JP3451772B2 - Oxygen barrier resin composition, method for producing the same, and oxygen barrier laminate - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition excellent in oxygen barrier property, which is widely used in packaging films, sheets, bottles, containers and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Since thermoplastic resins can be molded by various methods such as melt extrusion molding, injection molding and blow molding, they are widely used in, for example, packaging films, sheets, bottles and containers.

However, especially for packaging of contents such as foods that dislike oxygen, it is laminated with an oxygen-barrier and more expensive resin such as saponified ethylene-vinyl acetate copolymer or polyvinylidene chloride. It was actually used.

The present inventors have previously filed Japanese Patent Application Laid-Open No. 3-21334.
Japanese Unexamined Patent Publication (Kokai) No. 6 shows an example of a resin composition using a polyolefin and an oxidation catalyst, which does not use an expensive oxygen barrier resin and has excellent oxygen barrier properties. Although the combination showed a very high oxygen barrier property, the strength of the composition deteriorated due to the too fast oxygen absorption reaction.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve this problem, and the object of the present invention is to retain these oxygen barrier functions as a packaging material particularly for long-term storage. In addition, the present invention is to provide an oxygen-barrier resin composition having suppressed strength deterioration, a method for producing the same, and an oxygen-barrier laminate.

[0006]

In order to solve this problem, the present invention provides an oxygen barrier resin composition comprising a mixture of a polyolefin, an oxidation catalyst and maleic anhydride or itaconic acid. provide. Further, there is provided an oxygen-barrier resin composition comprising a resin composition comprising a polyolefin containing an oxidation catalyst and a resin composition comprising a polyolefin containing maleic anhydride or itaconic acid dispersed therein. The oxygen barrier resin composition is characterized in that the content of maleic anhydride or itaconic acid relative to the oxygen barrier resin composition is 0.01 to 5.0% by weight. In addition, as a method for producing the same, a polyolefin, an oxidation catalyst, and maleic anhydride or itaconic acid are melt-mixed and processed at the same time, or a resin composition comprising a polyolefin and an oxidation catalyst is melt-kneaded. Disclosed is a method for producing an oxygen-barrier resin composition, characterized by being dispersed in a mixture composed of a polyolefin containing maleic anhydride or itaconic acid. Further, the present invention provides an oxygen-barrier laminate, which comprises at least one layer composed of these oxygen-barrier resin compositions.

The present invention will be described in detail below. As the polyolefin used in the present invention, for example, low density polyethylene, medium density polyethylene, polyethylene such as high density polyethylene, polypropylene homo or block polymer or random copolymer, polybutene,
Examples thereof include ethylene-α olefin (having 3 or more carbon atoms) copolymer. The antioxidant content in the polyolefin is preferably 500 ppm or less.

Further, the above-mentioned polyolefin may contain a nucleating agent or various additives such as a compatibilizer, a lubricant, an anti-blocking agent, a stabilizer, an antifogging agent and a coloring agent.

The oxidation catalyst used in the present invention means that oxygen which permeates and permeates the polyolefin is reacted with the polyolefin by promoting the oxygen oxidation of the polyolefin to reduce the oxygen permeability, and as a result, the oxygen barrier of the polyolefin. As long as it can improve the property, an oxidation catalyst composed of a transition metal compound or the like is preferably used as such an oxidation catalyst.

In the case of such a transition metal, it is considered that oxygen reacts with polyolefin to act as an oxidation catalyst in the process of transition of the metal ion from the oxidized state to the reduced state and from the reduced state to the oxidized state.

As such a transition metal, metals such as Co, Mn, Fe, Cu, Ni, Ti, V and Cr are preferably used, and Co is preferably used.
As the compounds of these metals, salts of organic acids are used. Examples of such an organic acid include stearic acid,
Examples thereof include acetylacetonic acid, dimethyldithiocarbamic acid, linoleic acid, naphthenic acid, tallic acid, oleic acid, resin acid and capric acid.

As the transition metal compound, Al, Mg, Ca and Zn compounds can be used because they are hygienic, colorless and inexpensive. Further, also in the Fe compound, iron citrate, ammonium iron citrate, ferrous gluconate, iron lactate, iron pyrophosphate, ferrous nitrate and the like which are used as food additives are also used. The above-mentioned oxidation catalyst is preferably contained in the composition in an amount of 10 ppm or more in terms of metal atomic weight.

Further, the higher the concentration of such an oxidation catalyst, the more effective it is in terms of barrier properties.
If the content is too large, the polyolefin may deteriorate due to rapid oxygen absorption, causing discoloration or lowering of strength. Therefore, 2000 pp is added to the entire oxygen barrier resin composition.
It is preferably used at m or less.

The maleic anhydride or itaconic acid used in the present invention is used as a crosslinking aid in the field of resin modification. As a function of this cross-linking aid, when carrying out cross-linking for the purpose of modifying the polyolefin, the decomposition of the polyolefin occurs mainly when an organic peroxide-based cross-linking agent is used, so it is used to suppress this decomposition reaction. It is a thing. The purpose of the present invention is not to modify the polyolefin such as crosslinking, but to prevent the polyolefin from being rapidly oxidized by the action of an oxidation catalyst and causing a decomposition reaction of the polymer chain.

As the cross-linking aid, maleimide-based, methacrylic-based, allyl-based, and vinyl monomer-based cross-linking aids are used. Specifically, p-quinonedioxime, p.
p'-dibenzoylquinone dioxime, lauryl methacrylate, ethylene glycol acrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, diethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol dimethacrylate,
Trimethylol propene trimethacrylate, methyl methacrylate, diaryl fumarate, diaryl phthalate, tetraaryloxyethane, triaryl cyanurate, trimetaaryl isocyanurate,
Maleimide, phenylmaleimide, N, N'-m-phenylene dimaleimide, divinylbenzene, vinyl butyrate, vinyl stearate, vinyltoluene, sulfur,
Examples thereof include 1,2-polybutadiene and the like, which can be expected as a compound having the same action as maleic anhydride or itaconic acid in the present invention.

In particular, when maleic anhydride or itaconic acid is used, the resin modification such as the crosslinking reaction or the decomposition reaction occurring during the processing of the oxygen-barrier resin composition of the present invention is extremely small, and further, it depends on the oxidation catalyst after the processing. It is preferable because it has an excellent effect of suppressing decomposition and deterioration of the polymer chain for a long period of time. The amount of maleic anhydride and itaconic acid used is most preferably 0.01 to 0.5% by weight with respect to the oxygen-barrier resin composition. Particularly, if the amount is exceeded, modification of the resin during processing occurs or oxidation occurs. This is not preferable because the oxidation ability of the resin by the catalyst is suppressed too much, resulting in a decrease in oxygen barrier ability.

As one of the methods for producing the oxygen-barrier resin composition of the present invention, it is possible to melt-process and simultaneously process three compositions of polyolefin, an oxidation catalyst and maleic anhydride or itaconic acid. Further, it is formed by dispersing a polyolefin containing an oxidation catalyst in a mixture of a polyolefin and maleic anhydride or itaconic acid, but the combination of the polyolefin to be dispersed and the polyolefin containing an oxidation catalyst is not particularly limited. . That is, a polyolefin containing an oxidation catalyst is one that improves the oxygen barrier property by absorbing oxygen due to the reaction with the oxidation catalyst, even if it exists in islands scattered in the sea without melting in the polyolefin into which it is dispersed. Is. The preferred mixing ratio of the polyolefin containing the oxidation catalyst and the polyolefin containing maleic anhydride or itaconic acid in such dispersion is 1:99 to 9
It is 9: 1.

As another method for producing the oxygen barrier resin composition in the present invention, the oxidation catalyst and the polyolefin are melt-kneaded in advance using a biaxial kneader or the like, and then the polyolefin composition containing the oxidation catalyst. When processing packaging materials such as films, sheets and containers,
There is a method of dispersing in one of the polyolefins containing maleic anhydride or itaconic acid.

Thus, the oxidation catalyst is better dispersed in the polyolefin by melt-kneading in advance,
It becomes possible to improve the oxygen absorption reaction of the polyolefin.

In the present invention, an organic acid salt is preferably used as the oxidation catalyst. Such organic acids have been conventionally used as lubricants and the like, and have the function of lowering the viscosity of the polyolefin during processing. That is, by reducing the viscosity of the oxidation catalyst and the polyolefin composition,
On the other hand, an improvement in dispersion in polyolefin containing maleic anhydride or itaconic acid is achieved.

The oxygen-barrier resin composition of the present invention can be molded into a film, a sheet, a container or other packaging material by various molding methods using heat.

For example, a film, a sheet, a pipe, etc. may be formed by melt extrusion molding into a container shape by injection molding, and
By hollow molding, a hollow container such as a bottle can be molded. Hollow molding includes extrusion hollow molding in which a parison is molded by extrusion molding and then blown to perform molding, and injection hollow molding in which a preform is molded by injection molding and then blown to perform molding.

Further, the oxygen barrier resin composition of the present invention is used as one layer of a laminate, and one or both surfaces of the oxygen barrier resin composition layer may be another thermoplastic resin layer, for example, a thermoplastic resin layer containing no oxidation catalyst. It is also possible to form and use as a laminated body.

Other thermoplastic resin layers used include:
Examples of the layer include polyester, polyolefin, polyamide, polyurethane, polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile, polycarbonate and the like, or modified resins thereof. By laminating a small amount of these thermoplastic resins, when the oxygen barrier resin composition of the present invention is thinned, the initial value of the oxygen barrier is lowered, or the function as a strength of the entire laminated film Can be given.

As a method for laminating these layers, each method such as lamination using an adhesive, coextrusion molding, coextrusion hollow molding or coinjection hollow molding is used.

The oxygen barrier resin composition of the present invention can be used in various applications as follows. For example,
It can be used as a material for a container for storage of a substance that is easily modified by oxygen, such as food.

When molding into a sheet or film,
It can be used as a bag material, a blister pack material, a container lid, and the like. Further, in the case of forming into a pipe shape, a container can be obtained by closely adhering the openings at both ends with a metal lid or the like. For injection-molded containers and bottles,
It can be used as it is as a container.

[0028]

As described above, in the oxygen barrier resin composition of the present invention, the polyolefin reacts with oxygen in the air in the presence of the oxidation catalyst to accelerate the oxygen absorption reaction of the polyolefin by the radical reaction, It is speculated that oxygen in the atmosphere is consumed to improve the oxygen barrier property.

Here, the combination of the oxidation catalyst and the polyolefin exhibits a very high oxygen barrier property, but the decomposition and degradation of the polymer chain will occur due to the too fast oxygen absorption reaction. Maleic anhydride or itaconic acid is given as having a function of acting on a polymer radical generated by absorbing oxygen to deactivate the polymer radical,
As a result, it is presumed that oxygen barrier properties can be achieved, and decomposition and deterioration of polymer chains can be suppressed for a long period of time.

[0030]

EXAMPLES The present invention will be described in more detail with reference to the following examples.

<Example 1> 50 ppm of stearic acid Co (II) was used as an oxidation catalyst, and polypropylene was used as a polyolefin (manufactured by Mitsui Petrochemical Co., Ltd .: "J60").
0 "MI = 7.0, no antioxidant) was mixed with 0.1% by weight of maleic anhydride and extrusion-molded at an extrusion temperature of 190 ° C. to obtain a sheet having a thickness of 800 μm. .

<Example 2> 50 ppm of Co (II) stearate was used as the oxidation catalyst, and polypropylene was used as the polyolefin (manufactured by Mitsui Petrochemical Co., Ltd .: "J60".
0 "MI = 7.0, no antioxidant) was mixed with 0.08 wt% of itaconic acid, and extrusion molding was performed at an extrusion temperature of 190 ° C. to obtain a sheet having a thickness of 800 μm.

Comparative Example 1 Co (II) stearate 50
ppm and polypropylene (Mitsui Petrochemical Industry Co., Ltd.)
Made: "J600" MI = 7.0, no antioxidant) 2
The seeds were mixed (maleic anhydride or itaconic acid were not mixed), and extrusion molding was performed at an extrusion temperature of 190 ° C. to obtain a sheet having a thickness of 800 μm.

Table 1 shows the measurement results of the time-dependent oxygen transmission rate (O ₂ —TR) of each of the sheets obtained in Examples 1 and 2 and Comparative Example 1. The measurement is "Mokon Ox-TRAN
10/50 A "(manufactured by Modern Control Co.) at 25 ° C.

In addition, the above Examples 1 and 2 and Comparative Example 1,
The presence or absence of crack generation due to bending stress was observed for each sheet obtained in step 1.

[0036]

[Table 1]

As is clear from Table 1, the oxygen barrier sheets of the present invention of Examples 1 and 2 and Comparative Example 1 have a reduced oxygen transmission rate over time and have excellent oxygen barrier properties. ing. In the oxygen barrier sheets of Examples 1 and 2, cracks did not occur for a long period of time, but in Comparative Example 1, cracks occurred in a short period of time, and Examples 1 and 2 are resin compositions that can withstand long-term use. Is shown.

<Example 3> 200 ppm of Co (II) stearate was used as an oxidation catalyst, and polypropylene was used as a polyolefin (manufactured by Mitsui Petrochemical Industry Co., Ltd .: "J60").
0 "MI = 7.0, without antioxidant), these were mixed and extrusion-molded using a twin-screw kneading extruder at an extrusion temperature of 190 ° C. to obtain resin pellets. Polypropylene (Mitsui Petrochemical Industry Co., Ltd .: “J600” MI
= 7.0, no antioxidant), the mixing ratio is 25:75
(Weight ratio) were mixed. A mixture of 0.1% by weight of maleic anhydride with respect to the total amount of resin was extruded at an extrusion temperature of 190 ° C. to obtain a sheet having a thickness of 800 μm.

<Example 4> 200 ppm of Co (II) stearate was used as an oxidation catalyst, and polypropylene was used as a polyolefin (manufactured by Mitsui Petrochemical Industry Co., Ltd .: "J60").
0 "MI = 7.0, without antioxidant), these were mixed and extrusion-molded using a twin-screw kneading extruder at an extrusion temperature of 190 ° C. to obtain resin pellets. Polypropylene (Mitsui Petrochemical Industry Co., Ltd .: “J600” MI
= 7.0, no antioxidant), the mixing ratio is 25:75
(Weight ratio) were mixed. A mixture of 0.08% by weight of itaconic acid with respect to the total amount of the resin was extruded at an extruding temperature of 190 ° C. to obtain a sheet having a thickness of 800 μm.

<Example 5> 200 ppm of stearic acid Co (II) was used as an oxidation catalyst, and polypropylene was used as a polyolefin (manufactured by Mitsui Petrochemical Co., Ltd .: "J60").
0 "MI = 7.0, without antioxidant), these were mixed and extrusion-molded using a twin-screw kneading extruder at an extrusion temperature of 190 ° C. to obtain resin pellets. Polyethylene (Mitsui Petrochemical Industry Co., Ltd.): "Mirason 14
P ”) was mixed at a mixing ratio of 25:75 (weight ratio).
A mixture of 0.1% by weight of maleic anhydride with respect to the total amount of resin was extruded at an extrusion temperature of 190 ° C. to obtain a sheet having a thickness of 800 μm.

Example 6 200 ppm of Co (II) stearate was used as the oxidation catalyst, and polypropylene was used as the polyolefin (manufactured by Mitsui Petrochemical Industry Co., Ltd .: “J60”).
0 "MI = 7.0, without antioxidant), these were mixed and extrusion-molded using a twin-screw kneading extruder at an extrusion temperature of 190 ° C. to obtain resin pellets. Polyethylene (Mitsui Petrochemical Industry Co., Ltd.): "Mirason 14
P ”) was mixed at a mixing ratio of 25:75 (weight ratio).
0.08% by weight of itaconic acid to the total amount of resin
The mixture was extrusion-molded at an extrusion temperature of 190 ° C. to obtain a sheet having a thickness of 800 μm.

<Example 7> 200 ppm of acetylacetonate Fe was used as the oxidation catalyst, and polypropylene was used as the polyolefin (manufactured by Mitsui Petrochemical Industry Co., Ltd .: "J6").
00 "MI = 7.0, no antioxidant), these were mixed and extrusion-molded at a extrusion temperature of 190 ° C. using a twin-screw kneading extruder to obtain resin pellets. Polyethylene (Mitsui Petrochemical Industry Co., Ltd.): "Mirason 14
P ”) was mixed at a mixing ratio of 25:75 (weight ratio).
A mixture of 0.1% by weight of maleic anhydride with respect to the total amount of resin was extruded at an extrusion temperature of 190 ° C. to obtain a sheet having a thickness of 800 μm.

<Example 8> 200 ppm of acetylacetonate Fe was used as an oxidation catalyst, and polypropylene was used as a polyolefin (manufactured by Mitsui Petrochemical Industry Co., Ltd .: "J6").
00 "MI = 7.0, no antioxidant), these were mixed and extrusion-molded at a extrusion temperature of 190 ° C. using a twin-screw kneading extruder to obtain resin pellets. Polyethylene (Mitsui Petrochemical Industry Co., Ltd.): "Mirason 14
P ”) was mixed at a mixing ratio of 25:75 (weight ratio).
0.08% by weight of itaconic acid to the total amount of resin
The mixture was extrusion-molded at an extrusion temperature of 190 ° C. to obtain a sheet having a thickness of 800 μm.

<Comparative Example 2> A sheet was molded in the same manner as in Example 3 except that maleic anhydride was not included.

Comparative Example 3 A sheet was molded in the same manner as in Example 5 except that maleic anhydride was not included.

Comparative Example 4 A sheet was formed in the same manner as in Example 7 except that maleic anhydride was not included.

Comparative Example 5 A sheet was molded in the same manner as in Example 3 except that the amount of maleic anhydride added was 6.0% by weight.

Comparative Example 6 A sheet was molded in the same manner as in Example 4 except that the addition amount of itaconic acid was 6.0% by weight.

The oxygen barrier sheets of the present invention of Examples 3, 4, 5, 6, 7, and 8 and Comparative Examples 2, 3, 4, 5,
The composition of each sheet shown in Table 6 is shown in Tables 2 and 3.

[0050]

[Table 2]

[0051]

[Table 3]

The measurement results of the oxygen transmission rate with time (O ₂ -TR) of the respective sheets obtained in Examples 3, 4, 5, 6, 7, 8 and Comparative Examples 2, 3, 4, 5, 6 were shown. Table 4, Table 5
Shown in. Measurement is "Mokon Ox-TRAN10 / 50A"
(Manufactured by Modern Control) at 25 ° C.

In addition to the above-mentioned Examples 3, 4, 5, 6, 7, and 8.
Also, the presence or absence of crack generation due to bending stress was observed for each of the sheets obtained in Comparative Examples 2, 3, 4, 5, and 6.

[0054]

[Table 4]

[0055]

[Table 5]

As is clear from Tables 4 and 5, Example 3,
The oxygen barrier sheets of the present invention of Nos. 4, 5, 6, 7, and 8 and Comparative Examples 2, 3, and 4 have extremely low oxygen permeability and have extremely excellent oxygen barrier properties. There is. On the other hand, in Comparative Examples 5 and 6, since the amounts of maleic anhydride and itaconic acid added were large, respectively, the resin was not oxidized and no change in oxygen permeability with time was observed. Furthermore, in Examples 3 and 4,
In the oxygen barrier sheets of 5, 6, 7, and 8, cracks did not occur for a long period of time, and Comparative Examples 2, 3,
It is shown that the resin composition can withstand long-term use as compared with No. 4.

Example 9 In the production of the oxygen barrier sheet in Example 7, this was extruded into a film having a thickness of 40 μm. A urethane oxide adhesive is used to deposit a silicon oxide thin film layer (400 μm of a silicon oxide thin film layer on a stretched PET film of 12 μm by a plasma vapor deposition method).
Formed), the oxygen barrier film of the present invention, thickness 12μ
m PET film and 30 μm-thick unstretched PP film were sequentially laminated in this order to prepare a film by dry lamination.

Example 10 In the production of the oxygen barrier sheet in Example 8, this was extruded into a film having a thickness of 40 μm. Using urethane adhesive,
Silicon oxide vapor deposition film (400 μm of silicon oxide thin film layer by plasma vapor deposition method on stretched PET film of 12 μm)
Å), oxygen barrier film of the present invention, thickness 12
A film obtained by sequentially laminating a PET film having a thickness of 30 μm and an unstretched PP film having a thickness of 30 μm was prepared by dry lamination.

Comparative Example 7 A laminated film was prepared in the same manner as in Example 9 except that maleic anhydride was not included.

With respect to the laminated films obtained in Examples 9 and 10 and Comparative Example 7, the oxygen transmission rate with time (O ₂ -T
The measurement results of R) are shown in Table 6. Measurement is Mokon "Ox-T"
2 with RAN10 / 50A "(made by Modern Control)
Performed at 5 ° C.

In addition, Examples 9 and 10 and Comparative Example 7 described above
The presence or absence of crack generation due to bending stress was observed for each sheet obtained in step 1.

[0062]

[Table 6]

As is clear from Table 6, the oxygen barrier laminate films of Examples 9 and 10 of the present invention had a reduced oxygen transmission rate with time and no cracks were generated for a long period of time. It is shown that the oxygen barrier laminate can withstand long-term use as compared with Comparative Example 7. In comparison with the oxygen barrier sheets of Examples 7 and 8 shown in Table 4, the initial value of the oxygen barrier could be further reduced by laminating.

[0064]

As described in detail above, according to the present invention, saponified ethylene-vinyl acetate copolymer, polyvinylidene chloride, etc., which are expensive, can be used without using any other oxygen barrier resin or in a small amount. It is possible to provide a thermoplastic resin composition capable of having an excellent oxygen barrier property for a long period of time and a method for producing the same.

Further, by providing at least one layer of the resin composition to prepare a laminated film, a sheet, a bottle, a container or the like, it is possible to provide a packaging material having an oxygen barrier property which is an excellent oxygen barrier laminate.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C08K 5/092 C08K 5/092 // B65D 81/24 B65D 81/24 F (72) Inventor Keiko Nakamura 1 Taito, Taito-ku, Tokyo 1 5-5 No. 1 Toppan Printing Co., Ltd. (56) Reference JP-A-6-248122 (JP, A) JP-A-6-179779 (JP, A) JP-A-5-247276 (JP, A) (58) ) Fields surveyed (Int.Cl. ⁷ , DB name) C08L 23/00 C08K 5/09 C08K 5/092

Claims (6)

(57) [Claims] 1. An oxygen-barrier resin composition comprising a mixture of a polyolefin, an oxidation catalyst, and maleic anhydride or itaconic acid. 2. An oxygen-barrier resin composition comprising a resin composition comprising a polyolefin containing an oxidation catalyst dispersed in a resin composition comprising a polyolefin containing maleic anhydride or itaconic acid. . 3. The content of maleic anhydride or itaconic acid relative to the oxygen barrier resin composition is 0.01 to.
The oxygen barrier resin composition according to claim 1 or 2, wherein the oxygen barrier resin composition is 5.0% by weight. 4. A method for producing an oxygen-barrier resin composition, which comprises melt-mixing and processing a polyolefin, an oxidation catalyst, and maleic anhydride or itaconic acid at the same time. 5. An oxygen-barrier resin characterized by comprising melt-kneading a resin composition comprising a polyolefin and an oxidation catalyst and dispersing this in a mixture comprising a polyolefin containing maleic anhydride or itaconic acid. A method for producing a composition. 6. An oxygen barrier laminate, comprising at least one layer comprising the oxygen barrier resin composition according to claim 1, 2, or 3.