polyvinylidene chloride, acrylic resins, polystyrene-based resins, vinyl ester-based resins, polyester-based elastomers, polyurethane-based elastomers, polystyrene-based elastomers, halogenated polyolefins such as chlorinated polyethylene and chlorinated polypropylene, and aromatic or aliphatic polyketones.

[0089] Among these, polyamide-based resins, polyolefin-based resins, polyester-based resins, and polystyrene-based resins are preferable in terms of economy and productivity, and more preferably, polyolefin-based resins such as polyethylene-based resins, polypropylene-based resins, polycyclic olefin-based resins, and their unsaturated carboxylic acid-modified polyolefin-based resins.

[0090] When the layer structure of the multilayer structure is such that the resin composition layer is a (a1, a2, ···) and the base resin layer is b (b1, b2, ···), any combination such as a / b, b / a / b, a / b / a, a1 / a2 / b, a / b1 / b2, b2 / b1 / a / b1 / b2, b2 / b1 / a / b1 / a / b1 / b2, etc. is possible. Also, it is possible to provide a recycle layer containing a mixture of the resin composition of the present invention and the base resin, which is obtained by re-melting and molding the ends, defective products, etc. generated during the process of manufacturing the multilayer structure. The number of layers of the multilayer structure is usually 2 to 15, preferably 3 to 10 in terms of the total number. In the above layer structure, an adhesive resin layer containing an adhesive resin may be provided between each layer as necessary.

[0091] As the above adhesive resin, known ones can be used and can be appropriately selected according to the type of the thermoplastic resin used for the base resin layer "b". Typically, a modified polyolefin-based polymer containing a carboxy group obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin-based resin by an addition reaction, a graft reaction, etc. can be mentioned. Examples of the modified polyolefin-based polymer containing a carboxy group include maleic anhydride graft-modified polyethylene, maleic anhydride graft-modified polypropylene, maleic anhydride graft-modified ethylene-propylene (block and random) copolymer, maleic anhydride graft-modified ethylene-ethyl acrylate copolymer, maleic anhydride graft-modified ethylene-vinyl acetate copolymer, maleic anhydride-modified polycyclic olefin-based resin, maleic anhydride graft-modified polyolefin-based resin, etc. And one or more mixtures selected from these can be used.

[0092] In the multilayer structure, when an adhesive resin layer is used between the resin composition layer and the base resin layer, since the adhesive resin layer is located on both sides of the resin composition layer, it is preferable to use an adhesive resin having excellent hydrophobicity.

[0093] The above base resin and adhesive resin may contain, within a range that does not inhibit the gist of the present invention (for example, 30% by weight or less, preferably 10% by weight or less based on the total resin), conventionally known plasticizers, fillers, clays (such as montmorillonite), colorants, antioxidants, antistatic agents, lubricants, nucleating agents, antiblocking agents, waxes, etc.

[0094] The lamination of the resin composition of the present invention and the above base resin (including the case where an adhesive resin layer is interposed) can be carried out by a known method. For example, a method of melt-extrusion laminating the base resin onto a film, sheet, etc. of the resin composition of the present invention, a method of melt-extrusion laminating the resin composition of the present invention onto the base resin layer, a method of co-extruding the resin composition and the base resin, a method of dry-laminating the resin composition layer and the base resin layer using a known adhesive such as an organic titanium compound, an isocyanate compound, a polyester-based compound, a polyurethane compound, etc., a method of coating a solution of the resin composition on the base resin and then removing the solvent, etc. Among these, from the viewpoints of cost and environment, a method of co-extruding the resin composition and the base resin is preferable.

[0095] The above multilayer structure is subjected to a (heating) 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. Also, as the stretching method, those with a high stretching ratio among roll stretching method, tenter stretching method, tubular stretching method, stretch blow method, vacuum pressure forming, etc. can be adopted. The stretching temperature is near the melting point of the multilayer structure, usually selected from the range of about 40 to 170°C, preferably about 60 to 160°C. If the stretching temperature is too low, the stretchability becomes poor, and if it is too high, it becomes difficult to maintain a stable stretching state.

[0096] In addition, for the purpose of imparting dimensional stability after stretching, heat setting may then be carried out. Heat setting can be performed by well-known means. For example, the above-mentioned stretched film is heat-treated usually at 80 to 180°C, preferably 100 to 165°C for about 2 to 600 seconds while maintaining a tension state. Further, when the multilayer stretched film obtained from the resin composition of the present invention is used as a shrink film, in order to impart heat shrinkability, the above heat setting may not be performed, and for example, a treatment such as blowing cold air onto the stretched film for cooling and fixing may be carried out.

[0097] Also, in some cases, it is also possible to obtain cup- or tray-shaped multilayer containers using the above multilayer structure. In that case, a drawing molding method is usually adopted, and specifically, a vacuum molding method, a pressure air molding method, a vacuum pressure air molding method, a plug assist type vacuum pressure air molding method, etc. can be mentioned. Further, when obtaining tube- or bottle-shaped multilayer containers (laminated body structure) from a multilayer parison (hollow tubular preform before blowing), a blow molding method is adopted. Specifically, an extrusion blow molding method (double-headed type, mold moving type, parison shift type, rotary type, accumulator type, horizontal parison type, etc.), a cold parison type blow molding method, an injection blow molding method, a biaxial stretching blow molding method (extrusion type cold parison biaxial stretching blow molding method, injection type cold parison biaxial stretching blow molding method, injection molding in-line type biaxial stretching blow molding method, etc.) and the like can be mentioned. The obtained laminate can be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or melt coating treatment, bag making processing, deep drawing processing, box processing, tube processing, split processing, etc. as required.

[0098] The thickness of the multilayer structure (including the stretched one), and further the thicknesses of the resin composition layer, the base resin layer, and the adhesive resin layer constituting the multilayer structure cannot be generally determined by the layer structure, the type of the base resin, the type of the adhesive resin, the use and packaging form, the required physical properties, etc. However, the thickness of the multilayer structure (including the stretched one) is usually 10 to 5000 μm, preferably 30 to 3000 μm, particularly preferably 50 to 2000 μm. The resin composition layer is usually 1 to 500 μm, preferably 3 to 300 μm, particularly preferably 5 to 200 μm. The base resin layer is usually 5 to 3000 μm, preferably 10 to 2000 μm, particularly preferably 20 to 1000 μm. The adhesive resin layer is usually 0.5 to 250 μm, preferably 1 to 150 μm, particularly preferably 3 to 100 μm.

[0099] Furthermore, the ratio of the thickness of the resin composition layer to the base resin layer in the multilayer structure (resin composition layer / base resin layer) is the ratio of the thickest layers when there are multiple layers of each type, and is usually 1 / 99 to 50 / 50, preferably 5 / 95 to 45 / 55, particularly preferably 10 / 90 to 40 / 60. Also, the ratio of the thickness of the resin composition layer to the adhesive resin layer in the multilayer structure (resin composition layer / adhesive resin layer) is the ratio of the thickest layers when there are multiple layers of each type, and is usually 10 / 90 to 99 / 1, preferably 20 / 80 to 95 / 5, particularly preferably 50 / 50 to 90 / 10.

[0100] The films, sheets, bags made of stretched films, and containers such as cups, trays, tubes, and bottles obtained as described above are useful as various packaging material containers for general foods, seasonings such as mayonnaise and dressings, fermented foods such as miso, oil-based foods such as salad oil, beverages, cosmetics, pharmaceuticals, etc.

Examples

[0101] Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples as long as it does not exceed the gist. Unless otherwise specified, "parts" and "%" hereinafter mean weight basis.

[0102] Prior to the examples, the following components were prepared.

[0103] <Low-density biopolyethylene resin (A)> (A-1): Low-density biopolyethylene [SEB853 (Green PE manufactured by Braskem), MFR 2.7 g / 10 min (190 °C, load 2160 g), minimum biomass content 95% (plant-derived)] (A'-1): Linear low-density biopolyethylene [SLH118 (Green PE manufactured by Braskem), MFR 1.0 g / 10 min (190 °C, load 2160 g), minimum biomass content 84% (plant-derived)] (A'-2): High-density biopolyethylene [SGM9450F (Green PE manufactured by Braskem), MFR 0.33 g / 10 min (190 °C, load 5000 g), minimum biomass content 96% (plant-derived)] (A'-3): Petroleum-derived polyethylene [Novatec LF448K1 (manufactured by Japan Polyethylene Corporation), MFR 2.0 g / 10 min (190 °C, load 2160 g)]

[0104] <EVOH (B)> (B-1): Ethylene-vinyl alcohol copolymer [ethylene content 29 mol%, MFR 4 g / 10 min (210 °C, load 2160 g)] (B-2): Ethylene-vinyl alcohol copolymer [ethylene content 32 mol%, MFR 3 g / 10 min (210 °C, load 2160 g)] (B-3): Ethylene-vinyl alcohol copolymer [ethylene content 38 mol%, MFR 3 g / 10 min (210 °C, load 2160 g)] (B-4): Ethylene-vinyl alcohol copolymer [ethylene content 44 mol%, MFR 3 g / 10 min (210 °C, load 2160 g)]

[0105] <Component (C)> [EVA] (C-1): EVA [Ultra-Sen 3B53A (manufactured by Tosoh Corporation), vinyl acetate content 25 mol%, MFR 5.3 g / 10 min (190 °C, load 2160 g)] [Acid-modified polymer] (C-2): Maleic anhydride-modified ethylene-α-olefin copolymer [acid-modified Toughmer MA8510 (manufactured by Mitsui Chemicals), MFR 5.0 g / 10 min (230 °C, load 2160 g)] [EVA saponified product] (C-3): EVA saponified product [Melsene H0051K (manufactured by Tosoh Corporation), vinyl acetate content 11 mol%, MFR 6.5 g / 10 min (190 °C, load 2160 g)]

[0106] After uniformly mixing the above components by dry blending according to Tables 1 and 2 below, they were fed into a twin-screw kneader at a rate of 25 kg / h using a gravimetric feeder. Then, the strands were cut with a drum pelletizer to prepare the pelletized resin compositions of Examples 1 to 15, Comparative Examples 1 to 7, and Reference Examples 1 and 2. The kneading conditions are as follows. [Kneading conditions] · Twin-screw extruder: diameter 32 mm, L / D = 56 (manufactured by Japan Steel Works, Ltd.) · Extruder set temperature: C2 / C3 / C4 / C5 / C6 / C7 / C8 / C9 / C10 / C11 / C12 / C13 / C14 / C15 / C16 / D = 100 / 170 / 210 / 220 / 220 / 220 / 220 / 220 / 220 / 220 / 220 / 220 / 220 / 220 / 220 / 220 °C · Screw rotation speed: 270 ppm · Discharge rate: 25 kg / h · Strand cooling: water-cooling distance 40 cm · Take-up speed: 25 m / min · Die: 4 holes

[0107] Using the resin compositions of Examples 1 to 15, Comparative Examples 1 to 7, and Reference Examples 1 and 2 prepared above, evaluations of pellet shape, amount of occurrence of eyelets, coloring, biomass content, and MFR were carried out under the following conditions. These results are shown in Tables 1 and 2 below.

[0108] [Pellet shape] The shape of the obtained pellets was observed with a microscope (optical microscope) and evaluated according to the following criteria. [Evaluation criteria] ◎ (excellent): The pellet shape is very good. 〇 (very good): The pellet size is uniform, but there is slightly rough surface (sharkskin) or poor cutting. × (poor): There are many chipped, cracked, rough-surfaced (sharkskin), and poorly cut pellets.

[0109] 〔Amount of eye sludge generated〕 The above resin composition was fed into a twin-screw kneader at a rate of 25 kg / hour using a gravimetric feeder. When discharging 5 kg at this time, the amount of eye sludge generated was sampled and weighed, and the evaluation was carried out according to the following criteria. [Evaluation criteria] 〇 (very good): The total weight of the generated eye sludge is 0.1 g or less. × (poor): The total weight of the generated eye sludge is greater than 0.1 g.

[0110] 〔Color evaluation (YI)〕 The YI (ASTM D1925) of the obtained pellets was measured using a spectrophotometer "CM-3500d" manufactured by Konica Minolta (light source: D65, CM-A120 white calibration plate, CM-A126 petri dish set used, regular reflection measurement SCE, measurement diameter φ30 mm). Approximately 5 g of the sample was filled into a petri dish and spread evenly, and the measurement was carried out in this state to calculate the YI. The larger the value of this YI, the more yellow the resin composition is colored.

[0111] 〔Biomass content〕 The biomass content of each resin composition was calculated from the following formula. Biomass content (wt%) = M3 / M4 × 100 In the above formula, M3 is the total weight of the used bio-polyethylene resin, and M4 is the total weight of the used resin.

[0112] 〔MFR〕 The MFR (g / 10 min) of the obtained pellets was measured under the conditions of a temperature of 210 °C and a load of 2160 g.

[0113]

Table 1

[0114]

Table 2

[0115] The resin composition of the example having low-density biopolyethylene-based resin (A) and EVOH (B) in a specific ratio and containing component (C) can suppress the deterioration of the pellet shape, and can also suppress the appearance degradation such as the occurrence of surface defects and discoloration during molding.

[0116] On the other hand, the resin compositions of Comparative Example 1 without component (C), Comparative Example 2 and 6 in which the content of low-density biopolyethylene-based resin (A) is more than the range defined in the present invention had poor pellet shape or high YI and poor appearance. In addition, the resin compositions of Comparative Example 3, 7 in which the content of low-density biopolyethylene-based resin (A) is less than the range defined in the present invention, and Reference Example 1, 2 using petroleum-derived polyethylene had high YI and poor appearance. Furthermore, the resin compositions of Comparative Example 4 using linear low-density polyethylene and Comparative Example 5 using high-density biopolyethylene had a large amount of surface defects.

[0117] In the above examples, specific forms in the present invention were shown, but the above examples are merely illustrative and should not be construed in a limiting sense. Various modifications obvious to those skilled in the art are intended to be within the scope of the present invention.

Industrial Applicability

[0118] The resin composition of the present invention can suppress the deterioration of the pellet shape even when using biopolyethylene, and can also suppress the appearance degradation such as the occurrence of surface defects and discoloration during molding. Therefore, films, sheets, and stretched films made of the resin composition of the present invention are useful as materials for various packaging containers.

Claims

1. A resin composition containing a low-density biopolyethylene resin (A), an ethylene-vinyl alcohol copolymer (B) with an ethylene content of 20 to 60 mol%, and at least one component (C) selected from the group consisting of ethylene-vinyl acetate copolymer, maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, maleic anhydride-modified polybutene, maleic anhydride-modified ethylene-α-olefin copolymer, and ethylene-vinyl alcohol copolymer with an ethylene content of 70 to 90 mol%. The low-density biopolyethylene resin (A) is a low-density biopolyethylene resin excluding linear low-density biopolyethylene resin, and the weight ratio [(A) / (B)] of the component (A) to the component (B) is 10 / 90 to 49 / 51. The resin composition is characterized by this.

2. The resin composition according to Claim 1, wherein the component (C) is at least one component selected from the group consisting of ethylene-vinyl acetate copolymer, maleic anhydride-modified ethylene-α-olefin copolymer, maleic anhydride-modified polyethylene, and ethylene-vinyl alcohol copolymer with an ethylene content of 70 to 90 mol%.

3. The resin composition according to Claim 1, wherein the component (C) is at least one component selected from the group consisting of ethylene-vinyl acetate copolymer, maleic anhydride-modified ethylene-α-olefin copolymer, and ethylene-vinyl alcohol copolymer with an ethylene content of 70 to 90 mol%.

4. The resin composition according to any one of Claims 1 to 3, characterized in that the content of the component (C) is 0.1 to 20 parts by weight with respect to 100 parts by weight in total of the component (A) and the component (B).

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