Aluminum tubes-production process of welded composite tube
Today we will explain the production process of toothpaste packaging/empty hand cream tubes.
The production process of the welded composite tube is mainly divided into several steps such as film (blown film), compounding, slitting, printing, and tube making.
1. Film formation
Mainly produces composite sheet outer membrane and inner membrane. In terms of mechanical properties, heat-sealing properties, and production costs, the inner and outer films of the composite sheet mainly adopt the production process of blown film.
During production, according to different performance requirements, various polyethylene particles are added to melt in a certain proportion and then blown into a film. The film can be single-layer or multi-layer.
2. Compounding
Compounding is a process in which the outer film, inner film, and an intermediate barrier material of the sheet are combined together through the adhesive layer to form a composite sheet.
There are many kinds of compounding production processes, including extrusion compounding, dry compounding, solvent-free compounding, etc. Among them, extrusion compounding is a compounding method in which the hot-melt resin is uniformly extruded onto the composite substrate (film) through an extruder, and is laminated with another substrate under pressure and cooling; It is a composite method in which it is clothed on a film, the solvent is evaporated in an oven, and then pressed with another layer of film to form a composite film or sheet.
Due to the advantages of stable performance, low production cost, and flexible specification change, extrusion lamination is the main production method for composite sheets. Since the adhesive is suitable for a wider range of materials, dry lamination can make up for the defect that extrusion lamination has low bonding strength to certain materials, so it is also used in a small amount.
3. Slitting
That is, the composite sheet with a large width is longitudinally cut into rolls of the required width according to the subsequent printing and tube making.
4. Printing
The composite sheet is printed on a flat surface. The main printing processes include letterpress printing, flexographic printing, gravure printing, etc. In addition, processes such as screen printing, and hot stamping (hot stamping) can also be used to make the printing more beautiful and interesting, and improve the welding of composite tubes. decorative effect on the surface.
In addition, there are also a small number of inner printed composite sheets on the market, and the printing process is mainly gravure printing. The production process of the inner printed composite sheet is slightly different from that of the traditional composite sheet. After the film is blown, the sheet is first printed (in printed) and then composited.
5. Tube-aluminum welding
Tube making is the final step in the production of welded composite tubes. The main process is divided into three steps. First, the pre-produced composite sheet is welded and sealed to form a tube body. The pipeline is mainly welded and sealed by high frequency, and the two longitudinal ends of the composite sheet are generally welded and sealed into a tube by lap joint, so there is a longitudinal weld on the tube.
With the advancement of the pipe-making process, the production of invisible seam welded composite tubes is also increasing. In the main tube making process, before the composite sheet is rolled, the two sides of the sheet are trimmed at a certain level, and the two sides are spliced with each other as a complementary angle (as shown in the figure below), and finally heat-melted and sealed into a tube. The thickness of the welded seam is close to that of other parts of the tube, and there will be no obvious protrusions like the lap weld, which can effectively "hide" the weld.
The second process of tube making, the production of tube shoulders, is currently mainly used in two production processes.
(1) Compression molding process
That is, the polyolefin pellets (such as HDPE) are put into the extruder screw for extrusion processing. After the shearing action of the screw, the material is melted, extruded according to certain metering, and injected into the mold with the shape of the tube shoulder set. The mold with the molten tube shoulder material enters the next process, which is combined with the tube body fixed on the mandrel, extruded, and cooled to form a tube shoulder of a set shape, and the tube shoulder includes an opening and a thread on the outside of the tube head. The advantage of this process is that the tube body and the tube shoulder are integrated, the bonding strength between the tube shoulder and the tube body is more stable, and the appearance is natural. The disadvantage is that compression molding and cooling take more time, which affects the speed of tube making;
(2) Welding and sealing process of pipe shoulder
That is to say, the pipe shoulder is prefabricated by the injection molding process before making the tube, and it is directly heated and welded with the tube body when the tube is made. This saves the time of injection molding and cooling and improves the speed of tube making, but the stability and appearance of the adhesive strength of the tube shoulder are reduced to a certain extent.
6. Caps-plastic tubes with caps
The final process of tube making is to cover the prefabricated tube cap. After the cap locking equipment, it is screwed or positioned and pressed with the mouth/nozzle of the tube, and finally, a welded composite tube is produced.
Welded composite tubes have become widely used and now dominate the packaging of personal care products such as toothpaste. In the field of cosmetics, including hand cream, facial cleanser, conditioner, face cream, hair dye, hair removal cream, gel cream, and other products; in food, including a variety of sauces, condensed milk products; in medicine, including hemorrhoid cream, Burn ointment, eye ointment, etc.; other types of products such as pigments, shoe polish, etc. are used more and more. With the emergence of the existing advantages of welded composite hoses, as well as various new technologies and new products that are still emerging, the application prospects of welded composite tubes will be broader.
