Toothpaste tubes

Current usage is almost entirely associated with the good adhesion to aluminium. Specific applications include the bonding of aluminium foil to plastics films, as the adhesive layer between aluminium foil and polyethylene in multilayer extrusion-laminated non-lead toothpaste tubes and in coated aluminium foil pouches. Grades have more recently become available for manufacture by blown film processes designed for use in skin packaging applications. Such materials are said to comply with FDA regulations. 

While EVOH is of interest primarily for food packaging applications attention is now being turned to non-food outlets such as automotive fuel tanks, floor heating pipes and toothpaste tubes. 

Many polymers are used in barrier applications, either to keep contents in or contaminants out. Food packaging is an excellent example of such usage. Plastic films and containers of many types are used to package food. Blow moldedbottles often contain numerous layers, each of which provides specific benefits. Polyethylene layers are excellent water barriers, polyvinyl alcohol is a good oxygen barrier, and polyethylene terephthalate impedes the diffusion of carbon dioxide from carbonated drinks. Other barrier applications include toothpaste tubes, diaper backsheets, tarpaulins, and geomembranes, which are used to line containment ponds and landfill pits. 

Aluminum is very malleable, as anyone can see from the thin rolls of aluminum foil (sometimes wrongly called tin foil ) used in modem kitchens. Toothpaste tubes are made of aluminum, and so are many toys and various parts of cars. There is even an artificial ruby made of a compound of aluminum, used in jeweled watches. Aluminum does not corrode, and so it is used for kitchenware and for many items in the construction industry. Because aluminum is light, it is used a great deal in airplane construction. 

Explosive Toothpaste consisted of a toothpaste tube filled with 4.23 oz of a mixture of RDX 80.2 mineral oil with wax 19.8% and provided with an Igniter (p 258, Fig 195)... 

Cragg, P. J., Allen, M. C., Steed, J. W., A toothpaste tube model for ion transport through trans- membrane channels. 

Over the years letterpress printing has declined into niche markets, two of which are the printing of plastic self-adhesive labels on narrow-web rotary-offset letterpress machines that are fitted with UV drying and the common-impression rotary-offset letterpress and UV-curing on mandrel of plastic containers such as yoghurt tubs and toothpaste tubes. In uses such as these the most common self-adhesive plastic is PVC and the most usual for tubs and tubes are polystyrene, PVC, ABS, and polypropylene. 

Gather these materials Powdered calcium carbonate (CaC03) powdered orris root sodium bicarbonate (NaHC03) essence of peppermint an empty toothpaste tube a small bowl a teaspoon a pair of heavy-duty scissors and an eye dropper. 

Follow this procedure Straighten the toothpaste tube. With the scissors, cut off the flat bottom end of it. Rinse the tube out very carefully, including the cap. Replace the cap but pull the other end apart to make a wider opening. Set the tube aside to dry. In the small bowl, mix 2 teaspoonfuls of powdered calcium carbonate and 2 teaspoonfuls of powdered orris root. Add teaspoonful of sodium bicarbonate and 3 drops of essence of peppermint. Add water to this mixture, a drop at a time, stirring it constantly until a paste forms. Put the paste into the empty tube by the teaspoonful. Before trying to squeeze the toothpaste from the tube, close the open end by folding it up several times. 

The degradation of HDPE pellets and toothpaste tube laminate was performed at a range of temperatures between 450 and 700°C using the equipment shown in Figure 21.3. Details of the experimental method can be found elsewhere [85]. 

As mentioned in Section 2.2.1, the recovery of clean aluminium from real plastic-containing wastes has been one of the main focuses of the research into microwave pyrolysis. With the semi-batch apparatus shown in Figure 21.3, experiments were performed using toothpaste tube laminate and depulped drink carton laminate (a Tetra Pak ... 

Figure 21.6 From left to right original laminate, recovered condensable products and recovered aluminium. Top row, toothpaste tube laminate. Bottom row, depulped drink carton...

A gas can have considerable pressure. The pressure of the gases surrounding Earth, the atmosphere, crushed the soda bottle. The soda bottle could not be crushed when it was full, but was easily crushed when the air pressure was reduced on the inside. So why aren t we crushed when we exhale Or for that matter why are we able to stand upright The reason is that the pressure of the air is pushing in on us on all sides equally. If it were pushing only on the top of our heads, then yes, we would have a problem. The same principle applies to toothpaste tubes. You can squeeze out toothpaste only if you apply pressure to the middle or bottom. If you apply pressure equally to the bottom and the opening, the toothpaste stays in the tube. 

Films of EAA are also used in flexible packaging of meat, cheese, snack foods, and medical products in skin packaging and in adhesive lamination. Extrusion coating applications include condiment and food packages, coated paperboard, aseptic cartons, composite cans, and toothpaste tubes. FDA regulations permit use of up to 25% acrylic acid for copolymers of ethylene in direct food contact. 

Uses For extrusion coating applies, incl. foil-containing shampoo, toothpaste, towelette, condiment, and misc. non-food pouches and sachets, snack structures, toothpaste tubes, cable shield wrap, aseptic and hot-filled cartons other foil, metalized film, or paper coatings as heat seal or tie layer food-contact polymers Regulatory FDA 21 CFR 177.1330 compliant Properties Pellets sp.gr. 0.93 melt flow 10.0 dg/min f.p. 84 C m.p. 103 C Vicat soften, pt. 86 C 8.7% methacrylic acid Precaution Do not use in medical applies, involving permanent implantation in human body Nucrel 1214 [DuPont]... 

In extrusion, a pliable substance is given a shape by being pushed through an opening. Toothpaste is extruded from a toothpaste tube. 

Blowing can be considered as a special form of stretch forming from annular nozzles producing unbroken, continuous hollow bodies, which are used as such or else cut into film afterward. Blowing also enables hollow products of two components to be produced, e.g., toothpaste tubes, which consist of polyamide outside and poly(ethylene) inside. 

When two pieces of plastic must be joined together in service but must also be suited to simple disassembly, threaded joints are possible. Such joints may be plastic to plastic, as in toothpaste tubes and caps, where male and female threads are molded. If metal screws are to be used, female threads can be molded in a plastic part to accept the metal screw. If such a threaded application does not have to withstand much tension in the screw, a selftapping screw may be turned into a molded hole of appropriate diameter. Self-tapping screws designed for plastics applications are better suited than those for metal appUca-tions. Metal female-threaded inserts may be molded into plastic parts to accept metal screws in a subsequent assembly operation. Metal female-threaded inserts may also be staked into a molded hole of appropriate size, sometimes mechanically, often with heat ( heat staking ) to soften the thermoplastics at the interface so as to achieve more positive bonding (Figs. 9.16 and Fig. 9.17). 

To put it more simply, in the case of the toothpaste tube, the toothpaste is squeezed out only for as long as we squeeze the tube. 

Contrast the manufacture of toothpaste tubes from aluminum and polymeric material. 

The toothpaste, honey and water all have different viscosities. The toothpaste is the most viscous, the water the least. Viscosity represents the resistanee to flow. In viseous flow, a material continues to deform as long as a stress is applied. To put it more simply, in the ease of the toothpaste tube, we can squeeze out the toothpaste for as long as we squeeze the tube. 

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