SU718178A1 - Method of obtaining polymeric coat - Google Patents

Description

(54) METHOD FOR OBTAINING A POLYMER COATING

The invention relates to methods for producing surfacing materials from dispersed polymers and Materials on their 6s1kb ve, which can be used predominantly to obtain coatings from thermoplastic polymers having a high melt viscosity, and consequently, reduced film-like ability (for example, fluoroplastics). It is known that the acceleration of the process, the film formation is the primary technological problem in the preparation of powder polymers. First of all, this is due to the fact. that long-term film formation in air entails the developing thermal aging of the polymer coating, and, consequently, the deterioration of its physical and mechanical properties. Therefore, it usually tends to reduce the formation time of the coating and use various methods of compaction of powder coatings. They recommend the introduction of plasticizers into the starting materials, suggest that the formation of coatings should be carried out in a liquid inert to the polymer, or in a gas barrier under excessive pressure l. In accordance with the known inventions C2}, the application of the coating against the oxidative effect of air on the formation stations is considered an independent task and is ensured by the fact that the process of applying and subsequent melting of the polymer coating is carried out in vacuum. Oxidation reactions that occur during the formation of surfacing coatings under normal conditions (in air) cause destruction of the Polymer, which leads to a decrease in the melt viscosity and, consequently, acceleration of the film. Thus, from the point of view of spelling formation acceleration, the use of a non-oxidizing environment for the formation of polymer coatings or the introduction of an equilibrium term is not always effective. The most close to the described by technical essence and achieved by re. , 3 7 sutatt a method of obtaining a pogameric coating by spraying a powder of a thermo-plastic polymer on a metal substrate with an increasing immersion into a liquid medium inert to the polymer and heated above the ireMnepatypibi polymer melt to melt the last C3. However, this method has the following. grievances; the melting of the dispersed polymer in a liquid is accompanied by the formation of gas inclusions (bubbles) and their subsequent blocking in the coating volume. The presence of this type of porosity leads to the formation of defective coatings, significantly impairs the coalescence of polymer particles, and, consequently, reduces film formation. The purpose of the invention is the acceleration of the process of formation. This goal is achieved by the described method of producing polymer pitch snag consisting in spraying thermoplastic polymer powder on a metal substrate, followed by immersion in an inert medium to the polymer and heated above the melting point of the polmer — molten metal alternating with vacuum processing. The proposed method is achieved due to uniformly distributed excess pressure applied to the coating with the molten metal, as well as due to Allen at evacuation of gaseous inclusions from the coating during its periodic recovery id melt. . Example 1. The formation of fluoroplastic (fluoroplastic-3) materials on plates made of steel (Art. 3, GOST 380-71) and Ml grade copper is carried out on the plates. The dimensions of the plate are 7OxOx2 mm under periodic action of a low (10 mm vacuum). and increased pressure (PAC-40). The product, with a pre-applied vibratory powder coating method, is placed in the pumped volume and upon reaching a pressure of 10 mm Hg. Using a special tool, the steel is periodically immersed in the POS-4O melt, the temperature is maintained at 525 K. The reduced pressure is created in the working volume of the vacuum drying cabinet HS-0.035, continuously pumped out by a mechanical vacuum pump HV-416 M, The con- trol and vacuum measurement is performed by the instrument. WIT-2. The cooling of the coating at the final stage is carried out in the course of the procedure. The coatings obtained are characterized by good continuity. The formation time of the coating is 60 s. To obtain comparative data, coatings are formed in parallel on similar substrates in vacuum. (1-batch) and POS-40 melt (2-batch) with all other conditions being identical. On substrates of the 1st batch of coating, satisfactory solid was obtained in only 6 seconds. The products of the 2nd batch of coatings cannot be obtained (there is a decrease in gas-saturated coatings.). Thus, the use of alternating underpressure and overpressure formation of the fluoroplastic coatings allows to reduce the total formation time by 10 times. PRI mme R 2. In Example 1, the formation of polyethylene (polyethylene grade 21006-075 GOST 16338-70) coatings pre-applied by a vibro-vortex method on the inner surface of aluminum pipes (inner diameter of 47.5 mm, outer-50 , 5mm, pipe length - 70 mm). The pipe is fixed in a horizontal position and immersed in the POS-40 melt, which is under vacuum, to a depth equal to its longitudinal axis, ensuring the continuous process of simultaneously proceeding monolithizing the coating and removing gas inclusions from its volume. At the same time, the formation time of the coating is about 25 seconds, the resulting coatings are free from gas inclusions and have a good appearance. Coatings obtained using a combination of media melt POS-40 air, were oxidized; the formation time required to provide a satisfactory continuity of the coating is about 60 seconds. Thus, the use of the proposed method for producing coatings in comparison with the known methods for producing coatings in vacuum and in liquid has the following advantages: it allows to significantly speed up film formation and, consequently, to increase the productivity of the process for producing coatings, without degrading their quality.

 7181786

invention formula Sources of information.

The method of obtaining the polymer coated is taken into account in the examination by spraying a powder of a thermoplastic polymer onto a metal sub-1. USSR author's certificate spoon with the subsequent immersion in an ere- jN 352966, cl. C 25 D 13 / 00.22.03,71. inert to polymer and heated up

melting point of the polymer, about t l and-2. Japan Patent No. 21710,

that with the purpose of usko-cl. 24 H 411, 1968.

rennie film formation, as a medium3. USSR author's certificate

use the molten metal and immersion V O5 L 3/02, 01/18/68

6, the melt alternate with processing, in vacuum. (Prototype).

Claims (1)

Claim A process for preparing the polymeric coating by spraying powder of a thermoplastic polymer on a metal substrate, followed by immersion in ₅ sre- row, inert to the polymer and heated above the melting temperature of the polymer, of t πη4 and w and d w i with the fact that, in order to accelerate film formation, as a medium, a molten metal is used and immersion of the ή molten metal is alternated with processing in a vacuum.