WO2017110568A1 - Resin composition and molded article - Google Patents

Abstract

Provided are: a resin composition that has excellent appearance properties and long-run properties when being melted and molded, and that can inhibit the occurrence of yellowing even after being repeatedly re-used; and a molded article obtained using such a composition. The resin composition according to the present invention contains EVOH as a major ingredient, and is characterized in that the resin composition contains a phosphorus compound and a metal salt, the phosphorus compound is a condensed phosphoric acid, a compound having two or more phosphonic acid groups, or a combination thereof, the contained amount of the phosphorus compound is not less than 0.1 ppm but less than 50 ppm, the contained amount of the metal salt is 5-500 ppm in terms of the elemental metal. The metal salt is preferably an alkali metal salt, an alkaline-earth metal salt, or a combination thereof. The molded article according to the present invention has a portion formed of the resin composition.

Description

Resin composition and molded body

The present invention relates to a resin composition and a molded body.

An ethylene-vinyl alcohol copolymer (hereinafter abbreviated as EVOH) is widely used as various packaging materials for films, sheets, containers, and the like because of its excellent oxygen barrier properties. These packaging materials are usually molded by a melt molding method, and EVOH is required to have excellent appearance characteristics (low coloration such as yellowing) and excellent long-run property during melt molding.

The packaging material is often configured as a multilayer structure, but may be an EVOH resin composition containing metal ions in EVOH in order to improve interlayer adhesion of the multilayer structure. However, when metal ions are contained in EVOH, coloring tends to occur, resulting in a disadvantage that the appearance characteristics of the molded body are deteriorated.

Also, usually, when a molded product is commercialized, an extra sheet end (trim) is cut, and this trim is collected and reused for the purpose of effective use. However, in this case, EVOH undergoes repeated heat histories, causing thermal degradation, causing inconveniences such as yellowing or other coloring and deterioration of the appearance characteristics of the molded body. For this reason, there is a need for EVOH resin compositions that do not deteriorate in appearance characteristics even when subjected to repeated heat history during reuse.

EVOH has a large number of highly reactive hydroxyl groups in its molecular structure. For this reason, when EVOH is operated continuously for a long time, defects such as gels and blisters increase over time, and streaky appearance defects increase over time, resulting in commercial value as a molded product. Has a problem related to long-run properties such as a decrease in In addition, about long run problems such as the increase in gels and blisters and the appearance of streaky appearance, which problem occurs depends on the equipment and operating conditions used for molding, both problems May occur. In any case, such an EVOH resin composition excellent in long run properties with little change with time even in continuous operation for a long time is desired.

In order to improve the above-mentioned various properties required for EVOH, JP-A-64-66262 discloses an EVOH resin composition containing an acid such as a carboxylic acid and a metal ion. Japanese Patent No. 5619874 describes an EVOH resin composition containing a polyvalent carboxylic acid and a metal ion. These EVOH resin compositions are said to be excellent in appearance characteristics and long run properties.

However, demands on the quality of molded products such as hue and appearance characteristics have been increasing in recent years. Even with the above-mentioned EVOH resin composition, hue and appearance characteristics (gels, butts, streaks, etc.) have been increasing in recent years. The actual situation is that the quality required for) is not fully met. Reuse of trim is becoming more important from the viewpoint of environmental considerations, but there is no effective measure against deterioration of appearance characteristics due to occurrence of yellowing due to repeated heat history as described above. Is the actual situation.

JP-A 64-66262 Japanese Patent No. 5619874

The present invention has been made on the basis of the circumstances as described above, and has excellent appearance characteristics and long run properties in melt molding, and can suppress the occurrence of yellowing even after repeated reuse. It aims at providing the composition and the molded object obtained using such a composition.

The invention made in order to solve the above problems is a resin composition containing EVOH as a main component, containing a phosphorus compound and a metal salt, wherein the phosphorus compound is condensed phosphoric acid, two or more phosphonic acid groups Or a combination thereof, wherein the phosphorus compound content is 0.1 ppm or more and less than 50 ppm, and the metal salt content is 5 ppm or more and 500 ppm or less in terms of metal element.

The resin composition is considered to cause yellowing or the like by setting the content of a specific phosphorous compound that is condensed phosphoric acid, a compound having two or more phosphonic acid groups, or a combination thereof in the above range. It is considered that a phosphate group or a phosphonic acid group is stably coordinated with a metal ion and can incorporate the metal ion. That is, the presence of metal ions in a coordinated state in this manner can suppress the catalytic function for reactions such as yellowing of EVOH possessed by metal ions, and as a result, repeated reuse. Even in such a case, the occurrence of coloring such as yellowing can be suppressed. In addition, since the resin composition contains a metal salt in the above range, defects such as gels and blisters do not increase over time even during long-time molding, or streaky appearance defects even during long-time molding. Can exhibit an excellent long-run property such that does not increase with time.

The metal salt is preferably an alkali metal salt, an alkaline earth metal salt, or a combination thereof. The metal salt is preferably an alkali metal salt. In particular, the alkali metal salt can suitably exhibit a long run property such that defects such as gels and blisters do not increase with time even during long-time molding. It is also preferable that the metal salt is an alkaline earth metal salt, and the content of the alkaline earth metal salt is 5 ppm or more and 100 ppm or less in terms of metal element. In particular, the alkaline earth metal salt can exhibit a long run property such that a streak-like appearance defect does not increase with time even in a long-time molding.

The resin composition further contains a monocarboxylic acid, and the content of the monocarboxylic acid is preferably 5 ppm or more and 500 ppm or less. Moreover, the said resin composition contains a boron compound further, and it is preferable that content of the said boron compound is 5 ppm or more and 2,000 ppm or less in conversion of a boron element.

The molded product of the present invention is a molded product having a part formed from the resin composition. Since the molded body is provided with a portion obtained from the resin composition having excellent appearance characteristics and long run properties as described above, the occurrence of coloring such as yellowing, gel, butts, fish eyes, and streaks is suppressed. It has a good appearance.

According to the present invention, a resin composition having excellent appearance characteristics and long run property in melt molding, and particularly capable of suppressing the occurrence of yellowing even after repeated reuse, and such a composition are used. It is possible to provide a molded product obtained in this way.

Hereinafter, embodiments of the present invention will be described in detail in the order of the resin composition and the molded body.

[Resin composition]
The resin composition of the present invention contains EVOH as a main component and a phosphorus compound and a metal salt. In addition, a main component means a component with most content on a mass basis.

(EVOH)
EVOH is a copolymer having ethylene units and vinyl alcohol units. However, this EVOH may contain one or more other structural units.

EVOH can be produced by a known method. As a minimum of ethylene unit content of EVOH, 15 mol% is preferred, 20 mol% is more preferred, and 25 mol% is still more preferred. On the other hand, the upper limit of the ethylene unit content of EVOH is preferably 60 mol%, more preferably 55 mol%, and even more preferably 50 mol%. By setting the ethylene unit content of EVOH within the above range, yellowing after melt molding is suppressed, and a resin composition that is more excellent in long run properties is obtained. If the ethylene unit content of EVOH is smaller than the above lower limit, the long-run property of the resin composition, the water resistance, hot water resistance and gas barrier property under high humidity of the resulting molded product may be deteriorated. On the other hand, when the ethylene unit content of EVOH exceeds the above upper limit, the gas barrier property and the like of the resulting molded article may be lowered.

The lower limit of the saponification degree of EVOH is preferably 80 mol%, more preferably 95 mol%, and even more preferably 99 mol%. If the saponification degree of EVOH is smaller than the above lower limit, the gas barrier properties and appearance characteristics of the obtained molded product may be deteriorated.

The EVOH production method will be specifically described below. EVOH is usually obtained by saponifying an ethylene-vinyl ester copolymer obtained by copolymerizing ethylene and a vinyl ester. The polymerization of ethylene and vinyl ester may be carried out by any known method such as solution polymerization, suspension polymerization, emulsion polymerization, bulk polymerization, etc., and may be either continuous type or batch type. For example, the polymerization conditions in the case of solution polymerization are as follows.

Solvent: Alcohols are preferable, but other organic solvents (such as dimethyl sulfoxide) that can dissolve ethylene, vinyl ester, and ethylene-vinyl ester copolymer can be used. As alcohols, methyl alcohol, ethyl alcohol, propyl alcohol, n-butyl alcohol, t-butyl alcohol and the like can be used, and methyl alcohol is particularly preferable.

Polymerization initiator: 2,2'-azobisisobutyronitrile, 2,2'-azobis- (2,4-dimethylvaleronitrile), 2,2'-azobis- (4-methoxy-2,4-dimethyl) Valeronitrile), azonitrile initiators such as 2,2′-azobis- (2-cyclopropylpropionitrile), isobutyryl peroxide, cumylperoxyneodecanoate, diisopropylperoxycarbonate, di-n-propyl Organic peroxide initiators such as peroxydicarbonate, dicyclohexylperoxydicarbonate, t-butylperoxyneodecanoate, lauroyl peroxide, benzoyl peroxide, t-butyl hydroperoxide, diacetyl peroxide, etc. Can be used.

Temperature: 20 ° C. or higher and 90 ° C. or lower, preferably 40 ° C. or higher and 70 ° C. or lower.
Time: 2 hours to 15 hours, preferably 3 hours to 11 hours.
Polymerization rate: 10% to 90%, preferably 30% to 80% with respect to the charged vinyl ester.
Resin content in the solution after polymerization: 5% to 85%, preferably 20% to 70%.

Typical vinyl esters used for polymerization include vinyl acetate, but other aliphatic vinyl esters such as vinyl formate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl versatate, capron. Examples include vinyl acid.

In addition, other ethylenically unsaturated monomers that can be copolymerized can be copolymerized in a small amount as long as the effects of the present invention are not inhibited. Examples of such ethylenically unsaturated monomers include α-olefins such as propylene, n-butene, isobutylene and 1-hexene;
Unsaturated monomers having 1,2-diester groups such as 3,4-diacetoxy-1-butene;
2-methylene-1,3-propanediol diacetate (1,3-diacetoxy-2-methylenepropane), 2-methylene-1,3-propanediol dipropionate, 2-methylene-1,3-propanediol dibuty Unsaturated monomers having a 1,3-diester group such as a rate;
Acrylic acid and its salts;
An unsaturated monomer having an acrylate group;
Methacrylic acid and its salts;
An unsaturated monomer having a methacrylate group;
Acrylamide, N-methyl acrylamide, N-ethyl acrylamide, N, N-dimethyl acrylamide, diacetone acrylamide, acrylamide propane sulfonic acid and its salts, acrylamide propyl dimethylamine and its salts (eg quaternary salts);
Methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid and salts thereof, methacrylamidepropyldimethylamine and salts thereof (eg quaternary salts);
Methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether, 2,3-diacetoxy-1-vinyloxypropane, etc. Vinyl ethers;
Vinyl cyanides such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride and vinyl fluoride;
Vinylidene halides such as vinylidene chloride and vinylidene fluoride;
Allyl compounds such as allyl acetate, 2,3-diacetoxy-1-allyloxypropane, allyl chloride;
Unsaturated dicarboxylic acids such as maleic acid, itaconic acid, fumaric acid, and salts or esters thereof;
Vinylsilane compounds such as vinyltrimethoxysilane;
And isopropenyl acetate.

After carrying out polymerization for a predetermined time to reach a predetermined polymerization rate, a polymerization inhibitor is added as necessary, and after removing unreacted ethylene gas, unreacted vinyl ester is removed. As a method for removing unreacted vinyl ester from the ethylene-vinyl ester copolymer from which ethylene has been removed by evaporation, for example, the copolymer solution is continuously supplied at a constant rate from the upper part of a column packed with Raschig rings, An ethylene-vinyl ester copolymer solution in which an organic solvent vapor such as methanol is blown from the bottom of the column, a mixed vapor of an organic solvent such as methanol and unreacted vinyl ester is distilled from the top of the column, and the unreacted vinyl ester is removed from the bottom of the column. The method of taking out is adopted.

The saponification of the ethylene-vinyl ester copolymer is performed by a known method such as acid saponification or alkali saponification. For example, when alkali saponification is performed, an alkali catalyst is added to the copolymer solution from which the unreacted ethylene and unreacted vinyl ester obtained above are removed, and the vinyl ester portion in the copolymer is saponified. The saponification method can be either a continuous type or a batch type. As the alkali catalyst, sodium hydroxide, potassium hydroxide, alkali metal alcoholate or the like is used, and the following conditions are preferably used.
Copolymer solution concentration: 10% or more and 50% or less.
Reaction temperature: 30 ° C or higher and 60 ° C or lower.
Catalyst usage: 0.02 equivalents to 0.6 equivalents (per vinyl ester component).
Time: 1 hour 6 hours or less.

The thus obtained EVOH after the saponification reaction contains catalyst residues, by-product salts, and other impurities used in the saponification reaction, and is removed by neutralization and washing as necessary. It is preferable.

The lower limit of the EVOH melt flow rate (according to JIS K 7210, temperature 210 ° C., load 2160 g, hereinafter abbreviated as MFR) is preferably 0.1 g / 10 minutes, preferably 0.5 g / 10. Minute is more preferable, 1 g / 10 minutes is further more preferable, and 3 g / 10 minutes is particularly preferable. On the other hand, the upper limit of MFR of EVOH is preferably 200 g / 10 minutes, more preferably 50 g / 10 minutes, further preferably 30 g / 10 minutes, still more preferably 15 g / 10 minutes, and particularly preferably 10 g / 10 minutes. By setting the MFR of EVOH in the above range, the appearance characteristics after melt molding and the long run property are excellent.

The lower limit of the EVOH content in the resin composition is, for example, preferably 80% by mass, and more preferably 90% by mass. Furthermore, 99 mass% may be sufficient as the minimum of content of EVOH, and 99.9 mass% may be sufficient as it. When the content of EVOH is equal to or more than the above lower limit, the obtained molded body can exhibit various characteristics of EVOH more effectively. In addition, content of each component in the said resin composition is a ratio with respect to the whole dried resin composition (hereinafter the same).

(Phosphorus compound)
The resin composition contains a specific phosphorus compound. The phosphorus compound is condensed phosphoric acid, a compound having two or more phosphonic acid groups (—P (O) (OH) ₂ ), or a combination thereof. That is, as this phosphorus compound, only one type of condensed phosphoric acid, a compound having two or more phosphonic acid groups may be used, or a plurality of types may be used in combination.

By including such a phosphorus compound, the resin composition is not affected by other components constituting the resin composition, and yellowing occurs after melt molding and after repeated reuse. Can be suppressed. It is considered that a condensed phosphoric acid or a phosphorus compound having two or more phosphonic acid groups can stably coordinate to a metal ion that is responsible for yellowing or the like and take in the metal ion. It is presumed that the phosphorus compound is stably present in a coordinated state with the metal ion, thereby suppressing the action of the metal ion that catalytically promotes the decomposition and coloring of EVOH.

Examples of condensed phosphoric acid include pyrophosphoric acid (also called diphosphoric acid), tripolyphosphoric acid, tetrapolyphosphoric acid, and the like, and pyrophosphoric acid is preferred. Examples of the compound having two or more phosphonic acid groups include etidronic acid (also referred to as 1-hydroxyethane-1,1-diphosphonic acid), alendronic acid, nitrotris (methylenephosphonic acid), ethylenediaminetetra (methylenephosphonic acid) Among them, etidronic acid and alendronic acid are preferable. In addition, the condensed phosphoric acid may or may not have two or more phosphonic acid groups. Further, the compound having two or more phosphonic acid groups may contain condensed phosphoric acid having two or more phosphonic acid groups. On the other hand, the compound having two or more phosphonic acid groups may be a compound other than condensed phosphoric acid having two or more phosphonic acid groups.

These phosphorus compounds may exist in the state of oxygen acid, or may exist as phosphates or phosphonates that form salts with counter cations such as metal ions. Moreover, a hydrate may be sufficient. In the resin composition, it may be dissociated as ions or not. As the phosphate, any of the first phosphate, the second phosphate and the third phosphate may be used. As the phosphonate, either the first phosphonate or the second phosphonate may be used. It may be in the form. Further, the counter cation species is not particularly limited. When a phosphorus compound that forms a salt with a metal ion of a counter cation is mixed, the metal ion also acts as a metal ion in a metal salt described later.

The molecular weight of this phosphorus compound is not particularly limited, but the upper limit is preferably 1,000, for example, and more preferably 600. On the other hand, the lower limit is 170, for example. By being a compound having a molecular weight within the above range, more stable coordination to a metal ion is possible, and the ability to suppress yellowing is increased.

The number of phosphoric acid groups (—O—P (O) (OH) ₂ ) and phosphonic acid groups possessed by the phosphorus compound is 2 or more, and the upper limit is, for example, 6 and 4 is preferable, 3 is more preferable, and 2 is more preferable. When the number of the phosphoric acid group and the phosphonic acid group that the phosphorus compound has is within the above range, more stable coordination to the metal ion is possible, and the ability to suppress yellowing is increased.

The lower limit of the content of the phosphorus compound is 0.1 ppm, preferably 0.5 ppm, more preferably 3 ppm, still more preferably 10 ppm, and particularly preferably 20 ppm. By setting the content of the phosphorus compound to the above lower limit or more, not only the coloring of the resin composition itself, such as yellowing, can be suppressed, but also the occurrence of yellowing can be suppressed in the molded product after repeated reuse. can do. On the other hand, the content of this phosphorus compound is less than 50 ppm, preferably less than 45 ppm, and more preferably less than 35 ppm. By making content of a phosphorus compound less than the said upper limit, it can be set as the resin composition excellent in long run property.

(Metal salt)
The resin composition contains a metal salt. Examples of the metal salt include alkali metal salts, alkaline earth metal salts, and other transition metal salts, and may be a single metal species, or may be composed of a plurality of these metal species. good. As said metal salt, an alkali metal salt, alkaline-earth metal salt, or these combination is preferable. However, this metal salt does not include a metal salt of the specific phosphorus compound (a compound having two or more condensed phosphoric acid and phosphonic acid groups).

The lower limit of the metal element equivalent amount of the metal salt is 5 ppm, preferably 30 ppm, more preferably 50 ppm, and 100 ppm with respect to the entire resin composition. On the other hand, the upper limit of the metal element equivalent amount of the metal salt is 500 ppm, preferably 400 ppm, more preferably 300 ppm, and may be 200 ppm. By containing the metal salt in the above range, defects such as gels and blisters do not increase over time even during long-time molding, or streaky appearance defects do not increase over time even during long-time molding. It is possible to obtain a resin composition having a balance between long run properties and excellent appearance characteristics such as suppression of coloring such as yellowing.

The resin composition in which the metal salt is an alkali metal salt is preferable in that an increase in generation of defects such as gels and bumps with time is suppressed even during long-time molding. Examples of the alkali metal that forms the alkali metal salt include lithium, sodium, and potassium, and sodium and potassium are preferable. Examples of the alkali metal salt include aliphatic carboxylates such as lithium, sodium, and potassium, aromatic carboxylates, carbonates, hydrochlorides, nitrates, sulfates, phosphates, metal complexes, and the like. Among these, sodium acetate, potassium acetate, sodium carbonate, potassium carbonate, sodium phosphate and potassium phosphate are more preferable because they are easily available.

The lower limit of the content of the alkali metal salt in terms of metal element is preferably 5 ppm, more preferably 50 ppm, and even more preferably 100 ppm with respect to the entire resin composition. On the other hand, the upper limit of the content of alkali metal salt in terms of metal element is 500 ppm, preferably 400 ppm, and more preferably 300 ppm. When the content of the alkali metal salt is not less than the above lower limit, EVOH cross-linking can be suppressed, and the generation of gels and blisters can be suppressed even during long-time molding. On the other hand, coloring, such as yellowing, can be suppressed because content of an alkali metal salt is below the said upper limit.

A resin composition in which the metal salt contains an alkaline earth metal salt is preferable in that an increase in the appearance of streaky appearance over time is suppressed even during long-time molding. Examples of the alkaline earth metal salt include salts of beryllium, magnesium, calcium, strontium, barium and the like. Magnesium salts and calcium salts are preferred from the viewpoint of industrial availability, aliphatic carboxylates, aromatic carboxylates, carbonates, hydrochlorides, nitrates, sulfates, phosphates, metal complexes, etc. Is mentioned.

The lower limit of the content of the alkaline earth metal salt in terms of metal element is preferably 5 ppm, more preferably 30 ppm, based on the entire resin composition. On the other hand, the upper limit of the content of the alkaline earth metal salt in terms of metal element may be 150 ppm, but is preferably 100 ppm, and more preferably 80 ppm. By setting the content of the alkaline earth metal salt to the above lower limit or more, an increase in the appearance of streak-like appearance over time is effectively suppressed. On the other hand, the fall of the external appearance characteristic by coloring, such as yellowing, is effectively suppressed by making content of alkaline-earth metal salt below the said upper limit.

The lower limit of the phosphorus compound content ratio (phosphorus compound / metal salt) to the metal salt content (in terms of metal element) in the resin composition is preferably 0.001, more preferably 0.005, 0.01 is more preferable, 0.05 is particularly preferable, and 0.1 is further particularly preferable. Further, when the metal salt is an alkaline earth metal salt, the lower limit of this ratio is more preferably 0.3. On the other hand, the upper limit of this ratio is preferably, for example, 5 and more preferably 1. Furthermore, when the metal salt is an alkali metal salt, the upper limit of this ratio is more preferably 0.5, and even more preferably 0.3. By setting the ratio of the content of the metal salt and the phosphorus compound within the above range, the effects of the present invention can be more effectively exhibited.

(Monocarboxylic acid)
The resin composition may contain a monocarboxylic acid. A monocarboxylic acid is a compound having one carboxy group in the molecule.

The content of monocarboxylic acid is preferably 500 ppm or less, more preferably 300 ppm or less, based on the entire resin composition from the viewpoint of reducing odor. When the monocarboxylic acid content is not more than the above upper limit, the odor generated when the resin composition is melt-molded is reduced in addition to the odor of the resin composition itself, so that the working environment is reduced. Improved. In addition, since the odor of the molded article after melt molding is reduced, the molded article using the resin composition is particularly suitable for contents such as cooked rice and drinking water in which odor generation impairs the commercial value. Can also be preferably used as a packaging material.

On the other hand, the content of the monocarboxylic acid is preferably 5 ppm or more, more preferably 50 ppm or more with respect to the entire resin composition from the viewpoint of quality stability. When the content of the monocarboxylic acid is not less than the above lower limit, the pH of the aqueous solution can be easily controlled during the production of the resin composition, and it becomes easy to obtain a product with stable quality.

Examples of the monocarboxylic acid include formic acid, acetic acid, propionic acid, butyric acid, caproic acid, capric acid, acrylic acid, methacrylic acid, benzoic acid, and 2-naphthoic acid. Among these, acetic acid is preferable. These monocarboxylic acids may have a hydroxy group or a halogen atom.

(Boron compound)
The resin composition may contain a boron compound. Examples of the boron compound include boric acid, boric acid ester, borate, and borohydride. Specifically, examples of boric acid include orthoboric acid (H ₃ BO ₃ ), metaboric acid, and tetraboric acid. Examples of boric acid esters include triethyl borate and trimethyl borate. Examples of the salt include alkali metal salts, alkaline earth metal salts, borax and the like of the various boric acids described above. Of these, orthoboric acid is preferred.

The lower limit of the boron compound content of the boron compound is preferably 5 ppm, more preferably 10 ppm, based on the entire resin composition. On the other hand, the upper limit of the boron element content of the boron compound is preferably 2,000 ppm, more preferably 1,000 ppm, and even more preferably 500 ppm. When the boron compound content of the boron compound is in the above range, the thermal stability during melt molding of the resin composition can be improved, and as a result, the long run property during molding processing is further improved. can do. Specifically, when a boron compound is blended in the resin composition, it is considered that a chelate compound is generated between EVOH and the boron compound, thereby improving the thermal stability and mechanical properties of the resin composition.

(Other additives)
The resin composition may contain an appropriate amount of components other than the above-described EVOH, phosphorus compound, metal salt, monocarboxylic acid, and boron compound as long as the effects of the present invention are not impaired. Examples of such other components include a plasticizer, a stabilizer, a surfactant, a colorant, an ultraviolet absorber, a slip agent, an antistatic agent, a drying agent, a crosslinking agent, a filler, an oxygen absorber, and various fibers. Can be mentioned. However, the content of these additives (components other than EVOH, phosphorus compound, metal salt, monocarboxylic acid and boron compound) in the resin composition is less than 10% by mass, less than 1% by mass, and further 0.1% by mass. %.

In addition, an appropriate amount of a thermoplastic resin other than EVOH can be blended into the resin composition as long as the effects of the present invention are not impaired. Examples of the thermoplastic resin include various polyolefins (polyethylene, polypropylene, poly (1-butene), poly (4-methyl-1-pentene), ethylene-propylene copolymer, ethylene and α-olefin having 4 or more carbon atoms. Copolymer, copolymer of olefin and maleic anhydride, ethylene-vinyl ester copolymer, ethylene-acrylic ester copolymer, or modified polyolefin obtained by graft-modifying these with unsaturated carboxylic acid or derivatives thereof, etc. ), Various nylons (such as nylon 6, nylon 66, nylon 6/66 copolymer), polyvinyl chloride, polyvinylidene chloride, polyester, polystyrene, polyacrylonitrile, polyurethane, polyacetal, and modified polyvinyl alcohol resin. When the resin composition contains a thermoplastic resin other than EVOH, the blending amount is preferably less than 50% by mass, more preferably less than 30% by mass, further preferably less than 10% by mass, and even more preferably less than 1% by mass. Preferably, it may be less than 0.1% by mass.

The preferable range of MFR of the resin composition is the same as that of the above-mentioned MFR of EVOH, and the effect obtained by setting the range is the same as that of EVOH.

The resin composition can be formed into various molded bodies such as pellets, films, sheets, containers, pipes and fibers by melt molding.

(Production method of resin composition)
The resin composition includes, for example, a copolymerization step (step 1) in which ethylene and vinyl ester are copolymerized to obtain an ethylene-vinyl ester copolymer, and EVOH is obtained by saponifying the ethylene-vinyl ester copolymer. The production method includes a saponification step (step 2), and further includes a mixing step (step α) of mixing the ethylene-vinyl ester copolymer or EVOH with the phosphorus compound and metal salt after the copolymerization step. Can be obtained. The phosphorus compound and the metal salt may be mixed simultaneously or separately. Hereinafter, each step will be described in detail.

(Step 1: Copolymerization step)
In the copolymerization step, in addition to the copolymerization step of ethylene and vinyl ester, a polymerization inhibitor is added as necessary, and then unreacted ethylene and unreacted vinyl ester are removed to remove ethylene-vinyl ester copolymer. Obtaining a coalesced solution. Examples of the copolymerization method of ethylene and vinyl ester include known methods such as solution polymerization, suspension polymerization, emulsion polymerization, and bulk polymerization. Specific polymerization conditions and the like are as described above for the EVOH production method.

(Process 2: Saponification process)
Next, an alkali catalyst or the like is added to the ethylene-vinyl ester copolymer solution to saponify the copolymer in the solution. Specific conditions and the like during saponification are as described above for the EVOH production method.

(Process α (1): Mixing process)
In this mixing step, the ethylene-vinyl ester copolymer obtained in the copolymerization step or EVOH obtained in the saponification step is mixed with the phosphorus compound and the like. However, as will be described later, the mixing step can be performed after the granulation of EVOH. As this mixing step (step α (1)), for example, (1) a method of previously adding the phosphorus compound to a solution containing an ethylene-vinyl ester copolymer used for the saponification step,
(2) A method of adding the phosphorus compound during the saponification reaction of the ethylene-vinyl ester copolymer in the saponification step, and (3) a method of mixing the phosphorus compound after obtaining EVOH in the saponification step. .

(Process 3: Granulation process)
In order to obtain the resin composition in the form of pellets, a granulation step may be provided after the copolymerization step and the saponification step. Since EVOH is obtained in the form of a solution containing the solvent used in the saponification reaction, washing is performed in order to remove a catalyst such as alkali and a by-product such as sodium acetate remaining in the solution. In order to facilitate this washing operation, it is preferable to granulate the EVOH-containing solution obtained in the saponification step into EVOH hydrous pellets.

As granulation operations, for example, (I) a method in which an EVOH-containing solution is extruded into a coagulation bath and is cooled and solidified or cut immediately after, or (II) the EVOH solution is brought into contact with water vapor in advance to contain EVOH-containing water. The method of cutting as a resin composition is mentioned. The moisture content of the EVOH hydrous pellets obtained by these methods is preferably 40% by mass or more and 200% by mass or less based on the dry mass of EVOH.

(Process 4: Drying process)
The EVOH hydrous pellets obtained in the granulation step are preferably dried to form EVOH dry pellets. The moisture content in the dry pellets is preferably 1.0% by mass or less and 0.8% by mass or less with respect to the entire dry pellets for the purpose of preventing molding troubles such as generation of voids during molding. Is more preferably 0.5% by mass or less.

Examples of the method for drying the water-containing pellets include stationary drying and fluidized drying. These drying methods may be used alone or in combination. The drying treatment may be performed by either a continuous method or a batch method. Moreover, when performing combining several drying methods, a continuous type and a batch type can be freely selected about each drying method. It is also preferable to perform the drying at a low oxygen concentration or an oxygen-free state from the viewpoint that the deterioration of the resin composition due to oxygen during drying can be reduced.

(Process α (2): Mixing process)
The mixing step may be performed after granulation. As a method of mixing a phosphorus compound or the like after the granulation step, for example, (1) a method of bringing a water-containing pellet of EVOH into contact with a solution containing the phosphorus compound or the like, and (2) a water-containing pellet of EVOH and the phosphorus compound And the like are melt kneaded in an extruder. At this time, monocarboxylic acid, alkali metal salt, alkaline earth metal salt, boron compound and the like can be mixed with EVOH at the same time.

When immersed as in (1) above, the shape of the water-containing pellet is arbitrary, and the operation may be either a batch method or a continuous method. The immersion may be divided into a plurality of solutions in which each component to be contained in the resin composition is individually dissolved, or may be processed at once using a solution in which a plurality of components are dissolved.

In addition, in the manufacturing method of the said resin composition, you may perform a mixing process simultaneously with a granulation process. That is, for example, in the granulation operation, the above phosphorus compound and metal salt may be previously contained in the coagulation bath.

[Molded body]
The said molded object is a molded object which has a part formed from the said resin composition. The said molded object may be formed only from the said resin composition, for example, a laminated body etc. which have a part formed from the said EVOH resin in part may be sufficient as it.

Examples of the molded body include pellets, films, sheets, containers, pipes, fibers, and the like. The molded body is usually molded by melt molding of the resin composition. These molded bodies can be pulverized and molded again for the purpose of reuse. It is also possible to uniaxially or biaxially stretch films, sheets, fibers, and the like. As the melt molding method, for example, any known molding method such as extrusion molding, inflation extrusion, blow molding, melt spinning, and injection molding can be applied.

The melting temperature at the time of melt molding is preferably about 150 ° C. or more and 300 ° C. or less, and usually a melting temperature of about 200 ° C. or more and 250 ° C. or less is employed. The molded body thus obtained has excellent appearance characteristics in which coloring such as yellowing after melt molding is suppressed and gel, butts, fish eyes, streaks and the like are suppressed.

The molded body may be a multilayer structure including at least one layer obtained from the resin composition. Since the multilayer structure has a layer obtained from a resin composition having excellent appearance characteristics and long run properties, coloring such as yellowing, generation of gels and blisters, fish eyes and stripes are suppressed. Has excellent appearance characteristics.

As the layer structure of the multilayer structure, for example, when the layer obtained from the resin composition is represented by E, the layer obtained from the adhesive resin is represented by Ad, and the layer obtained from the thermoplastic resin is represented by T, T / E / T, E / Ad / T, and T / Ad / E / Ad / T. Each of these layers may be a single layer or a multilayer. Moreover, you may include other layers other than the above.

Examples of the adhesive resin include an adhesive resin containing a carboxylic acid-modified polyolefin. As the carboxylic acid-modified polyolefin, a modified olefin containing a carboxyl group obtained by chemically bonding an ethylenically unsaturated carboxylic acid, its ester or its anhydride to an olefin polymer (for example, addition reaction, graft reaction, etc.) A polymer can be preferably used. Examples of the ethylenically unsaturated carboxylic acid, its ester or its anhydride include maleic acid, fumaric acid, itaconic acid, maleic anhydride, itaconic anhydride, maleic acid monomethyl ester, maleic acid monoethyl ester, maleic acid diethyl ester, fumaric acid Acid monomethyl ester and the like, and maleic anhydride is more preferable. These adhesive resins may be used alone or in admixture of two or more.

Examples of the thermoplastic resin include linear low density polyethylene, low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, polypropylene, propylene-α-olefin copolymer Polyolefins such as polymers, polybutenes, polypentenes or copolymers thereof; polyesters such as polyethylene terephthalate; polyester elastomers; polyamides such as nylon 6 and nylon 66; polystyrenes; polyvinyl chloride; polyvinylidene chloride; Resin, polyurethane elastomer, polycarbonate, chlorinated polyethylene, and chlorinated polypropylene. Among these, polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polyamide, polystyrene and polyester are preferably used.

Examples of the method for producing the multilayer structure include the following methods.
(1) Method of melt-extruding a thermoplastic resin on a molded body obtained from the resin composition (2) Method of co-extruding the resin composition and another thermoplastic resin (3) The resin composition and heat Method of co-injecting a plastic resin (4) Method of laminating a molded body obtained from the resin composition and another substrate using an adhesive

Among these methods, the method (2) can be preferably used. This is because the resin composition of the present invention is excellent in long run properties even when melted under high temperature conditions, and subsequent coloring is also suppressed, so even if it is co-extruded with other thermoplastic resins having a high melting point, It is because coloring can be suppressed and a multilayer structure excellent in appearance characteristics can be obtained. Examples of the co-extrusion method include a multi-manifold joining method T-die method, a feed block joining method T-die method, and an inflation method.

By subjecting the multilayer structure obtained by the above-described coextrusion to secondary processing, for example, the following molded body is obtained.
(1) A multilayer stretched sheet or film obtained by stretching and heat-treating a multilayer structure (sheet or film, etc.) in a uniaxial or biaxial direction. (2) Obtained by rolling a multilayer structure (sheet or film, etc.). Multi-layer rolled sheet or film (3) Multi-layer tray or cup-shaped container obtained by thermoforming a multi-layer structure (sheet or film, etc.) such as vacuum forming, pressure forming, vacuum pressure forming, etc. (4) Multi-layer structure Bottles, cup-shaped containers, etc. obtained by stretch blow molding from (pipe etc.)

Note that secondary processing methods other than those described above may be used. The molded body obtained by these secondary processing methods can be preferably used as food containers such as deep-drawn containers, cup-shaped containers, and bottles.

Hereinafter, the present invention will be described in more detail with reference to examples. In Examples and Comparative Examples described later, analysis and evaluation were performed by the following methods.

(1) Measurement of water content of water-containing EVOH pellets Using a halogen water content analyzer, the water content of water-containing EVOH pellets was measured by a thermodry weight measurement method under the conditions of a drying temperature of 180 ° C., a drying time of 20 minutes, and a sample amount of 10 g. did. The water content of the water-containing EVOH shown below is set to mass% based on the dry EVOH.

(2) Determination of phosphorus compound 0.5 g of resin composition pellets were placed in a Teflon (registered trademark) pressure vessel, and 5 mL of concentrated nitric acid was added thereto and decomposed at room temperature for 30 minutes. After decomposition, the lid was covered, and further decomposition was carried out by heating at 150 ° C. for 10 minutes and then at 180 ° C. for 5 minutes by a wet decomposition apparatus (“ACTS Corporation” MWS-2), and then cooled to room temperature. This treatment liquid was transferred to a 50 mL volumetric flask (manufactured by TPX) and diluted with pure water to obtain a measurement sample solution. About this sample solution, content of the phosphorus element was calculated | required with the ICP emission-spectral-analysis apparatus ("OPTIMA4300DV" of Perkin Elmer). From the phosphorus element content, the amount of the phosphorus compound was quantified using the molecular weight of the phosphorus compound used.

(3) Quantification of metal salt 0.5 g of resin composition pellets were placed in a pressure vessel made of Teflon (registered trademark), and 5 mL of concentrated nitric acid was added thereto and decomposed at room temperature for 30 minutes. After decomposition, the lid was covered, and further decomposition was carried out by heating at 150 ° C. for 10 minutes and then at 180 ° C. for 5 minutes by a wet decomposition apparatus (“ACTS Corporation” MWS-2), and then cooled to room temperature. This treatment liquid was transferred to a 50 mL volumetric flask (manufactured by TPX) and diluted with pure water to obtain a measurement sample solution. About this sample solution, content of the metal element was calculated | required with the ICP emission-spectral-analysis apparatus ("OPTIMA4300DV" of Perkin Elmer), and the amount of metal salts was quantified in conversion of the metal element.

(4) Quantification of monocarboxylic acid 10 g of EVOH powder obtained by freeze-pulverizing the resin composition pellets and 50 mL of ion-exchanged water were put into a 100 mL conical flask with a stopper, attached with a cooling condenser, and at 95 ° C. for 10 hours. An extract was obtained by stirring. A solution obtained by adding 2 drops of phenolphthalein as a titration indicator to 25 mL of the obtained extract was subjected to neutralization titration with a 0.01 mol / L sodium hydroxide solution to calculate the acid amount. The amount of the monocarboxylic acid contained in the resin composition from the molecular weight of the monocarboxylic acid used was obtained by subtracting the amount of acid derived from the phosphorus compound determined above from the amount of acid obtained and assuming that it was the equivalent of the amount of monocarboxylic acid. Was quantified.

(5) Quantitative determination of boron compound 0.5 g of resin composition pellets were placed in a pressure vessel made of Teflon (registered trademark), 5 mL of concentrated nitric acid was added thereto, and the mixture was decomposed at room temperature for 30 minutes. After decomposition, the lid was covered, and further decomposition was carried out by heating at 150 ° C. for 10 minutes and then at 180 ° C. for 5 minutes by a wet decomposition apparatus (“ACTS Corporation” MWS-2), and then cooled to room temperature. This treatment liquid was transferred to a 50 mL volumetric flask (manufactured by TPX) and diluted with pure water to obtain a measurement sample solution. With respect to this sample solution, the amount of the boron compound was quantified in terms of boron element using an ICP emission spectroscopic analyzer (“OPTIMA4300DV” manufactured by PerkinElmer).

(6) Production of single layer film using resin composition The resin composition pellets were produced by using a 20 mm extruder “D2020” (D (mm) = 20, L / D = 20, compression ratio = 2. (0, screw: full flight) was used to form a single layer under the following conditions, and a take-up roll speed was adjusted for each of Examples and Comparative Examples to obtain a 20 μm single layer film.
Extrusion temperature: supply unit / compression unit / metering unit / die = 170/210/210/210 ° C.
Screw rotation speed: 40rpm
Take-up roll temperature: 80 ° C

(7) Appearance characteristics (whether or not yellowing occurs on the film end face)
The single-layer film produced by the above method was wound around a paper tube, and the degree of coloring of the film end face was determined with the naked eye as follows. Standard C is a border level that can withstand actual use.
Judgment: Criteria A: No coloring B: Slightly yellowing C: Slightly yellowing D: Yellowing

(8) Evaluation of colorability during repeated reuse About 2 kg of resin composition pellets, 20 mm extruder “D2020” (D (mm) = 20, L / D = 20, compression ratio = 2.0, Toyo Seiki Seisakusho Co., Ltd.) Using a screw: full flight, pelletization was performed under the following conditions. The operation of pelletizing the obtained EVOH pellets again under the same conditions is repeated 5 times, and the colorability at the time of repeated reuse is evaluated according to the following criteria by visual evaluation of the coloring degree of the finally obtained pellets. did. Standard C is a border level that can withstand actual use.
<Pelletization conditions>
Extrusion temperature Supply unit / Compression unit / Measuring unit / Die = 180/210/210/210 ° C.
Screw rotation speed 40rpm
Number of die holes 2 holes Solidification bath cooling water temperature 30 ° C
<Coloring criteria after repeated reuse>
Judgment: Criteria A: Almost not colored B: Slightly colored C: Slightly colored D: Very colored

(9) Long-run (increased over time)
Using 200 g of the resin composition pellets, heat treatment was performed at 210 ° C. for 30 minutes with a hot air drier, and coarsely pulverized (same size as pellets) with a pulverizer. Separately, 2 kg of EVOH pellets that were not heat-treated were prepared, and a 20 mm extruder “D2020” (D (mm) = 20 and L / D = 20, compression ratio = 2.0, screw: full flight). The extrusion conditions were set to supply part / compression part / metering part / die = 170/210/210/210 ° C. Using the obtained pellets, a 20 mm extruder “D2020” (D (mm) = 20, L / D = 20, compression ratio = 2.0, screw: full flight) manufactured by Toyo Seiki Seisakusho Co., Ltd. A single-layer film was formed under the same conditions as in 6). A single layer film obtained 30 minutes after the start of film formation was sampled to count gel-like particles (about 150 μm or more that can be confirmed with the naked eye) and evaluated according to the following criteria. Standard C is a border level that can withstand actual use.
Judgment: Criteria A: Number of nuggets 10 or less / 0.1 m ²
B: The number of bumps is 11 or more and less than 50 / 0.1 m ²
C: 50 to less than 300 pieces / 0.1 m ²
D: 300 or more pieces / 0.1 m ²

(10) Long run characteristics (Increase of streak-like appearance over time)
About 5 kg of resin composition pellets, manufactured by Toyo Seiki Seisakusho Co., Ltd. using a 20 mm extruder “D2020” (D (mm) = 20, L / D = 20, compression ratio = 2.0, screw: full flight) Membrane was performed. The extrusion conditions were set to supply part / compression part / metering part / die = 190/210/210/210 ° C. After performing the film forming operation at a screw rotation speed of 100 rpm for 20 minutes, the screw rotation was stopped and the temperature setting of the extruder was set to supply unit / compression unit / metering unit / die = 150/150/150/150 ° C. Three hours after the screw rotation stopped, the extrusion temperature was again set to supply part / compression part / metering part / die = 190/210/210/210 ° C., and a single-layer film was formed at a screw speed of 100 rpm. Sampling the single-layer film obtained after resuming screw rotation and counting gel-like spots (about 150 μm or more that can be confirmed with the naked eye) until the number of spots reaches 10 or less / 0.1 m ² Was evaluated according to the following criteria as an index corresponding to the increase in the appearance of streaky appearance over time. Standard C is a border level that can withstand actual use.
Determination: reference A: seeding number is less than 10 or less /0.1m become time ² is 10 minutes B: seeding number is less than 10 or 30 minutes or less /0.1m to become time ² more than 10 minutes C: seeding number Is 10 minutes or less / 0.1 m ² 30 minutes or more and less than 60 minutes D: The time when the number of bumps is 10 pieces or less / 0.1 m ² is 60 minutes or more

<Example 1>
1-hydroxyethane-1,1-diphosphonic acid (HEDP) is 0.08 g / L, sodium acetate is 0.84 g / L, acetic acid is 0.38 g / L, and boric acid is 0.25 g / L. 10.0 kg of hydrous EVOH pellets (ethylene unit content (Et) 32 mol%, saponification degree (DS) 99.98 mol%) having a water content of 105 mass% were added to 92.4 L of an aqueous solution in which each component was dissolved in water. Then, the immersion was performed at 25 ° C. for 6 hours with occasional stirring. The pellet after the immersion was subjected to centrifugal dehydration, and then dried in a hot air dryer at 80 ° C. for 3 hours and then at 120 ° C. for 24 hours to obtain a resin composition pellet. As a result of analyzing the obtained pellets according to the above, it contained 30 ppm of 1-hydroxyethane-1,1-diphosphonic acid, 200 ppm of sodium acetate as a metal salt, 200 ppm of acetic acid as a monocarboxylic acid, and 175 ppm of boric acid as a boron compound. It was. When the above-mentioned (7) appearance characteristics (whether or not yellowing of the film end face occurred) was evaluated, no color was seen on the film end face, and it was judged as A. (8) Colorability evaluation during repeated reuse No coloration was observed, and the determination was A. Further, (9) The long run property (increase in puncture over time) was judged as A with the number of lumps being 10 or less / 0.1 m ² .

<Examples 2 to 17 and Comparative Examples 1 to 9>
Except having changed the component mix | blended in aqueous solution and its density | concentration as shown in Table 1, it operated similarly to Example 1 and obtained the pellet of the resin composition. Table 2 shows the results of analysis and evaluation of the obtained pellets according to the above. In each table, HEDP is 1-hydroxyethane-1,1-diphosphonic acid, NTMP is nitrotris (methylenephosphonic acid), and EDTMP is ethylenediaminetetrakis (methylenephosphonic acid) hydrate. .

<Comparative Example 19>
Water content containing 0.2% sodium acetate at a water content of 105% by mass in 17.8 L of an aqueous solution in which the respective components are dissolved in water so that pyrophosphoric acid is 0.89 g / L and acetic acid is 1.4 g / L 10.0 kg of EVOH pellets (ethylene unit content (Et) 55 mol%, saponification degree (DS) 97 mol%) were added and immersed at 25 ° C. for 4 hours with occasional stirring. The pellet after the immersion was subjected to centrifugal dehydration, and then dried in a hot air dryer at 80 ° C. for 3 hours and then at 120 ° C. for 24 hours to obtain a resin composition pellet. Table 2 shows the results of analysis and evaluation of the obtained pellets according to the above.

<Examples 18 to 20>
By operating in the same manner as in Example 1 except that the types of hydrous EVOH pellets used (Et of EVOH), the components blended in the aqueous solution, and the concentrations thereof were changed as shown in Table 1, pellets of the resin composition were obtained. Obtained. Table 2 shows the results of analysis and evaluation of the obtained pellets according to the above.

As shown in Table 2, when the resin composition contains a specific phosphorus compound and a metal salt in a specific amount, it becomes a determination of C or more in all evaluation items, and the color resistance and the time-dependent increase in the thickness It was possible to obtain a resin composition having excellent long-run properties such as suppression of corrosion. Moreover, the said characteristic was further improved by containing monocarboxylic acid and boric acid in a predetermined quantity.

<Example 21>
Except having changed the component mix | blended in aqueous solution and its density | concentration as shown in Table 3, it operated similarly to Example 1 and the pellet of the resin composition was obtained. Table 4 shows the results of analyzing the obtained pellets according to the above. When the above-mentioned (7) appearance characteristics (whether or not yellowing of the film end face occurred) was evaluated, no color was seen on the film end face, and it was judged as A. (8) Colorability evaluation during repeated reuse No coloration was observed, and the determination was A. In addition, (10) Long run property (time-dependent increase in streak-like appearance defect) was less than 10 minutes for the number of bumps to be 10 or less / 0.1 m ² , and was judged as A.

<Examples 22 to 31 and Comparative Examples 10 to 18>
Except having changed the component mix | blended in aqueous solution and its density | concentration as shown in Table 3, it operated similarly to Example 21, and the pellet of the resin composition was obtained. Table 4 shows the results of analysis and evaluation of the obtained pellets according to the above.

<Examples 32 to 34>
The pellets of the resin composition were prepared by operating in the same manner as in Example 21 except that the types of hydrous EVOH pellets used (Et of EVOH) and the components and concentrations thereof contained in the aqueous solution were changed as shown in Table 3. Obtained. Table 4 shows the results of analysis and evaluation of the obtained pellets according to the above.

As shown in Table 4, when the resin composition contains a specific phosphorus compound and a metal salt in a predetermined amount, it becomes a determination of C or more in all evaluation items, and in coloration resistance and long-time molding In addition, it was possible to obtain a resin composition excellent in long run properties such that fish eyes and streaks are not generated. Moreover, the said characteristic was further improved by containing monocarboxylic acid and boric acid in a predetermined quantity.

Claims (7)

1. A resin composition comprising an ethylene-vinyl alcohol copolymer as a main component,
   Containing a phosphorus compound and a metal salt;
   The phosphorus compound is condensed phosphoric acid, a compound having two or more phosphonic acid groups, or a combination thereof;
   The phosphorus compound content is 0.1 ppm or more and less than 50 ppm,
   Content of the said metal salt is 5 ppm or more and 500 ppm or less in conversion of a metal element, The resin composition characterized by the above-mentioned.
2. The resin composition according to claim 1, wherein the metal salt is an alkali metal salt, an alkaline earth metal salt, or a combination thereof.
3. The resin composition according to claim 2, wherein the metal salt is an alkali metal salt.
4. The metal salt is an alkaline earth metal salt;
   The resin composition according to claim 2, wherein the content of the alkaline earth metal salt is 5 ppm or more and 100 ppm or less in terms of a metal element.
5. Further containing a monocarboxylic acid,
   The resin composition according to any one of claims 1 to 4, wherein a content of the monocarboxylic acid is 5 ppm or more and 500 ppm or less.
6. Further containing a boron compound,
   The resin composition according to any one of claims 1 to 5, wherein a content of the boron compound is 5 ppm or more and 2,000 ppm or less in terms of boron element.
7. A molded body having a portion formed from the resin composition according to any one of claims 1 to 6.