Method for surface treatment of an inner surface of a container

Abstract

Method (1) for surface treatment of an inner surface of a container (7), wherein in a first process step (2) the container (7) to be treated is filled with an abrasive dispersion (12) comprising abrasive media, wherein in a process step (3) following the first step the filled container (7) is tilted by an angle (α) of 10° to 60° to the horizontal (H) and the filled container (7) is set into rotation in a process step (3) following the first step, wherein the method (1) for surface treatment of the container (7) is combined with an electropolishing process, wherein the electropolishing process is carried out after the surface treatment, wherein a liquid or solid oxidizing agent is added to the abrasive dispersion, which helps to achieve a passivation layer on the inner metallic surface, wherein the container (7) is a hollow cylinder and comprises a bottom (9), a lid (8) and a shell.wherein in a process step (3) the container (7) is rotated about an axis of rotation (D) which corresponds to a longitudinal axis of the container (7), characterized in that the longitudinal axis runs parallel to a cylinder axis and through a lateral surface (10) of the container (7).

Description

State of the art

[0001] Containers intended for use in the pharmaceutical, food or chemical industries, for example, must meet certain guidelines, such as GMP guidelines, which specify requirements for the surface of the container, particularly with regard to roughness.

[0002] The current state of the art involves having highly qualified personnel manually grind down the containers. A disadvantage of this method is that undesirable micro-defects or micro-cracks can form on the container's surface, allowing particles and microorganisms to adhere to the treated surface. This can lead to particle contamination and cross-contamination. Furthermore, these micro-defects on the container's surface reduce its corrosion resistance over time.

[0003] The following patents are cited as prior art: EP 3028780 A1, DE 10143771 C1, JP 2011-104666 A, KR 102041077 B1, DE 102008008894 A1, JP 2015-140860 A and US 9343649 B1. Purpose and advantages of the invention

[0004] The invention is based on the objective of optimizing the treatment of surfaces for containers.

[0005] This problem is solved by the features of claim 1.

[0006] Preferred and advantageous embodiments of the method according to the invention are specified in the dependent claims.

[0007] The invention relates to a method for the surface treatment of an inner surface of a container.

[0008] The container is made of a metal and / or a metal alloy. The metal material is preferably a rust-free, corrosion-resistant steel, such as stainless steel. Preferably, the container is made entirely or partially of metal. The container can also consist of two different materials, one of which is preferably metal. Containers made of mineral, plastic, or light metal are also conceivable.

[0009] The container has a hollow cylindrical shape, comprising a base, a lid or top, and a shell. The container may also have connections and / or flanges. The shell and base of the container enclose an interior space, with the interior surfaces of the container to be treated surrounding this interior space.

[0010] The core of the invention lies in the fact that in a first process step the container to be treated is filled with an abrasive dispersion, wherein in a process step following the first the filled container is tilted by an angle of 10° to 60° to the horizontal and the filled container is set into rotation in a process step following the first.

[0011] The abrasive dispersion preferably comprises mainly liquid and abrasive particles. When filling the container, the liquid can be added first, followed by the abrasive particles, or first by the abrasive particles followed by the liquid, or a dispersion comprising both the abrasive particles and the liquid can be added. The abrasive dispersion is preferably filled into the interior or an internal volume of the container.

[0012] The container can be tilted first and then rotated, or rotated first and then tilted, or tilted and rotated simultaneously.

[0013] The container is preferably oriented vertically or upright before tilting, such that one longitudinal axis of the container is, for example, at a 90° angle to a horizontal. When the container is tilted, the angle between the longitudinal axis and a horizontal is changed, so that the longitudinal axis of the container is tilted by 10–60° to the horizontal.

[0014] It is advantageous if the tilting angle is between 10° and 50°, 10° and 40° or 10° and 30°, as this also makes it advantageous to treat the bottom of the container more evenly, for example.

[0015] Advantageously, rotating the container ensures that the inner surface, particularly the shell and bottom, is treated uniformly and consistently. A homogeneous surface with an isotropic micrograph is advantageously achieved on the inner surface. An isotropic micrograph is present when a uniform micrograph is obtained in all directions.

[0016] Furthermore, it is advantageous if the grinding media are designed in such a way that only a comparatively small amount of material is removed from the inner surface of the container.

[0017] It is advantageous if, in one process step, the container is filled with abrasive media, preferably with mineral abrasive media.

[0018] The solid abrasive media preferably comprise a solid abrasive and a solid bonding material in which the abrasive media are bonded. The abrasive media can have different grit sizes and hardnesses. The abrasive media are preferably made of a natural or synthetic mineral material, such as corundum, ceramic, and / or zirconium oxide. The liquid in the container preferably comprises water, in particular distilled water and / or ultrapure water. Furthermore, the liquid may also contain additives, such as surfactants or the like, to reduce the surface tension of the liquid. The abrasive media preferably have a spherical, cylindrical, triangular, star-shaped, pyramidal, or conical shape.

[0019] Another advantage is that in one process step the container is filled to 30-70% with the grinding dispersion.

[0020] The container is filled with the grinding dispersion to a specific concentration of 30-60%, 30-50%, 30-40%, 40-70%, 40-60%, 50-70%, or 50-60%. The ratio of liquid to abrasive particles can vary.

[0021] In one process step, the cylindrical container is rotated around a cylinder axis.

[0022] Advantageously, the cylinder axis is an axis of symmetry, with the axis of symmetry passing through the centers of the bottom and top of the container.

[0023] According to the invention, in one process step the container is rotated about an axis of rotation which corresponds to a longitudinal axis of the container.

[0024] The longitudinal axis runs parallel to the cylinder axis and passes through the surface of the container. The container is then rotated around a longitudinal axis of the surface, with an edge between the bottom and the surface being the highest point and the lowest point at different times during a 360° rotation. For example, when the container rotates around the axis of rotation, which corresponds to a longitudinal axis, the contents move from one section of the surface to the opposite section.

[0025] Furthermore, the container can be rotated about a vertical axis of rotation. Depending on the tilting angle of the container, the vertical axis of rotation can pass through an edge between the base and the outer surface, and / or through an edge between the lid and the outer surface, and / or through a single outer surface, and / or through two outer surfaces. For example, the vertical axis of rotation can pass through an edge between the base and the outer surface and a outer surface of the container, or through a outer surface and an edge between the lid and the outer surface, or through two outer surfaces of the container.

[0026] The container can also be rotated around various spatial axes that are oriented perpendicular to the vertical, for example around a horizontal axis that passes through two opposite points on the lateral surfaces, so that when rotating by 180° the lid of the container is aligned with the floor.

[0027] It is also advantageous if, in one process step, the container is moved by wobbling around different axes of rotation.

[0028] Advantageously, the container can transition from rotation around one axis to rotation around a second axis. For example, the container can first be rotated around a longitudinal axis, then around a cylindrical axis, and then again around a longitudinal axis. Further variations of the different axes of rotation are also possible.

[0029] Furthermore, it is advantageous that in one process step the container is rotated around the axis of rotation at a speed of 10 to 60 revolutions per minute.

[0030] The rotational speed at which the container is rotated around a rotary axis is particularly in the range of 10 to 50 revolutions per minute, 10 to 40 revolutions per minute, 10 to 30 revolutions per minute, 10 to 20 revolutions per minute or 20 to 60 revolutions per minute, 30 to 60 revolutions per minute, 40 to 60 revolutions per minute, 50 to 60 revolutions per minute.

[0031] Furthermore, it is advantageous to vary the rotational speed of the container during surface treatment in a process step, so that the container is moved differently relative to the grinding media.

[0032] The rotational speed of the container is selected such that the abrasive media remain relatively stable during rotation. Preferably, in cross-section, the abrasive media are arranged within a volume defined by an edge between the bottom and the outer surface, and along a downward-facing outer surface. During the rotation of the container, both the downward-facing outer surface and the edge of the abrasive media pass by the volume while the volume remains essentially stationary, thus preferably treating the entire inner surface of the container. Advantageously, at least half of the bottom is covered with the abrasive dispersion, preferably more than half, and in particular, the entire bottom surface is covered with abrasive dispersion, so that the entire bottom surface is ground during rotation.Furthermore, it is advantageous if a lateral surface, especially the entire longitudinal axis, is covered with abrasive dispersion so that the entire surface can be processed by rotation. For this purpose, it is advantageous if the dispersion layer extends at least to a lower edge of the lid and the surface in cross-section.

[0033] Advantageously, the direction of rotation of the container is varied during surface treatment in one process step.

[0034] The container can be rotated either clockwise or counterclockwise around its axis of rotation during surface treatment, with varying the direction of rotation being advantageous. The direction of rotation is advantageously oscillating due to the changing direction.

[0035] It is advantageous if the grinding media are designed in such a way that, in one process step, the grinding media remove material from the inner surface of the container through frictional contact.

[0036] By rotating the container, material, particularly container material, is advantageously removed from the inner surface of the container by abrasion due to the relative movement between the container and the abrasive media. Because the container is tilted and rotated, the entire inner surface of the container, especially the inner outer surface and the inner bottom surface, can preferably be ground or abraded uniformly by the abrasive media. During the abrasive movement between the abrasive media and the container, a portion of the abrasive media is also worn away or removed by the relative movement between the abrasive media and the container.

[0037] Advantageously, the removed material is incorporated into the grinding dispersion in one process step.

[0038] A binder can be added to the liquid of the grinding dispersion, which preferably helps to bind the removed material from the container and the grinding media in the liquid.

[0039] Advantageously, the removed material can be removed from the container with the liquid even without the use of a binding agent, by simply rinsing the material away with the liquid. This advantageously prevents the removed material from adhering to the inner surface of the container or becoming incorporated into its surface.

[0040] It is also advantageous if, in one process step, the inner surfaces of the container are oxidized by the grinding dispersion.

[0041] According to the invention, a liquid or solid oxidizing agent is added to the abrasive dispersion, which aids in achieving a passivation layer on the inner metallic surface. The oxidizing agents are preferably permissible in the area for which the containers are to be used and comply with the relevant guidelines. Examples of oxidizing agents that can be used include peroxides, peracetic acid, perborates, percarbonates, sulfuric acid, citric acid, and / or hypochlorites.

[0042] According to the invention, the surface treatment method for the container is combined with an electropolishing process. This advantageously allows for particularly low surface roughness and thus an improved passivation layer to be achieved through the oxidizing agents. According to the invention, the electropolishing process is carried out after the surface treatment process with the abrasive dispersion. It is also conceivable to perform the electropolishing process multiple times between the surface treatments.

[0043] Another advantage is that the container is sealed to be liquid-tight.

[0044] Preferably, a sealing material is arranged between the lid and the casing. The sealing material is preferably silicone and / or ethylene propylene diene monomer rubber and / or Viton and / or tetrafluoroethylene hexafluoropropylene copolymer. Advantageously, the lid is closed to the casing by a clamping ring.

[0045] The treatment of the inner surface of the container can also take place without a lid, for example.

[0046] It is advantageous if, in one process step, the rotation of the filled container is carried out for a period of time of 1 to 72 hours.

[0047] Preferably, the rotation of the filled container is carried out for a period of time of 10 to 72 hours, 20 to 72 hours, 30 to 72 hours, 40 to 72 hours, 50 to 72 hours and / or 60 to 72 hours.

[0048] Advantageously, the abrasive dispersion is selected such that improved surface roughness is achieved after just one hour. The longer the surface treatment is carried out, the lower the mean roughness values ​​of the inner surface of the treated container become. The surface treatment is advantageously continued until the mean roughness value (Ra) of the inner surface is below 0.5 µm, 0.4 µm, 0.3 µm, 0.2 µm, and particularly below 0.1 µm.

[0049] After a certain period of time, the surface treatment of the container is completed by advantageously stopping the container's rotation and tilting it back into a vertical position. This can be done either by first stopping the rotation and then tilting the container back into a vertical position, or by first tilting the container back into a vertical position and then stopping the rotation. It is also possible to perform both process steps simultaneously.

[0050] The container is then preferably emptied completely, removing the liquid along with the abrasive media and the removed material. Advantageously, at least some of the abrasive media can be reused for further surface treatment processes.

[0051] To remove the finely abraded material from the container, it is preferably washed or cleaned, for example with ultrapure water and / or hygienic agents, after the container has been completely emptied.

[0052] The surface-treated container can be used in particular for filling with nanoparticles, micronized powders and / or powdered, pasty and liquid excipients in the cosmetics, pharmaceutical, food or chemical industries.

[0053] The invention also extends to a container having a bottom and a shell, wherein the bottom and shell enclose an interior space, and wherein the inner surfaces of the bottom and shell of the container are treated according to a method described above.

[0054] The container is a hollow cylinder comprising a bottom, a lid or upper end, and a shell. The container may also have connections and / or flanges. The shell and bottom of the container enclose an interior space, with the interior surfaces of the container to be treated surrounding this interior space. The shell, bottom, and lid of the container advantageously have a preferably uniform wall thickness of 1 to 5 mm, preferably between 1 and 3 mm.

[0055] The diameter of the container is advantageously between 100 mm and 900 mm. In particular, the diameter of the container is between 200 mm and 900 mm, 300 mm and 900 mm, 400 mm and 900 mm, 500 mm and 900 mm, 600 mm and 900 mm, 700 mm and 900 mm, 800 mm and 900 mm, or 100 mm and 800 mm, 100 mm and 700 mm, 100 mm and 600 mm, 100 mm and 500 mm, 100 mm and 400 mm, 100 mm and 300 mm, and 100 mm and 200 mm.

[0056] The usable volume of the container is preferably between 0.5 and 400 liters.

[0057] The container is preferably pressure-resistant, so that the container is designed for pressures from -1 bar to +6 bar. Character description

[0058] An exemplary embodiment is explained in more detail with reference to the schematic drawings below, along with further details and advantages.

[0059] They show: Fig. 1 A schematic representation of a process according to the invention for treating an inner surface of a container. Fig. 2. A perspective view from a slant above of a container to be treated. Fig. 3 a side sectional view of a container according to Fig. 2, which is filled with the grinding dispersion.

[0060] In the Fig. Figure 1 shows an embodiment of a method 1 according to the invention, wherein a surface treatment is carried out on a container 7 in, for example, five process steps 2, 3, 4, 5 and 6.

[0061] The container 7 has a cylindrical shape and two circular base surfaces, which correspond to a lid 8 and a bottom 9 of the metal container 7, and has a lateral surface 10 (see. Fig. 2) In a first process step 2, an abrasive dispersion 12 is filled into an internal volume 11 of the container 7 (see Fig. 3) The grinding dispersion 12 preferably comprises liquid 13 and grinding media 14.

[0062] The liquid 13 may advantageously contain additives such as oxidizing agents or binders. The abrasive bodies 14 preferably comprise abrasives and a bonding material in which the abrasives are bound. The abrasives may have different grit sizes and hardnesses. Furthermore, the abrasive bodies 14 may be made of different materials, preferably mineral materials, and may have different shapes.

[0063] In a next process step 3, the filled container 7 is rotated about a rotation axis D and tilted by a tilting angle α to the horizontal H (see. Fig. 3) In this process step 3, the container 7 can first be tilted and then rotated, or first rotated and then tilted, or the tilting and rotation can take place simultaneously.

[0064] In this embodiment, the axis of rotation D is a cylindrical axis, which represents an axis of symmetry of the container 7. The cylindrical axis passes through the centers of the bottom 9 and the lid 8 of the container 7. The tilting angle α is preferably in the range of 10 to 60°.

[0065] When the container 7 is rotated around the axis of rotation D, the container 7 is advantageously moved relative to the grinding bodies 14, which causes an abrasion of material on the inner surface of the container 7 (see figure). Fig. 3) The abraded material is advantageously bound by the liquid 13, the binding of which can be improved, for example, by binders in the liquid 13. By tilting and rotating the container 7, the inner surfaces of the container 7, which are in contact with the abrasive dispersion 12, are abraded predominantly uniformly. Advantageously, the outer surface 10 and the bottom 9 of the container 7 are abraded in particular.

[0066] In a next process step 4, the rotation about the axis of rotation D of the container 7 is stopped and the container 7 is tilted back by the tilting angle α into its vertical starting position (see Fig. 1) Here, the rotation can be stopped first and then the container 7 is tilted back into its starting position, or the container 7 can be tilted back into its starting position first and then the rotation can be stopped, or the steps can happen simultaneously.

[0067] In a further process step 5, the container 7 is preferably completely emptied, whereby the liquid 13 is removed from the container 7 along with the grinding media 14 and the removed material. Advantageously, at least some of the grinding media 14 can be reused for further surface treatment processes 1.

[0068] To remove the finely abraded material from the container 7, the container is preferably cleaned in a further process step 6 after the container 7 has been emptied (see Fig. 1) Container 7 is cleaned, for example, with ultrapure water and / or hygiene agents.

[0069] It is also conceivable to rotate the container 7 by 180° perpendicular to the axis of rotation D before emptying, in order to be able to machine the lid 8, in particular with process step 3.

[0070] It is also conceivable to process the inner surface sequentially with different grinding dispersions 12 in order to achieve desired surface qualities. Reference symbol list 1 Procedure 2nd process step 3. Procedure step 4. Procedure step 5. Procedure step 6. Procedure step 7 containers 8 lids 9 Floor 10 Surface area 11 Internal volume 12 Grinding dispersion 13 Liquid 14 grinding wheels H Horizontal D axis of rotation α Tilt angle

Claims

[1] Method (1) for the surface treatment of an inner surface of a container (7), wherein in a first method step (2) the container (7) to be treated is filled with an abrasive dispersion (12) comprising abrasive particles, wherein in a method step (3) following the first, the filled container (7) is tilted by an angle (α) of 10° to 60° to the horizontal (H), and the filled container (7) is set in rotation in a method step (3) following the first, wherein the method (1) for the surface treatment of the container (7) is combined with an electropolishing process, wherein the electropolishing process takes place after the surface treatment, wherein a liquid or solid oxidizing agent is added to the abrasive dispersion, which helps to achieve a passivation layer on the inner metallic surface, wherein the container (7) is a hollow cylinder and comprises a base (9), a lid (8), and a casing,wherein in a method step (3) the container (7) is rotated about an axis of rotation (D) which corresponds to a longitudinal axis of the container (7), , characterized by that the longitudinal axis runs parallel to a cylinder axis and through a lateral surface (10) of the container (7). [2] Method (1) according to claim 1, characterized by that in a process step (2) the container (7) is filled to 30-70% with the grinding dispersion (12). [3] Method (1) according to one of the preceding claims, characterized by that in a process step (3) the container (7) is rotated around the axis of rotation (D) at a speed of 10 to 60 revolutions per minute. [4] Method (1) according to one of the preceding claims, characterized by in that in a method step (3) the speed (D) at which the container (7) is rotated is varied during the surface treatment, so that the container (7) is moved differently relative to the grinding bodies (14). [5] Method (1) according to one of the preceding claims, characterized by that in a process step (3) the direction of rotation of the container (7) is varied during the surface treatment. [6] Method (1) according to one of the preceding claims, characterized by that the grinding bodies (14) are designed in such a way that in a process step (3) the grinding bodies (14) remove material from the inner surface of the container (7) by frictional contact. [7] Method (1) according to one of the preceding claims, characterized by that in a process step (3) the removed material is absorbed in the grinding dispersion (12). [8] Method (1) according to one of the preceding claims, characterized by that the container (7) is sealed liquid-tight. [9] Container (7) which is a hollow cylinder and has a bottom (9) and a shell, wherein the bottom (9) and shell enclose an interior space (11) characterized by that in the container (7) inner surfaces of the bottom (9) and shell are treated according to a method (1) according to claims 1 to 8.

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