阅读说明：本技术 一种用粉末涂料涂覆三片罐罐身焊缝的试验方法 (Test method for coating weld joints of three-piece can bodies with powder coating ) 是由 陆永亮 曹美霞 于 2020-05-21 设计创作，主要内容包括：本发明公开了一种用粉末涂料涂覆三片罐罐身焊缝的试验方法,解决现有在实验室用粉末涂料涂覆三片罐罐身焊缝的试验成本高以及无法检测焊缝涂膜附着力的技术问题。本发明一种用粉末涂料涂覆三片罐罐身焊缝的试验方法,包括：1)制备三片罐罐身试样；2)用粉末涂料涂覆试样内表面焊缝；3)对试样焊缝的粉末涂层进行热固化处理；4)制备三片罐罐身焊缝涂膜附着力检测试样；5)评价试样焊缝涂膜的附着力。本发明方法流程简单,操作简便,便于实施；检测方法的分辨力高；检测效率高。(The invention discloses a test method for coating three-piece can body welding seams with powder coating, and solves the technical problems that the existing test method for coating three-piece can body welding seams with powder coating in a laboratory is high in cost and the adhesion of a welding seam coating film cannot be detected. The invention relates to a test method for coating weld joints of three-piece can bodies with powder coating, which comprises the following steps: 1) preparing a three-piece can body sample; 2) coating the weld seam on the inner surface of the sample by using powder coating; 3) carrying out thermosetting treatment on the powder coating of the welding seam of the sample; 4) preparing a three-piece can body weld joint coating adhesive force detection sample; 5) and evaluating the adhesion of the coating film of the welding line of the sample. The method has simple flow, simple and convenient operation and convenient implementation; the detection method has high resolution; the detection efficiency is high.)

1. A test method for coating weld seams of a three-piece can body with powder coating is characterized by comprising the following steps:

1) preparing three-piece can body sample with height of 10-30cm, diameter of 6-12cm, and thickness of inner surface coating of 5-15g/m²(ii) a Cutting a three-piece can body sample which is coated on the inner surface and welded, wherein the length of the sample is 10-25cm, the width of the sample is 2-5cm, and clamping two ends of the sample by using a clamp so that the sample is horizontally placed and the inner surface of the sample faces upwards;

2) by powder coatingsCoating the inner surface weld of the sample, uniformly spraying the powder coating on the inner surface weld of the sample by using a sampling spoon, wherein the powder coating covers 3-10mm of two ends of the inner surface coating, and the thickness of the powder coating at the weld of the sample is controlled to be 20-60g/m²；

3) And (3) carrying out thermosetting treatment on the powder coating of the welding line of the sample, adopting a rapid heating device, heating the outer surface of the sample at the heating rate of 30-50 ℃/s at the heating temperature of 150-300 ℃ for 5-30s, finishing the thermosetting treatment of the powder coating of the welding line of the sample after the powder coating at the welding line on the inner surface of the sample is changed into a smooth surface, and air-cooling the sample to 15-25 ℃.

2. The test method for coating the weld of the can body of the three-piece can with the powder coating according to claim 1, wherein the powder coating is an epoxy coating or a polyester coating.

3. A method for detecting the adhesion of a three-piece can body weld coating film, which is prepared by the test method of claim 1, is characterized by comprising the following steps:

1) preparing a three-piece can body weld coating adhesive force detection sample, cutting a weld coating area of the three-piece can body sample into a rectangular sample, wherein the length of the sample is 8-20cm, and the width of the sample is 2-3 cm; carrying out 180-degree bending deformation on the sample for a plurality of times by using a handheld bending experimental instrument until a coating film in a welding seam coating area of the sample is completely separated from the cold-rolled electroplated tin steel plate, and controlling the coating film not to break;

2) evaluating the adhesive force of the sample welding seam coating, fixing one end of a sample on a platform, rapidly tearing the powder coating at the other end of the sample sheet in a 45-degree oblique upward direction, and measuring the separation length L of the sample welding seam coating and the cold-rolled electroplated tin steel plate₁And the separation length L of the sample welding seam coating and the three-piece can body inner surface coating₂According to the maximum detachment length max (L) of the two₁,L₂) The adhesion rating of the coating film of the welding line of the sample is carried out, and the maximum separation length max (L)₁,L₂) Coating film for welding seam of sample with thickness less than or equal to 3mmThe adhesive force is qualified; maximum disengagement length max (L)₁,L₂) The adhesive force of the coating film of the welding line of the sample with the thickness larger than 3mm is unqualified.

Technical Field

The invention relates to a three-piece can body weld coating film, in particular to a test method for coating three-piece can body weld seams with a powder coating, and particularly relates to a test method for coating three-piece can body weld seams with a powder coating and a detection method for the adhesion of the weld coating film of the three-piece can body weld seams.

Background

The cold-rolled electroplated tin steel plate is widely applied to the field of metal packaging, the inner surface, the outer surface and a welding seam of a food and beverage can are always required to be coated with paint in the process of manufacturing the food and beverage can, the coated paint is subjected to thermosetting treatment to form a compact organic film layer, the organic film layer can give consideration to attractiveness, simultaneously can isolate the corrosion of air outside the can and objects contained in the can, and prolong the service life of the food and beverage can.

The cold-rolled electroplated tin steel plate used as the can body generally needs three important links of metal printing, can manufacturing and filling, and the production process of the three-piece can body is as follows: firstly, coating and thermosetting treatment are carried out on a large piece of cold-rolled electroplated tin steel plate (with the length of 900-1050mm and the width of 750-950mm), and because the welding treatment is required subsequently, the thermosetting coating is not conductive, so that the area of about 5-10mm at the two ends of each small piece of iron can not be coated; then, cutting the large cold-rolled electroplated tin steel plate into small tin plates, welding the small cold-rolled electroplated tin steel plates into a cylindrical can body through a narrow lap welding process, and fusing a welding seam and a base metal into a whole in the welding process; and finally, curing the coating at the welding seam and the front coating at the edge of the welding seam through full-automatic coating equipment and a drying room, and connecting the front coatings at two ends of the welding seam to form a complete film layer.

The welding seam area is usually coated with liquid coating or powder coating, the coating usually covers the tin plate and also covers the front inner surface coating by 3-10mm, and the thickness of the powder coating is usually 20-60g/m²The coating is beneficial to avoiding the damage of the metal packaging container and the leakage of the contents in the can through a heat curing process.

The liquid coating can be attached to the surface of the tin plate in a coating rod or roller coating mode, subjected to heat curing treatment at different baking temperatures, and then tested and rated according to an adhesion testing method specified in QB/T2763-2006.

However, the powder coating at the weld cannot be applied by laboratory simulation using the above-described coating bar or roller coating. In industrial production, a printing and coating can manufacturing enterprise generally adopts an electrostatic spraying mode to spray the powder coating to a welding seam on the inner wall of a can body, then thermosetting film forming is carried out, the surface of the thermosetting powder coating is very smooth, and the powder coating cannot be tested and rated according to an adhesion force test method specified in QB/T2763-2006.

In order to better simulate the coating method of the powder coating in a laboratory and evaluate the adhesion of the sample, a full-automatic coating equipment is required, and the equipment is expensive and occupies a large area.

The prior art lacks and does not find a simulation coating method and an adhesion evaluation method suitable for powder coating.

Disclosure of Invention

The invention aims to provide a test method for coating three-piece can body welding seams with powder coating, which solves the technical problems that the test cost is high and the adhesion of a welding seam coating film cannot be detected in the existing test method for coating three-piece can body welding seams with powder coating in a laboratory; the method reduces the test cost of coating the weld seam of the three-piece can body with the powder coating for the laboratory, and realizes the detection and the accurate detection of the adhesive force of the weld coating film.

The technical idea of the invention is that powder coating simulation coating and thermosetting are carried out on a welded sample with a printed inner surface coating before coating, deformation treatment is carried out on the sample after the simulation coating and thermosetting treatment, quantitative rating is carried out according to the separation length of the powder coating, a cold-rolled electroplated tin steel plate and the inner surface coating before coating, the defects of flat plate test are made up, and the risk of poor adhesion of the powder coating after filling is identified in advance.

The invention adopts the technical scheme that a test method for coating weld joints of a three-piece can body by using powder coating comprises the following steps:

1) preparing three-piece can body sample with height of 10-30cm, diameter of 6-12cm, and thickness of inner surface coating of 5-15g/m²(ii) a Cutting a three-piece can body sample which is coated on the inner surface and welded, wherein the length of the sample is 10-25cm, the width of the sample is 2-5cm, and clamping two ends of the sample by using a clamp so that the sample is horizontally placed and the inner surface of the sample faces upwards;

2) coating the welding line on the inner surface of the sample with the powder coating, uniformly spraying the powder coating on the welding line on the inner surface of the sample by using a sampling spoon, covering the two ends of the inner surface coating with the powder coating by 3-10mm, and controlling the thickness of the powder coating at the welding line of the sample to be 20-60g/m²；

3) And (3) carrying out thermosetting treatment on the powder coating of the welding line of the sample, adopting a rapid heating device, heating the outer surface of the sample at the heating rate of 30-50 ℃/s at the heating temperature of 150-300 ℃ for 5-30s, finishing the thermosetting treatment of the powder coating of the welding line of the sample after the powder coating at the welding line on the inner surface of the sample is changed into a smooth surface, and air-cooling the sample to 15-25 ℃.

The principle of the powder coating simulated coating method adopted by the invention is that the powder coating generally contains epoxy and polyester, and the thickness of the powder coating is 20-60g/m²The invention exactly solves the technical problem that the production line of downstream can printing and manufacturing enterprises adopts an electrostatic spraying mode to carry out coating, and a laboratory can not adopt conventional bar coating or roller coating to carry out simulated coating.

The method for detecting the adhesive force of the three-piece can body weld coating obtained by the method comprises the following steps:

1) preparing a three-piece can body weld coating adhesive force detection sample, cutting a weld coating area of the three-piece can body sample into a rectangular sample, wherein the length of the sample is 8-20cm, and the width of the sample is 2-3 cm; carrying out 180-degree bending deformation on the sample for a plurality of times by using a handheld bending experimental instrument until a coating film in a welding seam coating area of the sample is completely separated from the cold-rolled electroplated tin steel plate, and controlling the coating film not to break;

2) evaluating the adhesive force of the sample welding seam coating, fixing one end of a sample on a platform, rapidly tearing the powder coating at the other end of the sample sheet in a 45-degree oblique upward direction, and measuring the separation length L of the sample welding seam coating and the cold-rolled electroplated tin steel plate₁And the separation length L of the sample welding seam coating and the three-piece can body inner surface coating₂According to the maximum detachment length max (L) of the two₁,L₂) The adhesion rating of the coating film of the welding line of the sample is carried out, and the maximum separation length max (L)₁,L₂) The adhesive force of a coating film of a welding seam of a sample with the thickness less than or equal to 3mm is qualified; maximum disengagement length max (L)₁,L₂) The adhesive force of a sample welding line coating film with the thickness larger than 3mm is unqualified。

Based on the following researches of the applicant, the powder coating used by the method is an epoxy coating or a polyester coating, the powder coating formed by thermosetting has very good flexibility, and can be firmly attached to the surface of the tin plate at the welding seam and the inner surface coating of the front channel at the welding seam, wherein the attachment of the powder coating to the inner surface of the front channel is better than that of the powder coating to the surface of the tin plate; the powder coating is thick and the surface is very smooth, so that the adhesion performance index cannot be evaluated by adopting a check method or a circle drawing method; according to the invention, the cold-rolled electroplated tin steel plate is broken without breaking the coating by adopting 180-degree bending deformation for several times, so that a guarantee is provided for subsequent adhesion evaluation; furthermore, the adhesion is evaluated by adopting the separation length of the powder coating, the cold-rolled electroplated tin steel plate and the front inner surface coating which are easy to measure, the defect that the adhesion cannot be truly represented by the original evaluation method is overcome, the rapid and accurate evaluation of the adhesion of the powder coating is realized, and the powder coating performance difference can be conveniently mastered by practitioners in the tin plate and downstream printing and coating can making industry.

The technical scheme of the invention has the following reasons:

1. the test method for coating the weld seam of the three-piece can body with the powder coating provides possibility for subsequent adhesion detection in order to simulate the powder coating process at the weld seam of a downstream printing and coating can manufacturing enterprise; by adopting the simulated coating test method, the investment of large-scale electrostatic spraying equipment can be saved, the method is feasible and efficient, the sample preparation of different types of powder coatings and different thicknesses of powder coatings can be realized, and the adhesive force performance of the powder coating, the cold-rolled electroplated tin steel plate and the inner surface coating of the previous channel can be conveniently mastered by practitioners in the tin plate and downstream printing and coating can making industries;

2. according to the method for detecting the adhesive force of the three-piece can body weld coating, a sample is bent for 180 degrees for several times, so that the cold-rolled electroplated tin steel plate can be broken without breaking a coating, and the subsequent adhesive force detection is guaranteed; the length of the powder coating, the cold-rolled electroplated tin steel plate at the welding seam and the length of the front inner surface coating are adopted for quantitative rating, so that the adhesive force of the powder coating, the cold-rolled electroplated tin steel plate and even the front inner surface coating is represented, the separation length is convenient to measure, uniform cognition of tin plates and downstream tin printing can making practitioners is easy to achieve, the adhesive force performance of the powder coating, the cold-rolled electroplated tin steel plate, the powder coating and the front inner surface coating can be respectively obtained through one-time test, and a good effect is achieved.

Compared with the prior art, the invention has the following positive effects: 1. large-scale electrostatic spraying equipment is not required to be purchased, so that the investment is saved; the practical working condition of downstream printing and coating can manufacturing enterprises can be well simulated by performing powder coating simulation coating and thermosetting on the welded sample with the inner surface coating before printing and coating. 2. The testing method has the advantages of simple flow, simple and convenient operation, convenient implementation and greatly improved testing efficiency, can simultaneously obtain the adhesive force performance indexes of the powder coating and the cold-rolled electroplated tin steel plate and the adhesive force performance indexes of the powder coating and the inner surface coating of the front passage through one-time testing, is convenient for tin plate and downstream tin printing and can making practitioners to master the performance of the powder coating, and avoids the defective products from flowing into filling enterprises and consumer markets. 3. The method can simulate the powder coating process and the adhesive force detection method of downstream can printing and manufacturing users, and better guide the users to stabilize production and improve quality.

Detailed Description

The present invention will be further illustrated with reference to the following specific embodiments.

Example 1, a test method for coating a three-piece can body weld with a powder coating, the method comprising:

1) preparing three-piece can body sample, wherein the height of the three-piece can body is 20cm, the diameter is 8cm, and the thickness of the coating film on the inner surface is 10g/m²(ii) a Intercepting a welded three-piece can body sample with a film coated inner surface, wherein the length of the sample is 15cm, the width of the sample is 4cm, clamping two ends of the sample by using a clamp, and horizontally placing the sample with the inner surface upward;

2) coating the inner surface welding line of the sample with the powder coating, uniformly spraying the polyester powder coating at the inner surface welding line by using a sampling spoon, wherein the powder coating covers 5mm of two ends of the inner surface coating, and controlling the thickness of the powder coating at the welding line of the sample to be 50g/m²；

3) And (3) carrying out thermosetting treatment on the powder coating of the welding line of the sample, heating the outer surface of the sample by adopting a rapid heating device at the heating rate of 40 ℃/s, keeping the temperature for 15s, finishing the thermosetting treatment of the powder coating of the welding line of the sample after the powder coating of the welding line on the inner surface of the sample is changed into a smooth surface, and air-cooling the sample to 20 ℃.

The method for detecting the adhesive force of the three-piece can body weld coating obtained by the method comprises the following steps:

1) preparing a three-piece can body weld coating adhesive force detection sample, cutting a weld coating area of the three-piece can body sample into a rectangular sample, wherein the length of the sample is 12cm, and the width of the sample is 3 cm; carrying out 180-degree bending deformation on the sample for a plurality of times by using a handheld bending experimental instrument until a coating film in a welding seam coating area of the sample is completely separated from the cold-rolled electroplated tin steel plate, and controlling the coating film not to break;

2) evaluating the adhesive force of the sample welding seam coating film, and measuring the separation length L of the sample welding seam coating film and the cold-rolled electroplated tin steel plate₁3.5mm, the separation length L of the weld coating film of the sample and the coating film on the inner surface of the three-piece can body was measured₂2.1mm, according to the maximum detachment length max (L) of the two₁,L₂) The adhesion rating of the coating film of the welding line of the sample is carried out, and the maximum separation length max (L)₁,L₂) 3.5mm, and the adhesive force of the sample welding seam coating film is unqualified.

Example 2, a test method for coating a three-piece can body weld with a powder coating, the method comprising:

1) three can body samples were prepared as in example 1;

2) coating the inner surface welding line of the sample with the powder coating, uniformly spraying the polyester powder coating at the inner surface welding line by using a sampling spoon, wherein the powder coating covers 5mm of two ends of the inner surface coating, and controlling the thickness of the powder coating at the welding line of the sample to be 30g/m²；

3) And (3) carrying out thermosetting treatment on the powder coating of the welding seam of the sample, heating the outer surface of the sample by adopting a rapid heating device at the heating rate of 40 ℃/s, keeping the temperature for 10s at 180 ℃, finishing the thermosetting treatment of the powder coating of the welding seam of the sample after the powder coating of the welding seam on the inner surface of the sample is changed into a smooth surface, and air-cooling the sample to 20 ℃.

The method for detecting the adhesive force of the three-piece can body weld coating obtained by the method comprises the following steps:

1) preparing a three-piece can body weld coating adhesive force detection sample, cutting a weld coating area of the three-piece can body sample into a rectangular sample, wherein the length of the sample is 12cm, and the width of the sample is 3 cm; carrying out 180-degree bending deformation on the sample for a plurality of times by using a handheld bending experimental instrument until a coating film in a welding seam coating area of the sample is completely separated from the cold-rolled electroplated tin steel plate, and controlling the coating film not to break;

2) evaluating the adhesive force of the sample welding seam coating film, and measuring the separation length L of the sample welding seam coating film and the cold-rolled electroplated tin steel plate₁1.8mm, and the separation length L of the weld coating of the sample and the coating on the inner surface of the three-piece can body was measured₂0.5mm, according to the maximum detachment length max (L) of the two₁,L₂) The adhesion rating of the coating film of the welding line of the sample is carried out, and the maximum separation length max (L)₁,L₂) The thickness is 1.8mm, and the adhesive force of the sample welding seam coating film is qualified.

Example 3, a test method for coating a three-piece can body weld with a powder coating, the method comprising:

1) three can body samples were prepared as in example 1;

2) coating the inner surface welding line of the sample with the powder coating, uniformly spraying the epoxy powder coating at the inner surface welding line by using a sampling spoon, wherein the powder coating covers 5mm of two ends of the inner surface coating, and controlling the thickness of the powder coating at the welding line of the sample to be 30g/m²；

3) And (3) carrying out thermosetting treatment on the powder coating of the welding seam of the sample, heating the outer surface of the sample by adopting a rapid heating device at the heating rate of 40 ℃/s, keeping the temperature for 15s at 200 ℃, finishing the thermosetting treatment of the powder coating of the welding seam of the sample after the powder coating of the welding seam on the inner surface of the sample is changed into a smooth surface, and air-cooling the sample to 20 ℃.

The method for detecting the adhesive force of the three-piece can body weld coating obtained by the method comprises the following steps:

1) preparing a three-piece can body weld coating adhesive force detection sample, cutting a weld coating area of the three-piece can body sample into a rectangular sample, wherein the length of the sample is 12cm, and the width of the sample is 3 cm; carrying out 180-degree bending deformation on the sample for a plurality of times by using a handheld bending experimental instrument until a coating film in a welding seam coating area of the sample is completely separated from the cold-rolled electroplated tin steel plate, and controlling the coating film not to break;

2) evaluating the adhesive force of the sample welding seam coating film, and measuring the separation length L of the sample welding seam coating film and the cold-rolled electroplated tin steel plate₁0.8mm, and the separation length L of the weld coating film of the sample and the coating film on the inner surface of the three-piece can body was measured₂0.3mm, according to the maximum detachment length max (L) of the two₁,L₂) The adhesion rating of the coating film of the welding line of the sample is carried out, and the maximum separation length max (L)₁,L₂) The thickness is 0.8mm, and the adhesive force of the sample welding seam coating film is qualified.

The laboratory simulation coating method of the powder coating is realized through the embodiment, and meanwhile, the adhesive force difference of different types of powder coatings, the powder coating thickness, the thermosetting temperature and the like on the tin plate at the welding seam and the inner surface coating of the front channel can be distinguished through the embodiment, so that the influence of the powder coating on subsequent filling can be better identified.

In addition to the above embodiments, the present invention may have other embodiments. All technical solutions formed by adopting equivalent substitutions or equivalent transformations fall within the protection scope of the claims of the present invention.