Blow needle

The type of molding machine available has an important influence upon the blow opening system used. Some machines, for instance, use needle blowing exclusively. Hollow needle insertion at the mold parting line is considered when a very small opening is required that may even need closing or if the hollow object must be blown up on the side, e.g., on carousels with a series of molds. 

The needle blow method Is also used for squeezed canister handles. A separated blast chamber Is necessary so that no filling material can sediment (environmental protection). It Is therefore Important that the area where the needle enters Is less and regularly stretched to ensure clean, reproducible production. 

If for any reason it is foxmd to be impossible to blow out the end of the tube, the cut end of a capillary can very often be opened out by using a mormted needle from a set of dissecting instruments as a tool but this is not recommended if the tube can be blown. 

A manufacturing method predominately used by the thermoplastic industry for the manufacture of hollow components, also used for thermosetting rubber. The polymer is forced against the inside of the mould surface by gas pressure applied either by a hollow needle or by the decomposition of a blowing agent. 

Fig. 1.10. Transfer of air-sensitive liquids from metal cylinders, (a) A three-way metal stopcock constructed for use with syringes may be modified by the addition of a threaded fitting so that it mates with a lecture bottle. The side inlet is used to purge the apparatus initially and to blow liquid out of the syringe needle at the completion of the transfer. The cylinder is put under a low pressure of inert gas before the transfer is begun, (b) Sometimes air-sensitive liquids are sold in siphon-type cylinders, and the liquid from such a cylinder can be dispensed as shown here. As with the previous example, inert gas is used to force the liquid out of the cylinder.

In 1959 Strehlow and Becker developed a pressure-jump apparatus that enclosed a conductivity cell containing the reaction solution, and a reference cell under xylene in an autoclave. The reaction and reference solutions were pressurized to about 6.1 MPa with compressed air. By the blow of a steel needle, a thin metal disk used to close the autoclave was punctured and the pressure was released within about 60 s. 

In principle, the gas-assisted injection molding process is similar to co-injection molding. Here, the second or core component is nitrogen, which is injected through a needle into the polymer melt, blowing the melt out of the way and depositing it against the mold surfaces. 

In the intratracheal administration a polyethylene tube previously filled with DDT powder was inserted through a large needle directly into the trachea. The powder was expelled by blowing air through the tube with a large syringe. The other methods of administration were an oil solution in a capsule direct into the rumen, an oil solution direct into the jugular vein, or pelleted alfalfa hay which was exposed before harvest. 

Beilstein Handbook Reference) AI3-02247 BRN 1912251 Dimethyl 1,3-benzenedi-carboxylate Dimethyl isophthalate Dimethyl m-phthalate Dimethylester kyseliny isoftalove EINECS 215-951-9 HSDB 6138 Isophthalic acid dimethyl ester Methyl 3-(carbomethoxy)benzoate Methyl isophthalate Morflex 1129 NSC 15313 Uniplex 270. Chemical intermediate in the synthesis of polyesters. Used as a plasticizer, modifies clarity and melting point of PET resins used in films, blow-molded bottles, and similar products. Needles mp = 67.5° bp = 282° d = 1.194 Xm = 280, 288 nm (MeOH) slightly soluble in H2O, Morfiex Unitex. 

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