WO2008118034A1 - Activated mineral scale or flake-like filler for composite materials - Google Patents

Abstract

The invention relates to activated mineral scale or flake-like filler for composite materials (platelike) fillers and can be used for producing different composite materials. The inventive mineral filler of a basalt group (scale, flake-like) is obtained by melting a pre-ground and pre-heated to a temperature of 250-900°C initial mineral, by forming solid particles from a melt, the viscosity of which ranges from 30 to 100 poises, and by exposing the thus obtained particles to thermochemical and mechanical treatment in air for 5-30 min which could be optionally associated with a simultaneous air blasting process. Melting is carried out at a temperature of 1250-1500°C, forming being carried out by dispersing a thin layer of melt or by crushing a melt jet by means of a cooling air flow.

Description

 Activated mineral flake or flaky filler for composite materials.

Description.

Purpose of the invention.

The invention relates to activated, mineral fillers from natural materials of the basalt group (basalts, andesitobasalts, andesites, gabbro, etc.), which can be used in the chemical and electrical industries of building materials, in shipbuilding and automotive, Machine and aircraft building, as well as other areas of the national economy.

In particular, flake fillers from a mineral melt are used both for applying thin-layer coatings to objects for various purposes with the aim of protecting them from corrosion and abrasive wear, and in the manufacture of chemically resistant and durable composites, heat-insulating materials, roofing materials, papers and other products and composite materials.

Background of the invention and prior art.

Three main types of rock composition of the basaltic group are known.

The first type is the composition of the rock enriched in Fe and Ti oxides (~ 70% Fe ₂ O ₃ and 20% TiO ₂ ). The second type is basalt rocks enriched with Al and Si oxides (~ + 25% Al ₂ O ₃ and 55% SiO ₂ ) and the third type is basalt rocks enriched with Mg and Ca, Fe (~ 12% MgO and ~ 20% CaO , 10% Fe ₂ O ₃ ). All these compositions are designed to produce basalt filler, both in the form of fiber, and in the form of flakes, flakes (lamellar filler).

The use of highly silicate inorganic fibers from natural materials as raw materials makes it possible to produce environmentally friendly, weather-resistant, replacing in many cases asbestos, glass, metal, wood and other materials used in construction. Therefore, the need for these materials is increasing.

Numerous methods for producing highly silicate are known from the existing prior art. inorganic continuous, staple and coarse rock fibers.

So from RU 2102342, 01/20/1998, a method for producing continuous fiber from rocks is known, including the operations of crushing the rock, melting it in a smelting furnace and drawing continuous fiber from the melt through a die. The rocks of the basalt group from the main to the middle composition are used as rocks in the described method, and the temperature in the melting furnace is set in the range of 1500-1600 ⁰ C.

The fibers obtained by the described method have insufficient tensile strength due to the presence of foreign inclusions, the melting temperature of which is higher than the melting temperature of the bulk of the rock.

High-silicate inorganic fibers obtained from rock previously crushed in a melting furnace, where it is melted, melt homogenized, subsequent stabilization of the melt in the feeder of the melting furnace, fiber drawing, its oiling and winding on a bobbin, are known from UA 10762, 12.25.1998. .

However, such continuous fibers obtained from andesitic rock have insufficient tensile strength due to the presence of foreign inclusions in them that are not removed from the melt due to insufficient temperature range, limited by the boiling point of the bulk of the crushed rock. Insufficient strength leads to a decrease in the length of the fibers, their breaks when winding on a bobbin, which limits the technological capabilities of the method.

From the monograph Dzhigiris D.D., Volynsky A.K., Kozlovsky P.P., Demyanenko Yu.H., Makhova M.F., Lizogub G.M. Basics of technology for producing basalt fibers and their properties. (In collection of scientific works: Basalt fiber composite materials and constructions. - Kiev: Naukova Dumka. - 1980 - S. 54-81). Known staple fibers from rocks obtained from crushed rock in a melting furnace, its melting, homogenization of the melt, subsequent stabilization of the melt in the feeder of the melting furnace and obtaining staple fiber from the melt flowing from the die.

However, the staple fibers obtained have insufficient tensile strength due to the presence of foreign inclusions in them, which cannot be removed from the melt due to the rather low temperature range used, limited by the boiling point of the bulk of the crushed rock. Insufficient strength leads to a decrease in fiber length, which limits the technological capabilities of the method. It has been known for some time now that fillers with flake or plate shaped particles are a special class of reinforcing fillers.

From GB 989671, 1965, in particular, there is known a method for producing glass flakes comprising preparing a molten glass, forming separate streams from it under the action of centrifugal force, dropping them onto a fixed surface and forming a thin layer of melt when these streams move down, turning it when cooled to film of glass, crushing it with a stream of compressed air onto discrete flakes in the zone of annular blasting, their deposition and selection using vacuum.

However, due to the fact that the film is uneven in thickness, as a result, the flakes formed during its crushing are also heterogeneous in thickness and, accordingly, in elasticity.

In addition, with chaotic destruction of the film by a stream of compressed air, it is rather difficult to obtain flake material with predetermined linear sizes of flakes. The disadvantage of this method is its increased material consumption.

So, it is now quite widely known that such flakes or flakes can serve as chemically active fillers of a variety of composite materials (preferably polymerizable composites) to obtain protective and protective-decorative coatings with high atmospheric and water resistance (when protecting metal tanks, bridges, offshore drilling platforms, etc.) and / or resistance to abrasion (for example, a pipeline for pumping pulp).

Accordingly, they must satisfy a set of systematically toughening difficultly incompatible requirements, of which the most important are: the highest possible chemical activity, estimated at least by their specific surface area of flakes or flakes of active sites, which contribute to the polymerization of various oligomeric binders and the establishment of a chemical relationship between macromolecules polymers and inorganic components; the highest possible mechanical strength, which determines the closed reinforcing effect in finished compositions even at low concentrations of plate fillers; the highest chemical stability possible (in particular, corrosion resistance), which facilitates the storage of fillers and their use in many composites, usually including corrosive ingredients in the initial uncured mixtures, and their availability for a wide range of circle of consumers, determined by the possibility of mass production and the cost of resources.

Separate fulfillment of these requirements does not present significant difficulties.

For example, from US patent 4363889, CL. From 08 K 3/40, 1982, glass flakes with an average thickness of 0.5 - 5.0 microns and a diameter of 100 - 400 microns and mixtures of May 10 - 70 are known as fillers available and having some chemical activity for polymerizable composites. including such flakes from May 10 to 150. including scaly metal pigments.

Glass flakes are usually very fragile, their surface chemical activity without additional processing (for example, vacuum metallization) is small, and metal flakes with a high specific surface are not resistant to corrosion.

Lamellar fillers of the type of artificial mica-like iron oxide pigments are also known (Carter E. Maseoseus and High Rigmept High Reperformance // POLYMER PAINT COLOR JOURNAL, 1986, v. 176, JVo 4164, pp. 226, 232, 232, 232, 232, 232. Compared to glass flakes, they are more durable and chemically resistant.

However, they are expensive, which is why their use is advisable when applying protective coatings only on such products or structures whose loss from failure significantly exceeds the costs of protection.

Therefore, one of the most preferred areas for creating plate fillers for predominantly polymer composites should be recognized as the manufacture of flakes or flakes from natural minerals.

Mineral plate filler (in the form of flocculent particles) is known from RU 2036748, 06/09/1995. It was obtained by melting the starting material (basalt), molding solid vitrified lamellar particles from a melt, and chemically heat treating such particles in an oxidizing gas medium to give them a predominantly crystalline structure, including heating vitreous particles at a rate of 40 to 190 ° / min. to a temperature in the range of 600 - 95O ⁰ C with simultaneous purging with air for 5 - 30 minutes. and subsequent forced cooling at a rate of at least 950 ° C / min. The mineral plate filler after such processing practically does not contain FeO and is characterized by a high (3g / cm ³ or more) density, which is at least 1.5 times higher than the density of vitrified particles, a high (up to 53% by weight) fraction of the crystalline phase (referred to as hereinafter referred to as the degree of crystallinity))) and a noticeable number of chemically active paramagnetic centers (hereinafter - PMC). These advantages made it possible to significantly improve the properties of the polymerizable composites containing the described mineral plate filler and the protective and protective-decorative coatings obtained from them (Veslovsky PA, Efanova BB, Petukhov I.P.

Investigation of the physicochemical, thermodynamic and mechanical properties of the boundary layers of network polymers // Mechanics of Composite Materials, 1994, T.ZO, JVb 5, p. 3 - 11.)

However, later it was found that this filler has no more than 6 * 10 ¹⁹ spin / cm ³ active in the polymerization of mono and / or oligomers of the PMC (Efanova V.V. Investigation of the properties of a new activated basalt filler for coatings // Ecotechnologies and Resource Saving, 1993 , JNb 5, pp. 67 - 72). In other words, the indicated degree of crystallinity and the chemical activity of the known filler are not “balanced”.

From RU 2119506, 09/27/1980, a mineral plate filler for composite materials is known obtained by melting a starting mineral, forming solid plate-like glassy particles from a melt and chemically-heat treating them in an oxidizing gas medium to obtain a crystalline phase. According to the invention, it was obtained by chemical-thermal treatment at temperature in the range from 68O ⁰ C to 85O ⁰ C until less than 12% by weight of the crystalline phase and more than 7 * 10 ¹⁹ spin / cm ³ chemically active PMC and cooled in air.

This filler is stable in mechanical strength due to a sufficient degree of crystallinity and due to the harmonious combination of crystallinity and chemical activity can serve as a highly effective means of improving the quality of mainly such binders that are formed during the polymerization of mono - and / or oligomers.

However, in view of the increased requirements for various composite materials that are widely used in the chemical industry, in construction, in transport, especially where increased wear resistance is required, chemical resistance (oil-gas resistance), the demand for such fillers increases, as do the requirements for them, especially in special operating conditions.

All this is due to the special purpose of the fillers introduced into various composite materials based on inorganic, organic and polymer binders, namely: not only saving these binders, but also improving their operational properties.

All these properties are very dependent on the activity of the filler, the ability to influence them on the properties of the binder materials. The technical task of the claimed invention is the creation of an active filler of the basalt group, which has certain structural features that provide composite materials in which it uses increased wear resistance in an oxidizing environment, increased water resistance and other enhanced extrusion properties.

A brief description of the invention.

So, the technical task is to increase the chemical activity of the mineral filler of the basalt group, increase its specific more developed surface containing active centers.

The stated technical problem is achieved by a mineral, flaky or scaly filler for composite materials, obtained by melting the initial mineral of the basalt group, previously crushed to sizes 5 - 40 mm and heated to 250 - 900 ⁰ C, molding from a melt with a viscosity of 30 - 100 poise of solid particles and their chemical-thermal and mechanical treatment in an oxygen-enriched air at 65O ⁰ C - 900 ⁰ C for 5 - 30 minutes. and possible simultaneous purging with (wet) air. The mineral flaky or scaly filler according to this invention was obtained by melting at 1250 - 1500 ⁰ C pre-crushed and heated mineral basalt group.

The mineral flaky or scaly filler of the basalt group is obtained by molding from a melt or by dispersing a thin layer of its melt cooled by a stream of compressed air, or by crushing a stream of melt in a stream of air, or by crushing a stream of melt in a stream of cooling air.

The mineral filler in the form of flakes or scales is obtained from the natural mineral of the basalt group, for example, basalts, andesites, andesite basalts, gabbro, etc.

A detailed description of the invention.

In general terms, the method of obtaining the mineral flaky or scaly filler of the basalt group declared as an invention includes the following steps: I. Preparation of vitreous solid particles (in the form of flakes or flakes) by:

• preliminary crushing of the selected mineral to obtain pieces suitable for loading into the melting furnace with sizes of 5 - 10 mm; • further preheating to 250 - 900 ⁰ C before loading the obtained pieces of basalt mineral into the furnace, which ensures drying, removal of crystallization water, uniform heating of basalt throughout the volume and, as a consequence, elimination (absence) of it in the melt during its further melting, not melted pieces; and also provides stability to the viscosity of the melt;

• further heating of these pieces to obtain a fluid melt (up to a temperature of 1250 1500 ⁰ C) with a viscosity of 30-100 Poise;

• molding vitreous particles by dispersing (for example, a turbine and / or air stream) a melt stream flowing out through a heated die; or dispersing a thin layer of a melt cooled by compressed air, for example, under a pressure of 0.5 - 1.2 kg / cm ² , before crushing the resulting film into discrete flakes as described for example in patent RU 2270811, 27,02,2006; IL Subsequent chemical-thermal treatment and mechanical treatment, obtained at stage (1) of the raw material in an oxidizing air gas atmosphere enriched with oxygen at 650 - 900 ⁰ C for 5 - 30 minutes and possible simultaneous blowing with air (humidified) for a more complete conversion of FeO to Fe ₂ O ₃ to obtain the maximum number of chemically active paramagnetic centers (PMC), in particular more than 14 * 10 ¹⁹ spin / cm ³ ; (in this context, machining should be understood, for example, crushing and sorting by size of a mineral flaky or scaly filler).

For the manufacture of solid glassy flakes, for example, basalt from the Kostopol deposit (Ukraine) containing about 10% FeO was used. Pieces of mineral rock were crushed to sizes of 5 - 40 mm. Next, the crushed basalt is heated in a heat exchanger to 350 - 900 ⁰ C with hot air and fed through a batcher to a melting furnace, where it melts at 1250 - 1500 ⁰ C until molten glass with a viscosity of 30 - 100 Poise is formed. Next, solid particles are molded from the melt, for example, by extruding a jet with a diameter, for example, from 8 to 10 mm, through a heated die made of heat-resistant steel. The melt in the stream was dispersed with a turbine having the temperature is usually around 1300 ⁰ C, in a stream of cooling air.

The formation of solid particles from the melt can be carried out by crushing a thin layer of the melt film, as it is described, for example, in the method known from RU 2270811.

The obtained gray flakes with a thickness of about 0.2 μm to about 3.0 μm in diameter from 25 μm to predominantly 3 mm were carefully (in order to avoid crushing and not compacting) poured onto pallets made of heat-resistant steel in loose layers with a thickness of 80-100 mm and subjected to chemical, thermal and mechanical processing in air in a muffle furnace at a temperature of 650 ⁰ C, 75O ⁰ C, 900 ⁰ C for 30, 15 and 5 minutes, respectively. and then removed from the oven and cooled in ambient air to room temperature.

The amount of PMC was determined on samples of flakes processed at the indicated temperatures by methods that are known to specialists.

The number of paramagnetic centers was determined by comparing the electron paramagnetic resonance (EPR) spectra of the mineral filler and diphenylpicrylhydraznine as a reference substance (see, for example, the article “Electron paramagnetic resonance)) in the Short Chemical Encyclopedia), vol. 5, M: Publishing House encyclopedia)), p. 961 - 968). EPR spectra were recorded on a radio spectrometer model E / x-2547 from PADIOPAN (Poland). The measurement results and the properties of the mineral filler are shown in tables 1 - 6.

Industrial applicability.

To assess the effect of the mineral plate filler according to the invention on the physicomechanical properties of the composites, standard samples were prepared to determine the adhesion strength (by tearing the steel “buckle” from the coating applied to the steel substrate), the compressive strength and tensile strength, and the transverse bending elastic modulus and specific impact strength and similar samples using filler-prototype (methods and equipment for such tests are well known to specialists)

A relatively simple mixture of acrylic monomers with polymer additives and a radical polymerization initiator was used as a binder in experimental polymerizable cold cured composites. The test results are given in table. N ° 3.

As follows from the tab. 1-6 mineral filler according to the invention is a more effective active filler of composite materials in comparison with the known, because has a significant impact on their mechanical and strength properties, as well as their chemical resistance, which makes it a promising filler in its application.

Table N ° 4 gives an example of the composition of a binder for a composite material.

Table JVs 1

The concentration of the crystalline phase and paramagnetic centers depending on the temperature of the chemical-thermal treatment.

Таблица JVa 2

Table JVa 2

Table JVs 3

The results of comparative tests of materials.

Table JY ° 4

An example of the composition of experimental polymerizable composites.

* Note: benzoyl peroxide is taken as a paste in dimethyl phthalate in a weight ratio of about 1: 1. Table JVs 5

The effect of heating on changes in density and ratio

FeO and Fe ₂ O ₃

Таблица JVs 6

Table JVs 6

The effect of heating on the properties of scales

Comparison of the claimed inventive activated mineral flake or flaky filler with other known flake fillers or non-flaky fillers of the basalt group shows the following. Known fillers such as basalt flour, chopped basalt fiber, flake fillers - iron, zinc, talc, graphite, do not provide an increase in such wear resistance, water resistance.

The activated basalt flakes obtained by the claimed invention have a corundum structure with a hexagonal close packing in which iron atoms occupy octahedral voids. This type of packaging is confirmed by studies of electron paramagnetic resonance (EPR). In an unactivated basalt flake, the EPR signal is absent; in the activated basalt flake, the EPR signal increases by 10–12 times, which indicates the formation of a rhombohedral phase with hexagonal packing. Due to the hexagonal packing (cordon structure) and the orientation of the iron atoms, the new filler - activated basalt scales - has high strength and high abrasion resistance, which significantly increases the wear resistance of various composite materials, in particular polymer coatings.

Basalt scales also provide the formation of strong chemical bonds of the polymer matrix with the surface of the scales, which increases the strength of the boundary layer and, as a result, increases water resistance. In addition, the presence of ferric ions in the crystal lattice of scales contributes to the attraction and partial the penetration of electrons from the boundary layer of the metal substrate into the polymer composition, forming a double electric layer, resulting in significantly increased adhesion of the composition to the metal, thereby increasing the water resistance at the metal-coating border.

Moreover, only the totality of all the essential features indicated in the claims allows to obtain the most optimal set of structural characteristics of the properties of basalt flake filler.

Claims

Claim 1. Mineral flaky or scaly filler for composite materials obtained by melting the source mineral of the basalt group, previously crushed to sizes 5 - 40 mm. and heated to 250 - 900 ⁰ C _{5 by} molding from a melt with a viscosity of 30-100 Poise, solid particles and their chemical-thermal and mechanical treatment in an oxygen-enriched air at 650 - 900 ⁰ C for 5 - 30 minutes. and possible simultaneous air purging. 2. Mineral flaky or scaly filler according to claim 1, characterized in that it is obtained by melting at 1250 - 1500 ⁰ C of a mineral of the basalt group. 3. Mineral flaky or scaly filler according to one of paragraphs. 1 or 2, characterized in that the molding is carried out by dispersing a thin layer of the melt cooled by a stream of compressed air or crushing a jet of melt in a stream of cooling air.