JPH0280442A - Ethylene polymer composition - Google Patents

Abstract

PURPOSE:To obtain an ethylene polymer composition having antifungal and mildewproofing properties and excelling in discoloration resistance and chemical resistance by adding a specified zeolite to a specified ethylene polymer. CONSTITUTION:At least 0.1wt.% (dry basis) zeolite having at least one metal in an ionized form, selected from among the metal groups of silver, copper, zinc and tin, is added to an ethylene polymer free from chlorides as the residues of a polymerization catalyst (provided that an ethylene homopolymer prepared by a high-pressure radical process is excluded), for example, an ethylene/alpha-olefin copolymer obtained by using a Phillips catalyst comprising chromium oxide supported on an inorganic support such as silica. In this way, an ethylene polymer composition having antifungal and mildewproofing properties and excelling in discoloration resistance and chemical resistance can be obtained. Desirable examples of the uses of this composition include chopping boards and food packaging films.

Description

DETAILED DESCRIPTION OF THE INVENTION [Background of the Invention] (Industrial Application Field) The present invention relates to an ethylene polymer composition that has antibacterial and antifungal properties and has excellent discoloration resistance and chemical resistance.

(Prior art) Conventionally, in order to impart antibacterial and antifungal properties to polyolefin resins, there has been a method of adding an a-type bactericide that has antibacterial and antifungal properties to polyolefins, or a method described in JP-A No. 62-241.
It has been common practice to add zeolite containing a metal that has a bactericidal effect in an ionic state, as described in Japanese Patent No. 939.

(Problem to be solved by the invention) Resin products that require antibacterial and antifungal properties are generally used in situations where they come into contact with food, drinking water, food waste, etc., and the required performance is antibacterial and antifungal properties. It goes without saying that it has anti-mold properties, but also that this performance is maintained even after long-term use, that the product has a hygienic appearance and is resistant to discoloration (particularly yellowing), and that it is durable. There has been a particular need for materials to have excellent environmental stress cracking resistance (ESCR) so as not to cause chemical deterioration due to detergents, seasonings, etc.

However, polyolefins containing organic compounds with antibacterial and antifungal properties, such as organic fungicides, generally lose their antibacterial and antifungal properties over time, and often deteriorate rapidly when they come into contact with fluids such as water. Furthermore, the compound may adhere to food, which is a food hygiene problem.

In general, these organic fungicides have a lower molecular weight than polyolefins and have a lower affinity with polyolefins, so they tend to bleed out (blooming) onto the surface of products, resulting in decreased transparency in films intended for see-through purposes. Problems include that even in opaque applications or thick molded products, poor appearance such as surface stickiness may occur, and that many of these organic fungicides are susceptible to discoloration.

On the other hand, with the addition of zeolite that retains a metal that has a bactericidal effect in an ionic state, the deterioration of the antibacterial and antifungal ability over time is small because the metal that has a bactericidal effect is held in an ionic state. Zeolite is an inorganic particle, so there is no stickiness on the product surface.
It has the following features.

However, when zeolite, which holds this bactericidal metal in an ionized state, is added to polyolefin and molded, the color changes to yellow or brown, and the color change progresses over time. It loses its value. Therefore, this point has become a very big problem that must be solved if this method is excellent in itself.

In addition, since such antibacterial and antifungal polyolefins are generally used in situations where they come into contact with food, drinking water, food waste, etc., they are often used in cleaning agents such as kitchen detergents and as additives in foods. It is also necessary to have resistance to many chemicals such as seasoning agents and seasonings, that is, to have excellent durability as typified by environmental stress cracking resistance.

[Summary of the invention]

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present inventors have developed a polyolefin composition that has antibacterial and antifungal properties even in long-term use, and has excellent discoloration and chemical resistance. As a result of extensive research with the aim of obtaining the following, we discovered an unprecedented and superior ethylene polymer composition by blending zeolite, which holds a metal with bactericidal action in an ionized state, with a specific ethylene polymer, and developed the present invention. reached.

That is, the ethylene polymer composition of the present invention having antibacterial and antifungal properties, discoloration resistance, and chemical resistance is an ethylene polymer composition that does not contain chlorine as a polymerization catalyst residue (an ethylene homopolymer obtained by a high-pressure radical method). silver, excluding
It is characterized by containing 0.1% by weight or more on an anhydrous basis of zeolite which holds one or more metals selected from the metal group of copper, zinc and tin in an ionic state. be.

(Effects of the present invention) According to the present invention, a specific ethylene polymer, that is,
At least one specific metal selected from the group consisting of silver, zinc, and tin as a polymerization catalyst residue that does not contain chlorine (and other than ethylene polymer obtained by high-pressure radical polymerization). By incorporating zeolite which maintains , in an ionic state, the problem of coloration in the prior art described above can be solved. It is understood that it was completely unexpected that the problem of coloring was solved by making the target ethylene polymer free of chlorine derived from catalyst residues.

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

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.

[Detailed description of the invention]

Overview of ethylene polymer The ethylene polymer that does not contain chlorine as a polymerization catalyst residue used in the present invention can be produced using a catalyst that does not contain chlorine in the polymerization catalyst, using a gas phase method, a solution method, or a slurry method. Any production method such as a method or a high-pressure method can be used, and in addition to an ethylene homopolymer, a product obtained by copolymerizing ethylene with one or more comonomers other than ethylene may be used.

However, the ethylene polymers that are the subject of the present invention include:
Ethylene homopolymers obtained by high-pressure radical methods are excluded. This is because this polymer has poor environmental stress cracking resistance. From the viewpoint of durability such as environmental stress cracking resistance,
The following specific ethylene polymers are preferred. These ethylene polymers can be used in combination within and between groups.

(1) An ethylene/α-olefin co-ffi polymer having an α-olefin content of 0.5 to 20% by weight, obtained using an ionic polymerization catalyst that does not contain chlorine.

(2) A copolymer of ethylene and a comonomer having 0.5 to 40% by weight of polar groups, obtained by high-pressure radical polymerization.

Preferred ethylene polymer (1) Linear ethylene α obtained using a chlorine-free ionic polymerization catalyst, which is the ethylene polymer of (1) above.
- Olefin copolymers can be produced using a chlorine-free catalyst using a gas phase method, solution method, slurry method, or under a pressure of 500
A typical example is one obtained by copolymerizing ethylene and α-olefin by applying a manufacturing process such as a high-pressure ionic polymerization method under conditions of kg/cd or higher and a temperature of 100 to 350°C.

In this case, the type of ionic polymerization catalyst is not particularly limited as long as it is an ionic polymerization catalyst that does not contain chlorine and has sufficient polymerization activity, but from the viewpoint of polymerization activity, chromium oxide is mainly used with silica, silica alumina, etc. Particularly preferred are catalysts supported on inorganic carriers, ie, Phillips-type catalysts.

The α-olefin to be copolymerized with ethylene includes α-olefins having about 3 to 12 carbon atoms, such as propylene,
Examples include butene-1, pentene-1, hexene-L4-methylpentene-1, octene-1, and the like. Particularly preferred 1-olefins are those having 4 to 8 carbon atoms, especially butene-olefins.
1, hexene-1,4-methylpentene-1 and octene-1. Two or more types of 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 (according to JIS-6760 test method), which is a guideline for molecular weight, of 0.01 to 1007/lO, especially 0.0
5 to 50 g/10 minutes is preferred. The lower the MFR, the better the polymer will be in environmental stress cracking resistance, strength, etc. However, if the MFR is too low (for example, less than 0.01, the moldability such as fluidity during molding will deteriorate. 1
If it exceeds 00, environmental stress cracking resistance, strength, etc. tend to be poor.

This copolymer has a density (according to J Is-6760 test method) of 0.85 to 0.97 gZc, which is a measure of rigidity.
m is preferred. 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 guideline for molecular weight distribution.
-50, preferably 5-30 are preferred. The lower the FR, the better the polymer will be in impact strength, but if the FR is less than 3, the moldability such as fluidity during molding will deteriorate. Furthermore, if the FR exceeds 50, impact strength etc. tend to be poor.

In addition, this FR refers to flow ratio, and is based on JIS
- The load to be tested using the flowability test method of 6760 is 10 kg.
The weight that flows in 10 minutes is MFR (2,16 kg).
It is the value divided by the load). Generally, the larger this number is, the broader the molecular weight distribution will be.

Preferred ethylene polymer (2) The ethylene polymer of (2) above, a copolymer of ethylene and a polar foundation H comonomer obtained by high-pressure radical polymerization, is a copolymer of ethylene and a polar foundation H comonomer. Polymerization of ethylene and a polar foundation a comonomer using a radical initiator such as chlorine-free) at a pressure of 500 kg/c or more and a temperature of 100 to 350°C, that is, the so-called high-pressure radical polymerization, A typical example is one obtained by copolymerizing ethylene and this comonomer by applying the manufacturing process of

The polar base white comonomer to be copolymerized with ethylene is particularly preferably one containing oxygen, sulfur, nitrogen or silicon as a polar group, particularly one having a carboxylic acid, ester bond or silane structure. Specifically, for example, (a) vinyl esters such as vinyl acetate and vinyl propionate, (b) ethylenically unsaturated carboxylic acids such as acrylic acid and methacrylic acid, and (c) methyl acrylate, ethyl acrylate, n-butyl acrylate, t-
Representative examples include alkyl (meth)acrylates (about 01 to 06) such as butyl acrylate and methyl methacrylate, and vinyltrialkoxy (about 01 to 06) silanes such as (d)vinyltrimethoxysilane and vinyltriethoxysilane. Vinylsilane is preferred. Two or more types of the polar group-containing co-11fa bodies can be used in combination. The content of polar base monodecamer in the copolymer is 0.
．． It is 5 to 40% by weight, preferably 1 to 30% by weight.

This ethylene/polar group af comonomer copolymer has an MFR (according to JIS-6760 test method), which is a guideline for molecular weight, of 0.01 to 100 g/10 min, especially 0.00 g/10 min.
05 to 50 g/10 minutes is preferred. The lower the MFR is, the better the polymer will be in environmental stress cracking resistance, strength, etc., but if the VFR is less than 0.01, moldability such as fluidity during molding will be poor. Furthermore, if the MFR exceeds 100, the environmental stress cracking resistance, strength, etc. tend to be poor.

This copolymer has a density (according to J Is-6760 test method) of 0.91 to 0.97 g/c, which is a measure of rigidity.
rA is preferred. The density of the copolymer increases with the amount of copolymerization due to the heavy weight of the copolymerized polar group-containing comonomer, but higher density is more flexible and has better environmental stress cracking resistance. This direction is different from that of olefin copolymers.

These ethylene polymers ((1) and (2) others)
It is preferable to use the MFR, density, and FR of the product depending on the actual usage and molding method. For example, for extrusion molding applications, low VFR/high FR products are used, and for injection molding applications, high MFR/FR products are used.
Conventional general usage such as low FR products can also be used as appropriate. Further, the density can be selected depending on the required performance such as flexibility and rigidity of the product.

Antibacterial and antifungal agent The antibacterial and antifungal agent used in the present invention is a porous synthetic or natural zeolite with a relatively small particle size, a large amount of ion exchange, and a large specific surface area, in consideration of its dispersibility in the polymer. , one or more metals selected from the group of metals copper, zinc, and tin are held in an ionic state (for example, by combining an aqueous solution of water-soluble salts of these metals with H-type or alkali metal-type zeolite). It is preferable to carry out ion-exchange by contacting the oxidants with ion-exchange), heat activation, and then dry-flame.

Here, as a porous material with a large amount of ion exchange,
Preferable synthetic products include A-type, 10μm
The following are preferred. The total amount of bactericidal metals in the zeolite is desirably 0.01% by weight or more and less than the saturated amount, based on the anhydrous zeolite.

In addition, the amount of this specific zeolite blended into the chlorine-free, H-free ethylene polymer derived from the polymerization catalyst residue is as follows:
0.1% by weight or more, preferably 0.5 to 10% by weight of zeolite based on the weight of the ethylene polymer on an anhydrous basis
, particularly preferably 1 to 5% by weight. The blending amount is 0.
If the amount is less than 1% by weight, the antibacterial and antifungal properties will be poor, while if the amount is too large, the cost of the product will increase, which is not preferable. The content of the bactericidal metal such as silver is preferably 0.01% by weight or more based on the weight of the ethylene polymer.

Composition Methods for adding this specific zeolite to a specific ethylene polymer include directly melt-kneading it in a mixer such as a roll, Banbury, or kneader 1 extruder, or using a Henschel-type zeolite to improve the dispersion of the zeolite. There are various known methods, such as mixing the powder with a specific ethylene polymer in a mixer etc. and then melting and kneading it in the above-mentioned kneader, or making a highly concentrated masterbatch and diluting it later. method can be applied.

In addition, if necessary, small amounts of other miscible resins such as polyester, polystyrene, etc., or antioxidants, neutralizing agents, lubricants, anti-blocking agents, antistatic agents, etc., may be added within a range that does not significantly impair the effects of the present invention. Additives such as ultraviolet absorbers, light stabilizers, fluorescent whitening agents, or organic pigments,
It is also possible to add coloring agents such as inorganic pigments directly or as a masterbatch such as resin. However, these additives, colorants, etc. may reduce the color fastness, antibacterial, and antifungal performance of the product, so please note that the type and/or
Care must be taken with the amount added.

In addition, it is preferable not to add anything that does not particularly require addition.

The ethylene polymer composition of the present invention can be used for tableware such as cups, sara, chopsticks, trays, films, tapes, etc.
Packaging such as filament, kitchen utensils such as cutting boards, drainers, etc., pipes such as pipes, ports, tubes, other shellfish, stationery, nets, drums, etc.
It can be used in a wide range of applications such as medical instruments and fibers such as woven and non-woven fabrics. Particularly preferred uses are cutting boards,
Examples include food packaging films.

Experimental Examples Example 1 (a) Creation of molded products In a gas phase process, ethylene was polymerized using a so-called Phillips type ionic polymerization catalyst in which chromium oxide and titanium oxide were supported on silicon dioxide in the presence of a trace amount of oxygen. Obtained MFRo, 3 g/10 min and density 0.96 g/cI
i! 97% by weight of polyethylene powder, 2.5% by weight of silver and 12% by weight of zinc on an anhydrous basis in type A zeolite.
3% by weight of the powder obtained by heating and drying at about 20°C after maintaining it in an ionic state so that A pellet was obtained. This pellet was compression molded using a hot press molding machine to a thickness of 211 mm to obtain a sheet molded product.

(b) Performance evaluation of molded products The molded products obtained in (a) above were tested for performance J-r value as follows. The results obtained are shown in Table 1 and ! t5
It was as shown in Table 2.

(Row 1) Mildew resistance In accordance with the test method of ASTM-021, Aspergillus nlger was added to the medium soaked with this press sheet.
The mold was inoculated and cultured for about 40 days at a relative humidity of 90%, and the growth status of the fungus was expressed according to the following criteria and used as a measure of antifungal properties.

Those that grow vigorously = × × Those that grow to some extent: × Those that grow only a little 20 Those that show no growth: ◎ (Row 2) Color fastness 909
The sample was placed in a constant temperature and humidity chamber (No. 6), and the degree of discoloration from yellow to brown was visually observed, and the color fastness was determined using the following criteria.

Severely discolored: X Slightly discolored: O: Almost no discoloration After making a notch to a depth of 0.35++i with a shaving blade, use a surfactant (trade name: Liponox NCI).
) The specimen was bent into a 50° C. aqueous solution containing 75% by weight and 25% by weight of pure water, and the time taken until 50% of the specimen broke was observed.

Example 2.3 Example 2 was carried out in the same manner as Example 1 except that the ethylene homopolymer in Example 1 was changed to a copolymer of ethylene and butene-1.

Example 3 is the same as Example 1 except that the ethylene homopolymer of Example 1 was changed to a copolymer of ethylene and hexene-1.
It was done in the same way.

Example 4.5 Examples 4 and 5 involve converting the ethylene homopolymer of Example 1 into copolymers of ethylene with vinyl acetate and with acrylic acid using an organic peroxide in a high-pressure radical polymerization process. The procedure was the same as in Example 1 except for the above.

Example 6.7 and Comparative Example 1.2 Example 6.7 and Comparative Example 1.2 are the same as the examples except that the addition port of the zeolite, which holds a metal with antibacterial and antifungal properties in an ionic state, was changed. This was done in the same way as 2.

Comparative Example 3 Comparative Example 3 was carried out in the same manner as 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. be.

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

Claims (1)

[Claims] Ethylene polymers that do not contain chlorine as a polymerization catalyst residue (excluding ethylene homopolymers produced by high-pressure radical method)
It is characterized by containing 0.1% by weight or more of zeolite, which holds one or more metals selected from the metal group of silver, copper, zinc, and tin in an ionic state, on an anhydrous basis. , an ethylene polymer composition with antibacterial and antifungal properties, color fastness, and chemical resistance.