JP2649263B2 - Ethylene polymer composition - Google Patents

Description

Description: BACKGROUND OF THE INVENTION (Industrial Application Field) The present invention relates to an ethylene polymer composition having antibacterial and antifungal properties, and excellent in discoloration resistance and chemical resistance.

(Prior art) Conventionally, in order to impart antibacterial / antifungal ability to a polyolefin resin, a method of adding an organic bactericide having antibacterial / antifungal ability to a polyolefin, or Japanese Unexamined Patent Publication No. Sho 62-241939
It has been common to add a zeolite in which a metal having a bactericidal action is kept in an ionic state, as described in Japanese Patent Application Laid-Open No. H10-209,086.

(Problems to be Solved by the Invention) Resin products that require antibacterial and antifungal properties are generally used in contact with food, drinking water, food garbage, etc., and the required performance is antibacterial. In addition to having antifungal properties, this property is maintained even during long-term use, the product is less likely to be discolored (especially yellowish) to give a hygienic appearance, and that it has durability. There has been a particular need for materials to have excellent environmental stress cracking resistance (ESCR) because they do not undergo chemical degradation due to detergents, seasonings, etc.

However, those obtained by adding an organic compound having an antibacterial and antifungal ability such as an organic bactericide to a polyolefin generally decrease in antibacterial and antifungal ability with time, and often decrease rapidly when they come into contact with a fluid such as water. In addition, the compound may adhere to food, which is a problem in food hygiene.

In general, these organic fungicides have a low molecular weight compared to polyolefins and have a low affinity for polyolefins, so they tend to bleed out (blooming) on the surface of the product, and the transparency of films intended for see-through is reduced.
Problems such as poor appearance such as stickiness of the surface may occur even in opaque uses or thick molded products, or that many of these organic disinfectants are liable to discolor.

On the other hand, in the case where zeolite in which a metal having a bactericidal action is added in an ionic state is added, since the metal having a bactericidal action is held in an ionic state, the antibacterial and antifungal ability has a small temporal change, that is, a small change with time, and Since zeolite is an inorganic particle, it has features such as no stickiness on the product surface.

However, when the zeolite holding the metal having a bactericidal action in an ionic state is added to polyolefin and molded, the color changes to yellow or brown, and the color changes further with the lapse of time. Worth it. Therefore, this point has become a very large problem that must be solved by this excellent method.

In general, such antibacterial and antifungal polyolefins are often used in contact with food, drinking water, food garbage, and the like, and therefore, detergents such as kitchen detergents,
It is also necessary to have resistance to various chemicals such as additives in foods or seasonings, that is, to have excellent durability represented by resistance to environmental stress cracking.

[Summary of the Invention]

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present inventors have a polyolefin composition having antibacterial and antifungal properties even in long-term use, and excellent in discoloration resistance and chemical resistance. As a result of intensive studies for the purpose of obtaining, by blending zeolite held in a metal ion state having a bactericidal action to a specific ethylene-based polymer, an excellent ethylene-based polymer composition that has never been found before was found in the present invention. Reached.

That is, the ethylene polymer composition having antibacterial / antifungal ability, discoloration resistance and chemical resistance according to the present invention is an ethylene polymer containing no chlorine as a polymerization catalyst residue (an ethylene homopolymer obtained by a high pressure radical method). Excluding zeolites containing at least one metal selected from the group consisting of silver, copper, zinc and tin in an ionic state, in an amount of 0.1% by weight or more on an anhydrous basis. It is assumed that.

(Effects of the Present Invention) According to the present invention, specific ethylene-based polymers, that is, those containing no chlorine as a polymerization catalyst residue (and those other than ethylene polymers obtained by a high-pressure radical polymerization method) are used. When the zeolite holding at least one kind of metal, that is, at least one selected from the group consisting of silver, zinc and tin in an ionic state is blended, the above-mentioned problem of coloring in the prior art is solved. It is understood that the problem of coloring was solved by making the target ethylene polymer free of chlorine derived from the catalyst residue, which was completely unexpected.

Further, the ethylene polymer composition according to the present invention has excellent durability, for example, resistance to environmental stress cracking.

Therefore, the ethylene-based polymer composition according to the present invention can be utilized as a highly practical material in fields where antibacterial and antifungal properties are required.

[Specific description of the invention]

Ethylene-based polymer Outline Ethylene-based polymer containing no chlorine as a catalyst residue for polymerization used in the present invention is a gas phase method, a solution method, if produced by a catalyst containing no chlorine in the polymerization catalyst, Any method such as slurry method and high pressure method can be applied,
In addition to the ethylene homopolymer, one obtained by copolymerizing one or more of ethylene and a co-monomer other than ethylene may be used. However, ethylene homopolymers obtained by the high-pressure radical method are excluded from the ethylene-based polymers that are the object of the present invention. This is because this polymer has poor environmental stress cracking resistance. From the viewpoint of durability such as resistance to environmental stress cracking, the following specific ethylene polymers are preferred. These ethylene-based polymers can be used together within a group and between groups.

(1) Ethylene. Having an α-olefin content of 0.5 to 20% by weight obtained by an ion polymerization catalyst containing no chlorine.
α-Orifine copolymer.

(2) A copolymer of ethylene and a co-monomer having a polar group in an amount of 0.5 to 40% by weight obtained by high-pressure radical polymerization.

Preferred Ethylene Polymers (1) The linear ethylene ethylene polymer obtained by the chlorine-free ionic polymerization catalyst, which is the ethylene polymer of the above (1).
α-olefin copolymer, using a catalyst containing no chlorine, gas phase method, solution method, slurry method, or pressure 500k
g / cm ² or more and a temperature of 100 to 350 ° C., and applying a manufacturing process such as a high pressure ionic polymerization method, ethylene and α-
Those obtained by copolymerizing olefins are typical.

The type of the ionic polymerization catalyst in this case is not particularly limited as long as it is an ionic polymerization catalyst containing no chlorine and has a sufficient polymerization activity, but from the viewpoint of the polymerization activity, chromium oxide is mainly used as silica, silica alumina, or the like. Those supported on an inorganic carrier, that is, Phillips type catalysts, are particularly preferred.

Examples of the α-olefin to be copolymerized with ethylene include α-olefins having about 3 to 12 carbon atoms such as propylene,
Butene-1, pentene-1, hexene-1, 4-methylpentene-1, octene-1 and the like. Particularly preferred 1-olefins are those having 4 to 8 carbon atoms, especially butene-1, hexene-1, 4-methylpentene-1 and octene-1. Two or more α-olefins can be used in combination. The α-olefin content in the copolymer is 0.5 to 20% by weight, preferably 1 to 15% by weight.

This ethylene / α-olefin copolymer has an MFR (based on a test method of JIS-K6760) of 0.01 to 1 as a standard of molecular weight.
Those having a rate of 00 g / 10 minutes, particularly those having a content of 0.05 to 50 g / 10 minutes, are preferred. Although the polymer has low MFR, its polymer is resistant to environmental stress cracking,
Although excellent in strength and the like, if it is excessively low, for example, if the MFR is less than 0.01, the moldability such as fluidity during molding deteriorates. Also, MF
If R exceeds 100, the environmental stress crack resistance, strength, and the like tend to be inferior.

This copolymer has a density (JIS-K6760) which is a measure of rigidity.
Of 0.85 to 0.97 g / cm ² is preferable. The density of the copolymer varies depending on the type and / or content of the copolymerized α-olefin.

This copolymer also has an FR of 3 which is a measure of the molecular weight distribution.
Preferred are those of ~ 50, preferably 5-30. FR
The lower the value, the better the impact strength and the like of the polymer, but if the FR is less than 3, the moldability such as fluidity at the time of molding is deteriorated. If the FR is more than 50, the impact strength and the like tend to be inferior.

Note that this FR is the flow ratio, which is JIS-K
It is the value obtained by changing the load to be tested in the flowability test method of 6760 to 10 kg and dividing the weight flowing for 10 minutes by the MFR (2.16 kg load). In general, the larger the value, the wider the molecular weight distribution.

Preferred Ethylene Polymer (2) The copolymer of ethylene obtained by high-pressure radical polymerization, which is the ethylene polymer of the above (2), and a polar group-containing comonomer is oxygen or an organic peroxide. Ethylene and a polar group-containing comonomer at a pressure of 500 kg / cm ² or more and a temperature of 1 using a radical initiator such as chlorine-free one.
Typical examples are those obtained by copolymerizing ethylene and this comonomer by applying a polymerization process under conditions of 00 to 350 ° C., that is, a so-called high-pressure radical polymerization process.

As the polar group-containing comonomer to be copolymerized with ethylene, those containing oxygen, sulfur, nitrogen or silicon as the polar group, particularly those having a carboxylic acid, ester bond or silane structure are particularly preferable. In particular,
For example, (a) vinyl esters such as vinyl acetate and vinyl propionate, (b) ethylenically unsaturated carboxylic acids such as acrylic acid and methacrylic acid, (c) methyl acrylate, ethyl acrylate, n-butyl acrylate, and t
- butyl acrylate, and methyl methacrylate (meth) acrylic acid alkyl (about C ₁ -C ₆₎ ester, and (d) vinyltrimethoxysilane, vinyl trialkoxy and vinyl triethoxysilane (about C ₁ -C ₆₎ Vinylsilane represented by silane is preferred. Two or more polar group-containing comonomers can be used in combination. The content of the polar group-containing comonomer in the copolymer is 0.5 to 40% by weight, preferably 1 to 30% by weight.

This ethylene / polar group-containing comonomer copolymer has an MFR (based on the test method of JIS-K6760), which is a standard of molecular weight, of 0.01.
100100 g / 10 min, especially 0.05 to 50 g / 10 min. The lower the MFR, the better the polymer is in environmental stress crack resistance, strength, etc., but if the MFR is less than 0.01, the moldability such as fluidity during molding will be poor. If the MFR exceeds 100,
There is a tendency that environmental stress cracking resistance, strength and the like are inferior.

This copolymer has a density (JIS-K6760) which is a measure of rigidity.
Of 0.91 to 0.97 g / cm ³ is preferable. The density of the copolymer increases with the amount of copolymerization due to the heavy weight of the copolymerized polar group-containing comonomer, but the higher the density, the more flexible and excellent the environmental stress cracking resistance, the higher the ethylene-α- The direction is different from that of the olefin copolymer.

The MFR, density, and FR of these ethylene polymers ((1) and (2) and others) are preferably selected depending on the actual application and molding method. For example, for extrusion molding, low MFR / high FR products, For injection molding applications, conventional general usage such as high MFR / low FR products can be appropriately used. Further, the density can be properly selected according to the required performance such as flexibility and rigidity of the product.

Antibacterial / antifungal agent The antibacterial / antifungal agent used in the present invention is a porous synthetic or natural zeolite having a relatively small particle size, a large ion exchange amount and a large specific surface area in consideration of dispersibility in a polymer. , One or more metals selected from the group consisting of copper, zinc, and tin in an ionic state (for example, an aqueous solution of a water-soluble salt of these metals and an H-type or alkali-metal-type zeolite). Is contacted to perform ion exchange), heat-activated, and then dried.

Here, as a porous material having a large ion exchange amount, an A-type, X-type, or Y-type zeolite as a synthetic product,
Synthetic mordenite, high silica zeolite and the like are preferable, while natural products are mordenite, clinoptilolite, chabazite and the like, and the average particle diameter is preferably 10 μm or less. The total amount of the germicidal metal in the zeolite is desirably not less than 0.01% by weight and not more than the saturation amount based on the anhydrous zeolite.

The amount of the specific zeolite to be added to the chlorine-free ethylene polymer derived from the polymerization catalyst residue is 0.1% by weight or more, preferably 0.5 to 0.5% by weight of the zeolite on an anhydrous basis with respect to the weight of the ethylene polymer. It is 10% by weight, particularly preferably 1 to 5% by weight. When the amount is less than 0.1% by weight, the antibacterial and antifungal properties are inferior. On the other hand, when the amount is too large, the cost of the product increases, which is not preferable. The content of a bactericidal metal such as silver is preferably 0.01% by weight or more based on the weight of the ethylene polymer.

Composition As a method of adding this specific zeolite to a specific ethylene polymer, a method of directly melt-kneading with a kneading machine such as a roll, a Banbury, a kneader, an extruder, or a Henschel type to improve the dispersion of the zeolite. Various known methods, such as a method of previously mixing with a specific ethylene-based polymer powder with a mixer or the like and then melt-kneading with the above-described kneader, or a method of once preparing a high-concentration master batch and diluting it later Can be applied.

Further, if necessary, a small amount of other miscible resins such as polyesters within a range not significantly impairing the effects of the present invention,
Polystyrene, etc., or antioxidants, neutralizers, lubricants,
Additives such as anti-blocking agents, antistatic agents, ultraviolet absorbers, light stabilizers, fluorescent brighteners, or coloring agents such as organic pigments and inorganic pigments, directly or as a masterbatch such as resin You can also. However, these additives, coloring agents, etc. may reduce the discoloration resistance, antibacterial and antifungal properties of the product, so care must be taken in the type and / or amount of the additives. It should be noted that those which do not require addition are preferably not added.

The present invention is applicable to the use of the ethylene-based polymer composition in cups, tableware such as Sarah, chopsticks, trays, films, tapes, packaging such as filaments, cutting boards, kitchen utensils such as garbage trays for draining, and pipes. It can be used for a wide range of applications, such as pipes such as hoses and tubes, other cancer tools, stationery, nets, drums, medical instruments, and fibers such as woven and non-woven fabrics. Particularly preferred applications include cutting boards, food packaging films, and the like.

Experimental Examples Example 1 (a) Preparation of molded article In a gas phase process, ethylene was polymerized using a so-called Phillips type ion polymerization catalyst in which chromium oxide and titanium oxide were supported on silicon dioxide in the presence of a trace amount of oxygen. 97% by weight of a polyethylene powder having an MFR of 0.3 g / 10 min and a density of 0.96 g / cm ³ , and 2.5 g of silver on a zeolite A on an anhydrous basis.
3% by weight of powder obtained by holding in an ionic state so that the weight% and zinc become 12% by weight and then heating and drying at about 200 ° C.
Were mixed with a Henschel mixer and melt-kneaded with a single screw extruder having a screw diameter of 40 mmφ to obtain pellets. The thickness of this pellet is 2mm with a hot press molding machine.
To obtain a sheet molded product.

(B) Performance evaluation of molded article The performance evaluation of the molded article obtained in the above (a) was performed as follows. The results obtained were as shown in Tables 1 and 2.

(B-1) Antifungal property In accordance with the test method of ASTM-G21, a fungus such as Aspergillus niger was inoculated into a medium immersed in the press sheet and cultured at 90% relative humidity for about 40 days. Was displayed according to the following criteria, and was used as a measure of fungicide resistance.

Those that grow violently: XX Those that grow to some extent: X Those that grow a little: ○ Those that did not show growth: ◎ (b-2) Discoloration resistance This press sheet was subjected to a temperature of 40 ° C. and a relative humidity of 90%. Was placed in a constant temperature / humidity bath, and the degree of discoloration from yellow to brown was visually observed.

Intensely discolored: × Slightly discolored: ○ Hardly discolored: ◎ (b-3) Environmental stress cracking resistance This press sheet is 0.35 mm with a hair sledge blade in accordance with the JIS-K6760 test method. After notching to a depth of 75% by weight of surfactant (Liponox NCI)-25% pure water
Fold into a 50% aqueous solution of 50% by weight
The time until the% cracked was observed.

Examples 2 and 3 Example 2 is similar to Example 1 except that the ethylene homopolymer of Example 1 was changed to a copolymer of ethylene and butene-1.
Was performed in the same manner as

Example 3 was carried out in the same manner as in Example 1 except that the ethylene homopolymer of Example 1 was changed to a copolymer of ethylene and hexene-1.

Examples 4 and 5 In Examples 4 and 5, the ethylene homopolymer of Example 1 was converted to a copolymer of ethylene and vinyl acetate and acrylic acid using an organic peroxide in a high-pressure radical polymerization process. Except for this, the procedure was the same as in Example 1.

Examples 6 and 7 and Comparative Examples 1 and 2 Examples 6 and 7 and Comparative Examples 1 and 2 were the same as the Examples except that the amount of zeolite holding a metal having antibacterial and antifungal properties in an ionic state was changed. 2 was performed in the same manner.

Comparative Example 3 Comparative Example 3 was performed in the same manner as in Example 1 except that the ethylene homopolymer of Example 1 was changed to an ethylene homopolymer using an organic peroxide in a high-pressure radical polymerization process. is there.

Comparative Example 4 In Comparative Example 4, triethylene as a cocatalyst was prepared by using the ethylene homopolymer of Example 1 in a gas-phase process in the presence of titanium trichloride, magnesium chloride and tetrahydrofuran on silicon dioxide in the presence of hydrogen in the presence of hydrogen. This was carried out in the same manner as in Example 1 except that a copolymer of ethylene and butene-1 obtained using a so-called Ziegler-type ion polymerization catalyst using aluminum was used.

Comparative Example 5 The ethylene homopolymer of Example 1 was replaced with a high-density polyethylene (HDPE) trade name of Showa Denko KK
The procedure was performed in the same manner as in Example 1 except that F5012M was used.

 Table 2 shows the results.

The high-density polyethylene (HDPE) trade name “Showex F5012M” manufactured by Showa Denko KK was analyzed by fluorescent X-ray. As a result, chromium oxide was not detected and chlorine was 36%.
Ppm by weight.

Claims (1)

(57) [Claims] Claims: 1. A chlorine-free ethylene polymer (excluding an ethylene homopolymer obtained by a high-pressure radical method) as a catalyst residue for polymerization, and one or more metals selected from the group consisting of silver, copper, zinc and tin An ethylene polymer composition having antibacterial and antifungal properties, discoloration resistance, and chemical resistance, characterized by comprising 0.1% by weight or more of zeolite holding the metal in an ionic state on an anhydrous basis. .