JPH0569708B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a rust-proof multilayer film suitable for packaging various metal products that require rust prevention. Conventional technology Conventionally, sulfites of various amines, such as dicyclohexylammonium nitrite, diisopropylammonium nitrite, and nitronaphthalene ammonium nitrite, were added to polyolefin resin as volatile rust preventive agents to produce transparent, heat-sealable metal rust-proof packaging materials. Various proposals have been made regarding mixing and forming into a film by melt extrusion. However, these volatile rust preventives and polyolefin resins generally have poor compatibility, and during melt extrusion molding, the volatile rust preventive agents decompose or evaporate and scatter, producing irritating gases and deteriorating the working environment. Alternatively, surging occurs due to poor penetration during extrusion molding, which often results in non-uniform films. Furthermore, if a large amount of a volatile rust preventive agent is added to increase the rust prevention effect, the resulting film not only bleeds the volatile rust preventive agent onto the surface over time, but also deteriorates in transparency. This causes problems such as a decrease in sealing performance and the generation of a bad odor. When a metal product is packaged using such a rust-preventing film, both the surface in contact with the film and the surface away from the film have a certain degree of rust-preventing effect on steel.
However, even though cast iron, which is often used as machine parts, is packaged using a rust-preventing film containing a large amount of the above-mentioned volatile rust-preventing agent, it is difficult to wrap the cast iron on the surface that is far from the film, or even in contact with it. There are limits to the use of volatile rust preventives on metal materials, such as the fact that they do not have sufficient rust preventive effects even on metal materials. On the other hand, mixtures of nitrite, ammonium compounds, and urea-based compounds are known to have a rust-preventing effect, but when these mixtures are added to polyolefin resin and melt-extruded, it is difficult to knead with a screw. When these mixtures come into contact inside the resin, they react rapidly due to the heat of melting and formation, generating gas, and the resulting film exhibits a significant foaming state, resulting in a decrease in rust prevention ability and, ultimately, It cannot be used because it reduces the product value. Similarly, ammonium nitrite, which is a reaction product, is highly volatile and has an excellent vapor phase rust prevention effect, but its decomposition temperature is low and it decomposes explosively when mixed with polyolefin resin and melt-extruded. It cannot be used because of the risk of Problems to be Solved by the Invention The present invention was made to solve these conventional problems using volatile rust preventive agents. It is an object of the present invention to provide a multilayer film in which separate polyolefin resin layers contain two or more types of antirust components that react to form a rust agent. Furthermore, the present invention enables steel,
It shows excellent rust prevention effects on cast iron, regardless of whether it is in contact with the film or not, and the rust preventive ingredients do not bleed even after long-term storage, and it has good transparency and heat sealability. Our goal is to provide a rust film. As a result of various studies on rust-preventing films, the present invention has developed a film that absorbs moisture in the air and hydrolyzes it, resulting in the production of highly volatile rust-preventive agents. The structure of the multilayer film has the above characteristics, consisting of one or more polyolefin resin layers containing one or more nitrites and one or more polyolefin resin layers containing one or more ammonium compounds and/or urea compounds. We have succeeded in obtaining a rust-preventing film having the following properties, and have completed the present invention. The present invention will be explained in detail below. Means for Solving the Problems The anticorrosive component of the present invention is highly volatile, producing ammonium nitrite, ammonia, and nitrous acid through hydrolysis and neutralization reactions by absorbing moisture in the air. It produces a highly rust-inhibiting agent, and the nitrite as its rust-inhibiting ingredient is potassium nitrite, sodium nitrite, calcium nitrite,
It is magnesium nitrite, the ammonium compounds are ammonium benzoate, ammonium phthalate, ammonium stearate, ammonium palmitate, and ammonium oleate, and the urea compounds are urea, urotropin, and phenyl carbamate. Using these compounds, in the construction of a synthetic resin multilayer film with two or more layers, one or more polyolefin resin layers containing one or more nitrites and one layer containing one or more ammonium compounds and/or urea compounds. This is a multilayer film consisting of the above polyolefin resin layer. Examples of the polyolefin resin include olefin polymers such as polyethylene and polypropylene, copolymers of ethylene and vinyl acetate, acrylic acid, acrylic esters, methacrylic acid, and methacrylic esters, and ionomers. Although the rust-preventing multilayer film thus obtained was separated into a layer containing nitrite and a layer containing ammonium compounds and urea-based compounds, surprisingly, the layers containing ammonium compounds and urea-based compounds were not contained in the film. After forming the film, both anti-corrosion components of the separation layer are
By absorbing moisture in the air, it hydrolyzes and releases nitrous acid and ammonium gas,
It is presumed that these two gases permeate through the polyolefin resin layer with high gas permeability and come into contact with each other, gradually reacting to produce ammonium nitrite having excellent vaporizable rust-preventing ability. In addition, in film melt extrusion molding, the rust-preventing component, which has relatively good stability, is melt-extruded independently, which eliminates the problem of rapid reaction when both components are mixed and heated during molding. Our inflation extruder for polyethylene molding allows molding to be carried out easily and economically under the same conditions, and the resulting multilayer film does not bleed out of its rust-preventing components even after long-term storage. It has excellent transparency and heat-sealability, and has excellent performance that cannot be achieved with conventional rust-preventive films containing volatile rust-preventive agents. EXAMPLES The present invention and its effects will be specifically explained below with reference to Examples and Comparative Examples. Examples 1 to 2 Nitrite, ammonium compound, and urea compound finely pulverized to a particle size of 20μ or less using a dry pulverizer were prepared, and the density was 0.922 and the melt index was 1.5.
(Example 1) and an ethylene-vinyl acetate copolymer (EVA) with a vinyl acetate content of 10% by weight having a density of 0.940 and a melt index of 3.0 (Example 2). The above-mentioned anti-rust components were separately added to 100 parts by weight as shown in Table 1, and mixed with stirring using a band blend to prepare molding compounds. The inner and outer layers of these compounds were combined and molded into a two-layer tubular film with an inner layer of 0.05 mm and an outer layer of 0.05 mm using an inflation extrusion molding machine at a molding temperature of 140 to 160°C. Example 3 The low density polyethylene (LDPE) molding compound prepared in Examples 1 to 2 was molded using a two-type, three-layer inflation extrusion molding machine at a molding temperature of 140 to 160°C to form an inner layer of 0.03 mm and an intermediate layer of 0.04 mm. , outer layer 0.03mm
A three-layer tubular film was molded. The compounds used in these Examples are shown in Table 1.

[Table] Comparative Examples 1 to 5 As shown in Table 2, a mixture of magnesium nitrite and ammonium benzoate was added to the inner layer of a commercially available 100μ single-layer film and two-layer film containing a volatile rust inhibitor. A film molded under the same conditions as Examples 1 and 2 will be given as a comparative example.

[Table] 5 Two-layer film Magnesium nitrite-Ammonium benzoate 3

Claims (1)

[Scope of Claims] 1. One or more polyolefin resin layers containing at least one nitrite, and one or more polyolefin resin layers containing at least one ammonium compound and/or at least one urea compound. A rust-proof multilayer film characterized by comprising a resin layer. 2. The multilayer film according to claim 1, wherein the nitrite is selected from the group consisting of sodium nitrite, potassium nitrite, calcium nitrite, and magnesium nitrite. 3. The multilayer film of claim 1, wherein the ammonium compound is selected from the group consisting of ammonium benzoate, ammonium phthalate, ammonium stearate, ammonium palmitate, and ammonium oleate. 4. The multilayer film according to claim 1, wherein the urea compound is selected from the group consisting of urea, urotropin, and phenyl carbamate.