JP3555991B2 - Polymer composition and packaging material suitable for coating etc. - Google Patents

Description

【００３２】
【表２】

【００３３】
実施例２
実施例１のエチレン・不飽和カルボン酸共重合体の代わりに、アクリル酸イソブチルを含む３元共重合体Ａ２（メタクリル酸含有量１０重量％、アクリル酸イソブチル含有量１０重量％、メルトフローレート１０）を用いた以外は、実施例１と同様に行い、マスターバッチ（Ｂ_２ 、Ｃ_２ ）及びサンプルの作成と臭気評価を行った。結果を表３、４に示す。
【００３４】
【表３】

【００３５】
【表４】

【００３６】
実施例３
実施例１のフェノール系酸化防止剤の代わりに、ＢＨＴ（Ｄ１：吉富製薬製ＳＤＲ 分子量２２０）、イルガノックス１０７６（Ｅ１：チバガイギー製 分子量５３１）を新たに用いた以外は、実施例１と同様に行った。結果を表５、６に示す。
【００３７】
【表５】

【００３８】
【表６】

【００３９】
【発明の効果】
本発明の重合体組成物は臭気が少なく、したがって食品包装材料として好適である。とくに、アルミニウム箔、シリカ蒸着フィルム、ポリエステル、ポリプロピレン、ポリアミドなど一層または二層以上からなる基材フィルム上に押出コーティングする材料として好適である。この場合、押出コーティングを２５０℃以上の高温で行っても、臭気レベルは低く、またこのように押出コーティングしたのち、４０℃のような高温度で長期保存しても、臭気レベルが悪化することはない。[0001]
[Industrial applications]
The present invention relates to a composition of an ethylene / unsaturated carboxylic acid copolymer or an ionomer having reduced odor and a packaging material using the composition.
[0002]
[Prior art]
It is known that zeolites adsorb odorous substances, and it is also known to mix zeolites for the purpose of reducing the odor of plastic materials. However, many zeolites do not have enough performance to reduce odor producing substances to a sufficiently satisfactory level.
[0003]
However, in recent years, hydrophobic crystalline siliceous molecular sieves having a pore size of 5.5 Å or more and at least 90% of the framework tetrahedral oxide units are SiO ₂ may be particularly useful for removing organic odors. (Japanese Patent Application Laid-Open No. 64-85113), and it has also been found that when this is blended with ethylene plastic or propylene plastic, it is particularly useful for removing odor / taste generating substances contained therein. Japanese Unexamined Patent Publication No. Hei 5-507759. Specifically, there is shown an example in which such a molecular sieve is blended with high-density polyethylene.
[0004]
[Problems to be solved by the invention]
In general, a copolymer of ethylene and a polar vinyl compound is more likely to retain an odor-causing substance due to the polar vinyl compound than polyethylene, and it is more difficult to reduce the odor. It was recognized that the above-mentioned hydrophobic crystalline siliceous molecular sieve was effective for reducing the odor of the copolymer.
[0005]
According to the present invention, there is provided a skeleton tetrahedral oxide unit having a pore diameter of 5.5 angstroms or more per 100 parts by weight of ethylene / (meth) acrylic acid or its ionomer (A). of at least 90% SiO ₂
A polymer composition comprising 0.1 to 5 parts by weight of a hydrophobic crystalline siliceous molecular sieve (B) and 0.01 to 2 parts by weight of a phenolic antioxidant (C) having a molecular weight of 300 or more. About.
[0006]
Therefore, the present inventors have studied to find a formulation that can reduce odor even when the ethylene / unsaturated carboxylic acid copolymer or its ionomer is used for the above-mentioned coating material. As a result, it was found that when a specific antioxidant was used in combination, a remarkable synergistic effect was observed, and the present invention was reached.
[0007]
That is, an object of the present invention is to provide a composition capable of reducing an organic odor peculiar to an ethylene / unsaturated carboxylic acid copolymer or an ionomer thereof, particularly a coating composition.
[0008]
[Means for Solving the Problems]
The present invention relates to an ethylene / unsaturated carboxylic acid copolymer or its ionomer (A) having a pore diameter of 5.5 Å or more based on 100 parts by weight of at least 90% of a skeleton tetrahedral oxide unit based on SiO _2. A polymer composition comprising 0.1 to 5 parts by weight of a hydrophobic crystalline siliceous molecular sieve (B) and 0.01 to 2 parts by weight of a phenolic antioxidant (C) having a molecular weight of 300 or more. About.
[0009]
The present invention also relates to a packaging material formed by extrusion-coating the polymer composition on a coating material comprising the polymer composition and a substrate comprising a metal foil or a plastic film.
[0010]
[Action]
In the present invention, the ethylene-unsaturated carboxylic acid copolymer or its ionomer, by containing a specific crystalline siliceous molecular sieve and a specific phenolic antioxidant in a certain quantitative ratio, to the polymer Unique organic odor can be removed.
[0011]
The ethylene / unsaturated carboxylic acid copolymer or its ionomer used in the present invention can be processed at a relatively low temperature and has excellent hygienic properties, like the olefin-based resin. It has the advantage that it can be extrusion-coated on a substrate and has a carboxyl group in the polymer chain, so that it can be strongly heat-bonded to various substrates by extrusion coating. However, the polar group also causes odor during heating processing such as extrusion coating.
[0012]
The crystalline siliceous molecular sieve used in the present invention has a pore size of 5.5 Å or more, and at least 90% of the skeleton tetrahedral oxide units are occupied by SiO ₂ . A-type zeolites, X-type zeolites, and the like, which are generally used as crystalline siliceous molecular sieves, have a much lower content of SiO ₂ than those described above, and these zeolites use more water than organic components. Since it is selectively adsorbed, it is not suitable for absorbing the odorant component of the copolymer. On the other hand, a molecular sieve having a rich SiO ₂ content of 90% or more is hydrophobic in nature, and has a fine pore size of 5.5 angstroms or more, and thus has a superior adsorption property to organic components. I have.
[0013]
However, the crystalline siliceous molecular sieve alone is not sufficient to prevent the odor of these copolymers at the time of coating, simply by being blended with the ethylene / unsaturated carboxylic acid copolymer or its ionomer. I understand. That is, the above-mentioned copolymer blended with a crystalline siliceous molecular sieve has the same odor prevention effect as that of the copolymer blended with only an antioxidant, as shown in the examples described below. The effect is still insufficient. In particular, in the case where a crystalline siliceous molecular sieve is blended with this copolymer, the tendency to smell becomes remarkable as the aging temperature increases.
[0014]
On the other hand, according to the present invention, when a phenolic antioxidant having a molecular weight of 300 or more is selected from the antioxidants and combined with the above-mentioned hydrophobic crystalline siliceous molecular sieve, an excellent odor prevention effect is obtained. Is obtained, and this odor preventing effect is still maintained even under aging conditions at high temperatures.
[0015]
In the present invention, a combination of a hydrophobic crystalline siliceous molecular sieve and a relatively high molecular weight phenolic antioxidant is used to prevent the odor of the ethylene / unsaturated carboxylic acid copolymer or its ionomer during coating or aging. Has been found as a phenomenon as a result of a number of experiments, for reasons not yet speculated, but with the free radical chain termination, peroxide decomposition, and phenolic antioxidants possessed. It is considered that the metal deactivating action and the selective adsorption action of the decomposition product of the hydrophobic crystalline siliceous molecular sieve act synergistically.
[0016]
It is also important for the prevention of odor that the molecular weight of the phenolic antioxidant is 300 or more, and if the molecular weight is less than 300, it is desirable from the viewpoint of preventing odor.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION The ethylene / unsaturated carboxylic acid copolymer used in the present invention is not only a binary copolymer of ethylene and (meth) acrylic acid but also a multi-component copolymer containing a third monomer as a copolymerization component. It may be united. Here, (meth) acrylic acid means acrylic acid or methacrylic acid . Examples of the third monomer include esters of unsaturated carboxylic acids, vinyl esters, and carbon monoxide. More specifically, as unsaturated carboxylic acid esters, methyl acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate, isooctyl acrylate, methyl methacrylate, isobutyl methacrylate, dibutyl maleate and the like, and vinyl esters Examples thereof include vinyl acetate and vinyl propionate.
[0018]
As the ethylene / unsaturated carboxylic acid copolymer, usually, ethylene is 50 to 96% by weight, particularly 60 to 95% by weight, unsaturated carboxylic acid is 2 to 30% by weight, particularly 5 to 20% by weight, and the third monomer is It is preferable to use those having a polymerization composition of 30% by weight or less, particularly 20% by weight or less.
[0019]
In the present invention, when an ionomer of an ethylene / unsaturated carboxylic acid copolymer is used, a part or all of the carboxyl groups of the above-mentioned ethylene / unsaturated carboxylic acid copolymer is neutralized with a metal ion. For example, those having a degree of neutralization of 90 mol% or less, preferably 50 mol% or less, more preferably 30 mol% or less can be used. As the metal ion, for example, lithium, sodium, potassium, calcium, magnesium, zinc and the like can be mentioned as typical examples. The metal ion may be of two or more kinds, and may contain an amino compound such as 1,3-dimethylaminocyclohexane in addition to the metal ion.
[0020]
Ethylene / unsaturated carboxylic acid copolymers or ionomers thereof can be of any molecular weight, but usually have a melt flow rate (MFR) at 190 ° C. and a load of 2160 g of 0.01 to 1000 g / 10 min, especially 0.1. Those having a content of 1 to 100 g / 10 minutes can be suitably used.
[0021]
The crystalline siliceous molecular sieve (B) used in the present invention has a pore size of 5.5 Å or more, preferably 6.2 Å or more, and at least 90% of the skeleton tetrahedral oxide units are SiO ₂ , preferably Is an aluminosilicate having a SiO ₂ / Al ₂ O ₃ (molar ratio) of 35 or more, particularly 200 to 5000. Such siliceous molecular sieves are hydrophobic and exhibit a water-absorbing capacity of 10% by weight or less, preferably 6% by weight or less, at 25 ° C. and 4.6 torr. It is preferable that the siliceous molecular sieve (B) has an average particle diameter of 10 μm or less, preferably 0.1 to 5 μm.
[0022]
This hydrophobic molecular sieve is available as ZSM-5 type zeolite, silicalite and the like. Although the effect is slightly lower, it is also possible to use a Y-type zeolite in which the amount of alumina is reduced by a steaming treatment. The hydrophobic zeolite may contain an alkali metal component such as sodium in addition to the silica component and the alumina component, or may be a hydrogen-type zeolite in which the alkali metal component is replaced with hydrogen.
[0023]
Hydrophobic molecular sieves such as ZSM-5 zeolite are known per se, for example, a method of hydrothermally treating a silica source, an alumina source, an alkali metal component and water with a basic organic nitrogen compound as a template, or using a template. It can be obtained by a method of hydrothermally treating an aqueous colloidal silica sol, an alkali aluminate, and an alkali hydroxide.
[0024]
The antioxidant (C) used in the present invention is a phenolic compound having a molecular weight of 300 or more, preferably 400 or more. Specifically, stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate Methane, 2,2-methylenebis (4-methyl-6-t-butylphenol), 2,2-methylenebis (4-ethyl-6-t-butylphenol), 4,4-thiobis (3-methyl-6-t -Butylphenol), 4,4-butylidenebis (3-methyl-6-t-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, bis [3,3-bis- (4-hydroxy-3-t Butylphenyl) butyric acid] glycol ester, and the like can be exemplified tocopherol.
[0025]
Even if a phenolic antioxidant having a small molecular weight, for example, 2,6-di-t-butyl-4-methylphenol is used instead of such an antioxidant, good results cannot be obtained.
[0026]
These additives contain 0.1 to 5 parts by weight, preferably 0.2 to 2 parts by weight, of the siliceous molecular sieve (B) per 100 parts by weight of the ethylene / unsaturated carboxylic acid copolymer or its ionomer (A). The phenolic antioxidant (C) is used in an amount of 0.01 to 2 parts by weight, preferably 0.05 to 1 part by weight.
[0027]
The polymer composition of the present invention may optionally contain other additives and polymers. Examples of such other additives include an antistatic agent, a lubricant, an anti-blocking agent, an ultraviolet absorber, a light stabilizer, a pigment, a dye, and an inorganic filler.
[0028]
The composition of the present invention is useful as an extrusion coating material for preparing a packaging material. For example, on a substrate consisting of one or more layers such as aluminum foil, silica-deposited film, polyester, polypropylene, polyamide, etc., extrude and coat the above composition in a film form, and laminate with a heat sealable inner surface material Can be a body. Also, a laminate by sandwich lamination can be manufactured by extruding between a plurality of films or metal foils. The thickness of the coating layer can be freely changed in the range of 3 to 300 μm. This packaging material is useful as a pouch, heat seal lid, or other flexible packaging material.
[0029]
【Example】
The effects of the present invention will be described with reference to the following examples.
[0030]
Example 1
(1) Preparation of a master batch of crystalline siliceous molecular sieve A crystalline siliceous molecular sieve is prepared based on 90 parts by weight of an ethylene / unsaturated carboxylic acid copolymer A1 (methacrylic acid content: 4% by weight, melt flow rate: 7 g / 10 minutes). 10 parts by weight of Absents 3000 (manufactured by UOP) were melt-mixed using a 30 mm diameter twin screw extruder at a resin temperature of 150 ° C. to prepare a master batch B1.
(2) Preparation of phenolic antioxidant masterbatch To 98 parts by weight of A1 described above, 2 parts by weight of Kilganox 1010 (Ciba Geigy Co., Ltd., molecular weight 1178) was used as a phenolic antioxidant using a 30 mm diameter twin screw extruder. The mixture was melted and mixed at a resin temperature of 150 ° C. to prepare a master batch C1.
(3) Preparation of sample 10 parts by weight of B1 alone (sample 2), 5 parts by weight of C1 alone (sample 3), 5 parts by weight of B1 and 5 parts by weight of C1 based on 100 parts by weight of A1 Part (sample 4) was melt-extruded from a T-die using a 65 mm diameter extruder at a die exit resin temperature of 300 ° C. so as to form a part (sample 4). The sample was subjected to extrusion coating under the conditions of a processing speed of 80 m / min and a coating thickness of 20 microns to obtain Samples-2, 3, and 4. Extrusion coating was performed in the same manner with A1 alone to obtain Sample-1.
(4) Odor evaluation An A4-size pouch was prepared using the above sample, and the internal odor after aging for one month at room temperature and 40 ° C was evaluated by six trained panelists. The average value of the odors of six persons was adopted, and the smaller the value, the better the result.
The results are shown in Tables 1 and 2.
[0031]
[Table 1]

[0032]
[Table 2]

[0033]
Example 2
Instead of the ethylene / unsaturated carboxylic acid copolymer of Example 1, a terpolymer A2 containing isobutyl acrylate (methacrylic acid content: 10% by weight, isobutyl acrylate content: 10% by weight, melt flow rate: 10%) ) Was carried out in the same manner as in Example 1 except that master batches (B ₂ , C ₂ ) and samples were prepared and odor was evaluated. The results are shown in Tables 3 and 4.
[0034]
[Table 3]

[0035]
[Table 4]

[0036]
Example 3
In the same manner as in Example 1 except that BHT (D1: SDR molecular weight 220 manufactured by Yoshitomi Pharmaceutical) and Irganox 1076 (E1: molecular weight 531 manufactured by Ciba Geigy) were newly used instead of the phenolic antioxidant of Example 1. went. The results are shown in Tables 5 and 6.
[0037]
[Table 5]

[0038]
[Table 6]

[0039]
【The invention's effect】
The polymer composition of the present invention has low odor and is therefore suitable as a food packaging material. In particular, it is suitable as a material to be extrusion-coated on a base film composed of one or more layers such as aluminum foil, silica-deposited film, polyester, polypropylene, and polyamide. In this case, even if the extrusion coating is performed at a high temperature of 250 ° C. or more, the odor level is low, and even if the extrusion coating is performed and stored at a high temperature such as 40 ° C. for a long time, the odor level is deteriorated. There is no.

Claims (3)

A copolymer of ethylene / (meth) acrylic acid or its ionomer (A) has a pore size of 5.5 angstroms or more per 100 parts by weight, and at least 90% of skeleton tetrahedral oxide units are SiO ₂ . A polymer composition comprising 0.1 to 5 parts by weight of a hydrophobic crystalline siliceous molecular sieve (B) and 0.01 to 2 parts by weight of a phenolic antioxidant (C) having a molecular weight of 300 or more. A coating material comprising the composition according to claim 1. A packaging material characterized by extrusion-coating the polymer composition according to claim 1 on a substrate comprising at least one layer of a metal foil or a plastic film.