A metal liner bottom anti-coating protection process

Abstract

The invention relates to the technical field of gas cylinder processing, and provides an anti-coating protection process for the bottom of a metal liner, comprising the following steps: S1. before coating, affixing a layer of an isolation film to the center of the bottom of the metal liner; the isolation film comprises an adhesive layer and surface paper and bottom paper arranged on both sides of the adhesive layer; the adhesive layer comprises the following components: 3-pyridinecarbamate phenyl modified ethyl acrylate, triethylenetetramine, maleimide, ethyl acetate, and a cross-linking agent; S2. applying a coating layer to the bottom of the metal liner, and then performing a coating operation; S3. after the coating is completed, taking out the metal liner, tearing off the isolation film, cleaning the center of the bottom of the metal liner, and directly bonding a tail plug; the process intervenes during the coating of the liner, and reserves a tail plug bonding area in advance without coating, and can ensure that the reserved area is always not affected by the coating layer during the coating process, and keeps the surface of the reserved area clean, so as to facilitate subsequent bonding of the tail plug.

Description

Technical Field

[0001] The present invention relates to the technical field of gas cylinder processing, and in particular to an anti-coating protection process for the bottom of a metal liner. Background Art

[0002] As a heavy-duty vehicle fueled by natural gas, natural gas trucks require large quantities of natural gas to maintain their range. This continuous supply of natural gas requires the transport of several large-capacity gas cylinders (compressed natural gas storage tanks) on the truck's body. These cylinders add significant weight to the truck, impacting its carrying capacity. The heavy weight of the cylinders also reduces the actual amount of natural gas loaded, making it difficult to improve its range. To further optimize the load capacity, range, and economy of natural gas trucks, lightweighting and reducing the cost of gas cylinders are effective measures. However, reducing the weight and cost of gas cylinders remains a pressing issue.

[0003] Compared to double-ended cylinders with the same outer diameter, single-ended wrapped cylinders have a higher volume-to-weight ratio, effectively reducing cylinder weight. Therefore, using single-ended wrapped cylinders can significantly reduce both cylinder weight and cost. Before wrapping, a tail plug is bonded to the bottom of the single-ended cylinder liner. This plug stabilizes the wrapping, provides tail support, prevents sagging during wrapping and curing, and provides support for small-angle wrapping.

[0004] The existing process involves grinding away the paint layer within a certain area around the center of the bottom of the liner after painting. After cleaning the surface, a tail plug is bonded to the center of the bottom using a specialized adhesive. However, grinding the paint layer on the bottom of the liner is time-consuming and labor-intensive, and it is difficult to achieve a complete clean finish. This results in a loose bond on the tail plug, which can fall off during winding or curing, resulting in wasted carbon fiber and even the destruction of the cylinder. Furthermore, grinding is labor-intensive and poses a safety hazard when using an angle grinder. Summary of the Invention

[0005] The purpose of the present invention is to provide an anti-painting protection process for the bottom of a metal liner, which intervenes when the liner is painted, reserves the tail plug bonding area in advance without painting, and can ensure that the reserved area is always not affected by the coating layer during the painting process, and keep the surface of the reserved area clean, which is convenient for subsequent tail plug bonding.

[0006] The embodiments of the present invention are achieved through the following technical solutions:

[0007] A metal liner bottom anti-coating protection process comprises the following steps:

[0008] S1. Before coating, apply a barrier film to the center of the bottom of the metal liner. The barrier film comprises an adhesive layer and two layers of face and backing paper disposed on either side of the adhesive layer. The adhesive layer comprises the following components: ethyl acrylate modified with phenyl 3-pyridinecarbamate, triethylenetetramine, maleimide, ethyl acetate, and a crosslinking agent.

[0009] S2. Apply a coating layer to the bottom of the metal liner and then perform a coating operation;

[0010] S3. After painting is completed, remove the metal liner, tear off the isolation film, clean the center of the bottom of the metal liner, and directly glue the tail plug.

[0011] The technical solutions of the embodiments of the present invention have at least the following advantages and beneficial effects:

[0012] 1. The present invention has a reasonable design and a simple structure. It intervenes during the coating of the inner liner and reserves the tail plug bonding area in advance without coating. This fundamentally solves the problem in the prior art that the bottom of the tail plug is not polished clean during the winding and curing process, resulting in poor adhesion and falling. It can also ensure that the reserved area is not affected by the coating layer during the coating process and keep the surface of the reserved area clean, which is convenient for subsequent tail plug bonding.

[0013] 2. The present invention adopts 3-pyridinecarbamic acid phenyl ester modified ethyl acrylate as the main component and prepares the adhesive layer under the synergistic action of triethylenetetramine and maleimide, which can increase the flexibility of the molecular chain, facilitate the molecules in the adhesive system to approach each other and generate adsorption force, better compatibility with the metal liner, improve the high temperature resistance and release force stability of the adhesive layer, and the release surface has excellent flatness and good wettability. It can form a uniform thin layer on the bottom surface of the metal liner to prevent degumming, residual glue, delamination, warping and other undesirable phenomena. Even under high temperature conditions, it has good adhesion, and there is little glue residue after peeling off the coating, so there is no need for polishing, and the tail plug can be directly bonded after cleaning. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0015] Figure 1 Schematic diagrams of two structural forms of isolation membranes provided by embodiments of the present invention;

[0016] Figure 2 A cross-sectional view of the isolation membrane provided by an embodiment of the present invention before use;

[0017] Figure 3 A cross-sectional view of the isolation membrane provided by an embodiment of the present invention in use;

[0018] Icon: 1-bottom paper, 11-circular fixed area, 12-easy-tear area, 2-adhesive layer, 3-face paper. DETAILED DESCRIPTION

[0019] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0020] The following is a detailed description of an anti-coating protection process for the bottom of a metal liner provided by an embodiment of the present invention.

[0021] A metal liner bottom anti-coating protection process comprises the following steps:

[0022] S1. Before coating, apply a barrier film to the center of the bottom of the metal liner. The barrier film comprises an adhesive layer 2, and two layers of face paper 3 and backing paper 1, disposed on either side of the adhesive layer 2. The face paper 3 is made of heat-resistant PET paper, and the backing paper 1 is made of heat-resistant glassine silicone oil paper. The adhesive layer 2 comprises the following components: ethyl acrylate modified with phenyl 3-pyridinecarbamate, triethylenetetramine, maleimide, ethyl acetate, and a crosslinking agent, wherein the crosslinking agent is borax or boric acid.

[0023] S2. Apply a coating layer to the bottom of the metal liner, and then heat it at 150-200°C for 1-2h for coating operation;

[0024] S3. After painting is completed, remove the metal liner, tear off the isolation film, clean the center of the bottom of the metal liner, and directly glue the tail plug.

[0025] Furthermore, the base paper 1 includes a circular fixed area 11 with a radius of r arranged coaxially and an easy-to-tear area 12 arranged around the periphery of the circular fixed area 11; in this way, when using the sticker, it is only necessary to tear off the base paper 1 at the easy-to-tear area 12 to leak out the adhesive layer 2, and stick it to the bottom of the metal liner to achieve an isolation effect. The inner circular fixed area has the same outer diameter as the tail plug used for the liner. In addition, circular fixed areas 11 of different sizes can be designed for use according to the different outer diameters of the tail plugs; after coating, the entire sticker is peeled off, and there is no coating layer, powder, or residual glue remaining within the outer diameter range of the center r. No polishing is required, and the tail plug can be directly bonded after cleaning. There is no need to polish the coating layer at the bottom of the liner. The shear strength and peeling strength of the bonded tail plug are high, meeting the bonding requirements, and fundamentally solving the problem of poor adhesion and falling caused by the bottom of the tail plug not being polished clean during the winding and curing process in the prior art. At the same time, it reduces manpower (polishing workers) and material costs (polishing sheets), shortens the process route time, improves production efficiency, and solves production bottlenecks.

[0026] Furthermore, the adhesive layer comprises the following components in parts by weight: 60-85 parts of 3-pyridinecarbamate-modified ethyl acrylate, 2-5 parts of triethylenetetramine, 2-5 parts of maleimide, 50-80 parts of ethyl acetate, and 0.1-5 parts of a cross-linking agent.

[0027] Furthermore, the preparation method of the 3-pyridinecarbamate-modified ethyl acrylate is as follows: using acetone as a solvent, reacting allylamine with 3-pyridinecarbamate-modified ethyl acrylate in a mass ratio of 1:1-2 under stirring and heating reflux conditions, and then reacting with ethyl acrylate in an amount of 2-3 times the total mass to obtain 3-pyridinecarbamate-modified ethyl acrylate.

[0028] The present invention adopts 3-pyridinecarbamate phenyl modified ethyl acrylate as the main component and cooperates with triethylenetetramine and maleimide to prepare the adhesive layer, so that the flexibility of the molecular chain can be increased, which is conducive to the molecules in the adhesive system to approach each other and generate adsorption force, and has better compatibility with the metal liner, thereby improving the high temperature resistance and release force stability of the adhesive layer. The release surface has excellent flatness and good wettability, and can form a uniform thin layer on the bottom surface of the metal liner, preventing undesirable phenomena such as debonding, residual glue, delamination, and warping. Even at about 200°C, it still has good adhesion, and there is little glue residue after peeling off after coating.

[0029] Furthermore, the preparation method of the isolation film is:

[0030] (1) Under a protective gas atmosphere, 3-pyridinecarbamate-modified ethyl acrylate and ethyl acetate are mixed and heated for a period of time, and then triethylenetetramine and maleimide are added. After mixing and heating, a crosslinking agent is added and the mixture is stirred and mixed to obtain an adhesive layer;

[0031] (2) After the adhesive layer is coated on the face paper, it is cured by a multi-step gradient heating and then gradient cooling method, and then the base paper is pressed onto the side of the face paper coated with the adhesive to obtain the finished product.

[0032] Furthermore, in step (2), during the gradient heating, the temperature is gradually increased from 70-80°C to 150-160°C at a heating rate of 3-10°C / min; and then gradually cooled to 70-80°C at a cooling rate of 3-10°C / min.

[0033] Example 1

[0034] A metal liner bottom anti-coating protection process comprises the following steps:

[0035] S1. Before coating, apply a barrier film to the center of the bottom of the metal liner. The barrier film comprises an adhesive layer flanked by PET face paper and glassine silicone oil primer. The adhesive layer comprises the following components: 70 parts ethyl acrylate modified with phenyl 3-pyridinecarbamate, 3 parts triethylenetetramine, 3 parts maleimide, 60 parts ethyl acetate, and 1 part boric acid.

[0036] The bottom paper includes a circular fixed area with a radius of r and a tear-off area surrounding the circular fixed area. When in use, the bottom paper at the tear-off area is torn off to expose the adhesive layer and then affixed to the bottom of the metal liner. The inner circular fixed area has the same outer diameter as the tail plug used in the liner.

[0037] The preparation method of the isolation film is as follows:

[0038] (1) Under a nitrogen atmosphere, 3-pyridinecarbamate-modified ethyl acrylate and ethyl acetate were mixed and heated to 45°C and kept warm for 1 hour, and then triethylenetetramine and maleimide were added. After mixing for 2 hours and heating to 65°C, boric acid was added and the mixture was stirred and mixed to obtain an adhesive layer;

[0039] (2) After applying the adhesive layer on the face paper, the temperature is gradually increased from 75°C to 160°C at a heating rate of 5°C / min; then the temperature is gradually decreased to 80°C at a cooling rate of 3°C / min for curing, and the backing paper is pressed onto the side of the face paper coated with the adhesive to obtain a finished release film;

[0040] S2. Apply a coating layer to the bottom of the metal liner and then heat it at 180°C for 1.5h for coating operation;

[0041] S3. After painting is completed, remove the metal liner, wait for it to cool, tear off the isolation film, clean the center of the bottom of the metal liner, and directly glue the tail plug.

[0042] During the painting process, the isolation film at the bottom of the metal liner did not fall off; after painting, when the entire isolation film was peeled off from the bottom of the metal liner, there was basically no glue residue on the bottom surface of the metal liner.

[0043] Example 2

[0044] The difference between this embodiment and embodiment 1 is that the adhesive layer includes the following components in parts by weight: 75 parts of 3-pyridinecarbamate-modified ethyl acrylate, 2 parts of triethylenetetramine, 4 parts of maleimide, 60 parts of ethyl acetate, and 0.5 parts of borax.

[0045] During the painting process, the isolation film at the bottom of the metal liner did not fall off; after painting, when the entire isolation film was peeled off from the bottom of the metal liner, there was basically no glue residue on the bottom surface of the metal liner.

[0046] Example 3

[0047] The difference between this embodiment and embodiment 1 is that the adhesive layer includes the following components in parts by weight: 65 parts of 3-pyridinecarbamate-modified ethyl acrylate, 4 parts of triethylenetetramine, 2 parts of maleimide, 65 parts of ethyl acetate, and 2 parts of borax.

[0048] During the painting process, the isolation film at the bottom of the metal liner did not fall off; after painting, when the entire isolation film was peeled off from the bottom of the metal liner, there was basically no glue residue on the bottom surface of the metal liner.

[0049] Example 4

[0050] The difference between this embodiment and embodiment 1 is that the adhesive layer includes the following components in parts by weight: 80 parts of 3-pyridinecarbamate-modified ethyl acrylate, 3.5 parts of triethylenetetramine, 2.5 parts of maleimide, 55 parts of ethyl acetate, and 3 parts of borax.

[0051] During the painting process, the isolation film at the bottom of the metal liner did not fall off; after painting, when the entire isolation film was peeled off from the bottom of the metal liner, there was basically no glue residue on the bottom surface of the metal liner.

[0052] Example 5

[0053] The difference between this embodiment and embodiment 1 is that the adhesive layer includes the following components in parts by weight: 85 parts of 3-pyridinecarbamate-modified ethyl acrylate, 1.5 parts of triethylenetetramine, 3 parts of maleimide, 75 parts of ethyl acetate, and 2.5 parts of borax.

[0054] During the painting process, the isolation film at the bottom of the metal liner did not fall off; after painting, when the entire isolation film was peeled off from the bottom of the metal liner, there was basically no glue residue on the bottom surface of the metal liner.

[0055] Example 6

[0056] The difference between this embodiment and embodiment 1 is that in step (2), during the gradient temperature increase, the temperature is gradually increased from 80°C to 160°C at a heating rate of 8°C / min; and then the temperature is gradually decreased to 70°C at a cooling rate of 5°C / min.

[0057] During the painting process, the isolation film at the bottom of the metal liner did not fall off; after painting, when the entire isolation film was peeled off from the bottom of the metal liner, there was basically no glue residue on the bottom surface of the metal liner.

[0058] Comparative Example 1

[0059] The difference between this comparative example and Example 1 is that the ethyl acrylate in the adhesive layer component is not modified.

[0060] After the entire isolation film is peeled off from the bottom of the metal liner, there is a lot of glue residue on the bottom of the metal liner.

[0061] Comparative Example 2

[0062] The difference between this comparative example and Example 1 is that the adhesive layer is ordinary acrylic adhesive; during the coating process, the isolation film at the bottom of the metal liner falls off, and after coating, the bottom of the metal liner still has a coating layer.

[0063] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A metal liner bottom anti-coating protection process, characterized by: The following steps are involved: S1. Before coating, apply a barrier film to the center of the bottom of the metal liner. The barrier film comprises an adhesive layer and two layers of face and backing paper disposed on either side of the adhesive layer. The adhesive layer comprises the following components: ethyl acrylate modified with phenyl 3-pyridinecarbamate, triethylenetetramine, maleimide, ethyl acetate, and a crosslinking agent. S2. Apply a coating layer to the bottom of the metal liner and then perform a coating operation; S3. After the coating is completed, remove the metal liner, tear off the isolation film, clean the center of the bottom of the metal liner, and directly glue the tail plug; The preparation method of the 3-pyridinecarbamate-modified ethyl acrylate comprises: using acetone as a solvent, reacting allylamine with 3-pyridinecarbamate under stirring and heating reflux conditions, and then reacting with ethyl acrylate in an amount of 2-3 times the total mass to obtain 3-pyridinecarbamate-modified ethyl acrylate; The base paper includes a circular fixed area with a radius r arranged coaxially and an easy-to-tear area arranged around the circular fixed area.

2. The anti-coating protection process for the bottom of the metal liner according to claim 1 is characterized in that: During the coating operation, keep the metal liner at 150-200℃ for 1-2 hours.

3. The anti-coating protection process for the bottom of the metal liner according to claim 1 is characterized in that: The adhesive layer comprises the following components in parts by weight: 60-85 parts of 3-pyridinecarbamate-modified ethyl acrylate, 2-5 parts of triethylenetetramine, 2-5 parts of maleimide, 50-80 parts of ethyl acetate, and 0.1-5 parts of a crosslinking agent.

4. The anti-coating protection process for the bottom of a metal liner according to claim 1, characterized in that: The mass ratio of the allylamine to 3-pyridinecarbamic acid phenyl ester is 1:1-2.

5. The anti-coating protection process for the bottom of the metal liner according to claim 3 is characterized in that: The cross-linking agent is borax or boric acid.

6. The anti-coating protection process for the bottom of a metal liner according to claim 1, characterized in that: The surface paper is PET paper; the bottom paper is glassine silicon paper.

7. The anti-coating protection process for the bottom of a metal liner according to claim 1, characterized in that: The preparation method of the isolation film is as follows: (1) Under a protective gas atmosphere, 3-pyridinecarbamate-modified ethyl acrylate and ethyl acetate are mixed and heated for a period of time, and then triethylenetetramine and maleimide are added. After mixing evenly and heating, a crosslinking agent is added and the mixture is stirred and mixed to obtain an adhesive layer; (2) After the adhesive layer is coated on the face paper, it is cured by a multi-step gradient heating and then gradient cooling method, and then the base paper is pressed onto the side of the face paper coated with adhesive to obtain the finished product.

8. The anti-coating protection process for the bottom of a metal liner according to claim 7, characterized in that: In step (2), during the gradient heating, the temperature is gradually increased from 70-80°C to 150-160°C at a heating rate of 3-10°C / min; and then gradually cooled to 70-80°C at a cooling rate of 3-10°C / min.

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