JP4601281B2 - Rust-proof polymer composition and process for producing the same - Google Patents

Description

  The present invention relates to a rust-proof polymer composition suitable as a packaging material for metal products and a method for producing the same. More specifically, the present invention relates to a rust preventive polymer composition that is less susceptible to powder blowing and has good rust prevention performance, and a method for producing the same.

  Conventionally, rust-proof paper coated or impregnated with a rust-preventing agent has been used as a packaging material for metal products, but it is opaque, highly moisture-permeable, and cannot be heat-sealed. Alternatives to polyethylene film with additives are in progress. However, the rust preventive film made of polyethylene also has a problem that the rust preventive agent is deposited on the film surface with time and is in a state where powder is blown. For this reason, there is a restriction in use as a packaging film such as a steel plate for electronic parts and a steel plate for beverage cans.

  In order to suppress the bleed-out speed of the vaporizable rust preventive agent in the polyethylene rust-proof film, it is already known that it is effective to blend a polar resin (see Patent Document 1). According to this patent document, some copolymers of ethylene and unsaturated monomers have been introduced as preferred examples of polar resins, but there is no description of the polymerization composition, specifically ethylene / acrylic. Only examples using two commercially available brands of ethyl acid copolymers are shown. According to the study by the present inventors, when such a copolymer is blended with a polyethylene anticorrosive film, it is difficult to sufficiently suppress the powder blowing phenomenon when the blending amount is small, while the blending amount is reduced. It has been found that there is a problem in that the properties of polyethylene film are impaired when it is increased.

  As an alternative to such a polyethylene rust-proof film, a film in which a vaporizable rust preventive agent is blended with an ionomer having an alkali metal or alkaline earth metal as an ion source has been proposed (Patent Document 2). Although this prescription has an excellent inhibitory effect on powder blowing as described above, there is a problem that rust prevention performance is hardly exhibited.

Japanese Patent Publication No. 47-4295 Japanese Patent Publication No. 64-8019

  Therefore, an object of the present invention is to prevent or suppress the powder blowing problem without impairing the advantages of excellent rust prevention, transparency, heat sealability, etc. when used as a film in a rust prevention polyolefin. An object of the present invention is to provide a rust-proof polymer composition that can be used and a production method thereof.

That is, according to the present invention, an ethylene / unsaturated carboxylic acid copolymer having an unsaturated carboxylic acid content of 5 to 30% by weight with respect to 100 parts by weight of the polyolefin-based polymer (A) not containing an acid group and / or Alternatively, the zinc ionomer (B) and the vaporizable rust preventive agent (C) are blended at a ratio of 0.1 to 10 parts by weight , and the amount ratio of the components (A), (B) and (C) is ( A rust-proof polymer composition in the range of A) / (B) / (C) = 100/2 / 0.2 to 88 / 10.5 / 1.5 (weight ratio) is provided.

  In order to develop the performance of such a rust-proof polymer composition to a high degree, a vaporizable rust preventive master batch is prepared in advance from component (B) and component (C). After mixing (A) in a solid state, it is preferable to prepare by melt-kneading, and in particular, a vaporizable rust preventive master batch is prepared in advance from a part of component (B) and component (C), Most preferably, this is mixed with the remainder of component (B) and component (A) in a solid state and then melt-kneaded.

  According to the present invention, it is possible to obtain a composition having excellent properties of a polyolefin polymer, excellent in rust prevention, and having no powder blowing phenomenon. Such a rust preventive composition is particularly useful as a packaging material for metal products, and can be used as a packaging film for steel plates for electronic parts and beverage cans that have strict quality requirements. Moreover, it is suitable not only for films but also for injection molded products such as rust-proof containers and metal surface protection parts.

  The polyolefin polymer (A) having no acid group used in the present invention is an α-olefin homopolymer, a copolymer of α-olefins, a large proportion of one or more α-olefins, and It is a copolymer with one or two or more polar monomers that do not contain a small proportion of acid groups, and is preferably a highly crystalline polymer.

  Examples of the above α-olefin homopolymer and α-olefin copolymer include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-decene, A polymer such as dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, or a copolymer of two or more of these. More specifically, medium / high density polyethylene, high pressure process low density polyethylene, linear low density polyethylene, linear ultra-low density polyethylene and other ethylene polymers, polypropylene, poly-1-butene, poly-4-methyl- Examples include 1-pentene.

When the ethylene polymer is a copolymer of ethylene and another α-olefin, the copolymer component is preferably an α-olefin having 3 to 20 carbon atoms, particularly 4 to 10 carbon atoms. In addition, in a linear low density polyethylene having a density of 900 to 935 kg / m ³ and a linear ultra low density polyethylene having a density of less than that, a catalyst system comprising a highly active titanium catalyst component and an organoaluminum compound catalyst component, a vanadium compound catalyst Those produced using various catalyst systems such as a catalyst system comprising a component and an organoaluminum compound catalyst component, and a catalyst system comprising a metallocene catalyst component and an aluminoxane can be used. In the case of ethylene-based polymers, those having a melt flow rate of 0.01 to 100 g / 10 min, particularly about 0.1 to 50 g / 10 min at 190 ° C. and a load of 2160 g are taken into consideration in consideration of moldability and product strength. It is preferred to use.

  Examples of the polypropylene that can be used as the polyolefin polymer include a propylene homopolymer, a random copolymer of propylene and another α-olefin, and a block copolymer of propylene and another α-olefin. In the propylene copolymer, it is preferable to use ethylene alone or a combination of ethylene and an α-olefin having about 4 to 8 carbon atoms as another α-olefin to be copolymerized with propylene. Such polypropylene can be produced in the presence of a stereospecific catalyst. In view of molding processability, product strength, etc., polypropylene having a melt flow rate of 0.01 to 100 g / 10 min, particularly about 0.1 to 50 g / 10 min at 230 ° C. and 2160 g load is used. Is preferred.

  Co-use of a large proportion of one or more α-olefins that can be used as the polyolefin polymer (A) having no acid groups and one or more polar monomers that do not contain a small proportion of acid groups. In the polymer, the α-olefin is particularly preferably ethylene. Also, polar monomers include vinyl esters such as vinyl acetate and vinyl propionate, methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, n-butyl acrylate, isooctyl acrylate, and 2-ethylhexyl acrylate. And methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, n-butyl methacrylate, dimethyl maleate, diethyl maleate, carbon monoxide, and the like. The polar monomer content in these copolymers is arbitrary, but if the content is too large, the rust-preventing effect is difficult to be exhibited, so in the copolymer, preferably 20% by weight or less, more preferably 10% by weight or less, Preferably, 5% by weight or less is used. These ethylene copolymers have a melt flow rate of 0.01 to 100 g / 10 min, particularly about 0.1 to 50 g / 10 min at 190 ° C. under a load of 2160 g in consideration of moldability, product strength, etc. Is preferably used. Such an ethylene copolymer can be produced by radical copolymerization under high temperature and high pressure.

  Of these polyolefin-based polymers (A) having no acid group, low-density polyethylene and ethylene / vinyl acetate copolymer are most preferred. ,

  In the present invention, when the vaporizable rust preventive agent (C) is blended with the polyolefin-based polymer (A) not containing an acid group, the unsaturated carboxylic acid content is 5 to 30% by weight, preferably 8 to 25% by weight. The ethylene / unsaturated carboxylic acid copolymer and / or its ionomer (B) are blended together. Here, the ethylene / unsaturated carboxylic acid copolymer may be a binary copolymer of only ethylene and an unsaturated carboxylic acid, or a multi-component copolymer in which other monomers are arbitrarily copolymerized. There may be. In such a multi-component copolymer, the other monomer may be copolymerized at a ratio of, for example, about 30% by weight or less, but in consideration of the balance between rust prevention performance and powder blowing prevention, It is most preferable to use a copolymer, and when a multi-component copolymer is used, it is preferable to use a copolymer having a content of other monomers of 10% by weight or less.

  Examples of the unsaturated carboxylic acid in the ethylene / unsaturated carboxylic acid copolymer include acrylic acid, methacrylic acid, monomethyl maleate, monoethyl maleate, maleic anhydride, etc., and particularly acrylic acid or methacrylic acid. It is preferable that When only an ethylene / unsaturated carboxylic acid copolymer is used as the component (B), it is most preferable to use an ethylene / methacrylic acid copolymer. Other monomers in the multi-component copolymer include vinyl esters such as vinyl acetate and vinyl propionate, methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, n-butyl acrylate, acrylic Examples include isooctyl acid, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, n-butyl methacrylate, dimethyl maleate, diethyl maleate, carbon monoxide and the like. .

As the component (B) in the present invention, the ionomer of the ethylene / unsaturated carboxylic acid copolymer can be used. Use an ionomer or use an ionomer in combination with an ethylene / unsaturated carboxylic acid copolymer rather than using an ethylene / unsaturated carboxylic acid copolymer alone because it is particularly effective when added in a small amount. Is preferred. Also in the ethylene / unsaturated carboxylic acid copolymer which is the base polymer of the ionomer, it is preferable that the unsaturated carboxylic acid component is acrylic acid or methacrylic acid. As an ion source in the ionomer, alkali metals such as lithium, sodium and potassium, alkaline earth metals such as magnesium and calcium, zinc and the like can be mentioned as preferred examples. A particularly suitable ionomer is a zinc ionomer having low hygroscopicity. The ionomer preferably has a neutralization degree of 90% or less, particularly about 10 to 80%.

  The ethylene / unsaturated carboxylic acid copolymer or its ionomer (B) also has a melt flow rate of 0 at 190 ° C. under a load of 2160 g in consideration of processability and miscibility with components (A) and (C). It is preferable to use one having a viscosity of about 0.01 to 500 g / 10 minutes, particularly about 0.1 to 300 g / 10 minutes. Such an ethylene / unsaturated carboxylic acid copolymer can be produced by radical copolymerization under high temperature and high pressure. The ionomer can be obtained by reacting an ethylene / unsaturated carboxylic acid copolymer with a metal oxide, hydroxide, carbonate or the like.

  As the vaporizable rust preventive agent (C) usable in the present invention, diisopropylamine succinate, diisopropylamine benzoate, isopropylamine benzoate, 2-butylamine benzoate, dicyclohexylamine caprate, cyclohexylamine Of organic carboxylic acid amine salts such as benzoate, dicyclohexylamine benzoate, morpholine benzoate, diisopropylamine nitrite, dicyclohexylamine nitrite, nitrite amine salt such as morpholine nitrite, cyclohexylamine phosphate Such as phosphate amine salt, carbonate amine salt such as cyclohexylamine carbonate, aromatic acid such as benzoic acid and naphtholic acid, heterocyclic such as benzotriazole and 3-amino-1,2,4-triazole Amine, m-dinitroben Emissions, such as aromatic nitro compounds such as nitronaphthalene and the like. These can be used singly or in combination of two or more. Among these, organic carboxylic acid amine salts, nitrite amine salts, phosphoric acid amine salts, carbonate amine salts and the like are particularly suitable.

  The suitable blending ratio of the polyolefin-based polymer (A), the ethylene / unsaturated carboxylic acid copolymer and / or its ionomer (B) and the vaporizable rust preventive (C) varies depending on the type or blending method. However, with respect to 100 parts by weight of the component (A), the component (B) is 1 to 100 parts by weight, preferably 2 to 50 parts by weight, more preferably 3 to 20 parts by weight, and the component (C) is 0.1 to 10 parts by weight. Part by weight, preferably 0.2-5 parts by weight, more preferably 0.3-3 parts by weight. When the blending ratio of the component (B) is less than the above range, the powder blowing suppression effect is hardly exhibited, whereas when the blending ratio exceeds the above range, the rust prevention effect is hardly exhibited. Moreover, when the compounding ratio of the component (C) is less than the above range, the rust preventive effect is hardly exhibited. On the other hand, when the mixing ratio exceeds the above range, a powder blowing phenomenon is likely to occur.

  The rust preventive polymer composition of the present invention can be prepared by melting and kneading the components (A), (B), and (C) all together. However, it is desirable that component (C) is made into a master batch with at least a part of component (B). That is, a method of melt-kneading the total amount of component (B) and component (C) to prepare a master batch, mixing this and component (A) in a solid state, and then melt-kneading, a part of component (B), A component (C) is melt-kneaded to prepare a master batch, and this, the remainder of the component (B) and the component (A) are mixed in a solid state, and then any one of the methods of melt-kneading may be adopted ( Even if the compounding quantity of B) component is small, it is preferable from the point that it is effective for powder blowing suppression. In particular, in the latter preparation method, an ionomer is used as the component (B) for the masterbatch, and the remaining component (B) mixed in the solid state has an unsaturated carboxylic acid content of 10 to 30% by weight, particularly 15 to 25%. It is preferred to use a weight percent ethylene / acrylic acid copolymer or ethylene / methacrylic acid copolymer.

  In preparing the masterbatch, the concentration of component (C) is preferably about 1 to 50 parts by weight, preferably about 1 to 20 parts by weight per 100 parts by weight of component (B). In the latter preparation method, it is preferable that the remaining component (B) to be blended directly with respect to a part of the component (B) used in the master batch is about equal weight or less, particularly about half amount or less.

  Various additives can be mix | blended with the antirust polymer composition of this invention as needed. Examples of such additives are antioxidants, heat stabilizers, light stabilizers, UV absorbers, antistatic agents, lubricants, antiblocking agents, pigments, dyes, crosslinking agents, crosslinking aids, foaming agents, foaming Auxiliaries, plasticizers, tackifiers, flame retardants, inorganic fillers and the like can be exemplified. Such additives can also be added in advance by making a masterbatch.

  In the preparation of the rust-proof polymer composition of the present invention, a Banbury mixer, a mixing roll, a kneader, a single screw extruder, a twin screw extruder, or the like can be used. Such a polymer composition is generally molded by supplying a polymer composition prepared in advance to a molding apparatus used for extrusion molding, injection molding, hollow molding, calendar molding, press molding, and the like. It is. However, it is also possible to supply the raw material of the polymer composition directly to the molding apparatus and simultaneously perform preparation and molding of the composition.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, the raw material and evaluation method which were used in the Example and the comparative example are as follows.

ＶＡ：酢酸ビニル、 ＭＡＡ：メタクリル酸、 ＡＡ：アクリル酸
ＭＦＲ（メルトフローレート）：１９０℃、２１６０ｇ荷重
1. Raw materials The raw materials shown in Table 1 were used.

VA: Vinyl acetate, MAA: Methacrylic acid, AA: Acrylic acid MFR (melt flow rate): 190 ° C., 2160 g load

2. Evaluation method The antirust film was evaluated by the following method.
(1) Rust prevention After cold-rolling a cold rolled steel plate (SPCC-SD, 60 mm × 80 mm × 2.3 mm) specified in JIS G3141 with # 180 and # 240 abrasive paper, xylene and acetone were added. Continue to use and wash. This steel sheet is put into a 100 mm × 150 mm bag made by heat sealing a rust-proof film, and hermetically packaged, and then 1 cycle [5 ° C. × 3 hours → 50 ° C. × 95% RH × 3 hours → 5 ° C. × 3 The temperature / humidity cycle test consisting of [time → 50 ° C. × 95% RH × 15 hours] was conducted 20 cycles to examine the occurrence of rust.

(2) Powder blowing The rust-proof film (tube shape with a folding diameter of 120 mm) obtained by inflation molding is allowed to stand for 2 weeks or more under an environmental condition of 23 ° C. × 50% RH, and the film surface (mainly the inner surface) is blown Was examined visually.

[Example 1]
LDPE, EMAA and vaporizable rust inhibitor are mixed at a weight ratio of 68.5 / 30 / 1.5 and supplied to a twin screw extruder (screw diameter 30 mm, same direction rotation, L / D = 35), resin Melt kneading was performed under the conditions of a temperature of 170 ° C. and a screw rotation number of 150 min ⁻¹ . The obtained blend was supplied to an inflation film molding machine (30 mmφ single screw extruder, L / D = 28, full flight screw, 50 mmφ spiral die, air-cooled), and the resin temperature was 180 ° C. and the folding diameter was 120 mm. An 80 μm thick film was formed. The obtained rust-preventing film was free from rusting and no powder blowing even in 20 cycles of the temperature and humidity cycle test. The results are shown in Table 2.

[Comparative Example 1]
LDPE and vaporizable rust preventive were mixed at a weight ratio of 98.5 / 1.5, and melt-kneading with a twin-screw extruder and film forming with an inflation film forming machine were carried out in the same manner as in Example 1. The performance of was evaluated. Although the obtained film had good anti-rust properties, remarkable powder blowing was observed on the entire surface of the film. The results are shown in Table 2.

[Comparative Example 2]
EMAA and vaporizable rust preventive were mixed at a weight ratio of 98.5 / 1.5, and melt kneading with a twin-screw extruder and film forming with an inflation film forming machine were carried out in the same manner as in Example 1. The performance of was evaluated. Although the obtained film was not sprayed, the rust prevention property was inferior, and rust was generated on a part of the steel sheet. The results are shown in Table 2.

[Example 2]
IONOMER and vaporizable rust preventive agent were mixed at a weight ratio of 92.5 / 7.5 and supplied to a twin screw extruder (screw diameter 30 mm, same direction rotation, L / D = 35), resin temperature 160 ° C., A vaporizable rust preventive masterbatch 1 was prepared by melt-kneading under conditions of a screw rotation number of 150 min ⁻¹ . Next, EVA and masterbatch 1 were weighed at a weight ratio of 80/20 and put into a polyethylene container for dry blending, and sufficiently shaken, stirred and mixed until EVA and masterbatch 1 were evenly mixed. . Subsequently, the mixture obtained in the inflation film forming machine used in Example 1 was supplied, melted and kneaded to perform film forming, and the performance of the film was evaluated. The results are shown in Table 2.

[Example 3]
IONOMER and vaporizable rust preventive are mixed at a weight ratio of 85/15 and supplied to a twin screw extruder (screw diameter 30 mm, same direction rotation, L / D = 35), resin temperature 160 ° C., screw rotation speed 150 min. ^A vaporizable rust preventive master batch 2 was prepared by melt-kneading under the conditions of ^-1 . Next, LDPE, Masterbatch 2 and EAA are weighed in a weight ratio of 88/10/2 and put into a polyethylene container for dry blending. Shake well, mix and mix until all three are evenly mixed. did. Subsequently, the mixture obtained in the inflation film forming machine used in Example 1 was supplied, melted and kneaded to perform film forming, and the performance of the film was evaluated. The results are shown in Table 2.

混練方法：（１）一括メルトブレンド後にフイルム成形
（２）フイルム成形時に防錆剤マスターバッチを添加
（３）フイルム成形時に防錆剤マスターバッチとＥＡＡを添加

Kneading method: (1) Film forming after batch melt blending
(2) Add rust preventive masterbatch when film forming
(3) Add rust inhibitor masterbatch and EAA during film forming

Claims (4)

  Ethylene / unsaturated carboxylic acid copolymer having an unsaturated carboxylic acid content of 5 to 30% by weight and / or its zinc ionomer (B) and vaporizability with respect to the polyolefin polymer (A) containing no acid group A rust preventive agent (C) is blended, and the quantity ratio of the components (A), (B), and (C) is (A) / (B) / (C) = 100/2 / 0.2 to 88. /10.5/1.5 (weight ratio) rust preventive polymer composition.   The rust preventive polymer composition according to claim 1, wherein the vaporizable rust preventive agent (C) is selected from the group consisting of organic carboxylic acid amine salts, nitrite amine salts, phosphoric acid amine salts and carbonate amine salts. .   A metal product packaging material comprising the rust-proof polymer composition according to claim 1.   A vaporizable rust preventive comprising an ethylene / unsaturated carboxylic acid copolymer having an unsaturated carboxylic acid content of 5 to 30% by weight and / or a part of its zinc ionomer (B) and a vaporizable rust preventive (C). Agent masterbatch, an ethylene / unsaturated carboxylic acid copolymer having an unsaturated carboxylic acid content of 5 to 30% by weight and / or the remainder of the zinc ionomer (B), and a polyolefin polymer containing no acid group ( A) is mixed in a solid state, melt-kneaded, and ethylene / unsaturated with an unsaturated carboxylic acid content of 5 to 30% by weight based on the polyolefin polymer (A) containing no acid group. A carboxylic acid copolymer and / or its zinc ionomer (B) and a vaporizable rust preventive agent (C) are blended, and the quantity ratio of the components (A), (B), (C) is (A) / (B) / (C) = 100/2/0. -88 / 10.5 / 1.5 method of manufacturing a rust-preventive polymer composition in the range (by weight).