WO2023004907A1 - Substrate having sanding surface and preparation method therefor, and tin-plated board/chrome-plated board - Google Patents

Abstract

A preparation method for a substrate having a sanding surface. The preparation method comprises: providing a flattening mill, which comprises a first rack and a second rack, wherein the first rack comprises a first working roll and a third working roll which are arranged opposite each other, the second rack comprises a second working roll and a fourth working roll which are arranged opposite each other, the first working roll and the second working roll are located on the same side, the first working roll is an electric spark texturing roll, the second working roll is a grinding and polishing roll, the roughness of a surface of the first working roll is 1.6-2.2 μm, and the roughness of a surface of the second working roll is 0.35-0.75 μm; and making the substrate sequentially pass between the first working roll and the third working roll and between the second working roll and the fourth working roll, so as to form a sanding surface on a first surface of the substrate. After the substrate having the sanding surface is subjected to tin plating or chromium plating, when the substrate is processed into a necking tank or an easy-to-open cap, coatings at a necking position and a pre-scribing film are not prone to being damaged, such that the corrosion resistance of same is good.

Description

Substrate with sanded surface, method for its preparation and tinplate/chromeplate technical field

The invention relates to the technical field of metal material processing, in particular to a substrate with a sanded surface, a preparation method thereof, and a tin-plated plate/chrome-plated plate.

Background technique

Tin-plated/chrome-plated sheets are widely used in beverage packaging. Usually, steel billets are hot-rolled into strips of about 2.0mm in steel plants, and then undergo processes such as acid rolling, annealing, smoothing, tin/chrome plating, and passivation. Finally, it is made into a tin plate/chrome plate, and then it is made into a can body through iron printing and can making processes, which is used to hold various beverages. Since the content contained is acidic, high-protein and other substances, it is required that the tin plate/chrome plate products have high corrosion resistance.

At present, the surface morphology of the tin plate/chrome plate selected for necking cans (attachment 1) or easy open end (attachment 2) is R1 (fine stone surface), and the roughness Ra is controlled between 0.29 and 0.55 μm , the texture of the board surface is stone-like, with a general sense of drawing (visually similar to thin and shallow scratches), and it presents a lighter graininess under strong light. However, during the use of the necked cans or easy-open ends made of such tin-plated/chrome-plated plates, the necked area or the pre-scored film (after the easy-opened The opening direction of the cover) is easily corroded by the contents and cannot meet the requirements of corrosion resistance.

Contents of the invention

The technical problem to be solved by the present invention is to provide a tin-plated/chrome-plated sheet from which necked cans or easy-open lids have good corrosion resistance so that they will not be corroded by the contents.

In order to solve the problems of the technologies described above, the present invention provides the following technical solutions:

The first aspect of the present invention provides a method for preparing a substrate with a sanded surface, comprising the following steps:

providing a screed machine comprising a first frame and a second frame,

The first frame includes a first work roll and a third work roll oppositely arranged, and the second frame includes a second work roll and a fourth work roll oppositely arranged,

The first work roll and the second work roll are located on the same side, the first work roll and the second work roll are used to contact the first surface of the substrate and form the sanding surface, wherein:

The first work roll is an electric spark textured roll, and the second work roll is a ground smooth roll; the roughness of the surface of the first work roll is 1.6-2.2 μm, and the roughness of the surface of the second work roll is The degree is 0.35～0.75μm;

The base plate to be cold-rolled is sent into the tempering machine, and the base plate is sequentially passed between the first work roll and the third work roll, between the second work roll and the fourth work roll, so that the The sanded surface is formed on the first surface of the substrate.

Further, the rolling force of the first stand is 3500-4500 kN, and the rolling force of the second stand is 3500-4000 kN.

Further, the roll changing period of the first work roll and the second work roll is 120±20km, and the rolling tonnage is 150±30t.

Further, when the second surface of the substrate is a bright surface, both the third work roll and the fourth work roll are ground smooth rolls, and the surface roughness of the first work roll is 1.8±0.2 μm, The roughness of the surface of the second work roll is 0.70±0.05 μm, the roughness of the surface of the third work roll is 0.70±0.05 μm, the roughness of the surface of the fourth work roll is 0.40±0.05 μm, the The rolling force of the first stand is 3500±100kN, and the rolling force of the second stand is 3500±100kN. After the substrate is cold-rolled by a temper mill, a bright surface is formed on the second surface.

Further, when the second surface of the substrate is a fine stone surface, the third work roll is an EDM textured roll, the fourth work roll is a ground smooth roll, and the surface of the first work roll is The roughness of the surface of the second work roll is 2.0±0.2μm, the roughness of the surface of the second work roll is 0.40±0.05μm, the roughness of the surface of the third work roll is 1.2±0.2μm, the roughness of the surface of the fourth work roll The rolling force of the first stand is 0.40±0.05μm, the rolling force of the first stand is 4000±100kN, and the rolling force of the second stand is 3500±100kN. A fine stone surface is formed on the second surface.

Further, when the second surface of the substrate is a rough stone surface, the third work roll is an EDM textured roll, the fourth work roll is a ground smooth roll, and the surface of the first work roll is The roughness of the surface of the second work roll is 2.0±0.2μm, the roughness of the surface of the second work roll is 0.40±0.05μm, the roughness of the surface of the third work roll is 1.5±0.2μm, the roughness of the surface of the fourth work roll The thickness is 0.70±0.05μm, the rolling force of the first stand is 4500±100kN, and the rolling force of the second stand is 4000±100kN. A rough stony finish is formed on the second surface.

The second aspect of the present invention provides a substrate with a sanded surface prepared by using the preparation method described in the first aspect, one side of the substrate is a sanded surface, the other side is a non-sanded surface, and the sanded surface Consisting of dot-like concave-convex bottoming lines and silky lines on part of the bottoming lines, the distribution of the bottoming lines and the silky lines makes the roughness of the sanding surface 0.50-0.80 μm .

Further, the material of the base plate is MR type, L type or D type original plate steel.

Further, the non-sanding surface is a smooth surface, a fine stone texture surface, a coarse stone texture surface, a silver surface, a rough silver surface or a matte surface.

The third aspect of the present invention provides a tinned plate, which is obtained by electroplating metal tin on the surface of the substrate described in the second aspect and reflowing.

Further, when electroplating metal tin, the concentration of divalent tin in the electroplating solution is 20-25g/L, the concentration of methanesulfonic acid is 30-50mL/L, the concentration of antioxidant is 35-60mL/L, and the concentration of additives The concentration is 20-30mL/L; during the electroplating process, the temperature of the electroplating solution is controlled to be 38-45°C, and the current density is 22-28A/mm ² .

Further, during reflow, the reflow setting temperature is 260-290°C, the reflow feedback temperature is 255-295°C, and the reflow power ratio is 30%-50%.

Further, one side of the substrate is a sanded surface, and the other side is a fine stone textured surface.

The fourth aspect of the present invention provides a chrome-plated plate, which is obtained by electroplating metal chromium and chromium oxide on the surface of the substrate as described in the second aspect.

Further, when electroplating metal chromium, the concentration of chromic anhydride in the electroplating solution is 140-160g/L, and the concentration of ammonium fluoride is 3-4g/L; during the electroplating process, the temperature of the electroplating solution is controlled to be 36-40°C, The current density is 50-80A/mm ² , the concentration of chromic anhydride in the first recovery tank is ≤50g/L, and the concentration of chromic anhydride in the second recovery tank is ≤40g/L.

Further, when electroplating chromium oxide, the concentration of chromic anhydride in the electroplating solution is 60-70g/L, the concentration of ammonium fluoride is 1-2g/L, and the concentration of sodium hydroxide is 8-10g/L; , controlling the temperature of the electroplating solution to be 31-35°C, the current density to be 9-22A/mm ² , and the weight of the formed chromium oxide layer to be 8-15g/m ² .

Further, one side of the substrate is a sanded surface, and the other side is a fine stone textured surface.

The fifth aspect of the present invention provides a necked tank, the necked tank is prepared from the tin-plated or chrome-plated plate.

The sixth aspect of the present invention provides an easy-open end, the easy-open end is prepared from the tin-plated sheet.

Compared with prior art, the beneficial effect of the present invention is:

1. The present invention creatively proposes a new treatment process for tin-plated/chrome-plated substrates, so that the substrate has two different surfaces inside and outside, and a new surface morphology is produced on the inner surface used to form the inner wall of the tank ——Sanded surface, the roughness of which is 0.50-0.80 μm, and the microscopic appearance includes dot-like concave-convex grounding lines and silky lines on some of the grounding lines. Substrates with such a sanded surface can be more evenly distributed on the surface of the substrate during tin or chrome plating. Therefore, when the obtained tin-plated/chrome-plated plate is processed into a necked can or an easy-open end, the coating at the necked part and the pre-scribed film is not easily damaged, has good corrosion resistance, and will not be corroded by the contents. The outer surface used to form the outer wall of the tank can retain the original surface morphology, so that the tin-plated/chrome-plated substrate produced by the present invention can retain the existing tank packages when forming various tank packages. visual characteristics, thereby avoiding the marketing cost caused by switching to new can packaging products, so that the substrate of the present invention has stronger universality.

2. The present invention improves the existing tin-plating and chrome-plating processes. The new electroplating process improves the compactness of the tin-plated layer and the chrome-plated layer and the uniformity of the alloy layer coverage, reduces the depth of the pores, so that the coating can be The substrate is better protected, and the corrosion resistance of the substrate is further improved.

Description of drawings

Fig. 1 is the structural representation of necking tank;

Fig. 2 is a schematic structural view of the easy-open end;

Figure 3 is the surface texture of the R1 surface under the microscope;

Figure 4 is the surface texture of the Rs surface under the microscope;

Fig. 5 is a schematic diagram of wire drawing lines on R1 surface (a) and Rs surface (b);

Fig. 6 is when adopting existing tinning process (a) and tinning process (b) of the present invention, the surface topography figure of tin layer on the substrate;

Fig. 7 is when adopting existing reflow process (a, b, c) and tin plating process (d, e, f) of the present invention, the surface topography figure of alloy layer on the substrate;

Fig. 8 is the surface topography figure of the metal chromium layer that adopts electroplating metal chromium process of the present invention to obtain;

Fig. 9 is an integrated surface topography diagram of a metal chromium layer and a chromium oxide layer obtained by the electroplating chromium oxide process of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and implement it, but the examples given are not intended to limit the present invention.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. The terms used in the description of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

As described in the background technology, at present, the surface morphology of the tin plate/chrome plate selected for the necking can (accompanying drawing 1) or the easy-open end (accompanying drawing 2) is R1 (fine stone surface), and the roughness Ra is controlled Between 0.29 and 0.55 μm, the texture of the surface of the board is stone-like, with a general feeling of drawing (visually similar to thin and shallow scratches), and it presents a lighter grainy feeling under strong light. However, the necked cans or easy-open lids made of such tin-plated/chrome-plated plates are easily corroded by the contents at the necked or pre-scribed areas during use, which cannot meet the corrosion resistance requirements.

After long-term research, the inventors found that the main reason why the constriction or the pre-scribing film is easily corroded by the content is the surface morphology of the tin/chrome-plated substrate. Since the content surface of the substrate in the prior art is the fine stone texture surface R1, its surface has a brushed appearance. The presence of wire drawing causes obvious height difference on the surface of the substrate. As shown in Figure 3, when observed under a microscope, the wire drawing part shows serious unevenness, which is generally distributed on the surface of the substrate like ravines.

Taking the tin plate as an example, when tin is electroplated on this substrate, under the condition of a certain amount of tin deposition, due to the existence of wire drawing, the amount of tin plating on the protruding part of the substrate will be greater than that on the concave part, thus hindering the tin plating. uniform deposition. During the reflow process, the tin deposited on the substrate will melt and flow. When it flows to the recessed part, the recessed part will hinder the further flow of the tin melt, thereby hindering the leveling of the tin after melting, and finally affecting Alloy layer formation. Therefore, when tin is electroplated on the surface of fine stone texture, the distribution of tin layer is uneven, and the tin content of the drawing part is obviously less. This leads to further damage to the less tin layer in the drawing part itself due to necking deformation or the pre-scribing process of the cover in the process of making cans or lids, so that the base material of the drawing part has no tin layer protection and is directly exposed to Externally, the corrosion resistance of the drawing part will drop sharply.

The same situation exists in the chrome plate. When metal chromium is electroplated on the surface of the substrate, the pores on the surface of the coating are less, but in the form of deep pits, which is mainly due to the body-centered cubic structure of the electroplated metal chromium layer, which is formed by the preferred orientation of the crystal lattice as the current density changes; and The current efficiency of chromium plating is generally 20% to 25%, and the side reaction is hydrogen evolution reaction, which increases the pores of the metal chromium layer along the longitudinal direction. In addition, due to the existence of wire-like scratches along the longitudinal direction on the fine stone surface of the substrate, the longitudinal pores are further deepened, so that the deposition of metallic chromium at the bottom of the wire-drawing groove is further reduced during the electrochrome plating process. The chromium oxide layer has a network and layered structure, and as the degree of gully increases, its protection to the metal chromium layer is further reduced, resulting in a decrease in the corrosion resistance of the chrome-plated plate.

At present, in the canning industry, the substrate surface morphology of tin plate/chrome plate has B (bright surface), R1 (fine stone surface), R2 (coarse stone surface), S1 (silver surface), S2 ( Coarse silver surface), M (matte surface), the appearance specifications and standards of each product are shown in Table 1.

Table 1 The appearance specifications and standards of existing tinplate/chrome plate products

The inventors found that none of the above surface topography is suitable as the inner surface of cans and lid materials. In order to overcome the problem that the tin-plated/chrome-plated plate in the prior art is easy to corrode, the inventor researched and designed a new surface morphology of the tin-plated/chrome-plated substrate, which is defined as a sanded surface and represented by Rs. As shown in Figure 4, when observed under a microscope, the surface of this Rs has a dot-shaped concave-convex texture and silky lines located on part of the texture, the texture and the silk The distribution of the shaped lines makes the roughness of the sanded surface 0.50-0.80 μm. When observed under normal light, the surface of Rs has a grainy feel, which is relatively fine, and there is a slight brushing feeling under strong light. The gloss of the board surface is slightly light silver, and the reflectivity is poor. As shown in Figure 5, compared with the R1 surface, the wire drawing lines on the Rs surface of the present invention are shorter and shallower, thereby reducing the degree of wire drawing (scratching), and eliminating the deposition and reflow of electroplated tin due to substrate grooves caused by wire drawing The impact of tin leveling in the process, so that the surface of the substrate is evenly covered with tin layer and alloy layer; and because tin has good ductility, it finally increases the corrosion resistance of the deformation zone in the process of can making and lid.

The invention provides a method for preparing a substrate with a sanded surface, which specifically includes the following steps:

(1) Provide a tempering machine, the tempering machine includes a first frame and a second frame, the first frame includes a first work roll and a third work roll oppositely arranged, the second frame including a second work roll and a fourth work roll oppositely arranged, the first work roll and the second work roll are located on the same side, and the first work roll and the second work roll are used to contact the first surface of the substrate And form the sanded surface, wherein:

The first work roll is an electric spark textured roll, and the second work roll is a ground smooth roll; the roughness of the surface of the first work roll is 1.6-2.2 μm, and the roughness of the surface of the second work roll is The degree is 0.35～0.75μm;

(2) Send the base plate to be cold-rolled into the tempering machine, so that the base plate passes between the first work roll and the third work roll, between the second work roll and the fourth work roll, thereby The sanded surface is formed on the first surface of the substrate.

The EDM texturing roll is a roll prepared by the EDM texturing (EDT) technology, which produces pit-shaped burrs on the surface of the roll based on the principle of EDM, and can be formed on the surface of the substrate by rolling the EDM texturing roll. granular morphology. The ground smooth roll is formed on the surface of the roll based on the grinding process. Through the rolling of the ground smooth roll, a wire-like morphology can be formed on the surface of the substrate. In the present invention, by controlling the topography and roughness of the surface of the first work roll and the second work roll, under the action of the external rolling force, the topography and roughness of the roll surface are printed on the surface of the substrate, thereby The surface of the substrate forms the sanded surface topography. Preferably, the rolling force applied by the first stand to the first work roll is 3500-4500 kN, and the rolling force applied by the second stand to the second work roll is 3500-4000 kN.

The first work roll and the second work roll need to be replaced after being used for a certain period of time, and whether they need to be replaced can be determined according to the roll change cycle or rolling tonnage. The roll change cycle refers to the total length of the base material rolled by the work rolls, and the rolling tonnage refers to the total weight of the base material rolled by the work rolls. For example, if the roll changing period is 120km, it means that the line will be stopped and changed after the work roll reaches 120km of substrate. Similarly, the rolling tonnage is 150 tons, which means that the line will be stopped and replaced after the work roll reaches 150 tons of substrate. roll. In the present invention, the roll changing cycle of the first work roll and the second work roll is preferably 120±20km, and the rolling tonnage is preferably 150±30t.

In addition, the inventor abandoned the traditional double-sided R1 surface manufacturing process, and adopted a new type of differentiated surface morphology control. The outer surface of the tank still adopts the original R1 surface, and the inner surface adopts the Rs surface of the present invention, thereby obtaining a differentiated shape. The appearance of the substrate Rs/R1. Through differential shape control (Rs content surface/R1 outer surface), the density and uniformity of the coating coverage of the substrate during the electroplating process are improved, so that the plate is not easy to deform and crack during expansion and contraction, thereby improving the resistance of the tank inside. Corrosion performance while maintaining visibility to the outside of the tank. The substrate with the Rs/R1 differential morphology can be used to prepare necked cans or easy-open lids after tin plating, and can be used to prepare necked cans after chrome plating.

The above-mentioned base plate can adopt the base plate material commonly used in the can making industry, preferably MR-type, L-type or D-type raw plate steel.

The substrate with the above Rs/R1 differential morphology can be prepared by controlling the types, surface roughness and rolling force of the third work roll and the fourth work roll. Specifically, the third work roll is controlled to be an EDM textured roll, the fourth work roll is a ground smooth roll, the surface roughness of the first work roll is 2.0±0.2 μm, and the second work roll is The roughness of the roll surface is 0.40±0.05 μm, the roughness of the surface of the third work roll is 1.2±0.2 μm, the roughness of the surface of the fourth work roll is 0.40±0.05 μm, and the The rolling force is 4000±100kN, and the rolling force of the second stand is 3500±100kN. After the substrate is cold-rolled by a temper mill, a fine stone surface (R1) is formed on the second surface of the substrate.

Through the same method, substrates with differentiated morphologies on the second surface can be obtained, such as Rs/B substrates, Rs/R2 substrates, and the like.

The method for preparing the above-mentioned Rs/B substrate is: control the third work roll and the fourth work roll to be ground smooth rolls, the surface roughness of the first work roll is 1.8±0.2 μm, and the second work roll The roughness of the roll surface is 0.70±0.05 μm, the roughness of the surface of the third work roll is 0.70±0.05 μm, the roughness of the surface of the fourth work roll is 0.40±0.05 μm, and the The rolling force is 3500±100kN, the rolling force of the second stand is 3500±100kN, and the bright surface (B) is formed on the second surface of the substrate after being cold-rolled by a temper mill.

The method for preparing the above-mentioned Rs/R2 substrate is: controlling the third work roll to be an EDM textured roll, the fourth work roll to be a ground smooth roll, and the surface roughness of the first work roll to be 2.0±0.2 μm, the roughness of the surface of the second work roll is 0.40±0.05 μm, the roughness of the surface of the third work roll is 1.5±0.2 μm, the roughness of the surface of the fourth work roll is 0.70±0.05 μm, The rolling force of the first stand is 4500±100kN, and the rolling force of the second stand is 4000±100kN. After the substrate is cold-rolled by a temper mill, rough stones are formed on its second surface. Textured surface (R2).

Table 2 shows in detail the roll matching schemes for preparing the above-mentioned substrates with different morphologies.

Table 2 Roll matching scheme of the tempering machine for metal substrates with differentiated morphology

Of course, according to the different needs of downstream users, the same method can also be used to prepare other substrates Rs/S1, Rs/S2s, and Rs/M with different shapes, and the specific methods will not be repeated here.

In addition to the surface morphology of the substrate, the influence of the electroplating process on the corrosion resistance of tin-plated/chrome-plated plates cannot be ignored. Therefore, the present invention further studies the tin plating and reflow process of the substrate.

Table 3 Existing tinning process parameters

Observing the surface of the tinplate through a microscope, it is found that the tin layer and the alloy layer are not all densely covered on the surface of the substrate by using the existing tin plating process. As shown in Figure 6(a), the grains of the tin layer are coarse and loose. , The gap between grains and grains is large, which will lead to poor corrosion resistance of tinplate. Therefore, in order to improve the corrosion resistance of tinplate, improving the density of the tin layer and the coverage of the alloy layer is the primary method.

The inventor improved the existing tinning process and provided a new tinning process, as shown in Table 4. When electroplating metal tin, the concentration of divalent tin in the electroplating solution is 15-25g/L, the concentration of methanesulfonic acid is 30-50mL/L, the concentration of antioxidant is 35-60mL/L, and the concentration of additives is 25 ~30mL/L. During the electroplating process, the temperature of the electroplating solution is controlled to be 38-45° C., and the current density is 22-28 A/mm ² . Preferably, it is 20g/L to control the concentration of divalent tin in the electroplating solution, the concentration of methanesulfonic acid is 40mL/L, the concentration of antioxidant is 45mL/L, and the concentration of additive is 25mL/L. The temperature was 42°C and the current density was 25A/mm ² .

It should be pointed out that the above-mentioned antioxidants can be selected from commonly used oxidants in the field, including but not limited to one or more of phenol, hydroquinone, resorcinol, and catechol. In the present invention, the antioxidant used is QUAKERTIN ^TM TPMW AOX antioxidant of Quaker Chemical. The above-mentioned additives may be additives commonly used in the art, including but not limited to one or more of surfactants and grain refiners. In the present invention, the additive used is Quake Chemical's QUAKERTIN ^™ Additive additive.

Table 4 Electrotin plating process parameter of the present invention

Using the improved electroplating process of the present invention for tin plating, the surface morphology of the tin layer on the substrate is shown in Figure 6(b). It can be seen from the figure that the grains of the tin layer are fine and compact, and the gap between grains is small, which can better protect the substrate and improve the corrosion resistance of the substrate.

After electroplating tin, the tin layer is melted and flowed through a reflow process to obtain an alloy layer, thereby improving the uniformity of the tin layer. Table 5 shows the existing electrolytic tin plating reflow process parameters.

Table 5 Existing tin reflow process parameters

project	Soft melting tank height (m)	Reflow set temperature (℃)	Reflow feedback temperature (℃)	Reflow power ratio (%)
target range	6-8	280-300	280-310	40-70
Control objectives	6.5	290	295	50

As shown in Figure 7(a)-(c), the alloy layer formed by the existing reflow process has relatively fine grains, so the corrosion resistance is also poor.

The present invention also improves the reflow process, as shown in Table 6. During reflow, the height of the reflow box used is 3.5-5.5m, the reflow setting temperature is 260-290°C, the reflow feedback temperature is 255-295°C, and the reflow power ratio is 30%-50%. Preferably, the height of the reflow box used is 4.5m, the set reflow temperature is 270°C, the reflow feedback temperature is 275°C, and the reflow power ratio is 40%.

Table 6 The reflow process parameter of the present invention

project	Soft melting tank height (m)	Reflow set temperature (℃)	Reflow feedback temperature (℃)	Reflow power ratio (%)
target range	3.5-5.5	260-290	255-295	30-50
Control objectives	4.5	270	275	40

Using the reflow process of the present invention, the surface morphology of the obtained alloy layer is shown in Figure 7(d)-(f). It can be seen from the figure that the grains of the alloy layer are coarse, columnar, and have good continuity, so the corrosion resistance is also better.

Further, the present invention also studies the chrome plating process of the substrate.

As previously mentioned, when adopting the existing technology (as shown in Table 7) to electroplate metal chromium, due to the preferred orientation growth of the crystal lattice and the characteristics of the chromium plating process itself (the current efficiency is low, generally 20% to 25%, side reactions For the hydrogen evolution reaction), the metal chromium layer produces deep pit-shaped pores along the longitudinal direction. Therefore, improving the density of grains and reducing the depth of pores in the process of metal chromium deposition are important measures to improve the corrosion resistance of chromium-plated plates.

Table 7 Existing Process Parameters for Electroplating Metal Chromium

The present invention improves the process of electroplating metal chromium, as shown in Table 8. When electroplating metal chromium, control the concentration of chromic anhydride in the electroplating solution to be 140-160g/L, the concentration of ammonium fluoride to be 3-4g/L, the concentration of chromic anhydride in the first recovery tank to be ≤50g/L, and the second recovery The concentration of chromic anhydride in the tank is ≤40g/L; during the electroplating process, the temperature of the electroplating solution is controlled to be 33-43°C, and the current density is 25-100A/mm ² . Preferably, when electroplating metal chromium, the concentration of chromic anhydride in the control electroplating solution is 150g/L, the concentration of ammonium fluoride is 3.5g/L, the concentration of chromic anhydride in the first recovery tank is 30g/L, the second recovery tank The concentration of internal chromic anhydride is 10g/L; during the electroplating process, the temperature of the electroplating solution is controlled at 38°C, and the current density is 65A/mm ² .

Electroplating metal chromium process parameter of the present invention of table 8

Using the above metal chromium electroplating process, the surface morphology of the obtained metal chromium layer is shown in FIG. 8 . It can be seen from the figure that a shallow and dense metal chromium layer with deep pits can be obtained through the above electroplating process. The metal chromium layer with this shape can better protect the substrate and improve its corrosion resistance.

In the process of electroplating chromium, since the interaction between metal chromium and chromium oxide is mutual, that is, when metal chromium is deposited, chromium oxide is also produced, and when chromium oxide is deposited, metal chromium will also be produced, interweaving each other. together. As shown in Table 9, when using the existing process to electroplate chromium oxide, the main components of the formed chromium oxide layer are Cr ₂ O ₃ , CrOOH, Cr(OH) ₃ , and the pores on the surface are flat and fine. It has a network and layered structure, which mainly plays the role of sealing the tiny pores of the metal chromium layer. Therefore, improving the density of the network structure of the chromium oxide layer can also improve the corrosion resistance of the chrome-plated plate.

Table 9 Existing process parameters for electroplating chromium oxide

In order to improve the compactness of the network structure of the chromium oxide layer, the present invention improves the electroplating chromium oxide process, as shown in Table 10. When electroplating chromium oxide, the concentration of chromic anhydride in the electroplating solution is 60-70g/L, the concentration of ammonium fluoride is 1-2g/L, and the concentration of sodium hydroxide is 6-12g/L; The temperature of the liquid is 27-37°C, the current density is 9-22A/mm ² , and the weight of the formed chromium oxide layer is 8-15g/m ² . Preferably, when electroplating chromium oxide, the concentration of chromic anhydride in the electroplating solution is 65g/L, the concentration of ammonium fluoride is 1.5g/L, and the concentration of sodium hydroxide is 9g/L; The temperature is 32°C, the current density is 19A/mm ² , and the weight of the formed chromium oxide layer is ≥10g/m ² .

Table 10 Electroplating chromium oxide process parameters of the present invention

Using the above-mentioned electroplating chromium oxide process, the integrated surface morphology of the obtained metal chromium layer and chromium oxide layer is shown in FIG. 9 . It can be seen from the figure that according to the chromium oxide electroplating process of the present invention, a dense reticular chromium oxide layer can be obtained, which is beneficial to improving the corrosion resistance of the chrome-plated plate.

In summary, the present invention provides a new surface topography Rs of tin-plated/chrome-plated substrates, the substrate with this surface topography has a more uniform coating distribution during the electroplating process, so that it can be used in the preparation of necking tanks/easy During the process of opening the cap, the coating at the neck and pre-scribing film is not easy to deform and crack, thus improving the corrosion resistance of the neck can/easy-open end. In addition, the present invention also improves the tin plating and chrome plating process, improves the compactness of the plating layer, and thus can also improve the corrosion resistance of the necked can/easy-open end.

The above-mentioned embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention. The protection scope of the present invention shall be determined by the claims.

Claims (20)

1. A method for preparing a substrate with a sanded surface, comprising the following steps:

   providing a screed machine comprising a first frame and a second frame,

   The first frame includes a first work roll and a third work roll oppositely arranged, and the second frame includes a second work roll and a fourth work roll oppositely arranged,

   The first work roll and the second work roll are located on the same side, the first work roll and the second work roll are used to contact the first surface of the substrate and form the sanding surface, wherein:

   The first work roll is an electric spark textured roll, and the second work roll is a ground smooth roll; the roughness of the surface of the first work roll is 1.6-2.2 μm, and the roughness of the surface of the second work roll is The degree is 0.35～0.75μm;

   The base plate to be cold-rolled is sent into the tempering machine, and the base plate is sequentially passed between the first work roll and the third work roll, between the second work roll and the fourth work roll, so that the The sanded surface is formed on the first surface of the substrate.
2. The method for preparing a substrate with a sanded surface according to claim 1, wherein the rolling force of the first stand is 3500-4500 kN, and the rolling force of the second stand is 3500 kN ~4000kN.
3. A method for preparing a substrate with a sanded surface according to claim 1, wherein the roll changing cycle of the first work roll and the second work roll is 120±20km, and the rolling tonnage is 150±30t .
4. The method for preparing a substrate with a sanded surface according to claim 1, wherein when the second surface of the substrate is a bright surface, the third work roll and the fourth work roll are both abrasive Paving rolls, the roughness of the surface of the first work roll is 1.8±0.2 μm, the roughness of the surface of the second work roll is 0.70±0.05 μm, and the roughness of the surface of the third work roll is 0.70±0.05 μm, the surface roughness of the fourth work roll is 0.40±0.05μm, the rolling force of the first stand is 3500±100kN, and the rolling force of the second stand is 3500±100kN; After the substrate is cold-rolled in a temper mill, a bright surface is formed on the second surface.
5. The method for preparing a substrate with a sanded surface according to claim 1, wherein when the second surface of the substrate is a fine stone grain surface, the third work roll is an EDM texturing roll , the fourth work roll is a ground smooth roll, the roughness of the surface of the first work roll is 2.0±0.2 μm, the roughness of the surface of the second work roll is 0.40±0.05 μm, and the surface roughness of the third work roll The roughness of the roll surface is 1.2±0.2 μm, the roughness of the fourth working roll surface is 0.40±0.05 μm, the rolling force of the first stand is 4000±100kN, the rolling force of the second stand The braking force is 3500±100kN; after the substrate is cold-rolled in a temper mill, a fine stone surface is formed on the second surface.
6. The method for preparing a substrate with a sanded surface according to claim 1, wherein when the second surface of the substrate is a rough stone surface, the third work roll is an EDM texturing roll , the fourth work roll is a ground smooth roll, the roughness of the surface of the first work roll is 2.0±0.2 μm, the roughness of the surface of the second work roll is 0.40±0.05 μm, and the surface roughness of the third work roll The roughness of the roll surface is 1.5±0.2μm, the roughness of the fourth work roll surface is 0.70±0.05μm, the rolling force of the first stand is 4500±100kN, the rolling force of the second stand The braking force is 4000±100kN; after the substrate is cold-rolled in a temper mill, a rough stone surface is formed on the second surface.
7. A substrate with a sanded surface prepared using the preparation method described in any one of claims 1-6, wherein one side of the substrate is a sanded surface, and the other side is a non-sanded surface, and the sanded surface The smooth surface includes dot-shaped concave-convex grounding lines and filamentary lines located on part of the grounding lines. The distribution of the grounding lines and the silky lines makes the roughness of the sanding surface 0.50- 0.80 μm.
8. The substrate with a sanded surface according to claim 7, wherein the material of the substrate is MR type, L type or D type original plate steel.
9. The substrate with a sanded surface according to claim 7, wherein the non-sanded surface is a smooth surface, a fine stone surface, a coarse stone surface, a silver surface, a rough silver surface or a matte surface.
10. A tin plate, characterized in that the tin plate is obtained by electroplating metal tin on the surface of the substrate according to claim 7 and reflowing.
11. A tinplate according to claim 10, characterized in that, when electroplating metal tin, the concentration of divalent tin in the electroplating solution is 20-25g/L, and the concentration of methanesulfonic acid is 30-50mL/L, The concentration of the antioxidant is 35-60mL/L, and the concentration of the additive is 20-30mL/L; during the electroplating process, the temperature of the electroplating solution is controlled at 38-45°C, and the current density is 22-28A/mm ² .
12. A tinplate according to claim 10, characterized in that, during reflow, the reflow setting temperature is 260-290°C, the reflow feedback temperature is 255-295°C, and the reflow power ratio is 30% ~50%.
13. The tinplate according to any one of claims 10-12, characterized in that one side of the substrate is a sanded surface, and the other side is a fine stone surface.
14. A kind of chrome-plated plate, is characterized in that, described chrome-plated plate obtains after electroplating metal chromium and chromium oxide on the surface of the substrate according to claim 7.
15. A chrome-plated sheet according to claim 14, characterized in that, when metal chromium is electroplated, the concentration of chromic anhydride in the electroplating solution is 140-160 g/L, and the concentration of ammonium fluoride is 3-4 g/L; In the process, the temperature of the electroplating solution is controlled at 36-40°C, the current density is 50-80A/mm ² , the concentration of chromic anhydride in the first recovery tank is ≤50g/L, and the concentration of chromic anhydride in the second recovery tank is ≤40g/L .
16. A chrome-plated sheet according to claim 14, characterized in that, when electroplating chromium oxide, the concentration of chromic anhydride in the electroplating solution is 60-70 g/L, the concentration of ammonium fluoride is 1-2 g/L, and the concentration of sodium hydroxide The concentration of the chromium oxide is 8-10g/L; during the electroplating process, the temperature of the electroplating solution is controlled at 31-35°C, the current density is 9-22A/mm ² , and the weight of the formed chromium oxide layer is 8-15g/m ² .
17. A chrome-plated sheet according to any one of claims 14-16, characterized in that one side of the substrate is a sanded surface, and the other side is a fine stone textured surface.
18. A necking tank, characterized in that the necking tank is prepared from the tin plate according to claim 13.
19. A necking tank, characterized in that the necking tank is prepared from the chrome-plated plate according to claim 17.
20. An easy-open end, characterized in that the easy-open end is prepared from the tin-plated sheet according to claim 13.

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