JP2020084017A - Blow molded container, and fuel container and bottle container each comprising the same - Google Patents

Abstract

To provide a blow molded container that has less streaks and particles and is excellent in impact resistance at a low temperature and to provide a fuel container and a bottle container each comprising the blow molded container.SOLUTION: The blow molded container comprises a layer formed from a resin composition containing (A) an ethylene/vinyl alcohol copolymer having an ethylene unit content of 20 to 60 mol% and (B) a boron compound. The boron compound (B) includes (C) free boric acid and the content of the boron compound (B) based on the ethylene/vinyl alcohol copolymer (A) in the resin composition is 100 ppm to 5,000 ppm in terms of orthoboric acid and the proportion of the free boric acid (C) in the boron compound (B) is 0.1 mass% to 10 mass% in terms of orthoboric acid.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a blow molded container, and a fuel container and a bottle container including the blow molded container.

Ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as “EVOH”) is a polymer material having excellent gas barrier properties, oil resistance, antistatic properties, mechanical strength, etc., and is widely used as various packaging materials. ing.

A blow-molded container having an EVOH layer is known as one of containers using EVOH (see Patent Document 1). In blow-molded containers, a multilayer structure including an EVOH layer and a layer of another thermoplastic resin having excellent moisture resistance and impact resistance is widely used. Blow-molded containers having an EVOH layer are used in various fields such as fuel containers and various bottles because they have excellent gas barrier properties.

On the other hand, when using EVOH as various packaging materials, an EVOH resin composition has been proposed which is relatively easy to perform melt molding and the like. In Patent Document 2, in producing a resin composition containing a specific amount of EVOH and a boron compound, EVOH having a water content of 20 to 80 mass% is brought into contact with an aqueous solution of a boron compound, and the content of the boron compound in the aqueous solution of the boron compound. Is 0.001 to 0.5 parts by mass based on 100 parts by mass of the total amount of water contained in the EVOH and the water contained in the aqueous solution of the boron compound, whereby the melt moldability is excellent, and particularly, the production of a multilayer laminate. It is described that it is possible to obtain an EVOH resin composition which can suppress the generation of fish eyes and the like and has good long-run moldability.

Patent Document 3 discloses that a boron compound is 100 to 5000 ppm in terms of orthoboric acid (H ₃ BO ₃ ), a carboxylic acid and/or its salt is 100 to 1000 ppm in terms of carboxylic acid, and an alkali metal salt is 50 to 300 ppm in terms of metal. Disclosed is a multi-layer structure obtained by co-extruding a melted multi-layered body comprising an EVOH resin composition layer and a carboxylic acid-modified polyolefin resin layer adjacent to the EVOH resin composition layer. It is stated that extrusion film forming stability is improved.

JP, 2005-089482, A JP, 11-293078, A International Publication No. 2000/020211

However, when the conventional EVOH resin composition is used for continuous multi-layer blow molding for a long time, the resulting blow-molded container may have defects in appearance such as streaks and spots. The streak is a transparent streak-like defect and is considered to be caused by layer disorder or partial cross-linking. Further, the lump is a granular defect and is said to be generated by gelation due to partial crosslinking.

These defects such as streaks and lumps cause not only deterioration of appearance but also deterioration of performance such as gas barrier property. For example, in order to store and transport foods, fuels, etc. at low temperatures, blow-molded containers are required to be resistant to impacts and maintain gas barrier properties even in low-temperature environments. However, in a blow-molded container including an EVOH layer, the EVOH layer tends to be hard at low temperatures, so that cracks and the like are likely to occur upon impact, and the gas barrier property tends to deteriorate. Here, if there are many streaks and lumps as described above, when an impact is received, these tend to act as starting points to cause cracks and the like, and the gas barrier property is deteriorated.

The present invention has been made based on the above circumstances, and an object thereof is a blow-molded container having less streaks and lumps and excellent in impact resistance at low temperature, and a fuel provided with such a blow-molded container. To provide a container and a bottle container.

That is, the present invention provides [1] an ethylene-vinyl alcohol copolymer (A) having an ethylene unit content of 20 to 60 mol% (hereinafter sometimes abbreviated as "EVOH (A)") and a boron compound (B). A blow molding container comprising a layer formed from a resin composition (α) containing therein, wherein the boron compound (B) contains free boric acid (C), and boron to EVOH (A) in the resin composition (α) is contained. The content of the compound (B) is 100 ppm or more and 5000 ppm or less in terms of orthoboric acid, and the ratio of free boric acid (C) in the boron compound (B) is 0.1% by mass or more and 10% by mass or less in terms of orthoboric acid. A blow molded container;
[2] The blow-molded container according to [1], wherein the resin composition (α) contains a phosphate compound in an amount of 1 ppm or more and 500 ppm or less in terms of phosphate radical.
[3] The blow-molded container according to [1] or [2], wherein the resin composition (α) contains a carboxylic acid and/or a carboxylate ion in an amount of 0.01 μmol/g or more and 20 μmol/g or less in terms of carboxylic acid radicals;
[4] The blow of any one of [1] to [3], in which the melt index of the resin composition (α) measured at 190° C. under a load of 2160 g is 0.1 to 15 g/10 minutes according to ASTM D1238. Molded container;
[5] A fuel container including the blow-molded container according to any one of [1] to [4];
[6] A bottle container including the blow-molded container according to any one of [1] to [4];
Is achieved by providing.

According to the present invention, it is possible to provide a blow-molded container that has less streaks and lumps and is excellent in impact resistance at low temperatures, and a fuel container and a bottle container including such a blow-molded container.

It is a side surface transparent explanatory view which shows the hot cutter used in the Example.

<Blow molding container>
The blow-molded container of the present invention is a blow-molded container provided with a layer formed from a resin composition (α) containing EVOH (A) and a boron compound (B), wherein the boron compound (B) is free boric acid. (C), the content of the boron compound (B) with respect to the EVOH (A) in the resin composition (α) is 100 ppm or more and 5000 ppm or less in terms of orthoboric acid, and the free boric acid (C ) Is a blow molding container having a ratio of 0.1% by mass or more and 10% by mass or less in terms of orthoboric acid.

Since the blow-molded container of the present invention has a layer formed of the resin composition (α) containing a predetermined amount of the boron compound (B) and containing a predetermined ratio of free boric acid (C), the streak and the stout are formed. Less and has excellent impact resistance at low temperature. The "impact resistance at low temperature" means the resistance to impact in a low temperature environment. Therefore, the blow-molded container of the present invention has a good appearance and also maintains a good gas barrier property even when an impact is applied at a low temperature. Furthermore, by using the resin composition (α), streak and spots are suppressed even when continuous multi-layer blow molding is performed at a relatively high temperature and high speed for a long period of time, so that the blow molding container of the present invention has high productivity. Is also high. The blow-molded container of the present invention is used in various applications such as fuel containers and various bottles.

The blow-molded container of the present invention only needs to have a layer formed from the resin composition (α) (hereinafter sometimes abbreviated as “layer (1)”), but has a layer structure further including other layers. Can be the body. Examples of the other layer include a layer containing a thermoplastic resin other than EVOH (A) as a main component (hereinafter sometimes abbreviated as “layer (2)”), a layer containing an adhesive resin as a main component (“ Hereinafter, a "layer (3)" may be abbreviated), a recovery layer (hereinafter abbreviated as "layer (4)"), and the like. The blow-molded container of the present invention preferably comprises layer (1), layer (2) and layer (3).

Specifically, the blow-molded container is, for example, layer (2), layer (3), layer (1), layer (3), layer (4), layer (2) from the container inner surface to the container outer surface. Order (hereinafter expressed as (inside) 2/3/1/3/4/4 (outside)), (inside) 2/3/1/3/2 (outside), (inside) 2/4 It is possible to employ a layered structure such as /3/1/3/4/4 (outside) or (inside) 4/3/1/3/4 (outside). The layer (4) may be provided in place of the layer (2). In the case of an arrangement in which a plurality of layers (1) to (4) are used, the resin constituting each layer may be the same or different. May be.

The overall average thickness of the blow-molded container of the present invention is preferably 300 to 10,000 μm, more preferably 500 to 8,000 μm, and further preferably 1,000 to 5,000 μm. In addition, these whole average thickness says the average thickness in the trunk|drum of a blow molding container. If the overall average thickness is too large, the weight becomes large, which adversely affects the fuel economy and increases the cost of the container when used in a fuel container such as an automobile. On the other hand, if the overall average thickness is too small, the rigidity cannot be maintained, and there is a risk of easy breakage. Therefore, it is important to set the thickness corresponding to the capacity and application. Hereinafter, each layer will be described in detail.

[Layer (1)]
The layer (1) is a layer formed from the resin composition (α). The resin composition (α) contains EVOH (A) and a boron compound (B), and the boron compound (B) contains free boric acid (C). Hereinafter, each component will be described.

(EVOH(A))
EVOH (A) is a copolymer having ethylene units and vinyl alcohol units and having an ethylene unit content of 20 to 60 mol %. EVOH (A) is usually obtained by saponification of an ethylene-vinyl ester copolymer, and the ethylene-vinyl ester copolymer can be produced and saponified by a known method. Vinyl acetate is a typical vinyl ester, but other aliphatics such as vinyl formate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl pivalate and vinyl versatate. It may be a carboxylic acid vinyl ester.

The ethylene unit content of EVOH (A) is 20 mol% or more, preferably 25 mol% or more, and more preferably 27 mol% or more. The ethylene unit content of EVOH (A) is 60 mol% or less, preferably 55 mol% or less, and more preferably 50 mol% or less. If the ethylene unit content is less than 20 mol %, the thermal stability at the time of melt extrusion decreases, gelation tends to occur, and streaks and spots tend to occur. This is particularly noticeable when operating at high temperature or high speed for a long time under general conditions. When the ethylene unit content exceeds 60 mol %, the gas barrier property tends to deteriorate.

The degree of saponification of EVOH (A) is preferably 90 mol% or more, more preferably 95 mol% or more, still more preferably 99 mol% or more. When the degree of saponification of EVOH (A) is 90 mol% or more, the gas barrier property, heat stability and moisture resistance of the resin composition and the blow molding container tend to be good. The saponification degree may be 100 mol% or less, 99.97 mol% or less, or 99.94 mol% or less.

The EVOH (A) may have a unit derived from a monomer other than ethylene, vinyl ester and its saponified product, as long as the object of the present invention is not impaired. When EVOH (A) has a unit derived from the other monomer, the content of the unit derived from the other monomer with respect to all the structural units of EVOH (A) is preferably 30 mol% or less, and 20 mol% The following is more preferable, 10 mol% or less is further preferable, 5 mol% or less is still more preferable, and 1 mol% or less is even more preferable. When EVOH (A) has a unit derived from the other monomer, the content thereof may be 0.05 mol% or more, or 0.10 mol% or more. The other monomers include, for example, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid or the like, their anhydrides, salts, or mono- or dialkyl esters; nitriles such as acrylonitrile and methacrylonitrile; Amides such as acrylamide and methacrylamide; olefin sulfonic acids such as vinyl sulfonic acid, allyl sulfonic acid, and methallyl sulfonic acid or salts thereof; vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(β-methoxy-ethoxy)silane, γ -Vinylsilane compounds such as methacryloxypropylmethoxysilane; alkyl vinyl ethers, vinyl ketones, N-vinylpyrrolidone, vinyl chloride, vinylidene chloride and the like.

The unit derived from the other monomer is represented by the structural unit (I) represented by the following formula (I), the structural unit (II) represented by the following formula (II), and the following formula (III). The structural unit (III) may be at least one kind.

In the structural unit (I), structural unit (II) and structural unit (III), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ is independently a hydrogen atom, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 10 carbon atoms, or a hydroxyl group. Represents. Also, a pair of R ¹ , R ² and R ³ , R ⁴ and R ⁵ , and R ⁶ and R ⁷ may be bonded. Part or all of the hydrogen atoms contained in the aliphatic hydrocarbon group having 1 to 10 carbon atoms, the alicyclic hydrocarbon group having 3 to 10 carbon atoms and the aromatic hydrocarbon group having 6 to 10 carbon atoms are hydroxyl groups, It may be substituted with an alkoxy group, a carboxyl group or a halogen atom. In the structural unit (III), R ¹² and R ¹³ each independently represent a hydrogen atom, a formyl group or an alkanoyl group having 2 to 10 carbon atoms.

When the EVOH (A) has the structural unit (I), (II) or (III), the flexibility and processing characteristics of the resin composition are improved, and the moldability and the like of the resin composition tend to be good. ..

In the structural unit (I), (II) or (III), examples of the aliphatic hydrocarbon group having 1 to 10 carbon atoms include an alkyl group and an alkenyl group, and an alicyclic carbon group having 3 to 10 carbon atoms. Examples of the hydrogen group include a cycloalkyl group and a cycloalkenyl group, and examples of the aromatic hydrocarbon group having 6 to 10 carbon atoms include a phenyl group.

In the structural unit (I), R ¹ , R ² and R ³ are preferably each independently a hydrogen atom, a methyl group, an ethyl group, a hydroxyl group, a hydroxymethyl group or a hydroxyethyl group, and among them, a resin composition From the viewpoint of further improving the moldability of the product, it is more preferable that each independently a hydrogen atom, a methyl group, a hydroxyl group and a hydroxymethyl group.

The method of incorporating the structural unit (I) into the EVOH (A) is not particularly limited, and for example, in the polymerization of ethylene and vinyl ester, a monomer derived from the structural unit (I) is copolymerized. Methods and the like. Examples of the monomer derived from the structural unit (I) include alkenes such as propylene, butylene, pentene, and hexene; 3-hydroxy-1-propene, 3-acyloxy-1-propene, 3-acyloxy-1-butene. , 4-acyloxy-1-butene, 3,4-diacyloxy-1-butene, 3-acyloxy-4-hydroxy-1-butene, 4-acyloxy-3-hydroxy-1-butene, 3-acyloxy-4-methyl -1-butene, 4-acyloxy-2-methyl-1-butene, 4-acyloxy-3-methyl-1-butene, 3,4-diacyloxy-2-methyl-1-butene, 4-hydroxy-1-pentene , 5-hydroxy-1-pentene, 4,5-dihydroxy-1-pentene, 4-acyloxy-1-pentene, 5-acyloxy-1-pentene, 4,5-diacyloxy-1-pentene, 4-hydroxy-3 -Methyl-1-pentene, 5-hydroxy-3-methyl-1-pentene, 4,5-dihydroxy-3-methyl-1-pentene, 5,6-dihydroxy-1-hexene, 4-hydroxy-1-hexene 5-hydroxy-1-hexene, 6-hydroxy-1-hexene, 4-acyloxy-1-hexene, 5-acyloxy-1-hexene, 6-acyloxy-1-hexene, 5,6-diacyloxy-1-hexene Alkenes having a hydroxyl group or an ester group such as Among them, propylene, 3-acyloxy-1-propene, 3-acyloxy-1-butene, 4-acyloxy-1-butene, from the viewpoint of copolymerization reactivity, processability of the obtained multilayer sheet and the like, and gas barrier property. 3,4-diacyloxy-1-butene is preferred. In addition, "acyloxy" is preferably acetoxy, specifically, 3-acetoxy-1-propene, 3-acetoxy-1-butene, 4-acetoxy-1-butene and 3,4-diacetoxy-1-butene. Is preferred. In the case of an alkene having an ester, the structural unit (I) is derived during the saponification reaction.

In the structural unit (II), R ⁴ and R ⁵ are preferably both hydrogen atoms. More preferably, both R ⁴ and R ⁵ are hydrogen atoms, one of R ⁶ and R ⁷ is an aliphatic hydrocarbon group having 1 to 10 carbon atoms, and the other is a hydrogen atom. The aliphatic hydrocarbon group is preferably an alkyl group or an alkenyl group. From the viewpoint of particularly emphasizing the gas barrier property in the obtained blow-molded container, it is more preferable that one of R ⁶ and R ⁷ is a methyl group or an ethyl group, and the other is a hydrogen atom. Further, it is more preferable that one of R ⁶ and R ⁷ is a substituent represented by (CH ₂ ) _h OH (where h is an integer of 1 to 8) and the other is a hydrogen atom. In the substituent represented by (CH ₂ ) _h OH, h is preferably an integer of 1 to 4, more preferably 1 or 2, and even more preferably 1.

The method of incorporating the structural unit (II) into EVOH (A) is not particularly limited, and examples thereof include a method of incorporating the monovalent epoxy compound into EVOH (A) obtained by a saponification reaction. Used. As the monovalent epoxy compound, compounds represented by the following formulas (IV) to (X) are preferably used.

In the formulas (IV) to (X), R ¹⁴ , R ¹⁵ , R ¹⁶ , R ¹⁷ and R ¹⁸ are each independently a hydrogen atom, an aliphatic hydrocarbon group having 1 to 10 carbon atoms (alkyl group, And an alicyclic hydrocarbon group having 3 to 10 carbon atoms (such as a cycloalkyl group and a cycloalkenyl group) or an aliphatic hydrocarbon group having 6 to 10 carbon atoms (such as a phenyl group). Further, i, j, k, p and q each independently represent an integer of 1 to 8. However, when R ¹⁷ is a hydrogen atom, R ¹⁸ has a substituent other than a hydrogen atom.

Examples of the monovalent epoxy compound represented by the formula (IV) include epoxyethane (ethylene oxide), epoxypropane, 1,2-epoxybutane, 2,3-epoxybutane, and 3-methyl-1,2-epoxy. Butane, 1,2-epoxypentane, 3-methyl-1,2-epoxypentane, 1,2-epoxyhexane, 2,3-epoxyhexane, 3,4-epoxyhexane, 3-methyl-1,2-epoxy Hexane, 3-methyl-1,2-epoxyheptane, 4-methyl-1,2-epoxyheptane, 1,2-epoxyoctane, 2,3-epoxyoctane, 1,2-epoxynonane, 2,3-epoxy Nonane, 1,2-epoxydecane, 1,2-epoxydodecane, epoxyethylbenzene, 1-phenyl-1,2-epoxypropane, 3-phenyl-1,2-epoxypropane and the like can be mentioned. Examples of the monovalent epoxy compound represented by the formula (V) include various alkyl glycidyl ethers. Examples of the monovalent epoxy compound represented by the formula (VI) include various alkylene glycol monoglycidyl ethers. Examples of the monovalent epoxy compound represented by the formula (VII) include various alkenyl glycidyl ethers. Examples of the monovalent epoxy compound represented by the formula (VIII) include various epoxy alkanols such as glycidol. Examples of the monovalent epoxy compound represented by the formula (IX) include various epoxy cycloalkanes. Examples of the monovalent epoxy compound represented by the formula (X) include various epoxy cycloalkenes.

Among the monovalent epoxy compounds, epoxy compounds having 2 to 8 carbon atoms are preferable. Particularly, from the viewpoint of easy handling of the compound and reactivity, the carbon number of the monovalent epoxy compound is more preferably 2 to 6, and further preferably 2 to 4. Further, the monovalent epoxy compound is particularly preferably the compound represented by the formula (IV) or the formula (V). Specifically, from the viewpoints of reactivity with EVOH (A), processability of resin composition and the like, gas barrier properties, etc., 1,2-epoxybutane, 2,3-epoxybutane, epoxypropane, epoxyethane or Glycidol is preferable, and among them, epoxypropane or glycidol is more preferable.

In the structural unit (III), R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ are preferably a hydrogen atom or an aliphatic hydrocarbon group having 1 to 5 carbon atoms, and the aliphatic hydrocarbon group is a methyl group. , Ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group or n-pentyl group are preferred.

The method of incorporating the structural unit (III) into EVOH (A) is not particularly limited, and examples thereof include the method described in JP-A-2014-034647.

EVOH (A) may be used alone or in combination of two or more. From the viewpoint of gas barrier properties and the like, the proportion of EVOH (A) in the resin composition (α) is preferably 70% by mass or more, more preferably 80% by mass or more, and particularly preferably 90% by mass or more. On the other hand, the proportion of EVOH (A) in the resin composition (α) may be, for example, 99.9% by mass or less, or may be 99% by mass or less.

(Boron compound (B))
The resin composition (α) contains a boron compound (B) containing free boric acid (C) described below in an amount of 100 ppm or more and 5000 ppm or less in terms of orthoboric acid (H ₃ BO ₃ ). The orthoboric acid equivalent content of the boron compound (B) is synonymous with the orthoboric acid equivalent content of all boron atoms contained in the resin composition (α). The quantification of the boron compound (B) can be performed by a known method such as ICP emission analysis, and specifically, it can be measured by the method described in the examples. In addition, ppm is based on mass.

Examples of the boron compound (B) include boric acid such as orthoboric acid (H ₃ BO ₃ ), metaboric acid, and tetraboric acid; sodium metaborate, sodium tetraborate, sodium pentaborate, borax, lithium borate, and the like. Examples thereof include borates such as potassium borate; borate esters such as triethyl borate and trimethyl borate, and the boron compound (B) reacts with a component other than the boron compound (B) (for example, EVOH (A)). The compound described above is also included in the boron compound (B). Among them, orthoboric acid, borax and derivatives thereof are preferably used from the viewpoint of cost and improvement of melt moldability. The derivative means a compound obtained by reacting with orthoboric acid or the like such as its ester or amide.

The content of the boron compound (B) with respect to EVOH (A) is 100 ppm or more in terms of orthoboric acid, preferably 500 ppm or more, more preferably 700 ppm or more, and even more preferably 1000 ppm or more. When the content of the boron compound (B) is less than 100 ppm, streaks due to layer disorder increase in blow molding for a long time. If the blow-molded container has many streaks, cracks and the like are likely to occur from these starting points, and the impact resistance at low temperatures is lowered, and the gas barrier property is likely to be lowered.

On the other hand, the content of the boron compound (B) is 5000 ppm or less in terms of orthoboric acid, preferably 2500 ppm or less, and more preferably 1500 ppm or less. When the content of the boron compound (B) exceeds 5000 ppm, streaks and spots increase in blow molding for a long time, and as a result, the impact resistance at low temperature decreases. The reason why streaks and spots increase when the content of the boron compound (B) exceeds 5000 ppm is not clear, but the high content of the boron compound (B) reduces the viscosity of the resin composition. It is presumed that it is affected by such things as being present.

(Free boric acid (C))
The boron compound (B) contains free boric acid (C) which is “unreacted boric acid or a salt thereof”. Usually, in the boron compound (B), most of the boron compound (B) other than free boric acid (C) is cross-linked boric acid. On the other hand, free boric acid (C) is present in the resin composition (α) in a non-crosslinked state. The amount of free boric acid (C) in the resin composition (α) is determined by a coordination compound capable of forming a complex ion with boric acid, such as 2-ethyl-1,3-hexanediol and free boric acid (C). ) And the reaction product, the reaction product can be quantified and calculated, and specifically can be quantified by the method described in Examples.

The ratio of free boric acid (C) in the boron compound (B) is 0.1% by mass or more in terms of orthoboric acid with respect to the boron compound (B), preferably 0.3% by mass or more, and 0.5 It is more preferably at least mass%. When the ratio of free boric acid (C) to the boron compound (B) is less than 0.1% by mass, streak increases in blow molding for a long time. Further, when the content of the boron compound (B) is relatively large and the content ratio of the free boric acid (C) is low, it means that the cross-linking is in progress, and the lumps are likely to increase in blow molding for a long period of time. .. When the ratio of free boric acid (C) to the boron compound (B) is less than 0.1% by mass, the streak and the spots are generated, so that the impact resistance at low temperature is lowered and the gas barrier property is lowered.

Moreover, the ratio of the free boric acid (C) in the boron compound (B) is 10 mass% or less in terms of orthoboric acid with respect to the boron compound (B), preferably 7 mass% or less, and 3 mass% or less. It is more preferably 1.5% by mass or less or 1% by mass or less in some cases. If the ratio of the free boric acid (C) to the boron compound (B) exceeds 10% by mass, the local cross-linking reaction due to the free boric acid (C) will proceed during long-term blow molding, and Streaks etc. increase. As a result, the impact resistance at low temperature is lowered and the gas barrier property is lowered. The ratio of free boric acid (C) in the boron compound (B) can be adjusted by the production method described later.

The upper limit of the content of free boric acid (C) with respect to EVOH (A) is 500 ppm (10% of 5000 ppm) in terms of orthoboric acid, but 200 ppm is preferable, 100 ppm is more preferable, and 20 ppm or 10 ppm is even more preferable. .. By setting the content of the free boric acid (C) to the above upper limit or less, it is possible to suppress the generation of seeds and the like and enhance the impact resistance at low temperatures. On the other hand, the lower limit of the content of free boric acid (C) is 0.1 ppm (0.1% of 100 ppm) in terms of orthoboric acid, preferably 0.5 ppm, more preferably 1 ppm, further preferably 3 ppm or 5 ppm. Sometimes. By setting the content of free boric acid (C) to the above lower limit or more, the occurrence of streaks and the like can be suppressed, and the impact resistance at low temperatures can be enhanced.

(Other optional ingredients)
The resin composition (α) may contain, as other components, a resin other than EVOH (A) and an additive other than the boron compound (B) within a range that does not impair the effects of the present invention. Good. Examples of the other resin include thermoplastic resins such as polyolefin. When the resin composition (α) contains another resin, the content of the other resin with respect to the resin composition (α) is preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably 3% by mass or less. ..

Examples of other additives include known additives such as antioxidants, ultraviolet absorbers, plasticizers, antistatic agents, lubricants, colorants, fillers, fillers, antiblocking agents, and desiccants. The method of incorporating these additives into the resin composition (α) is not particularly limited, but for example, a method of melting the resin composition (α) and mixing the additives, a method of adding the resin composition (α) in the extruder, and the like. Melt blending with an agent, pellets of resin composition (α) such as powder, granules, spheres, and cylindrical chips, and a solid, liquid or solution of these additives are mixed to obtain a resin composition ( Examples include a method of impregnating or spreading α). These methods can be appropriately selected in consideration of the physical properties of the additive and the permeability of the resin composition (α). When other additives are contained, the content thereof is preferably 5% by mass or less, more preferably 3% by mass or less, based on the resin composition (α).

Examples of the antioxidant include 2,5-di-t-butylhydroquinone, 2,6-di-t-butyl-p-cresol, 4,4′-thiobis-(6-t-butylphenol, 2,2′methylene. -Bis(4-methyl-6-t-butylphenol, tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, octadecyl-3-(3' , 5'-di-t-butyl-4'-hydroxyphenyl)propionate, 4,4'-thiobis-(6-t-butylphenol), etc. As the ultraviolet absorber, ethyl-2-cyano-3 is used. , 3-diphenyl acrylate, 2-(2'-hydroxy-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5 -Chlorobenzotriazole, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, etc. Examples of the plasticizer include dimethyl phthalate and phthalate. Examples thereof include diethyl acid, dioctyl phthalate, wax, liquid paraffin, phosphoric acid ester, etc. Antistatic agents include pentaerythritol monostearate, sorbitan monopalmitate, sulfated oleic acid, polyethylene oxide, carbowax and the like. Lubricants include ethylenebisstearylamide, butyl stearate, calcium stearate, zinc stearate, etc. Colorants include carbon black, phthalocyanine, quinacridone, indoline, azo pigments, titanium oxide, red iron oxide, etc. Examples of the filler include glass fiber, mica, ballastonite and the like.

Further, the resin composition (α) may contain various acids, metal salts and the like from the viewpoint of thermal stability or viscosity adjustment. Examples of the various acids include carboxylic acids and phosphoric acid compounds, and examples of the various metal salts include alkali metal salts and alkaline earth metal salts. In addition, you may mix and use these acids, a metal salt, etc. with EVOH (A) beforehand.

(Carboxylic acid and/or carboxylate ion)
When the resin composition (α) contains a carboxylic acid and/or a carboxylate ion, the color resistance during melt molding tends to be improved. Carboxylic acid is a compound having one or more carboxy groups in the molecule. The carboxylate ion is a hydrogen ion of the carboxy group of carboxylic acid desorbed. The carboxylic acid may be a monocarboxylic acid, a polyvalent carboxylic acid compound having two or more carboxyl groups in the molecule, or a combination thereof. The polyvalent carboxylic acid does not contain a polymer. Further, the polyvalent carboxylate ion is one in which at least one hydrogen ion of the carboxy group of the polyvalent carboxylic acid is eliminated. The carboxy group of the carboxylic acid may have an ester structure, and the carboxylic acid ion may form a salt with a metal.

The monocarboxylic acid is not particularly limited, and examples thereof include formic acid, acetic acid, propionic acid, butyric acid, caproic acid, capric acid, acrylic acid, methacrylic acid, benzoic acid and 2-naphthoic acid. These carboxylic acids may have a hydroxy group or a halogen atom. Further, examples of the carboxylate ion include those in which the hydrogen ion of the carboxy group of each of the above-mentioned carboxylic acids is eliminated. The pKa of the monocarboxylic acid (including the monocarboxylic acid that gives a monocarboxylic acid ion) is preferably 3.5 or more, more preferably 4 or more from the viewpoint of the pH adjusting ability and melt moldability of the resin composition (α). preferable. Examples of such monocarboxylic acids include formic acid (pKa=3.68), acetic acid (pKa=4.74), propionic acid (pKa=4.85), butyric acid (pKa=4.80), and the like. Acetic acid is preferred from the standpoint of ease of use.

The polycarboxylic acid is not particularly limited as long as it has two or more carboxy groups in the molecule, and examples thereof include oxalic acid, malonic acid, succinic acid, maleic acid, fumaric acid, glutaric acid, and adipine. Acids, aliphatic dicarboxylic acids such as pimelic acid; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid; tricarboxylic acids such as aconitic acid; 1,2,3,4-butanetetracarboxylic acid, ethylenediaminetetraacetic acid, etc. A carboxylic acid having 4 or more carboxyl groups; a hydroxycarboxylic acid such as tartaric acid, citric acid, isocitric acid, malic acid, mutic acid, tartronic acid, citramalic acid; oxaloacetic acid, mesooxalic acid, 2-ketoglutaric acid, 3-ketoglutaric acid Examples thereof include ketocarboxylic acids such as acids; amino acids such as glutamic acid, aspartic acid, and 2-aminoadipic acid. Incidentally, examples of the polyvalent carboxylate ion include these anions. Among them, succinic acid, malic acid, tartaric acid, and citric acid are particularly preferable because they are easily available.

When the resin composition (α) contains a carboxylic acid and/or a carboxylate ion, the content thereof is 0 in terms of a carboxylic acid radical in the resin composition (α) from the viewpoint of color resistance during melt molding. 01 μmol/g or more is preferable, 0.05 μmol/g or more is more preferable, and 0.5 μmol/g or more is further preferable. In addition, it is preferably 20 μmol/g or less, more preferably 15 μmol/g or less, still more preferably 10 μmol/g or less in terms of carboxylic acid radical.

(Phosphate compound)
When the resin composition (α) contains a phosphoric acid compound, long-run property during melt molding tends to be improved.

The phosphoric acid compound is not particularly limited, and examples thereof include various phosphorus oxygen acids such as phosphoric acid and phosphorous acid, and salts thereof. The phosphate may be contained in any form of, for example, a first phosphate, a second phosphate and a third phosphate, and its counter cation species is not particularly limited, and examples thereof include alkali metal salts. Alternatively, an alkaline earth metal salt can be used, and an alkali metal salt is preferable. Specifically, sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate or dipotassium hydrogen phosphate is preferable from the viewpoint of improving long-run property during melt molding.

When the resin composition (α) contains a phosphoric acid compound, the content thereof is preferably 1 ppm or more, more preferably 5 ppm or more, and further preferably 8 ppm or more in terms of phosphate radical. Further, it is preferably 500 ppm or less, more preferably 200 ppm or less, and further preferably 50 ppm or less in terms of phosphate radical conversion. When the content of the phosphoric acid compound is within the above range, the long-run property during melt molding can be further improved.

(Alkali metal salt)
When the resin composition (α) contains an alkali metal salt, the long-run property and the interlayer adhesive force when a multilayer structure is formed are improved. Examples of the alkali metal that constitutes the alkali metal salt include lithium, sodium, potassium, rubidium, and cesium, but sodium and potassium are more preferable from the viewpoint of industrial availability.

The alkali metal salt is not particularly limited, and examples thereof include aliphatic carboxylic acid salts of lithium, sodium, potassium, etc., aromatic carboxylic acid salts, phosphoric acid salts included in the aforementioned phosphoric acid compounds, metal complexes, and the like. Be done. Specifically, sodium acetate, potassium acetate, sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, lithium dihydrogen phosphate. , Trilithium phosphate, sodium stearate, potassium stearate, sodium salt of ethylenediaminetetraacetic acid, and the like. Among these, sodium acetate, potassium acetate and sodium dihydrogen phosphate are particularly preferable because they are easily available.

When the resin composition (α) contains an alkali metal salt, the content of the alkali metal salt in the resin composition is preferably 2.5 μmol/g or more, more preferably 3.5 μmol/g or more, and 4.5 μmol/g More than g is more preferable. The content of the alkali metal salt is preferably 22 μmol/g or less, more preferably 16 μmol/g or less, still more preferably 10 μmol/g or less. When the content of the alkali metal salt is 2.5 μmol/g or more, the interlayer adhesion of the obtained multilayer sheet tends to be more excellent. When the content of the alkali metal salt is 22 μmol/g or less, the blow-molded container tends to have a better appearance.

(Alkaline earth metal salt)
When the resin composition (α) contains an alkaline earth metal salt, the scrap recoverability of a multilayer sheet or the like containing the resin composition (α) is improved. Examples of the alkaline earth metal composing the alkaline earth metal salt include beryllium, magnesium, calcium, strontium, barium, etc. From the viewpoint of industrial availability, magnesium or calcium is preferable.

The resin composition (α) has a melt index (hereinafter, may be abbreviated as “MI”) measured according to ASTM D1238 at 190° C. under a load of 2160 g of 0.1 to 15 g/10 minutes. Preferably. By setting the MI within the above range, it is possible to suppress the occurrence of streaks due to layer disorder in blow molding for a long time and the occurrence of spots due to local crosslinking. Further, this can improve the impact resistance of the blow-molded container at low temperatures. In order to enhance the effect, MI at 190° C. under a load of 2160 g is preferably 15 g/10 minutes or less, more preferably 10 g/10 minutes or less, further preferably 6.6 g/10 minutes or less, and 6 g/10 minutes or less. Even more preferably, 2 g/10 minutes or less is particularly preferable. The MI at 190° C. under a load of 2160 g is preferably 0.2 g/10 minutes or more, more preferably 0.5 g/10 minutes or more.

The lower limit of the average thickness of the layer (1) is not particularly limited, and from the viewpoint of barrier properties and mechanical strength, the average thickness of all layers is preferably 0.5%, more preferably 1%, even more preferably 2%. .. The upper limit of the average thickness of the layer (1) is not particularly limited, and from the viewpoint of barrier properties and mechanical strength, 20% is preferable, 10% is more preferable, and 5% is further preferable with respect to the average thickness of all layers.

(Method for producing resin composition (α))
The resin composition (α) can be produced, for example, by the following steps.
(1) Step of polymerizing ethylene and vinyl ester to obtain ethylene-vinyl ester copolymer (EVAc) (polymerization step)
(2) A step of saponifying the EVAc to obtain EVOH (A) (saponification step)
(3) Step of obtaining pellets containing EVOH(A) from the solution or paste containing EVOH(A) (pelletizing step)
(4) Step of washing the pellet (washing step)
(5) Step of dehydrating the pellet (dehydration step)
(6) Step of drying the pellets (drying step)
The pellets used in the dehydration step include the boron compound (B). That is, the pellet containing the EVOH (A), the boron compound (B) and water, which is subjected to the dehydration step, is an example of the water-containing composition.

(1) Polymerization step The method of copolymerizing ethylene and vinyl ester is not particularly limited, and may be, for example, solution polymerization, suspension polymerization, emulsion polymerization, bulk polymerization, or the like, and may be continuous or batch type.

As the vinyl ester used for the polymerization, those mentioned above can be mentioned. In the case of copolymerizing a monomer other than ethylene and vinyl ester, the other monomer may be the one described above.

The solvent used for the polymerization is not particularly limited as long as it is an organic solvent capable of dissolving ethylene, vinyl ester and ethylene-vinyl ester copolymer, and examples thereof include methanol, ethanol, propanol, n-butanol, tert-butanol and the like. Alcohol; dimethyl sulfoxide and the like can be used. Of these, methanol is preferable because it can be easily removed and separated after the reaction.

Examples of the catalyst used for the polymerization include 2,2′-azobisisobutyronitrile, 2,2′-azobis-(2,4-dimethylvaleronitrile), 2,2′-azobis-(4-methoxy-). Azonitrile initiators such as 2,4-dimethylvaleronitrile) and 2,2′-azobis-(2-cyclopropylpropionitrile); isobutyryl peroxide, cumylperoxyneodecanoate, diisopropylperoxycarbonate, Examples thereof include organic peroxide-based initiators such as di-n-propylperoxydicarbonate, t-butylperoxy neodecanoate, lauroyl peroxide, benzoyl peroxide, and t-butyl hydroperoxide.

The polymerization temperature is, for example, preferably 20 to 90°C, more preferably 40 to 70°C. The polymerization time is preferably 2 to 15 hours, more preferably 3 to 11 hours. The polymerization rate is preferably 10 to 90%, more preferably 30 to 80%, based on the charged vinyl ester. The resin content in the solution after polymerization is preferably 5 to 85% by mass, more preferably 20 to 70% by mass.

Usually, after polymerization for a predetermined period of time or after reaching a predetermined polymerization rate, a polymerization inhibitor is added as necessary to remove unreacted ethylene and then unreacted vinyl ester. As a method for removing unreacted vinyl ester, for example, the reaction solution is continuously supplied at a constant rate from the upper part of the column filled with a filler such as Raschig ring, and an organic solvent such as methanol is blown as vapor from the lower part of the column, Examples include a method of distilling a mixed vapor of an organic solvent such as methanol and unreacted vinyl ester from the top of the column and taking out a copolymer solution from which the unreacted vinyl ester is removed from the bottom of the column.

(2) Saponification step Next, the EVAc obtained in the above step is saponified. The saponification method may be either continuous or batch. The saponification catalyst is not particularly limited, but an alkali catalyst is preferable, and for example, sodium hydroxide, potassium hydroxide, alkali metal alcoholate, etc. are used.

As the saponification conditions, for example, in the case of a batch system, the concentration in the EVAc solution is preferably 10 to 50% by mass, the reaction temperature is preferably 30 to 60° C., and the amount of the catalyst used is 0. It is preferably from 02 to 0.6 mol, and the saponification time is preferably from 1 to 6 hours. In the case of the continuous system, the methyl acetate produced by the saponification can be removed more efficiently, so that a resin having a high degree of saponification can be obtained with a smaller amount of catalyst than in the case of the batch system, while the EVOH produced by the saponification can be obtained. In order to prevent precipitation of (A), it is necessary to saponify at a higher temperature. Therefore, in the case of the continuous system, for example, the concentration in the EVAc solution is 10% by mass or more and 50% by mass or less, the reaction temperature is 70°C or more and 150°C or less, and the amount of the catalyst used is 0.005 mol or more per mol of vinyl ester structural unit 0.1 mol or less, and the saponification time can be 1 hour or more and 6 hours or less.

The saponification step gives a solution or paste containing EVOH (A). Since EVOH (A) after the saponification reaction contains an alkali catalyst, by-product salts such as sodium acetate and potassium acetate, and other impurities, these are removed by neutralizing and washing as necessary. Good. Here, when the EVOH (A) after the saponification reaction is washed with ion-exchanged water containing almost no metal ions, chloride ions, etc., the EVOH (A) is partially left with sodium acetate, potassium acetate, etc. May be.

(3) Pelletizing Step and (4) Cleaning Step Next, the obtained EVOH (A) solution or paste is pelletized. The method of pelletizing is not particularly limited, and examples thereof include a method of cooling and solidifying a solution of EVOH (A) and cutting, a method of melting and kneading EVOH (A) in an extruder, and then discharging and cutting. As a cutting method of EVOH (A), EVOH (A) is extruded in a strand shape and then cut by a pelletizer (method (i)), EVOH (A) discharged from a die is a center hot cut method or underwater cut. A specific example is a method of cutting by a method (method (ii)).

Method (i)
When the EVOH(A) solution is extruded into a strand and pelletized, the coagulating liquid for precipitating the EVOH(A) is water or a water/alcohol mixed solvent, aromatic hydrocarbons such as benzene, ketones such as acetone and methyl ethyl ketone. Examples thereof include ethers such as dipropyl ether, organic acid esters such as methyl acetate, ethyl acetate and methyl propionate, and water or a water/alcohol mixed solvent is preferable from the viewpoint of easy handling. As the alcohol, alcohols such as methanol, ethanol and propanol are used, but methanol is industrially preferable. The mass ratio (coagulating liquid/strand of EVOH(A)) of the coagulating liquid in the coagulating liquid and the strand of EVOH(A) is preferably 50 to 10,000. By setting the mass ratio within the above range, EVOH(A) pellets having a uniform size distribution can be obtained.

The temperature at which the EVOH (A) solution is brought into contact with the coagulating liquid (bath temperature during pelletizing) is preferably -10°C or higher, more preferably 0°C or higher. The bath temperature during pelletizing is preferably 40°C or lower, more preferably 20°C or lower, further preferably 15°C or lower, and particularly preferably 10°C or lower. If the bath temperature during pelletizing is −10° C. or higher, precipitation of low molecular weight components tends to be suppressed, and if it is 40° C. or lower, thermal degradation of EVOH (A) tends to be suppressed.

The EVOH (A) solution is extruded into a coagulating liquid in a strand shape by a nozzle having an arbitrary shape. The shape of the nozzle is not particularly limited, and for example, a cylindrical shape is preferable. The number of strands is not necessarily one, and can be extruded in any number between several and several hundreds.

Next, the EVOH (A) extruded in the form of strands is sufficiently solidified and then cut, pelletized, and then washed with water. The size of such pellets can be, for example, a diameter of 1 mm or more and 10 mm or less, a length of 1 mm or more and 10 mm or less in the case of a cylindrical shape, and a diameter of 1 mm or more and 10 mm or less in the case of a spherical shape.

Subsequently, a washing step of washing the EVOH (A) pellets with water in a water tank is performed. By this washing treatment, oligomers and impurities in the EVOH(A) pellets are removed. The water temperature during washing is preferably 5°C or higher, and preferably 80°C or lower. An aqueous acetic acid solution or ion-exchanged water can be used for washing, but it is preferable to finally wash with ion-exchanged water. The washing with ion-exchanged water is preferably performed twice or more for one hour or more. The water temperature of the ion-exchanged water at this time is preferably in the range of 5 to 60° C., and the bath ratio of the ion-exchanged water to the EVOH(A) pellets is preferably 2 or more.

After the washing step, the pellets are immersed in a solution containing the boron compound (B) (hereinafter sometimes abbreviated as “immersion solution”) to contain the boron compound (B) in the pellets. At this time, the solution may contain other components (for example, an acid component and a metal salt), so that the other components may be contained in the pellet.

The concentration of the boron compound (B) in the immersion solution is 0.01 to 2 g/L in terms of orthoboric acid, and an appropriate amount of the boron compound (B) can be contained in the dry EVOH (A) pellets. It is possible and preferable. The lower limit of the concentration of the boron compound (B) in the immersion solution is more preferably 0.05 g/L, and even more preferably 0.2 g/L. When it is 0.01 g/L or more, the MI of the resin composition (α) becomes sufficient due to a sufficient crosslinking effect, and the occurrence of streaks or the like tends to be further suppressed. The upper limit of the concentration of the boron compound (B) is more preferably 1.5 g/L, and even more preferably 0.8 g/L. When it is 2 g/L or less, gelation of the resin composition (α) is suppressed, and the generation of lumps tends to be further suppressed.

Method (ii)
When pelletizing is performed by melt kneading using an extruder, the shape of EVOH (A) before being charged into the extruder is not particularly limited, and pellets obtained by cutting the molten resin extruded into the air can be used. It may be used, and a solution of EVOH(A) after polymerization/saponification or the like, or a precipitate on crumb where the paste is solidified in an irregular shape can also be used.

The water content of EVOH (A) before being charged into the extruder is preferably 0.5% by mass or more, more preferably 5% by mass or more, and further preferably 7% by mass or more. Further, the water content of EVOH (A) before being charged into the extruder is preferably 70% by mass or less, more preferably 60% by mass or less, and further preferably 50% by mass or less.

In pelletizing by melt-kneading using an extruder, the boron compound (B) can be added to EVOH (A) in the extruder. When adding the boron compound (B) to the EVOH (A) in the extruder, the feed position of the boron compound (B) is preferably added at a position where the EVOH (A) is melted in the extruder. Is more preferable. In particular, it is preferable to add the boron compound (B) to EVOH (A) which is in a water-containing and molten state. The boron compound (B) can be added to the extruder at one location or at two or more locations, and at this time, other components (for example, an acid component and a metal salt) may be added at the same time.

When the boron compound (B) is added in the extruder, the amount supplied in the extruder is the content in the resin composition (α). The addition form of the boron compound (B) is not particularly limited, and it may be added as a dry powder in the extruder, as a paste impregnated with a solvent, as a suspension in a liquid, or as a solvent. Examples of the method include dissolving and adding as a solution. From the viewpoint of controlling the addition amount and uniformly dispersing the boron compound (B) in EVOH (A), the boron compound (B) is dissolved in a solvent. The method of adding as a solution is particularly preferable. The solvent is not particularly limited, and water is preferable from the viewpoint of solubility of the boron compound (B), economy, ease of handling, safety of working environment, and the like.

When adding the boron compound (B) as a solution to EVOH (A), the addition amount of the solution is preferably 1 part by mass or more based on 100 parts by mass of dry mass of EVOH (A), and preferably 3 parts by mass. More preferably, it is more preferably 5 parts by mass or more. Further, the addition amount of the solution is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and particularly preferably 20 parts by mass or less, based on 100 parts by mass of dry mass of EVOH (A). If the amount of the solution added is less than 1 part by mass, the concentration of the solution generally increases, and the dispersibility of the boron compound (B) tends to decrease. If it exceeds 50 parts by mass, the control of the water content of EVOH (A) tends to be difficult, and the resin and water contained in the resin tend to undergo phase separation in the extruder. The concentration of orthoboric acid in the solution is in the range of 0.2 g/L to 57 g/L, and is appropriately adjusted depending on the amount of orthoboric acid to be contained with respect to the dry mass of EVOH (A) and the addition amount of the solution.

The resin temperature in the extruder is preferably 70 to 170°C. When the resin temperature is lower than 70°C, EVOH (A) may not be completely melted, and the dispersibility of the added boron compound (B) may be insufficient. The resin temperature is more preferably 80°C or higher, still more preferably 90°C or higher. When the resin temperature exceeds 170° C., EVOH (A) tends to be easily deteriorated by heat. Furthermore, when the boron compound (B) is added as an aqueous solution, it becomes difficult to mix the EVOH (A) with the aqueous solution at a suitable aqueous solution concentration because the water evaporation becomes violent when the resin temperature exceeds 170° C. Tends to be. The resin temperature in the extruder is more preferably 150°C or lower, further preferably 130°C or lower. The method of adjusting the resin temperature is not particularly limited, and a method of suitably setting the temperature of the cylinder in the extruder is particularly preferable. In the present invention, the resin temperature means a temperature detected by a temperature sensor installed in the cylinder in the extruder, and the detection point indicates the temperature near the discharge port at the tip of the extruder.

The water content of the resin composition (α) immediately after being discharged from the extruder is preferably 5 to 40% by mass, more preferably 5 to 35% by mass. When the water content of the resin composition (α) immediately after being discharged from the extruder exceeds 40% by mass, the resin and water contained in the resin tend to undergo phase separation, and as a result, after the discharge from the extruder, Strands tend to foam. Further, when the water content of the resin composition (α) immediately after being discharged from the extruder is less than 5% by mass, the deterioration of EVOH (A) due to heating tends to be insufficiently suppressed, and the resulting pellets are resistant to coloring. Tends to be inferior in sex.

The method of pelletizing the resin composition (α) discharged from the extruder is not particularly limited, and a method of extruding the resin composition (α) into air from a die and cutting it to an appropriate length is exemplified. From the viewpoint of easy handling of pellets, the diameter of the die is preferably 2 to 5 mmφ (φ is the diameter. The same applies below), and the strand is preferably cut into a length of about 1 to 5 mm.

When pelletizing by melt-kneading using an extruder, the washing step may be the same as the method (i), but a step of washing in the extruder may be provided. When washing is performed in the extruder, a method of injecting the washing liquid into the extruder to wash the resin and then discharging the washing liquid from the downstream side of the extruder can be mentioned.

(5) Dehydration step The proportion of free boric acid (C) in the boron compound (B) in the resin composition (α) is determined by, for example, physically heating the water-containing pellets (water-containing composition) containing the boron compound (B) without heating. It can be adjusted by removing water by a suitable means and then drying. Examples of the method for removing water include centrifugal dehydration (separation) method, reduced pressure sieve (hydro sieve), gas flow, etc., and it is preferable to remove water adhering to the pellet preferentially. The centrifugal dehydration method is preferably used industrially.

The centrifugal dehydration method may be either a batch method or a continuous method, and the continuous method is preferably used industrially. Both batch type and continuous type have a bucket-shaped rotating body with perforation holes or slits, and the continuous type has a structure that allows continuous discharge without changing the shape of pellets The device) is not limited. The water content to be removed is adjusted by the diameter of the perforated plate, the number of rotations, the treatment amount (processing time), etc. The diameter of the perforated plate should be smaller than the diameter of the pellet, and is preferably about 0.1 to 3 mm. If the diameter of the perforated plate is less than 0.1 mm, the water removing ability is insufficient, and further, clogging by fine powder is likely to occur, while if it exceeds 3 mm, it is difficult to adjust the water removing ability. The rotation speed varies depending on the device, but is preferably 500 to 20,000 rpm, and the processing time is preferably 10 seconds or more and 15 minutes or less. If the rotation speed is too low, the proportion of the remaining free boric acid (C) tends to increase. On the other hand, if the rotation speed is too high, the proportion of the remaining free boric acid (C) tends to be low. Similarly, if the treatment time is less than 10 seconds, it causes an increase in the proportion of free boric acid (C) remaining in the obtained resin composition (α). The treatment time is preferably 45 seconds or longer, more preferably 1 minute or longer. When the treatment time exceeds 15 minutes, the ratio of free boric acid (C) in the obtained resin composition (α) tends to decrease. The treatment time is preferably 13 minutes or less, more preferably 10 minutes or less.

(6) Drying process The pellets that have undergone the dehydration process are subjected to the drying process. For the drying, the water content of the EVOH(A) pellets after drying is preferably 0.08 mass% or less. If the water content exceeds 0.08% by mass, the amount of cross-linked boric acid tends to decrease and the amount of free boric acid (C) tends to increase. The water content is preferably 0.05% by mass or less. The drying method is not particularly limited, and the content ratio of free boric acid (C) may increase or decrease depending on the drying means and the drying temperature. Examples include static drying method combined with air drying or nitrogen drying, fluidized drying method, vacuum drying method, etc., but multi-step drying combining several drying methods is preferred, and multi-step drying including preliminary drying and main drying. Is more preferable. Here, the pre-drying is used for drying from a relatively high water content to a water content of about 10% by mass in order to suppress thermal fusion between the high water content resin compositions (α) during drying. It means drying at a lower temperature than main drying. On the other hand, the main drying is used to reduce the water content of the resin composition (α) having a relatively low water content after the preliminary drying, and means drying performed at a higher temperature than the preliminary drying. For the preliminary drying, heating gas (hot air or the like), infrared rays, microwaves, or the like can be used. The temperature and time of the pre-drying are not particularly limited, and for example, the resin composition (α) having a desired water content is obtained by subjecting the resin to a drying time of 60° C. or more and 100° C. or less and 1 hour or more and 12 hours or less. You can For the main drying, the above-mentioned general drying means can be used, but among them, vacuum drying is suitable for setting the free boric acid (C) to a specific amount. With methods other than vacuum drying, controlling the specific amount of free boric acid (C) tends to be somewhat difficult.

The lower limit of the main drying temperature (atmosphere temperature) is preferably 70°C, more preferably 100°C, further preferably 110°C, particularly preferably 120°C. On the other hand, the upper limit is preferably 160°C, more preferably 150°C, and further preferably 130°C. When the temperature of the main drying is equal to or higher than the lower limit, sufficient main drying can be efficiently performed, and the time of the main drying can be shortened. On the other hand, when the temperature of the main drying is set to the upper limit or less, the thermal deterioration of EVOH (A) can be suppressed. When the temperature of the main drying is within the above range, the free boric acid (C) tends to be adjusted to an appropriate amount. For example, by lowering the main drying temperature, the proportion of free boric acid (C) tends to decrease. Further, the drying time at a specific main drying temperature is not particularly limited, and may be, for example, 80° C. for 30 hours or more and 160 hours or less, 120° C. for 15 hours or more and 100 hours or less, and 150° C. for 0.5 hours or more and 20 hours or less. Then, the resin composition (α) having a desired water content is obtained.

[Layer (2)]
The layer (2) is a layer whose main component is a thermoplastic resin other than EVOH (A). Thermoplastic resins other than EVOH (A) include, for example, polyolefin, polystyrene, polyvinyl chloride, polyvinylidene chloride, acrylic resin, vinyl ester resin, polyamide resin, polyester resin, polyurethane elastomer, polycarbonate, chlorinated polyethylene, Examples include chlorinated polypropylene and ionomers. When laminating the layer (2) on the layer (1) via the layer (3), the layer (2) has a solubility parameter of 11 (cal/cm ³ ) ^1/ calculated by the Fedors equation. It is preferably a layer containing a thermoplastic resin of ² or less as a main component. A thermoplastic resin having a solubility parameter calculated by this formula of 11 (cal/cm ³ ) ^1/2 or less has excellent moisture resistance. The solubility parameter calculated from the Fedors equation is a value represented by (E/V) ^1/2 . In the above formula, E is a molecular cohesive energy (cal/mol) and is represented by E=Σei. Note that ei is evaporation energy. V is a molecular volume (cm ³ /mol) and is represented by V=Σvi (vi: molar volume). The layer (2) is preferably arranged on the inner surface side and the outer surface side of the layer (1).

Examples of the thermoplastic resin having a solubility parameter of 11 (cal/cm ³ ) ^1/2 or less include polyolefin, polystyrene, polyvinyl chloride, polyvinylidene chloride, acrylic resin, vinyl ester resin, polyurethane elastomer, and polycarbonate. Examples thereof include chlorinated polyethylene and chlorinated polypropylene. As the polyolefin, polyethylene (linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, etc.), ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, polypropylene, propylene and carbon number 4 to 4 Examples thereof include copolymers with 20 α-olefins, and homopolymers or copolymers of olefins such as polybutene and polypentene. Among them, polyethylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polypropylene, and polystyrene are preferable, and high-density polyethylene is more preferable.

The lower limit of MI of the thermoplastic resin under load of 190° C. and 2,160 g is preferably 0.01 g/10 minutes, more preferably 0.02 g/10 minutes. On the other hand, the upper limit of the MI is preferably 0.5 g/10 minutes, more preferably 0.1 g/10 minutes and even more preferably 0.05 g/10 minutes.

The thermoplastic resin can be appropriately selected and used from commercially available products. Further, the layer (2) may contain other optional components similar to the layer (1) as long as the effects of the present invention are not impaired.

The lower limit of the average thickness of the layer (2) is not particularly limited and is preferably 10%, more preferably 30%, even more preferably 50%, 70% or 80% with respect to the average thickness of all layers. The upper limit of the average thickness of the layer (2) is not particularly limited, and is preferably 95%, more preferably 90% based on the average thickness of all layers.

[Layer (3)]
The layer (3) may be disposed between the layer (1) and the layer (2) and is a layer containing an adhesive resin as a main component. The layer (3) can function as an adhesive layer between the layer (1) and another layer such as the layer (2). Examples of the adhesive resin include carboxylic acid-modified polyolefin and the like. The carboxylic acid-modified polyolefin has a carboxy group or its anhydride group obtained by chemically bonding an ethylenically unsaturated carboxylic acid or its anhydride to an olefin polymer by an addition reaction, a graft reaction or the like. It refers to an olefin polymer.

The lower limit of MI of the adhesive resin at 190° C. under a load of 2,160 g is preferably 0.1 g/10 minutes, more preferably 0.2 g/10 minutes, and further preferably 0.3 g/10 minutes. On the other hand, the upper limit of the MI is preferably 15 g/10 minutes, more preferably 10 g/10 minutes, still more preferably 5 g/10 minutes. In addition, as such an adhesive resin, a commercially available product that is industrially manufactured can be used, and for example, used in Examples described later, both are trade names “ADMER NF642E” and “ADMER AT2235E” manufactured by Mitsui Chemicals, Inc. Examples thereof include “ADMER NF408E”.

The layer (3) may contain other optional components similar to the layer (1) in addition to the adhesive resin as long as the effects of the present invention are not impaired.

The lower limit of the average thickness of the layer (3) is not particularly limited, and is preferably 0.5% and more preferably 2% with respect to the average thickness of all layers. The upper limit of the average thickness of the layer (3) is not particularly limited, and is preferably 20% and more preferably 12% based on the average thickness of all layers. When the average thickness of the layer (3) as the adhesive resin layer is less than the lower limit, the adhesiveness may be reduced. If the average thickness of the layer (3) exceeds the upper limit, the cost may increase.

[Layer (4)]
The layer (4) is a layer containing, for example, EVOH (A), the thermoplastic resin, and the adhesive resin. Further, the layer (4) is preferably formed by using the recovered material of the layer (1), the layer (2) and the layer (3) in the process for producing a blow molded container. Examples of the recovered product include burrs generated in the manufacturing process of the blow-molded container, products that have failed the test, and the like.

The layer (4) can be used as a substitute for the above-mentioned layer (2), but since the mechanical strength of the layer (4) is generally lower than that of the layer (2), the layer (4) is often used. It is preferable to use (2) and the layer (4) in a laminated manner. When the blow-molded container of the present invention receives an impact from the outside, stress concentration occurs in the container, and a compressive stress against the impact acts on the inner layer side of the container in the stress concentration portion, which may cause damage, and The weak layer (4) is preferably arranged on the outer layer side of the layer (1). In addition, when it is necessary to recycle a large amount of resin such as when burr is often generated, the layer (4) which is a recovery layer may be arranged on both sides of the layer (1).

[Method for manufacturing blow molded container]
The blow-molded container of the present invention is preferably manufactured by a manufacturing method including a step of blow-molding the resin composition (α). Blow molding can be performed by a known method such as direct blow molding, injection blow molding, sheet blow molding, free blow molding.

Specifically, for example, by using the resin composition (α) pellets forming the layer (1) and each resin forming other layers as necessary, a blow molding machine is used at a temperature of 100°C to 400°C. It is blow-molded and cooled at a mold internal temperature of 10°C to 30°C for 10 seconds to 30 minutes. Thereby, the blow-molded hollow container can be molded. The heating temperature during blow molding may be 150°C or higher, 180°C or 200°C or higher. The heating temperature may be equal to or higher than the melting point of EVOH(A). On the other hand, the upper limit of this heating temperature may be 350°C, and may be 300°C or 250°C.

<Fuel container>
The blow molded container of the present invention can be used as a fuel container. The fuel container of the present invention may be equipped with a filter, a fuel gauge, a baffle plate and the like. Since the fuel container of the present invention is provided with the blow-molded container of the present invention, it has less streaks and lumps, is excellent in impact resistance at low temperature, and is excellent in gas barrier property, etc., and thus is suitably used as a fuel container. Here, the fuel container means a fuel container mounted on an automobile, a motorcycle, a ship, an aircraft, a generator, an industrial or agricultural device, or a portable fuel container for refueling these fuel containers, Means a container for storing fuel. In addition, as the fuel, representative examples include gasoline, particularly oxygen-containing gasoline blended with methanol, ethanol, MTBE, and the like, but also include heavy oil, light oil, kerosene, and the like. Among these, the fuel container of the present invention is particularly preferably used as a fuel container for oxygen-containing gasoline.

<Bottle container>
The blow-molded container of the present invention can be used as a bottle container. The bottle container of the present invention may further include configurations other than the blow-molded container of the present invention, such as a cover film and a cap. Examples of the method for molding the bottle container of the present invention include direct blow molding and injection blow molding. The bottle-shaped blow-molded container of the present invention is excellent in appearance, impact resistance at low temperature, gas barrier property, and the like, and thus is suitably used as a bottle container for foods, cosmetics, and the like.

Hereinafter, the present invention will be described in detail with reference to Examples and the like, but the present invention is not limited to these Examples. The obtained resin composition was evaluated as follows.

(1) Quantification of Boron Compound (B) in Resin Composition The dried resin composition pellets obtained in Production Example were pulverized by freeze pulverization. To 0.5 g of the obtained powder, 5 mL of nitric acid for precision analysis manufactured by Wako Pure Chemical Industries, Ltd. was added and wet-decomposed with Speedwave MWS-2 (manufactured by Berghof). The obtained liquid was diluted with ion-exchanged water to prepare a sample solution with a total liquid volume of 50 mL, and an elemental boron was quantified using an ICP emission spectrophotometer (“Optima 4300 DV”, manufactured by Perkin Elmer Japan Co., Ltd.). Analysis was performed and the amount of the boron compound (B) was calculated as an orthoboric acid conversion value (B1). For the quantification, a calibration curve prepared using an atomic absorption spectrophotometric standard stock solution of boron (1000 ppm) (manufactured by Kanto Chemical Co., Inc.) was used.

(2) Quantification of free boric acid (C) in resin composition (i) Preparation of sample solution The dried resin composition pellets obtained in Production Examples were pulverized by freeze pulverization. The obtained powder was sieved with a sieve having a nominal size of 1 mm (in accordance with the standard sieve standard JIS Z-8801), and a measurement sample of 1000 mg of the powder of the resin composition which passed through the sieve was taken as 2-ethyl-1,3- The mixture was mixed with 3.5 mL of a hexanediol/chloroform mixed solution (volume ratio: 10/90), left standing at room temperature for 24 hours, and then filtered using a 0.2 μm filter to obtain a filtrate.
(Ii) Method for quantifying free boric acid (C) Device name: ICP emission spectrometer iCAP6300 (manufactured by Thermo Fisher Scientific)
Measurement wavelength: 208.893 nm, 208.959 nm, 249.773 nm
Calibration curve: For atomic absorption analysis: Boron standard stock solution (1000 ppm) prepared using Kanto Chemical Co., Inc. Measurement sample: 0.6 g of filtrate was weighed and made up to 10 mL with ethanol.
All the obtained boron contents were considered to be derived from free boric acid (C), and were calculated as orthoboric acid conversion values (B2).
(Iii) Calculation of ratio of free boric acid (C) Calculated by the following formula using the measurement result (B1) of the boron compound (B) and the measurement result (B2) of the free boric acid (C) obtained by the above measurement. did.
Ratio (% by mass) of free boric acid (C)=measurement result of free boric acid (C) (B2)/measurement result of boron compound (B) (B1)×100

(3) Melt index (MI) of resin composition
According to ASTM-D1238, a melt indexer was used, and the measurement was performed under the conditions of a temperature of 190° C. and a load of 2160 g.

(4) Quantification of metal salt and acid component in resin composition (quantification of phosphate compound/metal ion)
A sample solution was prepared in the same manner as in (1), and quantitatively analyzed at each of the following observation wavelengths using an ICP optical emission spectroscopic analyzer Optima 4300 DV manufactured by Perkin Elmer Japan Co., Ltd. to quantify the amounts of metal ions and phosphate compounds. did. The amount of the phosphoric acid compound was calculated by quantifying the phosphorus element and converting it into a phosphate group. A calibration curve prepared by diluting various standard solutions was used for the quantification.
Na: 589.592 nm
K: 766.490 nm
P: 214.914 nm
(Quantification of carboxylic acid and carboxylate ion)
The dry resin composition obtained in Production Example was pulverized by freeze pulverization. The obtained pulverized resin composition is sieved with a sieve having a nominal size of 1 mm (standard sieving standard JIS Z8801-1 to 3), and 10 g of the resin composition powder that has passed through the sieve and 50 mL of ion-exchanged water with a stopper are 100 mL. The mixture was placed in an Erlenmeyer flask, a cooling condenser was attached, and the mixture was stirred at 95°C for 10 hours. 2 mL of the obtained solution was taken and diluted with 8 mL of ion-exchanged water. The diluted solution was subjected to quantification of carboxylic acid and carboxylate ion using an ion chromatography "ICS-1500" manufactured by Yokogawa Electric Co., Ltd. according to the following measurement conditions. For the quantification, a calibration curve prepared using a monocarboxylic acid or a polycarboxylic acid was used.
Measurement condition column: “IONPAC ICE-AS1 (9φ×250 mm, electric conductivity detector)” manufactured by DIONEX
Eluent: 1.0 mmol/L octanesulfonic acid aqueous solution Measurement temperature: 35°C
Eluent flow rate: 1 mL/min Analytical amount: 50 μL

Production example 1
A polymerization tank having a pressure resistance of 100 kg/cm ² was charged with 19600 parts of vinyl acetate, 2180 parts of methanol, and 7.5 parts of AIBN (2,2′-azobisisobutyronitrile). Then, the internal temperature was adjusted to 60° C. and the ethylene pressure was adjusted to 35.5 kg/cm ² . After maintaining the temperature and pressure for 3.5 hours for polymerization, 5 parts of hydroquinone was added, the polymerization tank was returned to normal pressure, and ethylene was removed by evaporation. Subsequently, this methanol solution was continuously flown down from the upper part of the Raschig ring-filled expelling column, while methanol vapor was blown from the bottom of the column to release unreacted vinyl acetate monomer from the top of the column together with methanol vapor. By removing through ethylene to obtain a 45% methanol solution of unreacted vinyl acetate 0.01% or less ethylene-vinyl acetate copolymer. At this time, the polymerization rate was 47% based on the charged vinyl acetate, and the ethylene content rate was 32 mol %. Next, a methanol solution of ethylene-vinyl acetate copolymer was charged into a saponification reactor, and sodium hydroxide/methanol solution (80 g/L) was added in an amount of 0.4 equivalent to the vinyl acetate component in the copolymer. As described above, methanol was added to adjust the copolymer concentration to 20%. The temperature was raised to 60° C. and the reaction was carried out for about 4 hours while blowing nitrogen gas into the reactor. Then, it was neutralized with acetic acid to stop the reaction, extruded into water from a metal plate having a circular opening to cause precipitation, and cut to obtain a pellet having a diameter of about 3 mm and a length of about 5 mm. The obtained pellets were deliquored with a centrifuge, and then washing and deliquoring were repeated by adding a large amount of water to obtain washed hydrated pellets. The degree of saponification of the obtained EVOH was 99.7 mol %. The washed water-containing pellets (300 g) were dispersed in an immersion liquid (0.5 L) containing orthoboric acid (0.06 g/L), acetic acid (0.1 g/L) and potassium dihydrogen phosphate (0.3 g/L), and the mixture was stirred for 4 hours. Then, the obtained pellets were taken out, dehydrated by a centrifuge (mesh diameter 1 mm, rotation speed 4000 rpm, processing time 15 minutes), and then preliminarily dried with a hot air dryer at 80° C. in an air atmosphere. It was dried for 3 hours. The water content of the pellets before centrifugation was 200 mass% on a dry mass basis, the water content after centrifugal dehydration for 15 minutes was 78 mass%, and the water content after preliminary air drying was 10 mass%. Then, using a vacuum dryer as main drying, it was dried at 80° C. for 142 hours under vacuum conditions. Vacuum drying was carried out until the water content in the pellets after the main drying became 0.08% by mass or less, to obtain a resin composition 1. Regarding the resin composition 1, the metal component and the acid component were quantified according to the method described in (4) above. As a result of the measurement, the acetic acid and its salt contained in the resin composition were 600 ppm (10 μmol/g) in terms of acetate, the alkali metal salt was 150 ppm in terms of metal, and the phosphate compound was 35 ppm in terms of phosphate.

Production Examples 2 to 24, Production Examples C1 to C14
Table showing the ethylene unit content (Et) of the EVOH used, the concentration of orthoboric acid in the immersion liquid in which the water-containing pellets after washing are immersed, the centrifugal dehydration conditions (treatment time and water content after centrifugal dehydration), and the treatment temperature of the main drying Resin compositions 2 to 24 and resin compositions C1 to C14 were produced in the same manner as in Production Example 1 except that the changes were made as shown in 1. In each of the production examples, main drying was performed for the treatment time shown in Table 1 until the water content in the pellets became 0.08 mass% or less. In addition, in the manufacturing example which did not perform centrifugal dehydration, the value described in the column of water content after centrifugal dehydration is the water content before performing predrying (the same applies hereinafter).

Production Examples C15 to C17
The orthoboric acid concentration of the immersion liquid for immersing the water-containing pellets after washing and the centrifugal dehydration conditions (treatment time, and water content after centrifugal dehydration) are as shown in Table 2, and the main drying was performed in a hot air dryer under an air atmosphere. Resin compositions C15 to C17 were produced in the same manner as in Production Example 1 except that air was dried under the conditions shown in Table 2 until the water content in the pellets became 0.08% by mass or less.

Production Examples C18 to C20
The concentration of orthoboric acid in the immersion liquid in which the water-containing pellets after washing are immersed and the centrifugal dehydration conditions (treatment time and water content after centrifugal dehydration) are as shown in Table 3, and as a main drying, a hot air dryer under a nitrogen atmosphere ( Resin compositions C18 to C20 were produced in the same manner as in Production Example 1 except that the oxygen content in the machine was 200 ppm) and the temperature was set to the conditions shown in Table 3 until the moisture content in the pellets was nitrogen-dried to 0.08 mass% or less. Manufactured.

Production Example 25
Up to the saponification step, the same procedure as in Production Example 1 was carried out to obtain a 20% EVOH methanol solution. Subsequently, a methanol solution of EVOH was introduced from the upper part of the tower type tray reaction vessel, steam was introduced from the bottom of the reaction vessel, and methanol was added with water under the conditions of a tower internal temperature of 130° C. and a tower internal pressure of 3 kg/cm ^2. By replacing, an EVOH-containing composition having a concentration of 50% was obtained from the bottom of the column. Subsequently, the obtained water-containing composition was introduced into an extruder having a slit for discharging water, extruded at a die temperature of 118° C., and cut and granulated with a center hot cutter to obtain pellet-shaped EVOH. The pellets thus obtained were introduced from the upper part of the tower type countercurrent washing device, pure water of 50°C was introduced from the lower part to wash the pellets countercurrently, and the pellets were taken out from the bottom part of the column and solid-liquid separated by a wet shifter to obtain ethylene An EVOH having a rate of 32 mol%, a saponification degree of 99.7 mol% and a water content of 35% by mass was obtained. The EVOH thus obtained was charged into a twin-screw extruder, the resin temperature at the discharge port was set to 100° C., and the acetic acid/orthoboric acid/sodium acetate/potassium dihydrogen phosphate aqueous solution was added from the trace component addition section at the discharge port side. The treatment liquid was added. The amount of EVOH charged per unit time was 10 kg/hr (including the mass of water contained), the amount of treatment liquid charged per unit time was 0.65 L/hr, and the composition of the treatment liquid was acetic acid 4. It was an aqueous solution containing 3 g/L, orthoboric acid 5.3 g/L, sodium acetate 4.6 g/L, and potassium dihydrogen phosphate 1.4 g/L.
Type Twin-screw extruder L/D 45.5
Caliber 30mmφ
Screw same direction complete meshing type rotation speed 300 rpm
Motor capacity DC22KW
Heater 13 division type Die hole number 5 holes (3mmφ)
Resin temperature in the die 105℃
The resin composition extruded from the outlet of the twin-screw extruder was cut into pellets by the hot cutter 10 having the form shown in FIG. Specifically, in the hot cutter 10 of FIG. 1, the resin composition discharged from the discharge port 11 of the twin-screw extruder is extruded from the die 12 and cut by the rotary blade 13. The rotary blade 13 rotates together with the rotary shaft 14 directly connected to the rotary blade 13. Cooling water 17 is supplied from the cooling water supply port 16 into the cutter box 15. The pellet immediately after being cut is cooled by the water film 18 formed by the cooling water 17, and the cooling water and the pellet 20 are discharged from the pellet discharge port 19. The discharged pellets were flat spheres, and the water content was 80% by mass. The pellets thus obtained were taken out and dehydrated by a centrifuge (mesh diameter 1 mm, rotation speed 4000 rpm, treatment time 2 minutes), and then preliminarily dried using a hot air dryer under air atmosphere at 80° C., 11 Time drying was performed to reduce the water content to 4.2% by mass. Subsequently, as main drying, drying was performed at 120° C. for 16 hours under vacuum conditions to obtain a resin composition 25 with a water content of 0.08 mass% or less. For the resin composition 25, the metal component and the acid component were quantified according to the method described in (4) above. The content of acetic acid and its salts is 300 ppm (5 μmol/g) in terms of acetate radicals, the content of phosphate compounds is 100 ppm in terms of phosphate radicals, and the content of alkali metal salts is 40 ppm in terms of metal equivalents for potassium and 40 ppm for sodium equivalents. Was 130 ppm.

Production Examples 26 to 30, Production Examples C21 and C22
Resin composition in the same manner as in Production Example 25 except that the concentration of orthoboric acid added to the extruder, centrifugal dehydration conditions (treatment time and water content after centrifugal dehydration), and the treatment temperature for main drying were changed as shown in Table 4. 26-30, resin composition C21 and C22 were manufactured. In each of the production examples, main drying was performed for the treatment time shown in Table 4 until the water content in the pellets became 0.08 mass% or less.

Production Examples 31 to 34
Resin was prepared in the same manner as in Production Example 1 except that the orthoboric acid concentration of the immersion liquid, centrifugal dehydration conditions (treatment time, and water content after centrifugal dehydration), and the atmosphere, temperature, and time of main drying were changed as shown in Table 5. Compositions 31-34 were produced.

Production Example C23
A resin composition C23 was produced in the same manner as in Production Example C2, except that the components of the immersion liquid were changed to 0.5L of the immersion liquid containing 1.66 g/L of orthoboric acid and 0.11 g/L of potassium hydroxide. .. The metal component and the acid component were quantified according to the method described in (4) above. The acetic acid and its salts were 0 ppm in terms of acetate radicals, the alkali metal salts were 160 ppm in terms of metals, and the phosphate compounds were 0 ppm in terms of phosphate radicals.

<Examples 1-34, Comparative Examples 1-23>
(Manufacture of blow molded containers)
Blow made by Suzuki Iron Works using the resin composition obtained in Production Example, high-density polyethylene (Prime Polymer HI-ZEX8200B, MI at 190° C., 2160 g = 0.03 g/10 min), and the following adhesive resin. A blow molding container of 3 types and 5 layers of high density polyethylene/adhesive resin/resin composition/adhesive resin layer/high density polyethylene (outer side) was prepared at 210° C. with a molding machine TB-ST-6P. In the production of blow-molded containers, the temperature inside the mold is cooled to 15° C. for 20 seconds, and the total thickness of the body is 1000 μm ((inside) high density polyethylene/adhesive resin/resin composition/adhesive resin/high density polyethylene (outside )=(inside) 430/50/40/50/430 μm (outside)). The bottom surface of this tank had an average diameter of 100 mm and an average height of 400 mm. An adhesive resin was selected and used according to the MI of the obtained resin composition so that blow molding could be performed.
(Adhesive resin)
A-1: ADMER NF642E (Mitsui Chemicals, Inc., 190° C., MI at 2160 g, 4.0 g/10 minutes)
A-2: ADMER AT2235E (Mitsui Chemicals, Inc., 190° C., MI at 2160 g, 0.3 g/10 minutes)
A-3: ADMER NF408E (manufactured by Mitsui Chemicals, Inc., MI at 190° C. and 2160 g, 1.6 g/10 minutes)

(A) Appearance Immediately after starting up the blow molding machine, after 48 hours of continuous operation, and after 96 hours of continuous operation, a 3L tank (blow molding container) molded respectively was cut along the long axis direction, held over the illumination of a fluorescent lamp, and visually inspected. The presence of streaks and spots was confirmed by and the evaluation was made according to the following criteria. In the case of A to C, it was determined that streaks or spots were suppressed.
(Streak evaluation criteria)
A: No streak is observed. B: Two or less thin streaks are confirmed. C: Many thin streaks are confirmed. D: Clear streaks are confirmed.
A: No spots are found B: Minute spots are seen C: Two or less clear spots are confirmed per container D: Three or more clear spots are confirmed per container

(B) Impact resistance at low temperature (gas barrier property)
2.5 L of propylene glycol was filled into a 3 L tank (blow molding container) molded after continuous operation for 96 hours, and the opening was heat-sealed with a film of polyethylene 40 μm/aluminum foil 12 μm/polyethylene terephthalate 12 μm to cover the container. This tank was stored at -40°C for 8 weeks.
A 10 cm square flat plate was cut out from the portion of the blow-molded container after storage which was close to the plane shape below the liquid surface, and the surface was washed. After that, the inner surface of the tank was fixed to the jig connecting the metal plate and the copper pipe with an epoxy adhesive so as to contact the metal plate, and MOCON OX-TRAN2/20 manufactured by Modern Control Co., Ltd. (detection limit 0.01 mL/(m ²・Day·atm)) was measured to measure oxygen permeability. The measurement conditions were 23° C. and 65% RH on both the carrier gas side and the oxygen gas side, the oxygen pressure was 1 atm, and the carrier gas pressure was 1 atm.
Further, the container stored at −40° C. was dropped from a height of 6 m while being kept at −40° C., and the oxygen permeability was measured for the unbroken container in the same manner as before the drop test. The following criteria were evaluated based on the oxygen permeability before and after the drop test. When the evaluation after the drop test was A to C, it was judged that the impact resistance at low temperature was excellent.
A: Less than 0.1 mL/(m ² ·day·atm) B: 0.1 mL/(m ² ·day·atm) or more and less than 1.0 mL/(m ² ·day·atm) C: 1.0 mL/( m ² ·day ·atm) or more and less than 10 mL/(m ² ·day ·atm) D: 10 mL/(m ² ·day ·atm) or more

For each example and comparative example using the resin compositions 1 to 34 and the resin compositions C1 to C23, a boron compound (B) was prepared according to the methods described in (1) to (3) and (a) and (b) above. ) And free boric acid (C), MI was measured and evaluated. The results are shown in Tables 6-11.

For example, from the comparison of Production Examples 3, 9, 10, 19, C2 and C9 (Examples 3, 9, 10, 19 and Comparative Examples 2, 9) in which boron was added by immersion, the treatment time of centrifugal dehydration was lengthened, Further, by lowering the temperature during the main drying, even if the concentration of the boron compound (B) is the same, the ratio of free boric acid (C) is low. Even when boric acid is added by an extruder, the same tendency can be seen from the comparison of Production Examples 26 to 29, C21 and C22 (Examples 26 to 29, Comparative Examples 21 and 22).

Focusing on the content of the boron compound (B), in Comparative Example 5 in which the content of the boron compound (B) is small, streaks are increased in blow molding for a long period of time. It is presumed that this is because the MI is too high and layer disorder easily occurs. Comparative Example 5 is considered to have low impact resistance at low temperature (gas barrier property after the drop test) because a large amount of streaks serve as a starting point of cracks. On the other hand, Comparative Example 6 containing a large amount of the boron compound (B) has many streaks and spots. It is presumed that this is because the MI is low and the viscosity is high. Comparative Example 6 is considered to have low impact resistance at low temperature (gas barrier property after the drop test) because a large amount of streaks and spots serve as the starting points of cracks.

Focusing on the content ratio of free boron (C), Comparative Examples 1 to 4, 13, 15, 17, 18, 21, and 23 in which the content ratio of free boron (C) is low show layer disorder in blow molding for a long time. It has happened and a streak is occurring. Since these streaks serve as the starting points of cracks, it is considered that impact resistance at low temperature (gas barrier property after drop test) is low. Further, in Comparative Examples 7 to 12, 14, 16, 19, 20, and 22 in which the content ratio of the free boron (C) is high, the free boron (C) causes local cross-linking, and thus tends to have many spots. It is considered that the impact resistance at low temperature (gas barrier property after the drop test) is low because these spots are the starting points of cracks. Further, from the comparison between Comparative Example 4 and Example 16, if the content of the boron compound (B) is high and the content ratio of the free boron (C) is low (Comparative Example 4), it may be because the crosslinking is progressing. It can be seen that the number of spots is increasing.

On the other hand, in Examples 1 to 34 in which the content of the boron compound (B) and the content ratio of the free boric acid (C) were within the predetermined ranges, streaks and spots were small, and the impact resistance at low temperature was low. The result was good.

Further, from the comparison of Examples 10, 33 and 34 (Production Examples 10, 33, 34), when the treatment temperature of the main drying is the same, by performing vacuum drying, the concentration of the boron compound (B) is the same. As a result, the ratio of free boric acid (C) becomes low. Further, from the comparison between Comparative Example 2 and Comparative Example 23 (Production Examples C2 and C23), it can be read that the presence of acid components such as acetic acid and phosphoric acid can suppress the generation of seeds.

According to the present invention, it is possible to provide a blow-molded container that has less streaks and spots and is excellent in impact resistance at low temperatures.

10 Hot Cutter 11 Discharge Port 12 Die 13 Rotating Blade 14 Rotating Shaft 15 Cutter Box 16 Cooling Water Supply Port 17 Cooling Water 18 Water Film 19 Pellet Discharging Port 20 Cooling Water and Pellets

Claims (6)

A blow molding container comprising a layer formed from a resin composition (α) containing an ethylene-vinyl alcohol copolymer (A) having an ethylene unit content of 20 to 60 mol% and a boron compound (B),
The boron compound (B) contains free boric acid (C),
The content of the boron compound (B) with respect to the ethylene-vinyl alcohol copolymer (A) in the resin composition (α) is 100 ppm or more and 5000 ppm or less in terms of orthoboric acid, and the free boric acid (C) in the boron compound (B) is Blow-molded container, wherein the ratio of) is 0.1% by mass or more and 10% by mass or less in terms of orthoboric acid. The blow molding container according to claim 1, wherein the resin composition (α) contains a phosphate compound in an amount of 1 ppm or more and 500 ppm or less in terms of phosphate radical. The blow molding container according to claim 1 or 2, wherein the resin composition (α) contains a carboxylic acid and/or a carboxylate ion in terms of carboxylic acid radicals in an amount of 0.01 µmol/g or more and 20 µmol/g or less. The blow molding container according to claim 1, wherein the resin composition has a melt index of 0.1 to 15 g/10 minutes measured according to ASTM D1238 under a load of 2160 g at 190° C. A fuel container comprising the blow-molded container according to claim 1. A bottle container comprising the blow-molded container according to claim 1.

Images