MXPA00010194A - Mineral flaky filler for composites - Google Patents

Abstract

A mineral flaky filler for composites, produced by melting a starting mineral, shaping hard flaky vitreous particles from the melt, and subjecting such particles to thermochemical treatment in an oxidizing atmosphere until a crystal phase is developed. With an object of obtaining such a crystallinity-reactivity balance that would provide for quality consistant protective and ornamental coatings on large-size articles and structures preferably for use in the tropical climate and of producing a filler that would be commercially available at the step of the thermochemical treatment the flaky particles were treated at a temperature range of 680 to 850°C until at least 12%by weight of the crystal phase and at least 7x1019spin/cm3 of reactive paramagnetic centers were developed, and followed by air cooling.

Description

LAMELAR MINERAL FILLING MATERIAL FOR COMPOUNDS TECHNICAL FIELD This invention relates to dispersible lamellar materials of uncertain chemical composition, which can be prepared from minerals containing lower iron oxides (preferably basalt, sands injected by wind, etc.), by melting the minerals, decomposing the melt to produce hard vitreous scales followed by a chemical modification and incomplete crystallization of the lamellar material by thermochemical treatment in an oxidizing atmosphere It has been well established that the flakes can be used as reactive fillers for various compounds (preferably polymerizable compounds) to prepare protective and protective and ornamental coatings that have a high resistance to the environment and water (to protect metallic tanks, bridges, offshore drilling platforms, etc.), and / or abrasion resistance (eg mud pipes) ANTECEDENTS OF THE TECHNIQUE As the description of the technical field suggests, filling materials of the type described are in high demand Consequently, such fillers must meet many requirements that are becoming more accurate and are not easily combinable. It is desirable that these filler materials are: as reactive as possible, the property is determined from at least the surface area and preferably by the presence of the active centers on the surface of such flakes. The active centers constitute a contributing factor in the polymerization of oligomeric binders and in the establishment of chemical interconnection between macromolecules and inorganic components: mechanically as strong as possible in order to provide appreciable reinforcement in the composite materials prepared even with low concentrations of lamellar filling materials, chemically as stable as possible (specifically corrosion resistant) to facilitate the storage and use of flakes to prepare many types of composite materials which usually contain corrosive ingredients while in an untreated state; commercially available to various customers as a result of large-scale production and low cost. These requirements, taken separately, are not too difficult to satisfy.

U.S. Patent No. 4,363,889 for one discloses a conferrally available and slightly reactive filler material for polymerizable compounds, prepared from glass flakes of a thickness ranging from 0 5 to 5 0 μm and from 5 100 at 400 [mu] m in diameter, or as a mixture of 10 to 70 parts by weight of such flakes and from 10 to 150 parts by weight of lamellar metallic pigments Glass flakes are extremely fragile and exhibit low surface reactivity unless undergo further treatment (eg vacuum metallization), while metal flakes with highly developed surface area are not stable to corrosion. Lamellar fillers such as various pigments of iron oxide (E) are also known in the art. 5 Crankcase, "Micaceous iron oxide pigments m high performance coatmgs", Polymer Pain t Color Journa l, 1986, vol 176, No 4164, pp 226, 228, 230, 232, 234) Compared to the scales Glass, are more durable and chemically stable However, such fillers are expensive, and this is why its use is advisable in the application of protective coatings only to articles and structures such where the costs of a failure are substantially greater than those of protective arrangements Therefore, one of the most preferable ways to provide lamellar filling materials is considered.

Designed primarily for use in polymeric compounds is using flakes produced from natural minerals.

The present inventor has been related as an originator: in the development of a technological package that includes: a process for the production of finely dispersed flakes (USSR patent No. 1,831,856), an apparatus for producing finely dispersed flakes (USSR patent) No. 1,823,293), a method of heat treatment of finely dispersed flakes and an apparatus for carrying out the method (UK Patent No. 2,036,748). USSR No. 1,831,856 discloses a mineral lamellar filler material produced by melting basalt and dispersing the melt to produce ellipsoidal flakes. When analyzed microscopically in terms of shapes and dimensions, the scales are characterized, in terms of the relationship between the minor and major axes of an ellipse, by a distortion of the circular shape within 0.80 and 0.95. Such scales remain in a vitreous state and are chemically unstable, due specifically to the presence of lower iron oxides, inherent in basalt (and sand injected by winds) that are used as raw material. These scales also have little chemical activity.

USSR Patent No. 1,823,293 describes the manufacture of a mineral lamellar filling material by substantially the same process and this filling material compared to that described above is more acceptable with respect to its particle size, specifically it contains up to 99 ° of flake shape. and substantially identical in size, these flakes again recall the vitreous state and are chemically unstable, and have little chemical activity. These disadvantages are remarkably eliminated in the mineral lamellar filler material narrowly founded in the invention and described in the RU patent No. 2,036,748. Filling material is produced by melting an initial mineral (basalt) to form hard vitreous lamellar particles of the melt and by subjecting such particles to a thermochemical treatment in an oxidizing atmosphere until a substantially crystalline structure develops. The thermochemical treatment includes heating vitreous particles to one V Efficiency of 140 to 190 ° C / minute at a temperature of 600 to 950 ° C and Simultaneously blowing air for 5 to 30 minutes, followed by induced cooling at a speed of at least 950 - / minute Filling material The mineral lamella treated as above contains substantially zero amounts of FeO and shows a high density (at least 3 g / cm), which is greater than that of vitreous particles by a factor of 1 5, a higher percentage (of up to 53% by weight) of a crystalline phase (hereinafter "crystallinity") and remarkable amounts of chemically active paramagnetic centers (PMC below). These advantages are provided for an appreciable improvement of the properties of polymerizable compounds reinforced with the described mineral flakes and of protective or ornamental coatings produced therefrom (Vesselovsky RA, Yevanova VV, IP Petukhov, "Study of physical, chemical, thermodynamic and mechanical properties of interface layers cross-linked polymers ", Mechamos of Compositions, 1994, vol 30, No. 5, pp. 3-11; Russian BeceJioBCKHf- P. A.. E aHOBa B. B.,? E? Yxoe 14 n Mcc ienoBaHMo? N3H? O-xnMHHec ?? x, TepMOíiHHaMHMecKHx H Mexa- HHH? CKHX CBOÍ.CTB rpaHHMHt-X C lO? DC? THaTblX? OjiHMepoB // Me-xaHHKa? OM? O3HTHbix Ma? EpHaj? OB, 1994, T 30, ° 5, c - ll) Subsequently, however, it has been found that this filling material has a maximum of 6 x 1019 spin / cm1 of PMC that are active in the polymerization process of monomers and oligomers (VV Yefanova, "Study of the properties of a new activated basalt filler for coating applications ", Eco technolgy and Savmg of Resources, 1993, No. 5, pp. 67-72, in Russian E? aHOBa B B. HccJie? OBaHHe CBOHCTB HOBO? o a? iBH- poBaHHoro 5a3ajib? oBoro Ha ? ojiHHTejiH Jim? o? pwTO // 3? o? ex HOJIO? HH H pecypcocóepeJKeHHe, 1993, NG 5, c 67-7-.) To put it another way, the aforementioned condition and the chemical activity of the prior art filling material are not in equilibrium. In addition, the published experimental findings of the present inventors have shown that the question for a higher crystallinity of the mineral lamellar filling material is not justified when considering also the efficiency process. For example, the flakes subjected to thermochemical treatment for 30 minutes at temperatures close to the smallest value of the indicated temperature range, that is, slightly higher than 600 ° C, do not show detectable detectability or a detectable increase in chemical activity, while an increase in treatment time of more than 30 minutes results in a decrease in product yield. A replacement to a relatively short process (approximately 5 to 10 minutes) of thermochemical treatment at approximately 900 ° C or even higher, has surprisingly been found to open to uncontrolled re-nitification and a decrease in the chemical activity of the particles that are more easily perceived in the upper ones are both the heating temperature of the particles and the cooling rate of the heat-treated particles. And finally, the rate of heating of the vitrified particles, before exposure thereof to a gaseous oxidant such as air, has appeared to have virtually no effect on the progress and result of the treatment. Consequently, the use of additional process instrumentation unreasonably increases the cost of the final product.

DESCRIPTION OF THE INVENTION Therefore, the technical problem underlying the present invention is to provide a mineral lamellar filler material for compound in which, by means of improving the operating conditions of the thermochemical treatment of the vitreous particles and the subsequent cooling thereof, the crystallinity and chemical activity is significantly closer to equilibrium, compared to the filling materials of the prior art, and may be commercially available and, when used in polymerizable compounds, provide more durable and decorative or resistant to protective coatings. abrasion For this purpose, the invention consists of a mineral lamellar filling material for compounds, produced by melting an initial mineral, with formation of hard lamellar vitreous particles of the melt, and subjecting said particles to thermochemical treatment in an oxidizing atmosphere until develop a crystalline phase, according to the invention in the thermochemical treatment step, the lamellar particles are treated in a temperature range of 680 to 850 ° C until at least 12% by weight of the crystalline phase develops and at least 7 > x 10 J spin / cm 'of reactive PMC, and followed by air cooling. The filling material produced in this way is mechanically strong, due to an adequate degree of crystallization and, due to the congruence of the crystallinity with the chemical activity, it can be used as a highly effective means to improve the quality of mainly thick coatings. (> 1, and typically> 3 mm), protective, protective, and abrasion resistant, preferably using such binders which are produced under the polymerization of monomers or oligomers, or both. It should be mentioned here that production costs are reduced due to a reduction in investment in heating, cooling and control equipment, as well as energy costs for thermochemical treatment and for the preparation and feeding of the refrigerant. The final product, therefore, is commercially available more easily. The mineral lamellar filler material of the invention is further characterized by containing at least 30% of particles having an average size of about 100 μm through the total amount of the particles, and at least 4 × 1019 spin / cm 3 of PMC to in this way allow such filler material is preferred for use with polymerizable compounds.

BEST MODE FOR CARRYING OUT THE INVENTION The invention is further explained by means of the general description and specific data of the experimentation with respect to the method for producing a mineral lamellar filler material for polymerizable compounds, which includes the values of the physical and chemical properties obtained, examples of the manner in which the filler material is used in polymerizable compounds for application as protective coatings, and results of comparative tests of the compounds for application of such coatings. Generally, the method for producing a mineral lamellar filling material of the invention comprises the steps of: (1) obtain hard vitreous particles (usually as flakes) by: crushing the selected material to suitable sizes for loading in a melting furnace, heating the load to obtain a thin fluid (especially at a temperature of 1400-1500 ° C to basalt and above 1500 ° C for sand injected by wind), decomposition of a melt stream that flows through the heated die, into vitreous particles example by a centrifuge or an air stream, or both); (2) thermochemical treatment of the vitreous particles of step (1) in an oxidizing atmosphere (preferably in air) at temperatures of 680 to 850 ° C (preferably 680-780 ° C) until incomplete crystallization develops. say, at least 12% by weight of the crystalline phase, and at least 7 x 1019 spin / cm3 of reactive PMC, followed by air cooling; and, optionally, 10 (3) mechanical treatment of the particles, for example by fragmentation and separation according to size, until a mineral lamellar filling material containing at least 30% of particles having an average particle size is obtained. approximately 100? ma through the total amount of the particles and at least 14 x 1019 spin / ci- of reactive PMC. In the production of hard vitreous scales, use is made of basalt containing approximately 10% FeO from the Kostopol deposits (Ukraine). The crushed stone from 5 to 40 mm in size is melted in a modified foundry furnace similar to a quartz glass furnace, in which the heating is supplied by gas burners. The melt is heated to a temperature of 1400-1450 ° C to be extruded through a heated die of heat-resistant steel, in a current of 8 to 10 mm in diameter. The melt current it decomposes in a stream of cooling air by a centrifuge heated generally to about 1300 ° C.

The obtained flakes have gray color, of approximately 3 μm in thickness and of 25 μm to predominantly 3 mm in transverse size. The flakes are carefully poured (to avoid breaking or compaction) on lower trays of heat-resistant steel in loose layers of 80 to 100 mm thickness, placed in a muffle furnace, and subjected to thermochemical treatment in air, at temperatures successive of 660, 680, 750, 850, and 875 ° C during • 90, 60, 30, 20, and 15 minutes, respectively, and then removed from the oven and cooled to room temperature in the air. The samples of the flakes treated at the above temperatures are analyzed to determine crystallinity and the PMC by conventional methods. X crystallinity is defined by the formula tp vp x = * 100. dcP - dvb where d.c is the density of the particles after treatment, dvp is the density of the vitreous particles, dcp is the density of the crystalline phase, dvt is the density of the vitreous body of the particles, substituting the density values defined in xylene in the formula (G A. Ras in, NA Polkovoi " Certain physicotechnical properties of stone are defined, "Glass and Ceramics", No. 10, 1963, pp. 11-14 - in Russian- PaiLIMH r A,? OjiKOBOií HA "Onpe.aej.eHHe He? O? Opt.x íM3H ? o?? exHH-? ecKHX CBOP? CTB KaM? HHoro Jin? bH "B wypHajie 'C? e? j? o H? epa-MHKa", 1963, No. 10. c 11 - 14) The PMCs are counted from the electronic paramagnetic resonance spectra (EPR) in a mineral filler material and diphenyl-pic? Lhydrazma, the latter being a reference substance ("Electron Paramagnetic Resonance" An Abridged Chemical Encyclopedia, V Moscow Soviet Encycloped 'a, pp 961-968 in Russian craTbí. "3Jie ?? poHHbM? ApaMarHMTHbií. Pe30HaHC" B "paTKOM XHMH .eCKOfl SHUHK IO? EüHH", T 5, M H3Ü-B0"Co- B? TCKas 3HUHKJionem.fi", c. 961-968) The EPR spectra are obtained from the radio spectrometer model E / x-2547 commercially available from RADIOPAN (Poland) The findings of the analysis are summarized in table 1 Table 1 CRYSTALLINITY AND PARAMAGNETIC CENTERS VERSUS TEMPERATURE TREATMENT -Iota: The respective indicators would constitute 0.0% and < 2.0 * 1019 spin / cm3 for vitreous particles before the thermochemical treatment, and 51.5% and approximately 6.0 x 101"spin / cm" for particles of the prior art, after the thermochemical treatment at 900 ° C, when essentially all the FeO has changed to Fe203 As will be seen from table 1, the thermochemical treatment of vitreous particles at temperatures lower to 680 ° C is not practicable since both crystallinity and PMC are significantly increased, nor is it practicable at temperatures above 850 ° C, because crystallinity and PMCs begin to be adversely affected, albeit insignificantly. 5 After the thermochemical treatment, the mineral lamellar filling material is crushed and separated according to the size of the particles to thereby improve the reactivity of the filler material. Experiments are carried out on the particles treated at 750 ° C. Samples are prepared which contain various portions of particles with an average size of about 100 μm cross, and the PMC number is determined. Table 2 shows the results of the experiments.

Table 2 PARAMAGNETIC CENTERS VERSUS TRANSVERSAL MEDIUM PARTICLE SIZE IN SAMPLES To determine the effect of the mineral lamellar filler material of the invention on the physicochemical properties of polymerizable compounds, standard samples are prepared. These are used to determine the adhesive strength (measured as the force needed to overcome a steel mushroom-like piece of a coating applied to a support also made of steel), the compressive strength, the tenacity, the modulus of elasticity in lateral bending and the impact resistance per unit area. Similar samples of the filling material of the prior art are also prepared and used in concurrent tests (the methods and equipment for performing such tests are well known to those skilled in the art) In the above tests, the filler material of the invention (hereinafter referred to as IF) is that produced by thermochemical treatment at 680 ° C prior to grinding and sorting, and therefore, has the crystallinity and the lower PMC counts, whereas the prior art filling material (hereinafter referred to as PF) is prepared at 900 _ and has a high standability and PMC scores A relatively simple mixture of Acrylic monomers containing polymeric additives and a polymerization initiator, which are included in the left column of Table 3, are used as a glutinant for experimental cold polymerizable compounds Table 3 COMPOSITION OF EXPERIMENTAL POLYMERIZABLE COMPOUNDS -ota Benzoyl peroxide in paste form is used as a mixture with dimethyl phthalate in an approximate weight ratio of 1 1 The ingredients are divided, methyl methacrylate, polybutyl methacrylate and polyvinyl chloride are previously mixed, and then introduce one of the filling materials, with agitation of the mixture, polnsocyanate and dimethylanilm is added (again with stirring), and finally benzoyl peroxide is introduced. After deep mixing, the compositions are conventionally formed in so many samples as required to obtain data on the physicochemical properties of the compounds, the mean square deviation is +/- 5%. The findings are summarized in table 4.

Table 4 COMPARISON OF PROVEN SAMPLES As can be seen from table 4, the mineral lamellar filling material according to the invention is more efficient compared to the filling material of the prior art.

INDUSTRIAL APPLICABILITY The industrial applicability of mineral lamellar filling materials is based on the above description in relation both to the possible large-scale production as well as its wide application.

Claims (2)

1. A mineral lamellar filling material for compounds, produced by melting an initial material, forming 5 hard lamellar vitreous particles from the melt and subjecting said particles to thermochemical treatment in an oxidizing atmosphere until a crystalline phase develops, characterized in that in the thermochemical treatment step the lamellar particles are treated at a temperature range of 10 680 to 850 ° C until at least 12% by weight of the crystalline phase develops and at least 7 x 1019 spin / cm3 of reactive paramagnetic centers, and followed by air cooling.

2. The mineral lamellar filling material, as described in claim 1, characterized in that it contains at least 30% of particles having an average size of about 100 μm transverse to the total amount of particles and at least 14 × 10'9 spin / cm3 of the paramagnetic centers. twenty