Packaging paper for rust-proof packaging and preparation method thereof

Abstract

The invention relates to the technical field of anti-rust paper, in particular to packaging paper for anti-rust packaging, the packaging paper comprises a three-layer structure composed of a contact layer, a base material paper layer and a polyvinyl chloride functional layer from bottom to top, the polyvinyl chloride functional layer is of a micropore structure, a gas phase corrosion inhibitor is loaded in the polyvinyl chloride functional layer, the micropore diameter is 50-200 nm, and the contact layer is made of polyvinyl chloride. According to the packaging paper for rust-proof packaging and the preparation method of the packaging paper, a PVC microporous carrier is innovatively adopted to load a compound corrosion inhibitor (VCI), and a slow-release channel is formed through phase separation of diisononyl phthalate, so that the release rate of the VCI is greatly reduced, and the utilization rate is increased.

Description

Technical Field

[0001] The invention relates to the technical field of rust-proof paper, and in particular to a wrapping paper for rust-proof packaging and a preparation method thereof. Background Art

[0002] Anti-rust paper is a paper material used to prevent metal from rusting. Its base material is usually packaging kraft paper. It is suitable for various metal materials and products. The carrier of anti-rust paper is rust-proof base paper. After being coated with VCI liquid, VCI will be continuously and slowly released from the kraft paper in an appropriate space, forming a saturated gas layer in a relatively closed space, thereby providing anti-rust protection for the metal materials in the environment.

[0003] However, most existing anti-rust papers use sodium nitrite / sodium benzoate solution to directly coat the paper base. VCI (vapor corrosion inhibitor) is exposed to the surface of the paper fiber, which can easily lose more than 40% of the active ingredient due to adsorption by the paper fiber, resulting in a corrosion inhibitor utilization rate of only 40-60%. When in a high humidity environment, such as a shipping container with a relative humidity of >90%, the water vapor permeability is as high as 8-15g / m 2 After 24 hours, the VCI molecules are replaced by water molecules and become ineffective, resulting in metal corrosion exceeding 5% of the area. In view of this, we propose a wrapping paper for rust-proof packaging and its preparation method. Summary of the Invention

[0004] The object of the present invention is to solve the deficiencies mentioned in the above background technology and to provide a wrapping paper for rust-proof packaging and a preparation method thereof.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A wrapping paper for rust-proof packaging comprises a three-layer structure from bottom to top: a contact layer, a substrate paper layer and a polyvinyl chloride functional layer. The polyvinyl chloride functional layer is a microporous structure loaded with a vapor phase corrosion inhibitor, and the micropore diameter is 50 to 200 nm.

[0007] Preferably, the polyvinyl chloride functional layer comprises the following raw materials in parts by weight:

[0008]

[0009] Preferably, the steps for preparing the polyvinyl chloride functional layer are specifically as follows:

[0010] Step 1: Premixing and melting: put polyvinyl chloride resin, plasticizer and graphene into a high-speed mixer for premixing, heat to 90°C and mix for 5 minutes, cool to 60°C, add composite corrosion inhibitor, and stir at low speed for 10 minutes to obtain a premix;

[0011] Step 2: Calendering film: feed the premix into a four-roll calender, control the roller distance to make the film thickness 0.05-0.1 mm, and the line pressure 8-12 MPa to obtain the polyvinyl chloride functional layer.

[0012] Preferably, the speed of the pre-stirring in step 1 is 800 rpm, and the speed of the low-speed stirring is 200 rpm.

[0013] Preferably, the roller temperatures of the four-roll calender in step 2 are: 160°C for the first roller, 165°C for the second roller, 170°C for the third roller, and 175°C for the fourth roller.

[0014] Preferably, the contact layer is made of polyester non-woven fabric with a thickness of 15g / m 2 .

[0015] Preferably, the heat stabilizer is one or more of zinc stearate, methyl tin mercaptan, butyl tin maleate, epoxy fatty acid calcium zinc and phosphite.

[0016] Preferably, the plasticizer is one or more of diisononyl phthalate, dioctyl terephthalate, dioctyl sebacate, dioctyl adipate and epoxy fatty acid octyl ester.

[0017] A method for preparing wrapping paper for rust-proof packaging, comprising the following steps:

[0018] Step 1: Choose a thickness of 40-80g / m 2 The substrate paper layer is balanced in an environment with a humidity of ≤30% for 24 hours, and the substrate paper layer is preheated to 80±5℃;

[0019] Step 2: Compounding the polyvinyl chloride functional layer and the preheated substrate paper layer with a hot pressing roller, cooling and setting to 25°C, thereby obtaining a wrapping paper for rust-proof packaging;

[0020] Step 3: Then cut and reel the wrapping paper used for rust-proof packaging, control the ambient humidity to ≤40%, and the moisture content of the finished product to <0.5%.

[0021] Preferably, the pressure of the hot pressing roller in step 2 is 0.5 MPa and the speed is 10 m / min.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The wrapping paper for rust-proof packaging and its preparation method innovatively adopt a PVC microporous carrier to load a composite corrosion inhibitor (VCI), and form a slow-release channel through diisononyl phthalate phase separation, which greatly reduces the VCI release rate and improves the utilization rate.

[0024] 2. The present invention adds graphene and PVC polar molecular chains to synergistically block water and oxygen, with a moisture permeability of ≤3.2g / m 2 ·24h, the anti-rust period is extended to more than 5 years. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. In the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0026] The present invention describes the above technical solution in detail through the following embodiments:

[0027] Example 1

[0028] A wrapping paper for rust-proof packaging, comprising a three-layer structure laminated from bottom to top: a thickness of 15g / m 2 The polyester non-woven fabric, kraft paper and polyvinyl chloride functional layer are microporous in structure, vapor phase corrosion inhibitor is loaded inside, and the micropore diameter is 100nm.

[0029] Preferably, the polyvinyl chloride functional layer comprises the following raw materials in parts by weight:

[0030]

[0031] Wherein, VCI is a complex of dicyclohexylamine nitrite and sodium benzoate, with a mass ratio of 3:1, and a loading amount of 12% of the total weight of the polyvinyl chloride functional layer.

[0032] The steps for preparing the polyvinyl chloride functional layer are as follows:

[0033] Step 1: Premixing and melting: put polyvinyl chloride resin, diisononyl phthalate, graphene and zinc stearate into a high-speed mixer for premixing at a speed of 800 rpm, heat to 90°C and mix for 5 minutes, cool to 60°C, add VCI composite corrosion inhibitor, stir at low speed for 10 minutes at a speed of 200 rpm to obtain a premix;

[0034] Step 2: Calendering film: feed the premix into a four-roll calender, with the first roller at 160°C, the second roller at 165°C, the third roller at 170°C, and the fourth roller at 175°C. Control the roller spacing to make the film thickness 0.1mm and the line pressure 12MPa to obtain the polyvinyl chloride functional layer.

[0035] A method for preparing wrapping paper for rust-proof packaging, comprising the following steps:

[0036] Step 1: Select a thickness of 50g / m 2 The substrate paper layer is balanced in an environment with a humidity of ≤30% for 24 hours, and the substrate paper layer is preheated to 80°C;

[0037] Step 2: Compound the polyvinyl chloride functional layer and the preheated substrate paper layer with a hot pressing roller at a pressure of 0.5 MPa and a speed of 10 m / min, and cool and set to 25° C. to obtain a wrapping paper for rust-proof packaging;

[0038] Step 3: Then cut and reel the wrapping paper used for rust-proof packaging, control the ambient humidity to ≤40%, and the moisture content of the finished product to <0.5%.

[0039] It should be noted that in this embodiment, the polar molecular chains (—Cl groups) encapsulate the composite corrosion inhibitor molecules through hydrogen bonds / van der Waals forces, reducing their thermal motion. The molecular chains entangle to form a physical barrier network, inhibiting water and oxygen penetration, and the moisture permeability is less than 5g / m 2 24h, replaces traditional PE / asphalt substrate and achieves peelable recycling.

[0040] Among them, micropore construction: during high-temperature calendering, diisononyl phthalate and PVC undergo thermodynamic phase separation, and after cooling, 50-200nm interconnected channels are formed. The channel size matches the molecular dynamics diameter of the composite corrosion inhibitor, dicyclohexylamine nitrite ≈ 0.8nm, achieving diffusion-controlled release. Therefore, the release rate of the composite corrosion inhibitor is reduced to 0.01g / m 2 h, the anti-rust period is extended to 5 years.

[0041] It should be noted that, in gas phase migration, amine groups adsorb on the metal surface and dissociate into NO2 - / RCOO - Formation of a passivation film; Directed enrichment: The carboxyl group of sodium stearate is electrostatically attracted to the cation of the composite corrosion inhibitor, driving it to migrate to the surface of the film, and the utilization rate of the composite corrosion inhibitor is >85%.

[0042] Example 2

[0043] The only difference between this embodiment and embodiment 1 is that: in this embodiment, the amount of diisononyl phthalate is 13 parts; the amount of polyvinyl chloride resin is 83 parts; the amount of VCI composite corrosion inhibitor is 10 parts; and the amount of graphene is 2 parts. Other conditions are the same.

[0044] Example 3

[0045] The only difference between this embodiment and embodiment 1 is that: in this embodiment, the amount of diisononyl phthalate is 17 parts; the amount of polyvinyl chloride resin is 87 parts; the amount of VCI composite corrosion inhibitor is 13 parts; and the amount of graphene is 4 parts. Other conditions are the same.

[0046] Example 4

[0047] In this embodiment, the amount of diisononyl phthalate is 20 parts; the amount of polyvinyl chloride resin is 90 parts; the amount of VCI composite corrosion inhibitor is 15 parts; and the amount of graphene is 5 parts, and other conditions are the same.

[0048] Comparative Example 1

[0049] The only difference between this comparative example and Example 1 is that no VCI composite corrosion inhibitor is added in this comparative example, and other conditions are the same.

[0050] Comparative Example 2

[0051] The only difference between this comparative example and Example 1 is that diisononyl phthalate is not added in this comparative example, and other conditions are the same.

[0052] Comparative Example 3

[0053] The only difference between this comparative example and Example 1 is that this comparative example uses traditional PE coating on the market, PE coating paper + surface coating VCI.

[0054] According to the above Examples 1 to 4 and Comparative Examples 1 to 3, packaging paper samples were prepared respectively, and the performance of the packaging paper was tested. The specific performance test items of the packaging paper are as follows:

[0055] Moisture permeability: GB / T 1037-2021 (38°C, 90% RH);

[0056] VCI release rate: Volatile amount per unit area at 40℃ (mg / m 2 h), GC-MS detection;

[0057] Rust resistance: cast iron specimen (40°C, 90% RH, 30 days), rust area % (ASTM D1748);

[0058] Salt spray test: 5% NaCl, 35°C, 168h (ASTM B117);

[0059] The specific data are as follows:

[0060]

[0061]

[0062] The data in the table above show that: when there is no diisononyl phthalate (DINP), the film has no microporous structure, the VCI release rate is reduced by 75%, and it becomes brittle at low temperatures; when there is no VCI composite corrosion inhibitor, the anti-rust function is completely lost, but the barrier property and toughness are still retained. Without the VCI composite corrosion inhibitor, the metal is fully corroded due to the lack of corrosion inhibitor. Without diisononyl phthalate (DINP), the VCI release is insufficient, and the corrosion area reaches 35.7%. Therefore, the lack of micropores prevents the corrosion inhibition molecules from effectively diffusing.

[0063] In summary, diisononyl phthalate (DINP) constructs 128nm-level micropores through phase separation, providing diffusion channels for VCI and increasing the release rate by 300%. The VCI composite corrosion inhibitor directly determines the rust prevention effect. Referring to Comparative Example 1, 100% rust was observed, and the microporous structure only optimized its utilization efficiency.

[0064] Based on the data in the above table, Example 2 can be preferred.

[0065] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. A wrapping paper for rust-proof packaging, characterized by: The invention comprises a three-layer structure from bottom to top: a contact layer, a substrate paper layer and a polyvinyl chloride functional layer. The polyvinyl chloride functional layer is a microporous structure, a vapor phase corrosion inhibitor is loaded inside the layer, and the micropore diameter is 50-200nm.

2. The wrapping paper for rust-proof packaging according to claim 1, characterized in that: The polyvinyl chloride functional layer comprises the following raw materials in parts by weight: Plasticizer: 10-20 parts; Polyvinyl chloride resin: 80-90 parts; Composite corrosion inhibitor: 8-15 parts; Graphene: 1-5 parts; Heat stabilizer: balance.

3. The wrapping paper for rust-proof packaging according to claim 1, characterized in that: The preparation steps of the polyvinyl chloride functional layer are specifically as follows: Step 1: Premixing and melting: put polyvinyl chloride resin, plasticizer and graphene into a high-speed mixer for premixing, heat to 90°C and mix for 5 minutes, cool to 60°C, add composite corrosion inhibitor, and stir at low speed for 10 minutes to obtain a premix; Step 2: Calendering film: feed the premix into a four-roll calender, control the roller distance to make the film thickness 0.05-0.1 mm, and the line pressure 8-12 MPa to obtain the polyvinyl chloride functional layer.

4. The wrapping paper for rust-proof packaging according to claim 3, characterized in that: The rotation speed of the pre-stirring in step 1 is 800 rpm, and the rotation speed of the low-speed stirring is 200 rpm.

5. The wrapping paper for rust-proof packaging according to claim 3, characterized in that: The roller temperatures of the four-roll calender in step 2 are: 160°C for the first roller, 165°C for the second roller, 170°C for the third roller, and 175°C for the fourth roller.

6. The wrapping paper for rust-proof packaging according to claim 1, characterized in that: The contact layer is made of polyester non-woven fabric with a thickness of 15g / m 2 .

7. The wrapping paper for rust-proof packaging according to claim 2, characterized in that: The heat stabilizer is selected from one or more of zinc stearate, methyl tin mercaptan, butyl tin maleate, epoxy fatty acid calcium zinc and phosphite.

8. The wrapping paper for rust-proof packaging according to claim 2, characterized in that: The plasticizer is selected from one or more of diisononyl phthalate, dioctyl terephthalate, dioctyl sebacate, dioctyl adipate and epoxy fatty acid octyl ester.

9. A method for preparing a wrapping paper for rust-proof packaging, applicable to the wrapping paper for rust-proof packaging according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1: Choose a thickness of 40-80g / m 2 The substrate paper layer is balanced in an environment with a humidity of ≤30% for 24 hours, and the substrate paper layer is preheated to 80±5℃; Step 2: Compounding the polyvinyl chloride functional layer and the preheated substrate paper layer with a hot pressing roller, cooling and setting to 25°C, thereby obtaining a wrapping paper for rust-proof packaging; Step 3: Then cut and reel the wrapping paper used for rust-proof packaging, control the ambient humidity to ≤40%, and the moisture content of the finished product to <0.5%.

10. The method for preparing the wrapping paper for rust-proof packaging according to claim 9, characterized in that: The pressure of the hot pressing roller in step 2 is 0.5 MPa and the speed is 10 m / min.

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