Resin composition and method for producing the same

Abstract

To provide a resin composition which is excellent in transparency, and a method for producing a resin composition.SOLUTION: A resin composition contains an ethylene-vinyl alcohol-based copolymer (A), and an inorganic laminar compound (B), and has an internal haze measured by the following measurement method of 15% or less. Measurement method: the internal haze of a film which is formed of the resin composition and has thickness of 30 μm is measured according to JIS K 7136.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a resin composition containing an ethylene-vinyl alcohol copolymer (hereinafter sometimes referred to as "EVOH") and an inorganic layered compound, and a method for producing the same, and more specifically, to a resin composition having excellent transparency and a method for producing the same.

Background Art

[0002] EVOH is excellent in transparency, antistatic property, durability, solvent resistance, gas barrier property, fragrance retention property, etc., and is a thermoplastic resin that can be melt-molded, and is used in various packaging material applications such as food packaging.

[0003] It is known that various properties are improved by blending an inorganic compound with such EVOH, and a method for improving the productivity and processability of a resin composition containing EVOH and an inorganic compound has been studied.

[0004] For example, in Patent Document 1, EVOH having a water content of less than 5% by mass is introduced into an extruder, and in the extruder, after melting EVOH at a temperature of 230°C, an aqueous dispersion of an inorganic compound is blended, and while driving a screw-type side feeder of the extruder, melt-kneading is performed to discharge water vapor while suppressing leakage of the resin composition from the side feeder, and a method for obtaining a resin composition having a water content of less than 5% by mass and a crystallinity of 36% or more has been proposed.

[0005] In Patent Document 2, a method for obtaining a resin composition is proposed by introducing EVOH and a carbonate into an extruder, melting EVOH at a temperature of 230°C in the extruder, and then blending and kneading an aqueous dispersion of an inorganic layered compound.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

[0007] However, a resin composition containing EVOH and an inorganic layered compound tends to have poor transparency (increased haze) in the film after molding. Therefore, there is room for improvement in the transparency of the resin compositions containing EVOH and an inorganic compound described in Patent Documents 1 and 2.

[0008] Therefore, in view of such circumstances, an object of the present invention is to provide a resin composition containing EVOH and an inorganic layered compound, which has excellent transparency, and to provide a method for producing the resin composition. [Means for Solving the Problems]

[0009] However, as a result of intensive studies by the present inventors in view of such circumstances, it has been found that the transparency of the resin composition can be improved by lowering only the barrel temperature in the vicinity of the dispersion liquid pressure inlet of the extruder in the production process of the resin composition containing EVOH and the inorganic layered compound, and the present invention has been completed.

[0010] That is, the present invention has the following aspects. [1] A resin composition containing an ethylene-vinyl alcohol copolymer (A) and an inorganic layered compound (B), wherein the internal haze measured by the following measurement method is 15% or less. Measurement method: The internal haze is measured in accordance with JIS K7136 for a film having a thickness of 30 μm made of the resin composition. [2] The resin composition according to [1], wherein the inorganic layered compound (B) is a kaolin mineral. [3] The resin composition according to [1] or [2], further containing a metal compound (C) in the resin composition. [4] The resin composition according to [3], wherein the metal compound (C) is an alkaline earth metal salt. [5] The resin composition according to [3] or [4], wherein the metal compound (C) is a carbonate. [6] A method for producing the resin composition according to any one of [1] to [5], comprising a step of mixing an aqueous dispersion of the ethylene-vinyl alcohol copolymer (A) and the inorganic layered compound (B) in an extruder, wherein the barrel temperature near the dispersion liquid injection part of the extruder is lower than the barrel temperature other than near the dispersion liquid injection part. A method for producing a resin composition. [7] The method for producing a resin composition according to [6], wherein the barrel temperature near the dispersion liquid injection part is 80 ° C or more lower than the maximum temperature in the barrel. [Advantages of the Invention]

[0011] The resin composition of the present invention is excellent in transparency. [Brief Description of the Drawings]

[0012]

Figure 1

[0013] Hereinafter, the present invention will be described in more detail based on the embodiments of the present invention, but the present invention is not limited to the following embodiments. In the present invention, when expressed as "Y to Z" (Y and Z are arbitrary numbers), unless otherwise specified, it means "Y or more and Z or less", and also includes the meaning of "preferably larger than Y" or "preferably smaller than Z". Further, when expressed as "Y or more" (Y is an arbitrary number) or "Z or less" (Z is an arbitrary number), it also includes the meaning of "preferably larger than Y" or "preferably less than Z". Furthermore, in the present invention, "y and / or z (where y and z are any structures or components)" means any of the three combinations: only y, only z, and y and z.

[0014] Hereinafter, the configuration of the present invention will be described in detail, but these are examples of preferred embodiments. Hereinafter, the present invention will be described in detail.

[0015] A resin composition according to an example of an embodiment of the present invention (hereinafter sometimes referred to as "the present resin composition") is a resin composition containing an ethylene-vinyl alcohol copolymer (A) and an inorganic layered compound (B), and has an internal haze of 15% or less as measured by the following measurement method. Measurement method: The internal haze is measured in accordance with JIS K7136 for a 30-μm-thick film made of the resin composition. Hereinafter, each component contained in the present resin composition will be described.

[0016] [EVOH (A)] The EVOH (A) used in the present resin composition 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.

[0017] As the 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 vinyl acetate include aliphatic vinyl esters such as vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, isobutyl vinyl acetate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, and vinyl versatate, and aromatic vinyl esters such as vinyl benzoate. Usually, aliphatic vinyl esters having 3 to 20 carbon atoms, preferably 4 to 10 carbon atoms, and particularly preferably 4 to 7 carbon atoms are used. These are usually used alone, but a plurality of types may be used simultaneously if necessary.

[0018] As the polymerization method for copolymerizing the ethylene and the vinyl ester monomer, any known polymerization method, such as solution polymerization, suspension polymerization, emulsion polymerization, etc., can be used. Generally, solution polymerization using methanol as a solvent is used. Also, the saponification of the obtained ethylene-vinyl ester copolymer can be carried out by a known method. The EVOH (A) produced in this way mainly contains structural units derived from ethylene and vinyl alcohol structural units, and contains a small amount of vinyl ester structural units remaining without being saponified.

[0019] The content of the ethylene structural unit in the EVOH is 20 to 60 mol%, preferably 25 to 50 mol%, particularly preferably 25 to 40 mol%. The content of the ethylene structural unit can be controlled by the pressure of ethylene when copolymerizing the vinyl ester monomer and ethylene. When such 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, the content of such ethylene structural unit can be measured based on ISO14663.

[0020] The saponification degree of the EVOH (A) is usually 90 to 100 mol%, preferably 95 to 100 mol%, particularly preferably 99 to 100 mol%. The saponification degree can be controlled by the amount, temperature, time, etc. of the saponification catalyst (usually an alkaline catalyst such as sodium hydroxide is used) when saponifying the ethylene-vinyl ester copolymer. When such saponification degree is too low, the gas barrier property, thermal stability, moisture resistance, etc. tend to decrease. The saponification degree of such EVOH (A) can be measured based on JIS K6726 (however, EVOH is used as a solution uniformly dissolved in a water / methanol solvent).

[0021] The melt flow rate (MFR) (at 210 °C under a load of 2160 g) of the EVOH (A) is usually 0.5 to 100 g / 10 min, preferably 1 to 50 g / 10 min, more preferably 3 to 35 g / 10 min, and particularly preferably 3.5 to 10 g / 10 min. When such MFR is too large, the stability during film formation tends to be impaired, and when it is too small, the viscosity becomes too high and melt extrusion tends to be difficult. The MFR is an indicator of the degree of polymerization of the EVOH (A), 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.

[0022] The melting point of the EVOH (A) is usually 240 °C or lower, preferably 170 to 230 °C, and particularly preferably 180 to 220 °C. When the melting point is too high, the EVOH tends to decompose easily during molding, and when it is too low, the extrusion moldability tends to become unstable. The melting point of such EVOH (A) can be measured, for example, using a differential scanning calorimeter, and taking the melting peak temperature determined according to the method of measuring the melting temperature after a certain heat treatment in JIS K7121 as the melting point.

[0023] In addition, the EVOH (A) may further contain structural units derived from the following comonomers (for example, 10 mol% or less of the EVOH (A)) as long as the effects of the present invention are not inhibited. Examples of the comonomer 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 thereof or mono- or dialkyl esters having 1 to 18 carbon atoms in the alkyl group; acrylamides such as acrylamide, N-alkylacrylamides 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 thereof or a quaternary salt thereof; methacrylamides such as methacrylamide, N-alkylmethacrylamides 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 thereof or a 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 ethers having 1 to 18 carbon atoms in the alkyl group, hydroxyalkyl vinyl ethers, and alkoxyalkyl vinyl ethers; 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.

[0024] Among them, hydroxy group-containing α-olefins are preferred, and particularly 3-butene-1,2-diol and 5-hexene-1,2-diol are preferred. When the hydroxy group-containing α-olefins are copolymerized, the resulting EVOH will have a primary hydroxyl group in the side chain. EVOH having a primary hydroxyl group in such a side chain, particularly EVOH having a 1,2-diol structure in the side chain, is preferred in that it has good secondary moldability while maintaining gas barrier properties.

[0025] When the EVOH (A) used in this embodiment has a primary hydroxyl group in the side chain, the content of the structural unit derived from the monomer having the primary hydroxyl group is usually 0.1 to 20 mol%, preferably 0.5 to 15 mol%, particularly preferably 1 to 10 mol% of the EVOH (A).

[0026] Further, as the EVOH (A), "post-modified" EVOH such as esterification, urethanization, acetalization, cyanoethylation, oxyalkylation, etc. can also be used.

[0027] When using the post-modified EVOH, the modification rate is usually 10 mol% or less, preferably 4 mol% or less. When the modification rate of the EVOH used is too high, it tends to be easily thermally deteriorated and the long-term property tends to decrease.

[0028] Furthermore, the EVOH (A) may be a mixture of EVOHs having different contents of ethylene structural units, saponification degrees, polymerization degrees, copolymerization components, etc.

[0029] [Inorganic layered compound (B)] The inorganic layered compound (B) referred to in this embodiment means a compound having a structure in which atoms are strongly bonded by covalent bonds or the like to form a sheet-like substance arranged densely, and these sheet-like substances are stacked almost parallel by van der Waals forces, electrostatic forces, etc. Typically, layered silicates are mentioned. Such inorganic layered compounds may be natural products or synthetic products.

[0030] Such layered silicates are composed of a tetrahedral sheet in which tetrahedral crystals containing inorganic elements such as silicon and aluminum are two-dimensionally bonded, and an octahedral sheet in which octahedral crystals containing inorganic elements such as aluminum, magnesium, and iron are two-dimensionally bonded. Kaolin minerals are cited as 1:1 type layered silicates in which the relationship between the tetrahedral sheet and the octahedral sheet is 1:1. Specifically, kaolinite, halloysite, chrysotile, etc. are cited. As 2:1 type layered silicates, mica such as talc, smectite, vermiculite, mica, and brittle mica are cited. Examples of smectite include montmorillonite and saponite. In addition to these, hydrotalcite is cited. From the viewpoints of cost and ease of availability, 1:1 type layered silicates are preferred, and kaolin minerals are more preferred. In particular, it is desirable to use kaolinite.

[0031] One example of kaolinite used in this embodiment may be surface-treated with a reactant such as a silane coupling agent. The silane coupling agent is represented by the general formula RSiX 3 wherein R is an organic functional group such as a vinyl group, styryl group, epoxy group, glycidyl group, glycidoxy group, methacryl group, amino group, mercapto group, etc., and X is mainly a chlorine and an alkoxy group.

[0032] Examples of the type of the silane coupling agent include aminosilane, vinylsilane, styrylsilane, epoxysilane, glycidylsilane, glycidoxysilane, methacrylsilane, mercaptosilane, etc., among which aminosilane is preferred. Specifically, for example, vinyltrimethoxysilane, vinyltriethoxysilane, p-styryltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, etc. can be mentioned. These can be used alone or in combination of two or more kinds.

[0033] The particle size (μm) of the inorganic layered compound (B) used in this embodiment is the median diameter corresponding to 50% of the volume ratio of the primary particles in the particle size distribution measured by a laser diffraction / scattering particle size distribution measuring device LA950 (manufactured by Horiba, Ltd.) when a dispersion liquid with pure water as the solvent and the concentration of the inorganic layered compound (B) being 1 to 10% by mass. Usually, it is 0.01 to 30 μm, preferably 0.01 to 10 μm, and particularly preferably 0.01 to 5 μm. If such a particle size is too large, the appearance of the molded product tends to deteriorate.

[0034] In addition, the primary particles of the inorganic layered compound (B) may form secondary particles. In this case, the median diameter corresponding to 50% of the volume ratio of the secondary particles in the particle size distribution measured by a laser diffraction / scattering particle size distribution measuring device LA950 (manufactured by Horiba, Ltd.) when a dispersion liquid with the concentration of the inorganic layered compound (B) being 1 to 10% by mass is usually 0.1 to 60 μm, preferably 1 to 30 μm, and particularly preferably 5 to 15 μm. If such a particle size is too large, the appearance of the molded product tends to deteriorate.

[0035] Also, the BET surface area (m 2 / g) is usually 1 (m 2 / g) or more, preferably 3 (m 2 / g) or more, particularly preferably 5 (m 2 / g) or more. In this case, the upper limit is usually 80 (m 2 / g). If such a surface area is too small, the dispersion stability tends to decrease.

[0036] <Dispersion of Inorganic Layered Compound (B)> This resin composition is produced by a method of blending an aqueous dispersion of an inorganic layered compound (B) with EVOH (A).

[0037] As a method for obtaining an aqueous dispersion of the inorganic layered compound (B), for example, it may be stirred with distilled water, ion-exchanged water, tap water, etc. using a stirring device. Further, in order to improve the dispersibility, a high-pressure dispersion device such as an ultra-high pressure homogenizer, a ball mill, an ultrasonic treatment device, etc. can also be used.

[0038] The solid content concentration of such an aqueous dispersion of the inorganic layered compound (B) is usually 1 to 90% by mass, preferably 3 to 80% by mass, more preferably 5 to 70% by mass. If such a solid content concentration is too low, since there is a large amount of water when adjusting the aqueous dispersion of the inorganic layered compound (B), it tends to be difficult to increase the concentration of the inorganic layered compound (B) in the resin composition. Further, if the amount of water in the aqueous dispersion is increased, drying in the extruder may be insufficient, and if the discharge amount of the resin composition is decreased, the productivity tends to decrease. On the other hand, if the solid content concentration is too high, the dispersibility of the inorganic layered compound (B) in the resin composition tends to decrease. Further, the viscosity of the aqueous dispersion increases, the fluidity decreases, and it tends to be difficult to charge it into the extruder.

[0039] [Metal Compound (C)] In the present embodiment, by blending a metal compound (C) with the resin composition containing the EVOH (A) and the inorganic layered compound (B), an effect that the processability is remarkably improved can be obtained.

[0040] The metal compound (C) is not particularly limited, and examples thereof include metal salts, oxides, hydroxides, etc. Examples of the metal salt include carbonate, carboxylate (specifically, acetate, stearate, dihydroxystearate), sulfate, etc. Among them, carbonate is preferable in terms of market availability. These can be used alone or in combination of two or more.

[0041] Also, the metal compound (C) is not particularly limited, and examples thereof include alkali metal salts, alkaline earth metal salts, transition metal salts, etc. More specifically, magnesium salts, calcium salts, sodium salts, potassium salts, zinc salts, etc. are included. Among them, alkaline earth metal salts are preferable in terms of processability, and particularly magnesium salts are preferable. These can be used alone or in combination of two or more.

[0042] In terms of the decomposability with respect to EVOH, since the metal compound (C) is preferably basic, the carbonate is preferably a basic carbonate, and the alkaline earth metal salt is also preferably a basic alkaline earth metal salt. That is, among the metal compounds (C), basic magnesium carbonate is particularly preferable. However, the metal compound (C) does not include the compounds listed in the inorganic layered compound (B).

[0043] From the viewpoint of processability and suppressing residence in a molding machine such as various extruders, the particle size of the metal compound (C) is preferably small. Preferably, in the particle size distribution measured by the aqueous powder addition method in the particle size distribution measurement by the laser diffraction scattering method, the median diameter corresponding to 50% by volume is usually 20 μm or less, preferably 1 to 15 μm, and particularly preferably 3 to 10 μm. If such a particle size is too large, the processability tends to decrease, and if it is too small, the handleability becomes difficult and the productivity tends to decrease.

[0044] The ratio of the primary particle diameter (μm) of the inorganic layered compound (B) to the particle diameter (μm) of the metal compound (C) is [primary particle diameter of inorganic layered compound (B) / particle diameter of metal compound (C)], which is usually from 0.005 to 0.1, preferably from 0.008 to 0.08, and particularly preferably from 0.01 to 0.05. When such a value is within the above range, the effects of the present invention tend to be obtained more efficiently.

[0045] [Resin composition] In this resin composition, the base resin component is EVOH (A). The content of EVOH (A) in this resin composition is usually 50% by mass or more, preferably 60% by mass, more preferably 70% by mass, still more preferably 80% by mass or more, and particularly preferably 88% by mass or more. The upper limit is usually 99% by mass, preferably 95% by mass or less, and particularly preferably 92% by mass or less. Resins other than EVOH (A) (for example, polyamide resins, polyolefin resins, etc.) can be blended within a range that does not inhibit the effects of the present invention, but the blending amount is usually less than 50% by mass, preferably less than 30% by mass, and particularly preferably less than 20% by mass.

[0046] In this resin composition, the content of the inorganic layered compound (B) relative to EVOH (A), in terms of mass ratio [(B) / (A)], is usually from 1 / 99 to 50 / 50, preferably from 5 / 95 to 30 / 70, and particularly preferably from 8 / 92 to 20 / 80. When such a ratio is too large, the effects of the present invention tend to be difficult to obtain.

[0047] When the metal compound (C) is blended in this resin composition, the content is usually from 10 to 1000 ppm in terms of metal relative to the total amount of the EVOH (A), inorganic layered compound (B), and metal compound (C), preferably from 100 to 800 ppm, particularly preferably from 300 to 700 ppm, and most preferably from 350 to 500 ppm. When such an amount is too small, the processability tends to decrease, and when it is too large, the productivity tends to decrease. The method for measuring the metal-converted content of the metal compound (C) is not particularly limited, but it can be measured, for example, by elemental analysis.

[0048] Also, the content of the metal compound (C) with respect to the inorganic layered compound (B) is usually 0.1 to 1, preferably 0.5 to 0.9, particularly preferably 0.6 to 0.8 in terms of the mass ratio [(C) / (B)]. If such a ratio is too small, the processability tends to decrease, and if it is too large, the productivity tends to decrease.

[0049] In this resin composition, first, the blending (mixing) ratio of the target EVOH (A) and the inorganic layered compound (B) is determined, and while considering the moisture content of the entire resin composition during mixing, the moisture content of EVOH (A), the solid content concentration in the aqueous dispersion of the inorganic layered compound (B), and the metal equivalent content of the metal compound (C) are determined and then subjected to kneading.

[0050] [Method for producing resin composition] This resin composition is produced by melt-kneading an aqueous dispersion of an inorganic layered compound (B) with EVOH (A) using an extruder. More specifically, methods such as a method of supplying EVOH (A) to the raw material supply section of the extruder and supplying the aqueous dispersion of the inorganic layered compound (B) from a part of the barrel of the extruder (side feed) can be mentioned. When performing this method, it is also possible to supply the aqueous dispersion using gravity from the dispersion liquid injection section (vent port) or to supply it under pressure. And this resin composition is characterized in that the barrel temperature near the dispersion liquid injection section of the extruder during production is lower than the barrel temperature other than near the dispersion liquid injection section.

[0051] As the extruder used for producing this resin composition, for example, extruders such as single-screw extruders and twin-screw extruders are preferably used. In particular, from the viewpoint of the dispersibility of the inorganic layered compound (B) in the resin composition, a twin-screw extruder is preferred.

[0052] As for the twin-screw extruder, those with an inner diameter of 20 mm or more (more preferably 30 to 150 mm) are preferred. If the inner diameter is too small, productivity tends to decrease. The L / D of the twin-screw extruder is preferably 20 or more (more preferably 30 or more). If the L / D is too low, the kneading time is short, and the dispersibility of the inorganic layered compound (B) in the EVOH (A) tends to decrease. Also, although the total length of the twin-screw extruder is not particularly limited, it is preferably 4,800 to 5,600 mm, and the dispersion liquid injection part 2 described below is preferably located 2,000 to 2,400 mm from the front (tip) of the twin-screw extruder.

[0053] Hereinafter, with reference to FIGS. 1(a) and 1(b), the melting and kneading of the aqueous dispersion of the EVOH (A) and the inorganic layered compound (B) in the twin-screw extruder will be described more specifically.

[0054] That is, the twin-screw extruder includes a cylinder and a screw disposed inside the cylinder. For the sake of facilitating the description of an embodiment of the present invention, the cylinder is shown in FIG. 1(a) and the screw is shown side by side in FIG. 1(b). First, the EVOH (A) is supplied from the raw material supply part 1 of the twin-screw extruder. The supplied EVOH (A) is sent rearward (rightward in the figure) while being heated by a barrel (not shown) in the full flight screw part 5a, and is kneaded in the kneading part 6a to be in a molten or semi-molten state. The resin in the molten or semi-molten state is sent by the full flight screw part 5b, and an aqueous dispersion of the inorganic layered compound (B) is added from the dispersion liquid injection part 2. Next, the EVOH (A) and the aqueous dispersion of the inorganic layered compound (B) are sent to the kneading part 6b, kneaded, then sent to the full flight screw part 5c, and after water vapor is released from the screw type side feeder 3, it is sent to the full flight screw part 5d through the seal ring part 7, and water vapor is released from the vacuum vent 4 to adjust the water content rate of the kneaded product of the EVOH (A) and the dispersion liquid of the inorganic layered compound (B). Then, the resin composition is discharged from the discharge port 8.

[0055] When blending the metal compound (C) into the present resin composition, it is preferable to supply the EVOH (A) and the metal compound (C) to the raw material supply section 1.

[0056] During the melting and kneading process, the barrel temperature when the aqueous dispersion of EVOH (A) and the inorganic layered compound (B) is sent backward varies depending on the ranges of before the dispersion liquid injection section (I), near the dispersion liquid injection section (II), and after near the dispersion liquid injection section (III) as shown in FIG. 1. Specifically, the barrel temperature near the dispersion liquid injection section (II) may be lower than the barrel temperatures of the parts other than near the dispersion liquid injection section (I) and (III).

[0057] Here, the vicinity of the dispersion liquid injection section (II) is a barrel portion having a length corresponding to 20 to 30% of the total length of the twin-screw extruder starting from the dispersion liquid injection section 2.

[0058] The barrel temperature near the dispersion liquid injection section (II) is preferably 80°C or more lower than the maximum temperature in the barrel, more preferably 90°C or more lower, still more preferably 100°C or more lower, and particularly preferably 120°C or more lower. The maximum temperature difference is 150°C.

[0059] The specific barrel temperature near the dispersion liquid injection section (II) is usually 100 to 180°C, preferably 110 to 170°C, and particularly preferably 120 to 160°C. Also, the barrel temperatures of the parts other than near the dispersion liquid injection section (II) are usually 180 to 280°C, preferably 190 to 260°C, and particularly preferably 200 to 250°C.

[0060] Also, the barrel temperature from near the dispersion liquid injection section (II) to after near the dispersion liquid injection section (III) is preferably increased stepwise, for example, by 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, or a combination thereof.

[0061] In addition, when the entire barrel temperature is as low as that near the dispersion liquid injection part (II), the melting of the resin becomes insufficient, and granulation tends to be difficult due to torque overshoot. Or even if granulation is possible, the productivity tends to decrease significantly.

[0062] The temperature of the resin composition in the die during kneading is not particularly limited, but it is also preferable to adjust the extrusion conditions (set temperature, screw shape, screw rotation speed, etc.) so that it becomes 120 to 300 °C (more preferably 150 to 280 °C). If such a temperature is too low, the extrusion may become unstable. Conversely, if it is too high, the quality of the resin composition may deteriorate (thermal degradation), which is not preferable. The temperature of the resin composition may be judged by applying the temperature measured by the temperature sensor installed in the extruder cylinder. The installation location of the temperature sensor is preferably near the extruder discharge port.

[0063] The rotation speed of the screw is selected from the range of 10 to 1000 rpm (more preferably 30 to 600 rpm). If such a rotation speed is too low, the productivity tends to decrease. Conversely, if it is too high, the quality of the resin composition tends to deteriorate (thermal degradation).

[0064] The charging speed of EVOH (A) may be arbitrarily determined according to the barrel diameter of the extruder, etc. Regarding the charging speed of the inorganic layered compound (B), it may be supplied in accordance with EVOH (A) so as to match the blending amount of the inorganic layered compound (B) in the target resin composition.

[0065] In addition, the residence time (kneading time) of the resin composition in the extruder is usually selected from the range of 10 to 300 seconds, preferably 50 to 300 seconds, and more preferably 100 to 300 seconds. If such a residence time is too short, the kneading becomes insufficient, and the dispersibility of the inorganic layered compound (B) and the dehydration efficiency tend to decrease. On the other hand, if the residence time is too long, the deterioration of the resin due to heat tends to be a concern.

[0066] The pressure applied to the resin composition (resin pressure) is preferably selected from the range of 0.5 to 30 MPa, more preferably 1 to 20 MPa. If such pressure is too low or too high, extrusion tends to become unstable. Also, it is preferable to seal the inside of the hopper and around the vent holes with nitrogen in order to prevent thermal degradation of the resin composition.

[0067] Note that the seal ring portion 7 is used to suppress water drainage to the front and / or rear. However, even without the seal ring portion 7, if the kneaded material fills the kneading portions 6a, 6b, etc. and stable production is possible, it is not particularly necessary. If there is water drainage to the front and / or rear, the water content of the resulting resin composition will increase, and there is a risk of problems such as foaming during melt molding (extrusion molding, injection molding, etc.) after drying.

[0068] The screw type side feeder 3 is provided behind the raw material supply portion 1 of the extruder. In the process of heating, melting the raw material supplied from the raw material supply portion 1 and discharging it from the opening at the tip of the extruder, it degasses the liquid contained in the raw material and forcibly pushes back the raw material that has risen from inside the extruder together with the liquid into the extruder. Therefore, in order for the screw type side feeder 3 to always reliably push back the raw material into the extruder, it is preferable to use a device using a co-rotating twin screw.

[0069] The inner diameter of the screw type side feeder 3 is preferably the same as or smaller than the inner diameter of the extruder, and the difference between the inner diameter of the screw type side feeder 3 and the inner diameter of the extruder is desirably within 15 mm.

[0070] Since the screw type side feeder 3 is connected by making a hole in the side of the extruder, it is practically impossible to make the inner diameter of the screw type side feeder 3 larger than the inner diameter of the extruder. Also, if the inner diameter of the screw type side feeder 3 is too small, the discharge amount of water vapor will decrease, which is not preferable.

[0071] The rotation speed of the screw type side feeder 3 is preferably 10 rpm or more (more preferably 30 rpm or more). If such a rotation speed is too low, the resin is likely to flow backward.

[0072] The L / D of the screw type side feeder 3 is preferably 3 or more. When such L / D is too short, the screw surface area of the screw type side feeder 3 becomes small, steam condenses and accumulates, and the discharge efficiency tends to decrease.

[0073] The screw type side feeder 3 may be equipped with a heating device such as a hot water jacket or a heater for heating the device. From the viewpoint of improving the discharge efficiency of steam, it is desirable to have a heating device. Furthermore, in order to improve the discharge efficiency of steam, equipment for promoting degassing such as a vacuum pump may be connected.

[0074] Also, as a method for removing moisture, dehydration means such as a vent, a slit barrel, a drain port, and a drain pump can also be used in the cylinder. The dehydration means shown above may be used alone, or a plurality of the same type may be used. Alternatively, different types may be combined and used. For example, it is reasonable to dehydrate by removing moisture using the screw type side feeder 3 and then further removing moisture from the vent port on the rear side.

[0075] The water content of the resin composition immediately after being discharged from the extruder is less than 5% by mass, preferably 2% by mass or less, and more preferably 0.5% by mass or less, which is preferable in terms of reducing troubles such as foaming during melt molding (extrusion molding, injection molding, etc.) after drying. Usually, the lower limit of the water content is 0.01% by mass.

[0076] Furthermore, after obtaining a resin composition with a water content of less than 5% by mass by the above method, a drying treatment (hot air drying, dielectric heating drying, microwave irradiation drying, etc.) can be performed as necessary for the purpose of readjusting the water content of the resin composition.

[0077] The resin composition produced by the manufacturing method of this embodiment is excellent in transparency. The internal haze of this resin composition is 15% or less, preferably 14% or less, more preferably 13% or less, and particularly preferably 12% or less. The lower limit is usually 0. The method for measuring such internal haze can be carried out by measuring a 30-μm-thick film made of the resin composition in accordance with JIS K7136.

[0078] The reason for being able to produce a resin composition with excellent transparency is not clear. However, it is presumed that by sufficiently melting EVOH in front of the dispersion liquid injection part (I) and lowering the temperature in the vicinity of the dispersion liquid injection part (II), the moisture in the dispersion liquid is better retained, the fine dispersion of the inorganic layered compound occurs, and by sufficiently melting the resin again in the finely dispersed state, a resin composition with excellent transparency can be produced.

[0079] The method for pelletizing the resin composition discharged from the extruder includes, for example, a method of manufacturing cylindrical resin composition pellets (strand cutting method) by cutting the strand-like material obtained by extruding and then cooling and solidifying the heat-melted resin composition to a certain size using a strand cutter, or a method of manufacturing spherical EVOH resin composition pellets (hot cutting methods such as underwater cutting method and air cutting method) by extruding the resin composition heated and melted in the extruder from the discharge port into the coagulating liquid and cutting it to a certain size using a cutter in the molten state, utilizing the surface tension during coagulation.

[0080] In the resin composition obtained by the manufacturing method of this resin composition, according to the purpose, plasticizers, heat stabilizers, light stabilizers, ultraviolet absorbers, anti-aging agents, pigments, colorants, natural fibers, various inorganic particles, various fillers, antistatic agents, mold release agents, plasticizers, fragrances, lubricants, crosslinking (vulcanizing) agents, crosslinking (vulcanizing) accelerators, crystal nucleating agents, crystallization accelerators, flame retardants, foaming agents, softeners, preservatives, antibacterial and antifungal agents, and other various coating additives can be blended as optional components other than the components (A) to (C) during the mixing or kneading of raw materials or during molding.

[0081] [Molded article] The resin composition obtained by the production method of this embodiment is widely used for the applications of molded articles, and is molded into films, sheets, containers, fibers, rods, tubes, various molded products, etc. by melt molding or the like. Also, the pulverized products of these (such as when reusing recycled products) can be used again for melt molding. As such a melt molding method, an extrusion molding method (T-die extrusion, inflation extrusion, blow molding, melt spinning, profile extrusion, etc.), an injection molding method are mainly adopted. The melt molding temperature is often selected from the range of 150 to 300°C.

[0082] [Multilayer structure] Also, the resin composition obtained by the production method of this embodiment can be used as a single molded article, but can also be used for a molded article of a multilayer structure. Specifically, it is useful to laminate a thermoplastic resin layer or the like on at least one side of the layer made of the resin composition to form a molded article having a multilayer structure.

[0083] In manufacturing the multilayer structure, another substrate is laminated on one or both sides of the layer made of the resin composition. As the lamination method, for example, a method of melt-extruding a thermoplastic resin onto a film or sheet made of the resin composition, conversely, a method of melt-extruding the resin composition onto a substrate such as a thermoplastic resin, a method of co-extruding the resin composition and another thermoplastic resin, and further, a method of dry laminating a film or sheet made of the resin composition of this embodiment and a film or sheet of another substrate using an adhesive such as an organotitanium compound, an isocyanate compound, a polyester-based compound, a polyurethane compound, etc. can be mentioned. Also, it is preferable to subject the resin composition obtained by the production method of this embodiment to co-extrusion molding.

[0084] As the resin on the other side in the case of co-extrusion, for example, polyolefin resins, polyester resins, polyamide resins, copolyamide, polystyrene resins, polyvinyl chloride resins, polyvinylidene chloride, acrylic resins, vinyl ester resins, polyester elastomers, polyurethane elastomers, chlorinated polyethylene, chlorinated polypropylene, aromatic and aliphatic polyketones, aliphatic polyalcohols, etc. can be mentioned, and preferably polyolefin resins are used.

[0085] As such polyolefin resins, specifically, linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), very low-density polyethylene (VLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), ethylene-vinyl acetate copolymer (EVA), ionomer, ethylene-propylene (block or random) copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid copolymer, ethylene-methacrylic acid ester copolymer, polypropylene, propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer, polybutene, polypentene, polymethylpentene and other olefin homopolymers or copolymers, or those obtained by graft-modifying these olefin homopolymers or copolymers with unsaturated carboxylic acids or their esters, or blends thereof, etc., can be mentioned. Among them, linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), very low-density polyethylene (VLDPE), ethylene-vinyl acetate copolymer (EVA), and ionomer are preferable in terms of excellent flexural fatigue resistance, vibration fatigue resistance, etc. of the resulting laminated packaging material.

[0086] Furthermore, when a molded article such as a film or a sheet is once obtained from the resin composition obtained by the production method of the present embodiment and another base material is extrusion-coated thereon, or when a film, a sheet, etc. of another base material is laminated using an adhesive, any base material (paper, metal foil, unstretched, uniaxially or biaxially stretched plastic film or sheet and its inorganic vapor deposition body, woven fabric, non-woven fabric, metal wool-like, woody, etc.) other than the above-mentioned thermoplastic resin can be used.

[0087] When the layer structure of the multilayer structure is such that the layers made of the resin composition obtained by the production method of the present embodiment are a (a1, a2, ···) and other base materials, for example, thermoplastic resin layers are b (b1, b2, ···), if it is in the form of a film, sheet, or bottle, not only a two-layer structure of a / b but also any combination such as b / a / b, a / b / a, a1 / a2 / b, a / b1 / b2, b2 / b1 / a / b1 / b2, b1 / b2 / a / b3 / b4, a1 / b1 / a2 / b2, etc. is possible. In the filament form, any combination such as a bimetal type, core (a)-sheath (b) type, core (b)-sheath (a) type, or eccentric core-sheath type of a and b is possible.

[0088] In addition, in the above layer structure, an adhesive resin layer can be provided between the respective layers as necessary, and various types of such adhesive resins can be used. Although it cannot be generally stated as it varies depending on the type of the resin of b, carboxyl group-containing modified olefin polymers obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to an olefin polymer (the above-mentioned polyolefin resin in a broad sense) by an addition reaction, graft reaction, or the like can be mentioned. Specifically, maleic anhydride graft-modified polyethylene, maleic anhydride graft-modified polypropylene, maleic anhydride graft-modified ethylene-propylene (block or random) copolymer, maleic anhydride graft-modified ethylene-ethyl acrylate copolymer, maleic anhydride graft-modified ethylene-vinyl acetate copolymer, etc. One or a mixture of two or more selected therefrom can be mentioned as a preferred one.

[0089] At this time, the amount of the unsaturated carboxylic acid or its anhydride contained in the olefin polymer is preferably 0.001 to 3% by mass, more preferably 0.01 to 1% by mass, and particularly preferably 0.03 to 0.5% by mass. If the amount of modification in the modified product is small, the adhesiveness tends to be insufficient, and conversely, if it is large, a crosslinking reaction occurs and the moldability tends to decrease.

[0090] These adhesive resins can also be blended with the resin composition obtained by the production method of the present embodiment, other EVOH, rubber and elastomer components such as polyisobutylene and ethylene-propylene rubber, and further with the resin of the b layer. In particular, blending a polyolefin resin different from the matrix polyolefin resin of the adhesive resin may improve the adhesiveness and is useful.

[0091] The thickness of each layer of the multilayer structure cannot be generally determined by the layer structure, type of b, use, container form, required physical properties, etc. Usually, a is 0.5 to 300 μm (more preferably 1 to 200 μm), b is 5 to 3000 μm (more preferably 10 to 2000 μm), and the adhesive resin layer is selected from the range of about 0.5 to 300 μm (more preferably 1 to 200 μm). If a is too thin, the gas barrier property tends to decrease, and the thickness control tends to become unstable. Conversely, if a is too thick, the flex fatigue resistance tends to decrease, and it is not economical and not preferable. Also, if b is too thin, the rigidity tends to decrease. Conversely, if b is too thick, the flex fatigue resistance tends to decrease, and the mass increases, which is not preferable. If the adhesive resin layer is too thin, the interlayer adhesiveness tends to decrease, and the thickness control tends to become unstable. Conversely, if the adhesive resin layer is too thick, the mass tends to increase, and it is not economical and not preferable. Also, in each layer of the multilayer structure, various additives, modifiers, fillers, other resins, etc. can be added within a range that does not inhibit the effects of the present invention in order to improve the moldability and various physical properties.

[0092] The multilayer structure is used as it is for various shapes. However, in order to further improve the physical properties of the multilayer structure, it is also preferable to perform a stretching treatment. Such stretching can be either uniaxial stretching or biaxial stretching. The higher the stretching ratio, the better the physical properties. A stretched film, stretched sheet, stretched container, stretched bottle, etc. can be obtained without pinholes, cracks, stretching unevenness, delamination, etc. during stretching.

[0093] As stretching methods, in addition to roll stretching method, tenter stretching method, tubular stretching method, stretch blow method, etc., those with a high stretching ratio among deep drawing forming, vacuum pressure forming, etc. can also be adopted. In the case of biaxial stretching, either a simultaneous biaxial stretching method or a sequential biaxial stretching method can be adopted. The stretching temperature is selected from the range of 50 to 170 °C, preferably about 60 to 160 °C.

[0094] After the stretching is completed, it is also preferable to perform heat setting next. Heat setting can be carried out by well-known means. While keeping the stretched film in a tensioned state, heat treatment is usually performed at 80 to 300 °C, preferably 100 to 280 °C for about 1 to 600 seconds. For example, when obtaining cup-shaped or tray-shaped multilayer containers from multilayer sheets or multilayer films, a drawing forming method is adopted, specifically, a vacuum forming method, a pressure air forming method, a vacuum pressure air forming method, a plug assist type vacuum pressure air forming method, etc.

[0095] Furthermore, when obtaining tube-shaped or bottle-shaped multilayer containers from multilayer parisons (hollow tubular preforms before blowing), a blow forming method is adopted. Specifically, an extrusion blow forming method (double-headed type, mold moving type, parison shift type, rotary type, accumulator type, horizontal parison type, etc.), a cold parison type blow forming method, an injection blow forming method, a biaxial stretch blow forming method (extrusion type cold parison biaxial stretch blow forming method, injection type cold parison biaxial stretch blow forming method, injection molding in-line type biaxial stretch blow forming method, etc.) can be mentioned.

[0096] Also, when used for heat shrink packaging applications such as fresh meat, processed meat, and cheese, it is made into a product film without performing heat setting after stretching. After storing the above-mentioned fresh meat, processed meat, cheese, etc. in the film, heat treatment is usually performed at 50 to 130 °C, preferably 70 to 120 °C for about 2 to 300 seconds to heat shrink the film for tight packaging.

[0097] The shape of the multilayer structure thus obtained may be arbitrary, and examples thereof include films, sheets, tapes, bottles, pipes, filaments, and extrusions with irregular cross-sections. Further, the obtained multilayer structure can be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or melt coating treatment, bag making, deep drawing, box making, tube making, split processing, etc., as necessary.

[0098] Containers such as cups, trays, tubes, and bottles obtained as described above, bags made of stretched films, and lid materials are useful as containers for various products such as general foods, seasonings such as mayonnaise and dressings, fermented foods such as miso, oil and fat foods such as salad oil, beverages, cosmetics, pharmaceuticals, detergents, toiletries, industrial chemicals, agricultural chemicals, and fuels. In particular, the multilayer structure of this embodiment is useful for cup-shaped containers for semi-solid foods and seasonings such as jelly, pudding, yogurt, mayonnaise, and miso, and for heat-stretch formed containers such as tray-shaped containers for raw meat and processed livestock products (ham, bacon, wieners, etc.).

Examples

[0099] Hereinafter, this embodiment will be specifically described by way of examples. However, this embodiment is not limited by the following examples. Unless otherwise specified, "parts" and "%" hereinafter mean mass basis. Prior to the examples, the following components were prepared.

[0100] [EVOH (A)] · EVOH (A1): ethylene structural unit content 29.2 mol%, saponification degree 99.7 mol%, MFR 4.1 g / 10 min (210 °C, load 2160 g), melting point 188 °C · EVOH (A2): ethylene structural unit content 38.1 mol%, saponification degree 99.7 mol%, MFR 4.4 g / 10 min (210 °C, load 2160 g), melting point 173 °C

[0101] [Inorganic layered compound (B)] · Kaolinite: The median diameter corresponding to 50% of the volume ratio of the primary particles in the particle shape distribution measured by a laser diffraction / scattering type particle size distribution measuring device LA950 (manufactured by Horiba, Ltd.) is 0.15 μm, and the BET surface area is 10 m 2 / g

[0102] [Metal compound (C)] · Magnesium carbonate: xMgCO 3 · yMg(OH) 2 · zH 2 O, which is basic magnesium carbonate (manufactured by Kyowa Chemical Industry Co., Ltd., magnesium carbonate for chemical use (brand name: light quality)), where (x, y, and z are integers respectively). In the particle size distribution measured by the aqueous powder addition method in the particle size distribution measurement by the laser diffraction scattering method, the median diameter corresponding to 50% of the volume ratio is 6 μm

[0103] <Example 1> [Production of resin composition pellets] 69 parts of the inorganic layered compound (B) and 31 parts of distilled water were put into a container and stirred at room temperature (25 °C) until the aggregates of the inorganic layered compound (B) disappeared, thereby obtaining an aqueous dispersion of the inorganic layered compound (B) (solid concentration: 69%). Using the EVOH (A1), the aqueous dispersion of such an inorganic layered compound (B), and the metal compound (C), they were mixed under the following compounding conditions using a twin-screw extruder, extruded into strands and cut to obtain cylindrical pellets. In 100 parts of such pellets, EVOH (A1) was 88 parts and the inorganic layered compound (B) was 12 parts.

[0104] (Compounding conditions) Prior to compounding, a twin-screw extruder (L / D = 56, 32 mm φ) having a screw configuration shown in FIG. 1, including full-flight screw parts 5a, 5b, 5c, 5d, kneading parts 6a, 6b, and a seal ring part 7, and having a cylinder configuration with a raw material supply part 1, a dispersion liquid pressure injection part 2, a screw type side feeder 3, and a vacuum vent 4 was prepared. The total length of the twin-screw extruder is 5200 mm, and the dispersion liquid injection part 2 is located approximately 2200 mm from the front of the twin-screw extruder. Then, as shown in Fig. 1, starting from the dispersion liquid injection part 2, the range corresponding to 20% of the total length of the twin-screw extruder is defined as the vicinity of the dispersion liquid injection part (II), the front and back of it are defined as the front of the dispersion liquid injection part (I) and the back of the vicinity of the dispersion liquid injection part (III). Then, the EVOH (A1) and the metal compound (C) were introduced from the raw material supply part 1 of the extruder. After melting the EVOH (A1) and the metal compound (C) at a barrel temperature of 220 °C, the aqueous dispersion of the inorganic layered compound (B) obtained above (solid content concentration: 69%) was continuously injected from the dispersion liquid injection part 2 and kneaded at a barrel temperature of 120 °C (slurry method). The kneaded resin composition was extruded into a strand shape into a water tank and cut by a pelletizer to produce resin composition pellets. The barrel temperature of the front of the dispersion liquid injection part (I) was 220 °C, the barrel temperature of the vicinity of the dispersion liquid injection part (II) was 120 °C, and the barrel temperature of the back of the vicinity of the dispersion liquid injection part (III) was 230 °C. The barrel temperatures of each range are shown in Table 1 below.

[0105] The content of the metal compound (C) in the obtained resin composition is 800 ppm (230 ppm in terms of magnesium conversion) with respect to the total amount of EVOH (A1), inorganic layered compound (B), and metal compound (C). Also, the mass ratio ((C) / (B)) of the metal compound (C) to the inorganic layered compound (B) in the obtained resin composition is 0.67.

[0106] <Example 2, Comparative Example 1> Pellets of the resin compositions of Example 2 and Comparative Example 1 were prepared in the same manner as in Example 1, except that the types of each component and the barrel temperatures of each range were changed as shown in Table 1 below.

[0107] Using the obtained resin compositions of Example 1, 2, and Comparative Example 1, the following internal haze evaluation was performed. The results are shown together in Table 1 below.

[0108] [Internal Haze Evaluation] Using the resin compositions of Examples 1 and 2 and Comparative Example 1, a single-layer T-die film forming machine (extruder: 40 mmφ, lip opening: 0.3 mm, manufactured by Plastic Industry Research Institute) was used to produce a film with a thickness of 30 μm at a set temperature of 220°C and a screw rotation speed of 40 rpm. Using a haze meter NDH-4000 (manufactured by Nippon Denshoku Industries Co., Ltd.), a sample was prepared by fixing the 30-μm-thick film formed above in a sample holder. After standard calibration using a quartz cell filled with liquid paraffin, the sample was inserted into this paraffin, and the haze was measured in accordance with JIS K7136. This was measured at n = 3, and the average value was taken as the internal haze value. The lower this value, the better the transparency of the resin composition.

[0109]

Table 1

[0110] From the results in Table 1 above, it can be seen that the resin compositions of Examples 1 and 2, where the barrel temperature near the dispersion liquid injection part (II) is lower than the barrel temperatures in other parts (I) and (III) outside the dispersion liquid injection part, have better internal haze than Comparative Example 1 where the barrel temperature near the dispersion liquid injection part (II) is made the same as the barrel temperatures in other parts (I) and (III) outside the dispersion liquid injection part. The reason for this is considered to be that by lowering the barrel temperature near the dispersion liquid injection part (II), the moisture in the dispersion liquid of the inorganic layered compound is better retained, the dispersibility of the inorganic layered compound is improved, and it is finely dispersed, resulting in a decrease in internal haze.

Industrial Applicability

[0111] The resin composition obtained by the production method of this embodiment can be used for films, sheets, containers, etc. It is useful as various packaging materials for general foods, retort foods, pharmaceuticals, industrial products, agricultural use, etc.

Explanation of Reference Numerals

[0112] 1: Raw material supply part 2: Dispersion liquid injection part 3: Screw type side feeder 4: Vacuum vent 5a, 5b, 5c, 5d: Full flight screw section 6a, 6b: Kneading section 7: Seal ring section (used for suppressing water drainage to the front and / or rear) 8: Discharge port I: Before the dispersion liquid injection section II: Near the dispersion liquid injection section III: After near the dispersion liquid injection section

Claims

1. A resin composition containing an ethylene-vinyl alcohol copolymer (A) and an inorganic layered compound (B), wherein the internal haze measured by the following measurement method is 15% or less. Measurement method: The internal haze is measured in accordance with JIS K7136 for a film with a thickness of 30 μm made of the resin composition.

2. The resin composition according to Claim 1, wherein the inorganic layered compound (B) is a kaolin mineral.

3. The resin composition according to Claim 1, further containing a metal compound (C).

4. The resin composition according to Claim 3, wherein the metal compound (C) is an alkaline earth metal salt.

5. The resin composition according to Claim 3, wherein the metal compound (C) is a carbonate.

6. A method for producing the resin composition according to any one of Claims 1 to 5, including a step of mixing an aqueous dispersion of the ethylene-vinyl alcohol copolymer (A) and the inorganic layered compound (B) in an extruder, wherein the barrel temperature near the dispersion liquid injection part of the extruder is lower than the barrel temperature other than near the dispersion liquid injection part.

7. The method for producing a resin composition according to Claim 6, wherein the barrel temperature near the dispersion liquid injection part is 80 °C or more lower than the maximum temperature in the barrel.

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