JP5418957B2 - Rust prevention sheet - Google Patents

Description

  The present invention relates to a rust preventive sheet for packaging articles including silver and copper members and parts, such as contacts and conductors, and articles in which corrosion due to hydrogen sulfide is a problem.

  Members and parts mainly made of silver or copper, such as contacts and conductors, are often used in electrical products. Although these members are relatively excellent in corrosion resistance, corrosion by hydrogen sulfide is difficult to avoid. In particular, when these products are stored in warehouses where vehicles come and go, the silver and copper parts and components are severely corroded due to hydrogen sulfide contained in the exhaust gas from the vehicles, resulting in product quality degradation. Bring.

For this reason, it has been proposed that these parts are packaged and stored with a packaging material having the capability of adsorbing hydrogen sulfide.
For example, JP-A-63-99399 (Patent Document 1) discloses an anticorrosion paperboard in which activated carbon fine powder; a metal compound such as copper and zinc; and a composition containing a binder are coated or impregnated on the paperboard. Proposed.

  In the anticorrosion board of Patent Document 1, activated carbon and a metal compound act synergistically to adsorb and fix hydrogen sulfide and mercaptans. The composition used in Patent Document 1 is an aqueous composition that uses copper sulfate as a metal compound and SBR latex as a binder and contains a surfactant for improving dispersibility.

Japanese Patent Application Laid-Open No. 2003-52800 (Patent Document 2) discloses a specific surface area of 40 to 100 m ² / g, a hydrogen sulfide deodorizing capacity of 3 mmol / g or more, and a primary particle diameter measured by a scanning electron microscope. A deodorant made of fine zinc oxide of 0.2 μm or less has been proposed, and it is proposed to introduce the deodorant in the paper making process of paper or apply and immerse a liquid dispersed with a binder on paper. Has been. And in an Example, 70 mass parts of acrylic resins and a dispersing agent with respect to the suspension liquid for coating (paragraph number 0051) which added 3 mass parts of the said zinc oxide, 3 mass parts of acrylic binders, and a xylene solvent 100 mass parts. A paste composition for coating (paragraph number 0055) containing 3 parts by mass and 200 parts by mass of zinc oxide is disclosed.

In addition, in JP 2006-124819 A (Patent Document 3), as a method for suppressing discoloration of the surface of a silver product, an inorganic oxide such as zinc oxide or titanium oxide having a primary particle diameter of 0.1 μm or less is mixed. It is disclosed that the acrylic resin coating is applied with a thickness of 0.2 to 10 μm. In order not to impair the color tone of silver, an acrylic resin paint excellent in transparency is used, but there is no disclosure about the content ratio of the inorganic oxide as an adsorbent and the acrylic resin paint.
JP-A-63-99399 JP 2003-52800 A JP 2006-124819 A

  As described above, various packaging materials have been proposed in which a composition containing zinc oxide and a binder is applied to the packaging material so as to impart adsorption ability of hydrogen sulfide that causes corrosion. The demand for corrosion resistance for silver and copper parts and parts is high due to the increase in precision and performance of products, and satisfactory products have not yet been obtained.

  This invention is made | formed in view of the above situations, The place made into the objective is to provide the rust prevention sheet as a packaging material which fully exhibited the hydrogen sulfide adsorption ability of zinc oxide. is there.

As a result of various studies on the kind of binder, the content ratio of zinc oxide and binder, the coating amount, etc., the present inventors have arrived at the present invention.
That is, the rust preventive sheet of the present invention has an average particle size of more than 0.2 μm and 1.0 μm or less as measured by a laser diffraction particle size distribution analyzer, and a hydrogen sulfide adsorption capacity of 0.01 to 1.m. 0 mmol / g such as zinc oxide, and a coating solution obtained by mixing a binder, it der made by coated or impregnated on at least one side of a support,
The zinc oxide content mass ratio (zinc oxide / binder solid content) to the binder solid content in the coating liquid is 95/5 to 80/20, and
The amount of increase in the air permeability of the rust preventive sheet relative to the air permeability of the support alone is 200 seconds or less .

Before SL zinc oxide is preferably contained in the rust in the sheet of the present invention 3 g / m ² or more.

  An aqueous emulsion is preferably used as the binder, and the coating liquid preferably uses water as a dispersion medium.

  Moreover, it is preferable that the chlorine ion content of the support is 5 to 200 ppm and the sulfate ion content is 30 to 150 ppm.

  The rust preventive sheet of the present invention is obtained by adhering specific zinc oxide to a support with a binder, and by adjusting the content ratio of zinc oxide and binder, adsorption of hydrogen sulfide by zinc oxide is effectively exhibited, Corrosion of packaging objects including silver and copper parts can be prevented.

  The rust preventive sheet of the present invention has an average particle size of more than 0.2 μm and 1.0 μm or less as measured by a laser diffraction particle size distribution analyzer, and a hydrogen sulfide adsorption capacity of 0.01 to 1.0 mmol / The coating liquid formed by mixing zinc oxide as g and a binder is applied or impregnated on at least one surface of the support.

[Coating composition]
First, the coating liquid (coating composition) used for creating the rust-proof sheet of the present invention will be described.
The zinc oxide used in the present invention has an average particle size measured by using a laser diffraction particle size distribution measuring apparatus of more than 0.2 μm and 1.0 μm or less, preferably more than 0.2 μm and 0.8 μm. Or less, more preferably 0.7 μm or less.
Here, the average particle diameter measured using a laser diffraction particle size distribution measuring device is an average particle diameter measured in the state of an aqueous dispersion and corresponds to the number average particle diameter.

  The zinc oxide used in the present invention has a hydrogen sulfide adsorption capacity of 0.01 to 1.0 mmol / g. Here, the hydrogen sulfide adsorption capacity is a value measured by the following method. A predetermined amount of zinc oxide is supported on a filter paper or the like of a predetermined size, dried, and then sealed in a gas bag (trade name Tedlar bag or the like) that does not allow air to pass through, and hydrogen sulfide is injected. Measure the concentration in the gas bag at the time of injection and after a certain time, and record the concentration when the remaining concentration in the gas bag almost does not drop. The amount of gas removed from zinc oxide is calculated from the initial concentration at this time and the concentration difference after a certain time, and this value is converted into the molar concentration of the gas. By dividing this molar concentration by the amount of zinc oxide supported, the adsorption capacity per gram of zinc oxide is calculated.

The binder used in the present invention has a role for fixing zinc oxide to a support.
As the binder, an emulsion type binder using water or an aqueous medium as a dispersion medium is preferably used. Specific examples include acrylic resin emulsion, SBR (styrene-butadiene rubber) latex, and NR (nitrile rubber) latex. Such an emulsion-type binder can form a porous coating film by adjusting the content ratio with zinc oxide.

  The acrylic resin emulsion can be copolymerized with a homopolymer or copolymer of acrylic ester or methacrylic ester (hereinafter collectively referred to as “(meth) acrylic ester” when not distinguished from each other) or (meth) acrylic ester. And a copolymer with one or more monomers.

  Examples of the (meth) acrylic acid ester include (meth) acrylic acid methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, etc. ) A C1-C10 alkyl ester of acrylic acid is used.

  Examples of the copolymerizable monomers include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid and crotonic acid; vinyl esters such as vinyl acetate and vinyl propionate; styrene and vinyltoluene Aromatic vinyl compounds such as vinylpyrrolidone and heterocyclic vinyl compounds; hydroxyalkyl esters of (meth) acrylic acid such as hydroxyethyl acrylate, hydroxyethyl methacrylate; acrylamide, methacrylamide, N-methylolacrylamide, N-methylol (Meth) acrylamide such as methacrylamide or derivatives thereof; α-olefins such as ethylene and propylene; and nitriles such as (meth) acrylonitrile.

The solid content and zinc oxide of the emulsion type binder as described above are contained in the coating composition in such a range that the binder solid content: zinc oxide (mass ratio) is 5:95 to 30:70. It is preferable. More preferably, it is 8: 92-20: 80, More preferably, it is 9: 91-15: 85.
If the binder content is too high, it will be difficult to obtain a porous coating layer with excellent gas permeability, and hydrogen sulfide to be captured can only be obtained on the surface of the coating film. There is a tendency that cannot be fully demonstrated.

  In the coating composition, in addition to the binder and zinc oxide, if necessary, known additives such as pigments, antifoaming agents, wetting agents, preservatives, dispersants, thickeners, antistatic agents. Various auxiliary agents such as these may be added as appropriate.

The coating composition used in the present invention is a dispersion obtained by dispersing the above components in a dispersion medium.
As the dispersion medium, water, lower alcohols such as methanol, ethanol and propanol, or a mixture thereof are used. Of these, water is particularly preferably used. By mixing an aqueous dispersion of zinc oxide and an emulsion-type binder, the dispersion medium of these components may become the dispersion medium of the composition, or by adding and mixing these components to the dispersion medium, the composition An article (coating liquid) may be prepared.

[Support]
As the support used for the rust-proof sheet of the present invention, paper, general rust-proof paper, coated paper coated with pigment, latex, etc. on the surface, synthetic paper of polyolefin resin, plastic film, polyethylene resin, polypropylene resin, etc. Can be selected from laminates obtained by laminating paper on paper, or composite sheets thereof.
Here, the general rust-proof paper is paper impregnated with volatile rust-preventing agent that has been conventionally used. On the other hand, it exhibits a rust prevention effect. As the rust preventive agent, for example, dicyclohexylammonium nitrite, dicyclohexylammonium caprylate, dicyclohexylammonium carbonate, diisopropylammonium nitrite, monoethanolammonium benzoate, sodium benzoate, benzoic acid, caprylic acid, capric acid, isopropyl benzoate, Butyl benzoate, butyl cinnamate, ammonium carbamate, monoethylamine, diethylamine, monoethanolamine, diethanolamine, triethanolamine, morpholine, methylmorpholine, ethylmorpholine, hexamethylenetetramine, benzotriazole, tolyltriazole, urea, thiourea, Sodium nitrite or the like can be used, and is appropriately selected according to the type of the package.

  The chlorine ion content of the support is preferably 5 to 200 ppm, more preferably 5 to 150 ppm. Moreover, it is preferable that the amount of sulfate ion of a support body is 30-150 ppm, More preferably, it is 30-100 ppm. Chlorine ions and sulfate ions themselves may cause rust, and by suppressing these contents in the support to a low level, it is possible to effectively exhibit the rust preventive effect of the rust preventive sheet.

Here, the chlorine ion content and the sulfate ion content of the support are defined by JIS P8144 “Analysis method of paper, paperboard and pulp water-soluble chloride” 8 and 9a, followed by ion chromatography (for example, In other words, it is an amount measured by ICS-2000 type manufactured by Dionex Co., Ltd.) and means the concentration relative to the support (mass). The above pretreatment means that a sample (about 12 g) which is cut into approximately 5 mm × 5 mm in an Erlenmeyer flask is poured into pure water (about 125 ml) and heated in a water bath with a reflux condenser. After extraction with water (1 hour) and returning to room temperature, the volume is increased in a 200 ml volumetric flask and filtered through a 0.45 μm chromatodisc.

[Manufacture of anti-rust sheet]
At least one surface of the support is coated or impregnated with the coating composition (coating solution) to prepare a rust-proof sheet.
The coating amount depends on the binder and zinc oxide content in the coating composition, but the air permeability increase amount of the finally obtained rust preventive sheet with respect to the air permeability of the support is 200 seconds or less. The amount is preferably 150 seconds or shorter, more preferably 120 seconds or shorter.

  This is because if the increase in air permeability exceeds 200 seconds, the expected hydrogen sulfide adsorption amount tends not to be obtained even if a predetermined amount of zinc oxide is contained in the rust preventive sheet. This means that the coating layer formed by applying or impregnating the coating composition becomes a dense coating, and the zinc oxide impregnated inside the coating or inside the support does not contribute to the adsorption of hydrogen sulfide. This is probably because of this.

  Here, the air permeability of the support alone and the rust preventive sheet is determined by the JAPAN TAPPI paper pulp test method No. According to 5-2: 2000, this is a value measured using a Oken air permeability meter (digital type Oken air permeability and smoothness tester manufactured by Asahi Seiko Co., Ltd.).

The coating amount of the coating solution may be an amount that can satisfy the above requirements, and although it depends on the composition of the coating composition, it is usually preferably 3 to ²⁰ g / m ^{2 in} terms of the coating amount after drying. About 18 g / m ² is more preferable, and about 7 to 15 g / m ² is more preferable.

  Examples of the application or impregnation method include conventionally known application or impregnation such as bar coating, air knife coating, roll coating, varibar blade coating, pure blade coating, gravure coating, rod coating, short dwell coating, curtain coating, and die coating. Any method can be adopted.

  In addition, when the support body which can absorb an aqueous medium from both surfaces, such as paper and coated paper, is used as a support body, either one side or both sides may be applied for the coating composition. The produced rust preventive sheet is preferably packaged so that the zinc oxide coated surface is on the inside. Thereby, it is possible to prevent hydrogen sulfide contained in the outside air from entering the package, and to protect the article to be packaged from hydrogen sulfide.

  When using a general rust preventive paper as a support, the coating composition is applied or impregnated on the surface opposite to the surface on which the rust preventive agent is applied. The produced rust preventive sheet is preferably packaged so that the zinc oxide coated surface is on the outer surface side. As a result, hydrogen sulfide contained in the outside air can be prevented from entering the package body, and the packaged material can be protected from hydrogen sulfide, and applied to the inner surface side of the packaging material inside the package body. The rust preventive agent evaporates, and corrosion of base metals such as zinc, nickel, and iron contained in the package can be prevented.

  Furthermore, when the laminated body of paper and an olefin resin film is used as a support body, the antirust sheet | seat which apply | coated or impregnated the composition for coating on the paper surface is produced. The prepared rust preventive sheet is preferably packaged so that the olefin resin film is on the outer surface and the zinc oxide coated surface is on the inner side. As a result, the olefin resin film prevents the outside air and moisture from penetrating into the package, and the hydrogen sulfide that has passed through the olefin resin film or the hydrogen sulfide originally present in the package is zinc oxide. By adsorbing, it is possible to prevent permeation to the atmosphere in the package and protect the package from hydrogen sulfide.

By applying or impregnating the coating composition according to the present invention, zinc oxide adheres to or is impregnated inside the support surface. The content of zinc oxide in the rust preventive sheet is preferably 3 g / m ² or more, more preferably 6 g / m ² or more, and further preferably 7 g / m ² or more. Although the upper limit of the content is not particularly defined, the adsorption effect is saturated at about 13 g / m ² , and therefore, it is preferably about 13 g / m ² or less from the viewpoint of cost.

The amount of zinc oxide in the rust preventive sheet is, in principle, an amount determined by the coating solution composition and the coating amount (solid content). Specifically, B is the weight of the support cut to 1/10 US tsubo, and C is the weight after drying a rust preventive sheet of 1/10 US tsubo prepared by coating at 105 ± 5 ° C. for 20 minutes. It is determined from the coating amount W calculated by the following formula and the zinc oxide content ratio relative to the total solid content in the composition.
W = A (CB)
In the formula, A is a magnification for converting to US tsubo.

  When the coating liquid composition is known, the zinc oxide content may be determined as described above when the zinc oxide contained in the coating liquid does not fall off from the coating layer during the production of the rust-proof sheet. As another method, zinc oxide can be identified from X-ray diffraction, and the amount of zinc oxide in the rust preventive sheet can be directly measured with a fluorescent X-ray analyzer.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. In the following examples, “part” means “part by mass”.

[Measurement evaluation method]
(1) Average particle diameter of zinc oxide The zinc oxide dispersion used for the preparation of the coating solution was measured with a laser diffraction particle size distribution measuring device (SALD2000, Shimadzu Corporation). The measured average particle size is the number average particle size.

(2) Hydrogen sulfide adsorption rate A 6.5 cm square rust preventive sheet of the present invention is placed in a 3 L Tedlar bag, and 1 L of 170 ppm of hydrogen sulfide is added, and the hydrogen sulfide concentration after 3 hours is measured. The hydrogen sulfide adsorption rate was calculated from the remaining hydrogen sulfide concentration. When hydrogen sulfide could not be detected, the hydrogen sulfide adsorption rate was set to 100%.

(3) Air Permeability and Air Permeability Increase The air permeability is measured according to JAPAN TAPPI Paper Pulp Test Method No. According to 5-2: 2000, measurement is performed using a Oken type air permeability meter (digital type Oken air permeability / smoothness tester manufactured by Asahi Seiko Co., Ltd.).
The increase in air permeability was calculated by subtracting the air permeability of the support from the air permeability of the rust preventive sheet.

(4) Chlorine ion amount and sulfate ion amount Pretreatment as described in JIS P8144 “Analytical method of paper, paperboard and pulp water-soluble chloride” 8 and 9a was performed. That is, in a Erlenmeyer flask, a sample (approx. 12 g) that was cut to about 5 mm × 5 mm was prepared, and pure water (about 125 ml) was added, followed by hot water extraction (1 hour) in a water bath with reflux cooling. After returning to room temperature, the volume was increased in a 200 ml volumetric flask and filtered through a 0.45 μm chromatodisc. About the sample after a process, the amount of chlorine ions and the amount of sulfate ions were measured using the ion chromatography method (ICS-2000 type | mold made by Dionex), and the density | concentration with respect to a support body (mass) was calculated | required.

(5) Content of zinc oxide The weight of the support after cutting to 1/10 US tsubo is B, and the weight after drying a rust preventive sheet of 1/10 US tsubo prepared by coating at 105 ± 5 ° C. for 20 minutes. C was determined from the coating amount W calculated by the following formula and the zinc oxide content ratio with respect to the solid content in the composition.
W = A (CB)
In the formula, A is a magnification for converting to US tsubo.

(6) Rust prevention test After packaging the diode terminal (the support is made of copper and the surface is silver-plated) with a rust prevention paper (trade name: SS-1, manufactured by Oji Paper Co., Ltd.), the produced rust prevention sheet is used. Wrapped. Store the resulting package in a warehouse with a large amount of forklift traffic (a lot of exhaust gas) for 1 week, then open the package and check for discoloration and blackening (silver rust) on the surface of the diode terminal. Was observed.

[Relationship between binder type and rust-proof sheet air permeability]
Rust prevention sheet No. 1-3
Zinc oxide 40% dispersion (trade name: ZCL-9214, average particle size: 0.40 μm, hydrogen sulfide deodorization capacity: 0.25 mmol / g, manufactured by Zeon Kasei Co., Ltd.) 90% by mass in terms of solid content, binder Was mixed at 10% by mass in terms of solid content, mixed and stirred to prepare an aqueous coating solution having a solid content concentration of 30%. Examples of the binder include acrylic resin emulsion (Nichigo Movinyl's Movinyl 8060 (trade name of aqueous emulsion of styrene-acrylic ester copolymer)), styrene / butadiene latex (Asahi Kasei L1571), polyvinyl alcohol (trade name: PVA117, manufactured by Kuraray Co., Ltd.) was used.
As a support, unbleached neutral kraft base paper (US basis: 60 g / m ² , air permeability: 28 seconds, chloride ion amount 53 ppm, sulfate ion amount 80 ppm) is applied on the one side as described above. The liquid was applied so that the coating amount after drying was 10 g / m ² to prepare a rust-proof sheet.
The produced antirust sheet No. While measuring the hydrogen sulfide adsorption rate and air permeability of 1-3, the rust prevention test was done. The results are shown in Table 1. The zinc content calculated from the coating amount and the coating composition is 9 g / m ² .

  It can be seen that the amount of increase in air permeability of the rust preventive sheet varies depending on the type of binder. As the increase in air permeability increases, the hydrogen sulfide adsorption rate decreases, and the increase in the air permeability increases for 372 seconds and the hydrogen sulfide adsorption rate is 73%. In part 3, rust was partially observed. These results show that when polyvinyl alcohol is used as the binder, a highly smooth coating film is formed on the support based on the excellent castability of the coating solution, and the hydrogen sulfide adsorption of zinc oxide inside the coating layer is achieved. It is thought that this is because of the low contribution to. On the other hand, no. In Nos. 1 and 2, the increase in air permeability was 100 seconds or less, the hydrogen sulfide adsorption rate was high, and no rust was observed. When acrylic resin emulsion or SBR latex is used, it is possible to form a porous coating film, and as a result, zinc oxide contained in the coating layer contributes to hydrogen sulfide adsorption as well as surface zinc oxide. It is thought that it was made.

[Binder solid content and zinc oxide content ratio]
Rust prevention sheet No. 4-7
A 40% dispersion of zinc oxide (trade name: ZCL-9214, average particle size: 0.40 μm, hydrogen sulfide deodorizing capacity: 0.25 mmol / g, manufactured by Zeon Kasei Co., Ltd.) and the acrylic resin emulsion are blended. In the coating liquid, the coating liquid No. 1 in which the content ratio of zinc oxide and binder solid content was changed as shown in Table 2. Rust prevention sheet No. 4 except having used 4-7. In the same manner as in No. 1, a rust-proof sheet was produced. While measuring the air permeability and hydrogen sulfide adsorption rate of the produced rust-proof sheet, a rust-proof test was conducted. The results are shown in Table 2.

  It can be seen that the hydrogen sulfide adsorption rate decreases as the binder content in the coating composition increases. That is, it is considered that the degree of porosity of the coating layer may decrease as the amount of the binder increases. When the content ratio of the binder solid content: zinc oxide was 33:67 (No. 4), the hydrogen sulfide adsorption rate was less than 80%, and part of the generation of rust was observed. On the other hand, when the content ratio of the binder solid content: zinc oxide is 10:90, the hydrogen sulfide adsorption rate becomes 100%, and further reduction of the binder solid content rate does not affect the improvement of the hydrogen sulfide adsorption rate. It seems not.

[Coating amount and air permeability of rust prevention sheet]
Rust prevention sheet No. 8-11
No. No. 1 except that the zinc oxide content was changed by changing the coating amount of the coating composition prepared in 1 as shown in Table 3. In the same manner as in No. 1, rust preventive sheets No. 8 to 11 were prepared, and the hydrogen sulfide adsorption rate and air permeability were measured, and a rust preventive test was performed. The results are shown in Table 3.

As the coating amount decreased, the increase in air permeability decreased. This is presumably because the degree of porosity of the formed coating layer increases. However, even when the amount of increase in air permeability is small, the amount of zinc oxide contained in the rust preventive sheet decreases as the coating amount decreases, so the hydrogen sulfide adsorption rate decreases. However, if the content of zinc oxide in the rust preventive sheet is 4.5 g / m ² or more and the air permeability increase amount is 120 seconds or less, a high hydrogen sulfide adsorption rate can be secured, and the rust preventive effect is obtained. It can be seen that it can be demonstrated.

[Air permeability of support and rust preventive sheet]
Rust prevention sheet No. 12-14
As the support, three types of kraft paper having different basis weights and air permeability are used. No. 1 coating composition, No. 1 was used. In the same manner as in No. 1, a rust-proof sheet was produced. The produced antirust sheet No. While measuring the air permeability and hydrogen sulfide adsorption rate of 12-14, the rust prevention test was done. The results are shown in Table 4.

Even if the air permeability of the support is different, when the same coating liquid is applied by the same coating amount (zinc oxide content: 9 g / m ² ), there is a slight difference in the air permeability increase amount. However, in both cases, the hydrogen sulfide adsorption rate could be maintained at 100% by setting the air permeability increase amount to 120 seconds or less. Therefore, by applying a coating composition containing a sufficient amount of zinc oxide necessary for hydrogen sulfide adsorption so that the amount of increase in air permeability is not more than a predetermined value, a desired level of hydrogen sulfide adsorption rate is achieved. It is thought that the antirust effect can be achieved.

  The rust preventive sheet of the present invention has an increased adsorption rate of hydrogen sulfide by zinc oxide, and can be used as a packaging material for silver and copper parts, and products having these parts, where corrosion by hydrogen sulfide is a problem. .

Claims (5)

Zinc oxide having an average particle diameter of more than 0.2 μm and 1.0 μm or less as measured by a laser diffraction particle size distribution analyzer, and a hydrogen sulfide adsorption capacity of 0.01 to 1.0 mmol / g, and a binder Is a rust preventive sheet formed by applying or impregnating at least one surface of a support ,
The zinc oxide content mass ratio (zinc oxide / binder solid content) to the binder solid content in the coating liquid is 95/5 to 80/20, and
The rust prevention sheet whose air permeability increase amount of the said rust prevention sheet with respect to the air permeability of the said support body is 200 second or less . The zinc oxide, rust sheet according to claim 1, which is contained 3 g / m ² or more in the anti-rust sheet. The rust preventive sheet according to claim 1, wherein an aqueous emulsion is used as the binder. The rust preventive sheet according to any one of claims 1 to 3 , wherein the coating liquid uses water as a dispersion medium. The rust preventive sheet according to any one of claims 1 to 4 , wherein the support has a chlorine ion content of 5 to 200 ppm and a sulfate ion content of 30 to 150 ppm.