RU2739570C1 - Method of manufacturing of dimensional items from thermoplastic - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to a method for manufacturing dimensional articles from thermoplastics. Technical result is achieved by the method of making dimensional items from plastic, which includes heating in a high-frequency electromagnetic field of a workpiece of plastic, assembled from sheets, films obtained by rolling or calendering of waste thermoplastic wastes. Workpiece billet is pressed in a form which is transparent for electromagnetic waves and the article is made from plastic monolith without internal temperature and shear stresses.

EFFECT: technical result is exclusion of temperature deformation due to residual stress of finished products.

5 cl, 2 dwg

Description

Thermoplastic polymers now make up the majority of plastic waste. The volume of this waste has become environmentally threatening, thanks to their own operational advantage - LONGEVITY. The technological advantage of such materials is the ability to be repeatedly formed.

A significant part of plastic waste is recycled in the production of plastic products themselves. But even in these industries, waste is generated that cannot be recycled under the conditions of existing industries - these are ingots from the run of material on forming machines.

The main part of polymer waste is made up of products that have lost their consumer qualities. Their preparation for re-processing is the most costly and consists of the stages of collection, sorting, crushing, cleaning, using detergents, drying, possibly with a granulation stage, since the granular material has several technological advantages in the molding process.

But the re-processing of thermoplastics leads to a change in the structure and properties of the material, the more so, the greater the frequency of processing. This process is out of our control. With an increase in the multiplicity, processing costs grow, the yield of products of satisfactory quality decreases. At the end of such a chain of transformations, plastic waste appears unsuitable for processing by known methods. At this stage, I offer my solution.

All efforts of the authors presented in the patent search list are directed to create useful products from waste polymers. Since the existing methods of polymer processing are based on heating from the surface of the material into the bulk of the material (whether it is a particle, granule, or an array of material), on a heating rate gradient, and when molded in the reverse cooling process, on a cooling rate gradient. It is difficult to create products with such methods that are large in mass and volume without non-melted joints; polymers call this "cold junctions" - these are the places where the product breaks during operation.

In the proposed method, the material loaded into the mold is heated in an electromagnetic field of high frequency, the heated material is then molded. High-frequency heating is used due to the properties of the polymers themselves, the impurities present in the waste; in addition, it is possible to use preliminary pollination of the layers of the pressing mass with powder or sawdust from magnetoactive materials, and introduce reinforcement. In this way, plates can be obtained that are practically unlimited in length and height.

High-frequency heating will make it possible to form large-sized products with an almost uniform temperature field, and this will avoid thermal deformation (uneven deformation due to residual stress) at the end of pressing. It is these phenomena that arise during injection or contact (surface) heating of the molded material. Internal stresses can arise only with an incorrect cooling process - fast for a given type of part.

The mold material is transparent for microwaves.

The method makes it possible to manufacture such dimensional products from thermoplastics, which are unrealistic to be produced by other modern methods. And also to mold waste plastic to such a degree of contamination that is unsuitable for other methods due to the rapid wear of equipment and accessories.

The method is intended primarily for processing waste thermoplastics, but is applicable to primary thermo- and thermosetting plastics.

A package of sheets and films is better suited as a blank for molding. Then, typing a package of sheets of various properties, you can modify the quality of the final product - additive technology. You can modify product properties using a set of workpiece layers and a sequence of workpiece sections.

Blank sheets are obtained by rolling or calendering of plastic waste, pre-sorted by type. When loading the mold, shredded plastic can also be used.

If the workpiece is obtained in the process of winding the film, then, by supplying high-frequency heating in the form of a point, mesh or in the form of a spot, it is possible to obtain areas of stiffness, elasticity or high elasticity - to simulate a “bird's wing”. The method is especially applicable if the film contains functional groups that can be initiated for crosslinking.

The proposed method makes it possible to exclude washing and drying of polymer waste, to exclude granulation, and to minimize the grinding process. Thus, to preserve strength and durability in a product under the influence of natural factors - all those positive performance qualities that the developers of primary materials tried to create.

The most effective method may be in road construction.

Plates in the form of "aqueducts" (an approximate diagram is shown in Fig. 1), laid under the roadbed, will ensure the flow of groundwater without washing out and subsidence of the roadway, the roots of plants will give the opportunity not to tear the pavement.

Due to locks of any design, the slabs are connected to a platform of any size - a "dry platform".

When constructing a road from the river bank, with the appropriate design and the shape of the slabs, excess water can be diverted to areas requiring irrigation. This will prevent or reduce flood damage.

The method is suitable for the manufacture of bumpers that enclose a motorway. The existing bump stop is used as a reinforcement; a polymer mass is fused onto it, which can partially absorb shock and serve as a protective coating against corrosion.

Given the durability of polymers, moisture and chemical resistance, it is possible to use them to create a protective coating in the manufacture of sleepers. Due to locks of any design, the slabs are connected to a platform of any size - a "dry platform".

The method is suitable for the manufacture of slabs (sheets) that cover road slopes from storm damage. And also for other structures that improve the performance of highways.

Literature applied

Kargin V.A., Slonimsky G.L. Brief essays on the physicochemistry of polymers, Moscow, 1967

Tager A.A.Physical chemistry of polymers, ML 967

Encyclopedia of Polymers, M. 1974-1977

V.K. Zavgorodniy Mechanization and automation of plastics processing, M., 1970

Claims (5)

1. A method of manufacturing large-sized plastic products, based on the ability of plastic to heat up under the action of a high-frequency electromagnetic field and subsequent molding, then a plastic blank, assembled from sheets, films obtained by rolling or calendering of thermoplastic waste, is heated in a high-frequency electromagnetic field, pressed in a mold , transparent to electromagnetic waves, and a product is obtained from a monolith of plastic without internal temperature and shear stresses. 2. The method according to claim 1 is characterized in that the workpiece is collected from sheets, films, purposeful additives, reinforcement are introduced into it, and a layer-by-layer modified product quality is obtained. Z. The method according to claim 2 differs in that the workpiece is collected not layer by layer, but by successive sections with different properties. 4. The method according to claim 1 is characterized in that the electromagnetic field is applied not uniformly, but in a dotted manner, with a mesh or a spot, then elasticity, elasticity or stiffness areas are obtained in the product, new possibilities are obtained in products made from films with functional groups. 5. The method according to claim 3 is characterized in that functional additives are applied to the film regions and then an article with a given topography of functions is obtained.

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