RU2678051C2 - Method of producing material for manufacturing panels of sound shields by extrusion method - Google Patents

Abstract

FIELD: technological processes.SUBSTANCE: extrusion of a mixture of isotactic polypropylene with a m-phenylene-bis-maleimide based modifier is performed. The extrusion product is cooled, cut into pellets and dried. The granulate is mixed with isotactic polypropylene and fibrous filler. The mixture is extruded. The extrusion product is cooled, cut into pellets and dried. Fibrous filler is a basalt fiber treated with a water-compatible silane-containing lubricant.EFFECT: improvement of physical and mechanical properties of panels of sound shields.1 tbl, 4 ex

Description

The invention relates to a technology for the manufacture of noise barriers installed along roads, railways, around industrial facilities and other noise sources.

The effectiveness of sound-absorbing screens is determined by the sound-absorbing and sound-insulating properties of the materials from which they are made, as well as their physical and mechanical properties, in particular: mechanical strength, resistance to stone shocks, protection from electric shock, which, in turn, depend both on the composition of the starting ingredients and on the method of manufacturing the product. Panels made by extrusion, unlike those made by casting, are strictly identical in thickness at all points, have an even end. The advantage of the extrusion method is high productivity and the ability to obtain products of continuous length. However, during the extrusion process, the starting material is exposed to high temperatures and shear stresses, which leads to a change in the structure of the components and technological properties of the material and can have a negative effect on the physicomechanical properties of the resulting product. In this regard, special requirements are imposed on the composition of the material intended for extrusion molding, and, consequently, on the conditions of the method for its production.

A known method of producing material for the manufacture of panels of noise barriers by extrusion by mixing polymethylmethacrylate obtained by extrusion polymerization with a fibrous filler - polyamide filaments (EP 1606457 B1).

However, panels made by extrusion of material obtained in a known manner have sound-reflecting properties, which is unacceptable due to the high noise level directly on the highways.

Closest to the proposed invention is a known method of obtaining material for the manufacture of panels of sound-absorbing screens by extrusion, comprising mixing isotactic polypropylene and a fibrous filler (DE 102012100567 A1). As a fibrous filler, lignocellulosic fibers are used in an amount of 50-85% by weight of the composition.

The disadvantage of this method is the low physical and mechanical properties of the panels of sound-absorbing screens.

An object of the invention is to provide a method for producing material for the manufacture of panels of sound-absorbing screens by extrusion, devoid of this drawback.

The technical result of the invention is to improve the physico-mechanical properties of the panels of sound-absorbing screens.

The specified technical result is achieved by the fact that in the method of producing material for the manufacture of panels of sound-absorbing screens by extrusion, comprising mixing isotactic polypropylene and a fibrous filler, basalt fiber treated with a water-incompatible silane-containing sizing agent is used as a fibrous filler, and an isotactic polypropylene-based mixture with an modifier is extruded with a modifier -phenylene-bis-maleinimide when their mass ratio is from 8.5: 1.0 to 9.0: 1.0, respectively, cool denie and cutting extrusion product into pellets, drying the resulting granulate modified isotactic polypropylene, a mixture of isotactic polypropylene and said fibrous filler with the resultant granulate modified isotactic polypropylene in the following ratio, wt. %:

isotactic polypropylene 67.0-70.0 modified isotactic polypropylene granulate 0.8-1.2 specified fibrous filler rest,

extruding the resulting mixture, cooling, cutting into granules and drying the extrusion product.

As a fibrous filler, basalt fiber treated with any water-incompatible silane-containing sizing agent is used. Such basalt fiber treated with a water-incompatible silane-containing sizing agent is commercially available or it can be prepared, for example, according to RU 2167838 C1, using sizing No. 4C (GOST R 53237-2008) or such as described in http://www.korsil.ru/ silan-zamaslivatel.html, RU 2101241 C1, RU 2389698 CI, SU 1666480 A1, etc. The treatment of basalt fiber with a water-incompatible silane-containing lubricant increases the antistaticity that prevents it from sticking together, eliminating the electrification of the fiber during friction with the extruder working bodies. The result of the use of basalt fiber as a fibrous filler, treated with a water-incompatible silane-containing sizing agent, is an increase in the physicomechanical properties of the panels of sound-absorbing screens made of the material obtained by the proposed method.

Another factor that improves the physicomechanical properties of panels of sound-absorbing screens made of the material obtained by the proposed method is the stage of extrusion of isotactic polypropylene with a modifier based on m-phenylene-bis-maleimide with a weight ratio of 8.5: 1.0 to 9.0: 1.0, respectively, followed by cooling the resulting product, cutting it into granules and drying to obtain a modified isotactic polypropylene granulate. As a modifier, any modifier based on m-phenylene-bis-maleimide can be used (Chemical additives to polymers. M, Chemistry, 1981, P.177-178; RU 2569544 Cl; http://libweb.kpfu.ru/z3950 /EPOS_ESIC/Halikova_komp.pdf and others).

The result of extrusion of a mixture of isotactic polypropylene with a modifier based on m-phenylene bis-maleimide is a product - a granulate of modified isotactic polypropylene, the physico-mechanical and technological properties of which differ from the properties of the product obtained by simple mixing, since during the extrusion of the initial components are exposed to high temperatures and shear stresses, which contributes to a change in their structure as a result of ongoing mechanochemical processes. At the next stage of the material production process, the modified isotactic polypropylene granulate undergoes a second extrusion and granulation cycle, and then, in the manufacture of sound-absorbing screen panels, to the third extrusion cycle (unmodified isotactic polypropylene in the manufacture of panels undergoes a second extrusion cycle). It is known that repeating extrusion cycles lead to significant changes in the molecular structural characteristics of vinyl polymers, which include polypropylene (http://www.dissercat.com/content/izmeneniya-struktury-i-svoistv-polimerov-vinilovogo-ryada-pri -mnogokratnoi-ekstruzii). As experiments showed, these changes lead to an improvement in the physicomechanical properties of the panels in the entire scope of the claims that limit the conditions of the proposed method for producing material for the manufacture of panels of sound-absorbing screens.

Example 1

A dry mixture of isotactic polypropylene with an industrial Maleid F modifier according to TU 6-14-1004-87 (http://ntcp.ru/work/library/5103/5211) with their mass ratio of 9.0: 1.0, respectively, is passed through extruder at a maximum melt temperature of 200 ° C. The strands extruded from the extruder with a diameter of 3-4 mm are cooled in a water bath and cut into granules 3-4 mm long. The obtained granulate of the modified isotactic polypropylene is dried at a temperature of about 80 ° C for at least 2 hours. The obtained granulate, isotactic polypropylene and basalt roving treated with a water-incompatible silane-containing sizing agent manufactured by Kamenny Vek LLC (http://www.b-composites.net/26.html) are fed to the extruder in the following ratio of components, wt. %:

isotactic polypropylene 69.0 granular isotactic extrusion product polypropylene with modifier based on m-phenylene-bis-maleinimide 1,0 fiberfill rest

The process is carried out in a twin-screw extruder with a screw diameter of 60 mm and a length to diameter ratio of 15 at 240-245 ° C. Strands with a diameter of about 4 mm emerging from the extruder are cooled in a bath with water and chopped on a granulator into segments 3-5 mm long. Then the obtained granules of the material are dried in a drum-type vacuum dryer at 75-85 ° C and a residual pressure of 0.4-0.6 kgf / cm ^{2 for} at least 4 hours. The resulting material is stored in a sealed container.

The panels of sound-absorbing screens in the form of profiled sheets with a thickness of 3 ± 0.1 mm and a width of 500 ± 1 mm are made by extrusion using a single-screw extruder, at the output of which a profiling die is installed. To facilitate the extrusion of profiled sheets, the dried granules of the material are poured into a dry mixing mixer (concrete mixer), castor oil is added in an amount of 1% by weight of the granules and mixed for 30 minutes. Then the resulting mixture is loaded into the feed hopper of the extruder.

The test results of the obtained samples of panels of sound-absorbing screens showed a noise reduction of 40 dBA, which confirms the possibility of realizing the purpose of the proposed method.

Example 2

The process is carried out as in example 1, but as a fibrous filler using unprocessed sizing basalt roving.

Example 3

The process is carried out as in example 1, but without the stage of obtaining granules of modified isotactic polypropylene. The ratio of components supplied to the mixing and subsequent extrusion is, wt. %: isotactic polypropylene - 70, basalt roving treated with a water-incompatible silane-containing lubricant, produced by Kamenny Vek LLC (http://www.b-composites.net/26.html) - 30.

Example 4

The process is carried out as in example 1, but without the stage of producing granules of modified isotactic polypropylene, and basalt roving that is not treated with a sizing agent is used as a fibrous filler. The ratio of components supplied to the mixing and subsequent extrusion is, wt. %: isotactic polypropylene - 70, basalt roving - 30.

In addition, comparative tests were carried out on samples made according to the procedure of Example 1 from a material obtained by the method according to DE 102012100567 A1 (prototype), using wood shavings as a fibrous filler.

The physical and mechanical properties of the samples obtained in examples 1-4, and the results of comparative tests demonstrating the achievement of a technical result, are shown in the table.

Claims (3)

A method of obtaining material for the manufacture of panels of sound-absorbing screens by extrusion, comprising mixing isotactic polypropylene and a fibrous filler, characterized in that basalt fiber treated with a water-incompatible silane-containing lubricant is extruded as a fibrous filler, and a mixture of isotactic polypropylene with a bis-phenyl modifier is extruded -maleinimide when their mass ratio is from 8.5: 1.0 to 9.0: 1.0, respectively, cooling and cutting into product granules extrusion, drying the obtained granulate of modified isotactic polypropylene, mixing isotactic polypropylene and said fibrous filler with the obtained granulate of modified isotactic polypropylene in the following ratio of components, wt. %: isotactic polypropylene 67.0-70.0 modified isotactic polypropylene granulate 0.8-1.2 specified fibrous filler rest, extruding the resulting mixture, cooling, cutting into granules and drying the extrusion product.