JP2776851B2 - Ethylene polymer composition - Google Patents

Description

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

(Conventional technology) Conventionally, in order to impart antibacterial or antifungal ability to a polyolefin resin, an organic bactericide having antibacterial or antifungal ability is added to polyolefin, and Japanese Patent Application Laid-Open No. 62-241939 discloses It has been common to add zeolite in which a metal having a bactericidal action as described is kept in an ionic state.

(Problems to be Solved by the Invention) Polyolefin resins having antibacterial and antifungal properties are often used in applications that come into contact with food, drinking water, food garbage and the like. Polyolefin resins used in such applications are not only excellent in antibacterial and antifungal properties, but also maintain this performance even in long-term use, and give a hygienic impression as appearance. In particular, it is particularly required that the product is not easily discolored (especially yellowish).

However, polyolefins added with compounds having antibacterial and antifungal properties such as organic germicides,
In general, the antibacterial and antifungal activities decrease with time, and often decrease rapidly when they come into contact with a fluid such as water.
In addition, there may be a case where a disinfectant adheres to food, and there is a problem in food hygiene.

Generally, these organic fungicides have a relatively low molecular weight compared to polyolefins and have low affinity with 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. In some cases, poor appearance such as sticky surfaces may occur even in opaque applications or thick molded products, or that many of these organic disinfectants are susceptible to discoloration,
Etc. is a problem.

On the other hand, those to which zeolite holding a metal having a bactericidal action in an ionic state is added, because the metal having a bactericidal action is held in an ionic state, the antibacterial and antifungal properties decrease with time, that is, a change with time. It is excellent in that it is small and has no stickiness on the product surface.
However, when zeolite in which the metal having a bactericidal action is kept in an ionic state is added to polyolefin and molded, there is a problem that the polyolefin discolors to yellow or brown, and the discoloration further progresses with the lapse of time. Such a discolored polyolefin has a low commercial value except when it is colored black. Therefore, this point has been a very serious problem that must be solved by adopting this excellent method.

[Summary of the Invention]

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present inventors have intensively studied a polyolefin composition having antibacterial and antifungal properties and excellent discoloration resistance even in long-term use. result,
The present inventors have found out that an unprecedented excellent ethylene polymer composition can be obtained by blending a specific additive with zeolite held in a state of a metal ion having a bactericidal action to the ethylene polymer, and reached the present invention.

That is, the ethylene polymer composition according to the present invention comprises, on an anhydrous basis, a zeolite holding one or more metals selected from a metal group consisting of silver, copper, zinc and tin in an ionic state. And 0.1 to 10% by weight of the above and the following additives (A) and (B) or (B).

(A) Metal soap 0.01 to 2% by weight (B) Fatty acid amide 0.01 to 0.5% by weight (Effect of the Invention) The polymer composition according to the present invention has excellent antibacterial and antifungal properties and has a long-term performance. It will be sustained. Moreover, the problem of coloring of the resin generated when zeolite is blended is also solved.

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

According to the present invention, a specific metal in the ethylene polymer, that is, silver, copper, zinc, at least one selected from the group consisting of tin, zeolite and a metal soap and a fatty acid amide, or a fatty acid amide, or a fatty acid holding an ion state Incorporation of an amide solves the problem of coloring in the prior art described above. It is understood that the use of metal soaps and fatty acid amides or fatty acid amides solves the problem of coloring, which was completely unexpected.

[Specific description of the invention]

Ethylene polymer The ethylene polymer used in the present invention is a gas phase method, a solution method,
Any production method such as a slurry method and a high pressure method can be applied. The ethylene polymer may be an ethylene homopolymer or a copolymer of ethylene with one or more other monomers. An ethylene polymer more preferable from the viewpoint of discoloration resistance is produced using a polymerization catalyst containing no chlorine. Some of such preferred ethylene polymers are as follows:

Preferred Ethylene Polymer (1) One preferred ethylene polymer is a linear ethylene homopolymer or ethylene-α-olefin copolymer obtained with a chlorine-free ionic polymerization catalyst, and does not contain chlorine. A gas phase method, a solution method, a slurry method, or a pressure of 500 kg / cm ² or more and a temperature of 100 to
A typical example is obtained by applying a production process such as a high-pressure ion polymerization method at 350 ° C. and copolymerizing ethylene or ethylene and an α-olefin.

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

As the α-olefin used for copolymerization with ethylene, α-olefins having about 3 to 12 carbon atoms, for example, propylene, butene-1, pentene-1, hexene-1,4
Methylpentene-1, octene-1 and the like.
Particularly preferred α-olefins are those having 4 to 8 carbon atoms,
In particular, 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 from 0.1 to 20% by weight, preferably from 0.5 to 15% by weight.

This ethylene polymer has an MFR (JIS
-According to the test method of K6760), 0.01 to 100 g / 10 minutes,
In particular, those having a content of 0.05 to 50 g / 10 minutes are preferable. The lower the MFR, the better the polymer is in strength, etc., but excessively low,
For example, if the MFR is less than 0.01, moldability such as fluidity during molding will be poor. On the other hand, if the MFR exceeds 100, the strength and the like tend to be inferior.

The polymer preferably has a density (based on the test method of JIS-K6760) as a measure of rigidity of 0.85 to 0.97 g / cm ³ . The density of the copolymer varies depending on the type and / or content of the copolymerized α-olefin.

The polymer preferably has an FR (flow ratio) of 3 to 50, particularly 5 to 30, as a measure of the molecular weight distribution. The lower the FR, the better the impact strength of the polymer, but if the FR is less than 3, the moldability such as fluidity during molding tends to be poor. If the FR is more than 50, the impact strength and the like tend to be inferior.

In addition, this FR changed the load to be tested by the flowability test method of JIS-K6760 to 10 kg and changed the weight flowing for 10 minutes to MFR (2.16 kg
Load). In general, the larger the value, the wider the molecular weight distribution.

Preferred Ethylene Polymer (2) Another preferred ethylene polymer is an ethylene homopolymer and a copolymer of ethylene and a polar group-containing comonomer obtained by high-pressure radical polymerization. Polymerization of ethylene and a polar group-containing comonomer under a pressure of 500 kg / cm ² or more and a temperature of 100 to 350 ° C. using a radical initiator such as a peroxide (but not containing chlorine), that is, a so-called Typical examples include those obtained by copolymerizing ethylene or ethylene with this comonomer by applying a production process of high-pressure radical polymerization.

As the polar group-containing monomer to be copolymerized with ethylene, those containing oxygen and silicon, particularly those having a carboxylic acid, ester bond or silane structure, are particularly preferred. Specifically, for example, vinyl acetate, acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, t-butyl acrylate, and vinylsilane represented by vinyltrimethoxysilane, vinyltriethoxysilane, and the like are preferable. 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 polymer has an MFR (JIS
(Based on the test method of -k6760) is preferably from 0.01 to 100 g / 10 min, particularly preferably from 0.05 to 50 g / 10 min. The lower the MFR, the better the strength and the like, but if the MFR is less than 0.01, the moldability such as fluidity during molding tends to be poor. On the other hand, if the MFR exceeds 100, the strength and the like tend to be inferior.

The polymer preferably has a density (according to JIS-K6760 test method) of 0.91 to 0.97 g / cm ³ as a measure of rigidity.
The density of the polymer increases with the amount of copolymerization due to the large specific gravity of the copolymerized polar group-containing comonomer. On the other hand, the higher the density, the more flexible and superior the impact strength.
The direction is different from that of the α-olefin copolymer.

These ethylene polymers ((1) and (2) and others)
It is preferable to use different MFR, density, and FR depending on the actual application and molding method.
For MFR / high FR products and 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 suitable for a porous synthetic or natural zeolite having a relatively small particle size and a large specific surface area with a large ion exchange amount in consideration of dispersibility in a polymer. , One or more metals selected from the group consisting of silver, 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). Is preferably brought into contact with zeolite 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 model night, high silica zeolite, etc., while natural products are preferably mordenite, clinobtyrolite, chabazite, etc., and the particle diameter is 10 μm in average particle diameter.
The following is preferred. The total amount of germicidal metal in the zeolite is
Desirably, the amount is not less than 0.01% by weight and not more than the saturation amount based on anhydrous zeolite.

The amount of the specific zeolite to be added to the ethylene polymer is 0.1 to 10% by weight on an anhydrous basis, preferably
It is 0.5 to 5% by weight, particularly preferably 1 to 3% by weight. If the amount is less than 0.1% by weight, the antibacterial and antifungal properties are inferior. On the other hand, if the amount exceeds 10% by weight, problems such as a decrease in impact strength and a tendency to discolor are apt to occur, which is not preferable. Excessive formulation also increases product costs.

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.

Metal soap The metal soap used in the present invention is a higher fatty acid salt of a metal such as zinc, calcium, magnesium, and aluminum. Considering the dispersibility in the polymer, a powder having a relatively small particle size is preferable. Further, those having 18 carbon atoms are preferable because they are versatile, inexpensive, and have a great effect on colorfastness. Specifically, for example, zinc stearate,
Calcium stearate, magnesium stearate,
Aluminum stearate and the like.

The amount of this metal soap is based on the ethylene polymer.
It is 0.01 to 2% by weight, preferably 0.02 to 1% by weight, particularly preferably 0.03 to 0.5% by weight. 0.01% by weight
If it is less than 10%, the discoloration resistance is poor. On the other hand, if the compounding amount exceeds 2% by weight, the impact strength tends to decrease, and discoloration tends to occur. Excessive blending also increases product costs.

Fatty acid amide The fatty acid amide used in the present invention is a primary to quaternary fatty acid amide and an N-substituted amide. Considering the dispersibility in the polymer, a powder having a relatively small particle size is preferable. Saturated fatty acid amides and unsaturated fatty acid amides having 18 and 22 carbon atoms are preferred because they have versatility, are inexpensive, and have a large discoloration resistance effect. Specifically, for example,
Stearic acid amide, behenic acid amide, oleic acid amide, erucic acid amide and the like.

The amount of the fatty acid amide is 0.01 to 0.5% by weight, preferably 0.02 to 0.3% by weight, particularly preferably 0.03 to 0.2% by weight, based on the ethylene polymer. If the amount is less than 0.01% by weight, the discoloration resistance is poor. On the other hand, if the amount exceeds 0.5% by weight, stickiness (bleed-out phenomenon) may occur on the surface of the product, and discoloration is likely to occur. Is not preferred because of the tendency to occur. Also,
Excessive formulation will increase the cost of the product.

Composition As a method of adding the specific zeolite, metal soap and fatty acid amide or fatty acid amide described above to the ethylene polymer and mixing the mixture, directly melt-knead with a kneading machine such as a roll, a Banbury mixer, a kneader, an extruder or the like. Method, in order to improve the dispersion of zeolite, after previously mixing with ethylene polymer powder with a Henschel mixer, etc., and then melt-kneading with the above-mentioned kneading machine, or once make a high-concentration master batch and dilute it later Various known methods such as a method can be applied.

If necessary, various additives and other miscible resins can be added to the ethylene polymer composition according to the present invention as long as the effects of the present invention are not significantly impaired. Typical of such additives and resins are, for example, resins such as polypropylene, polyester, and polystyrene, antioxidants, neutralizing agents, lubricants, antiblocking agents, antistatic agents, ultraviolet absorbers, light stabilizers. Additives such as fluorescent whitening agents, and coloring agents such as organic pigments and inorganic pigments. These can be added directly at the time of melt-kneading, or can be added as a master batch of resin or the like. These additives, coloring agents, etc. may degrade the discoloration resistance, antibacterial and antifungal performance of the product, so the type and / or the amount added need to be appropriately selected, and those which do not require addition in particular It is needless to say that it is more preferable to add no.

The most significant feature of the ethylene polymer composition of the present invention is that the antibacterial property, antifungal property and discoloration resistance of the composition are remarkably improved without depending on harmful substances. Therefore,
Utilizing its excellent characteristics, it can be applied to various applications. For example, tableware such as cups, hoods, and chopsticks, trays, films, tapes, filaments, and other packaging items, cutting boards, kitchen utensils such as garbage containers for drainers, pipes such as pipes, hoses, and tubes, and other cancer tools , Stationery, nets, drums, medical instruments and fibers such as woven and non-woven fabrics.

Particularly preferred uses include cutting boards, food packaging films, and the like.

EXPERIMENTAL EXAMPLES Example 1 (a) Preparation of molded article Ethylene and butene-1 using a so-called Phillips type ion polymerization catalyst comprising chromium oxide and titanium oxide supported on silicon dioxide in the presence of a small amount of oxygen in a gas phase process. Of ethylene-butene-1 copolymer powder having a MFR of 0.5 g / 10 min and a density of 0.922 g / cm ³ obtained by copolymerizing A type zeolite with 2.5% by weight of silver and 12% of zinc on an anhydrous basis. 1% by weight of a powder obtained by heating and drying at about 200 ° C after being kept in an ionic state so that the amount of the oleic acid amide is a commercial reagent.
0.1% by weight and mixed with a Henschel type mixer,
Pellets were obtained by melt-kneading with a single screw extruder having a screw diameter of 40 mmφ. The pellets were compression-molded with a hot press molding machine to a thickness of 2 mm 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 Table 1.

(B-1) Antibacterial property This press sheet is cut into 5 cm squares, placed horizontally in a petri dish, 1 ml of a liquid containing bacteria is dropped on the press sheet, kept at 23 ° C. for a certain period of time, and then placed on the press sheet. The bacteria were washed, and the wash was mixed with an agar medium to grow the bacteria, and the number of generated colonies was observed. There are two types of bacteria, Staphylococcus aureus and Vibrio parahaemolyticus.

The growth status of this bacterium was displayed according to the following criteria, and used as a measure of antibacterial activity.

The number of growth of bacteria is almost the same as the origin. 1st grade The number of growth of bacteria is slightly reduced. 2nd The number of growth of bacteria is greatly reduced. 3rd. The germs are almost dead. 4th grade (b-2) Discoloration resistance This press sheet is placed in a high-temperature, high-humidity chamber at a temperature of 40 ° C and a relative humidity of 90% for 20 days, and the degree of discoloration to yellow or brown is visually observed. And

Intensely discolored × slightly discolored △ slightly discolored ○ slightly discolored 実 施 Examples 2, 3 and 4 The same procedure as in Example 1 was carried out except that the additive or the amount added was changed.

Comparative example 1 It carried out like Example 1 except not adding an additive.

Comparative example 2 It carried out like Example 1 except having changed the ethylene polymer and not adding an additive.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ identification code FI C08K 5:20) (58) Investigated field (Int.Cl. ⁶ , DB name) C08L 23/04 C08K 3/34 C08K 5 / 09 C08K 5/20

Claims (1)

(57) [Claims] 1. A zeolite in which one or more metals selected from the group consisting of silver, copper, zinc and tin are held in an ionic state in an ethylene polymer on an anhydrous basis.
An ethylene polymer composition comprising 0.1 to 10% by weight and the following additives (A) and (B) or (B). (A) Metal soap 0.01 to 2% by weight (B) Fatty acid amide 0.01 to 0.5% by weight