MXPA99004099A - Composite materials - Google Patents

Abstract

A composite material is characterised by a substrate based on glass fibres, mineral fibres or wooden fibres, and by a nanocomposite in functional contact therewith obtained by surface modification of (a) colloidal inorganic particles with (b) one or several silanes of the general formula (I):Rx-Si-A4-x, in which the radicals A are the same or different and represent hydroxyl groups or hydrolytically splittable groups, except for methoxy, the radicals R are the same or different and represent non hydrolytically splittable groups and x equals 0, 1, 2 or 3, or when the percentage of silane is at least 50,x=1. This surface modification is carried out in the conditions of a sol-gel process with a substoichiometric amount of water, with respect to the available hydrolysable groups, forming a nanocomposite sol which if required is further hydrolysed and condensed before being brought into contact with the substrate and hardened.

Description

MATERIALS CCWPVfiSTQS DESCRIPTION OF THE INVENTION The invention relates to composite materials characterized by a substrate based on glass fibers, mineral fibers or wood by-products and by means of a nanocomposite which is in functional contact with the substrate and is obtained medium of the surface modification of a) inorganic colloidal particles with b) one or more "silanes of the general formula (I) wherein the radicals A are the same or different and are hydroxyl groups or groups that can be hydrolytically removed, except methoxy, R radicals are the same or different and are groups that can not be hydrolytically removed and x is 0, 1, 2 or 3, where x = 1 in at least 50 mol% of the silanes, under the conditions of the sol-gel process with a sub-stoichiometric amount of water, based on the hydrolyzable groups present with the formation of a nanocomposite sol, and subsequent hydrolysis and condensation of the nano sol compound, if desired before it is put in contact with the substrate followed by hardening. The substrate can have very different physical forms, and the nanocomposite can also be present with different distribution forms. For example the nanocomposite REF .: 29956 may cover the substrate partially or entirely in the form of a continuous coating or cover or may be present among a plurality of substrates in laminar form. Specific examples of composite materials of this type are fibers, twines, yarns and finished products such as woven, woven, braided or non-woven, provided that they are provided with thermally stable impregnation. Alternatively, the n -composite can form discontinuous or even dot-shaped contact zones C between a plurality of substrates and, for example, can bind a substrate of particles, flocculants or fibrous materials in the form of a matrix. Specific examples of composite materials of this type with insulating materials based on glass or mineral fibers and materials made of wood such as wood fiber chips, particleboard, plywood with wood center, plywood and wool shavings of wood. For special purposes mixtures of glass fibers and sawdust can be used, for example, for agglomerated boards with fire-retardant properties. Examples of suitable substrates are glass fibers, natural or synthetic mineral fibers such as asbestos, mineral wool, mineral wool and ceramic material fibers including those of oxide ceramics; materials derived from wood in the form of cellulose, wood wool, wood sawdust, wood chips, paper, cardboard, wooden plates, wooden edges and wooden laminates. The term fibrous substrates involves either individual fibers, including hollow and solid fibers, or bundles of fibers, threads, cords, twines and threads or semi-finished products or semi-finished products such as fabrics, yarns, braids, textiles, non-wovens, felts, networks, laminates and mats. Concrete examples of these are glass wool, fiberglass mats and mineral wool, for example mineral wool, ash wool, stony wool or basalt fibers. The nanocomposite used according to the invention is prepared by means of surface modification of colloidal inorganic particles (a) with one or more silanes (b), if desired in the presence of other additives (c) under the conditions of the process sol -gel. Details of the sol-gel process are described by C.J. Brinker, GWScherer: "Sol-Gel Science - The Physics and Chemistry of Sol-Gel Processing", Academic Press, Boston, San Diego, New York, Sydney (1990) and in DE 1941191, DE 3719339, DE 4020316 and DE 4217432 Here specific examples of the silanes (b) which can be employed according to the invention and of their radicals A which are hydrolytically removable and their radicals R which are not hydrolytically removable are given. Preferred examples of groups A that are hydrolytically removable are hydrogen, halogen (F, Cl, Br and I, in particular Cl and Br), alkoxy (in particular alkoxy with from 2 to 4 carbon atoms, such as ethoxy, n-propoxy, isopropoxy and butoxy), aryloxy (in particular aryloxy) with 6 to 10 carbon atoms such as phenoxy), alkaryloxy (for example benzyloxy), acyloxy (in particular acyloxy with 1 to 4 carbon atoms, acetoxy and propionyloxy) and alkylcarbonyl (for example acetyl). The A radicals which are also suitable are amino groups (for example mono- or dialkyl, -aryl- and aralkylamino groups having the aralkyl, aryl and aralkyl radicals mentioned above), amide groups (for example benzamido) and aldoxime or ketoxime groups . Two or three radicals can together form a fraction that forms complexes with the Si atom as for example in complexes Si-polyol derived from glycol, glycerol, or pyrocatechol. Particularly preferred radicals A are alkoxy groups with 2 to 4 carbon atoms, in particular ethoxy. The methoxy groups are less suitable for the purposes of the invention, since they have an excessively high reactivity (short processing time of the nanocomposite sol) and can give nanocomposites and / or composite materials with insufficient flexibility. The aforementioned hydrolysable groups A may, if desired, carry one or more customary substituents, for example halogen atoms or alkoxy groups. R radicals which can not be hydrolytically removed are preferably selected from alkyl (in particular alkyl having from 1 to 4 carbon atoms, such as methyl, ethyl, propyl and butyl), alkenyl (in particular alkenyl having from 2 to 4 carbon atoms) , such as vinyl, 1-propenyl, 2-propenyl and butenyl), alginyl (in particular alkynyl with 2 to 4 carbon atoms, such as acetylenyl and propargyl), aryl (in particular aryl with 6 to 10 carbon atoms) as phenyl and naphthyl) and the corresponding alkaryl and arylalkyl groups. These groups may, if desired, have one or more customary substitics, for example halogen, alkoxy, hydroxy, amino or epoxide. The aforementioned alkyl, alkenyl and alkynyl groups include the corresponding cyclic radicals, such as cyclopropyl, cyclopentyl and cyclohexyl. Particularly preferred radicals R are alkyl groups with from 1 to 4 carbon atoms, substituted or unsubstituted, in particular methyl and ethyl, and aryl groups with from 6 to 10 carbon atoms, whether or not substituted in particular phenyl. It is also preferable that x in the above formula (I) is 0, 1 or 2, particularly preferred 0 or 1. It is also preferable if x = 1, at least 60 mole%, in particular at least 70 mole% of the eilanos of the formula (I). In particular cases, it may be more favorable if x = 1 in more than 80 mol%, or even more 90 mol% (for example 100 mol%) of the silanes of the formula (I).

The composite materials according to the invention can be prepared, for example, from pure methyltriethoxysilane (MTEOS) or mixtures of MTEOS and tetraethoxysilane (TEOS), as component (b). Concrete examples of silanes of the general formula (I) are compounds of the following formulas: Si (OC2H5) 4, Si (On-or iso-C3H7) 4, Si (OC4H9) 4, SiCl4, Si (OOCCH3) 4, CH3-SiCl3, CH3-Si (OC2H5) 3, C2H5-SiCl3-, C2H5- YES (OC2H5.} .3, C3H7-YES (OC2H5) 3, C6H5-Si- (OC2H5) 3, C6H5-Si { OC2H5) 3, < C2HS0) 3-Si-C3H6-Cl, (CH3) 2SiCl ?, (CH3) 2Si (OC2H5) 2, (CH3) 2Si (OH) 2, (C6H5) 2S1212, (C6H5) 2Y (OC2H5) 2, (C6H5 ) 2Si (OC2H5) 2,. { Íso-C3H7) 3SÍOH, CH2 = CH-Si (OOCCH3) 3, CH2 = CH-SiCl3, CH2 = CH-Si (OC2H5) 3, HSiCl3, CH2 = CH - Si. { OC2H4OCH3) 3, CH2 = CH-CH2-Si (OC2H5) 3, CH2 = CH-CH2-Si (OOCCH3) 3, CH2 = C (CH3) COO-C3K7-Si- (OC2H5) 3 CH2 = C (CH3) -COO-C3H7-YES (OC2K5) 3, n-C6H13-CH2-CK2-Si (OC2H5) 3, ri-CBHi7-CH2-CH2-Si (OC2H5) 3, (C2H50) 3Si- (CH2) 3-0 -CH2-CH-CH2. Those silanes can be prepared by means of known methods, for example those described by W. Noli, "Chemie und Technologie der Silicone" [Chemistry and technology of the eicicones] Verlag Chemie GmbH, Weinheim (Bergstrasse, Germany (1968). Based on the aforementioned components (a), (b) and (c), the proportion of the component (b) is usually from 20 to 95% by weight, preferably from 40 to 90% by weight and particularly preferred from 70. to 90% by weight, expressed as the polysiloxane of the formula: R ^ SiO ^ o. ^, which is formed in the condensation The silanes of the general formula (I) used according to the invention can be used completely or partially in precondensation form, that is compounds produced by partial hydrolysis of the silanes of the formula (I), either alone or in a mixture with other hydrolysable compounds.Such oligomers, preferably soluble in the reaction medium can be low weight partial condensers ac molecular straight or cyclic (polysanganosiloxane) with a degree of condensation of for example from about 2 to 100, in particular from about 2 to 6. The amount of water used for hydrolysis and condensation of the silanes of the formula (I) is preferably from 0.1 to 0.9 mol, and particularly preferable from 0.25 to 0.75 mol of water per mol of hydrolysable groups that are present.

Particularly good results are obtained frequently with 0.35 to 0.45 mol of water per mole of hydrolysable groups that are present. Specific examples of particular colloidal inorganics (a) are soles and powders dispersible at the nano level (particle size preferably up to 300 nra, in particular up to 100 nm and particularly preferably up to 50 nm) of Si02, Ti02, Zr02 / A1203 / Y203, Ce02, Sn02, ZnO, iron or carbon oxides (black carbon and graphite) in particular of SiO2.

The proportion of component (a) based on components (a), (b) and (c) is generally from 5 to 60% by weight, preferably from 10 to 40% by weight and particularly preferred from 10 to 20% by weight. weight. To prepare the nanocomposites, other additives can be used in amounts of up to 20% by weight, preferably up to 10% by weight, and in particular up to 5% by weight, as optional components (c); examples are hardening catalysts such as metal salts and metal alkoxides (for example aluminum alkoxides, titanium alkoxides or zirconium alkoxides), organic binders such as polyvinyl alcohol, polyvinyl acetate, starch, polyethylene glycol and gum arabic, pigments, dyes , fire retardants, composed of glass-forming elements (for example boric acid, boric acid esters, sodium methoxide, potassium acetate, aluminum sec-butoxide, etc.), anti-corrosion agents and coating aids. According to the invention, the use of binders is less preferred. The hydrolysis and condensation are carried out under sol-gel conditions in the presence of acid condensation catalysts (for example hydrochloric acid) with a pH of preferably 1 to 2., until a viscous sun is produced. It is preferable that no additional solvent be used in addition to the solvent produced in the hydrolysis of the alkoxy groups. If desired, however, alcoholic solvents, such as ethanol or other polar, protic or aprotic solvents, such as tetrahydrofuran, dioxane, dimethylformamide or butyl glycol, for example, may be employed. In order to achieve a favorable sol particle and sun viscosity morphology, the resulting nanocomposite sol is preferably subjected to a special post-reaction step in which the reaction mixture is heated at temperatures of 40 to 120 ° C for a period of several hours to several days. Special preference is given to storage for one day at room temperature or heating for several hours at 60 to 80 ° C. This gives a nanocomposite sol with a viscosity of preferably 5 to 500 mPas, particularly preferably 10 to 50 mPas. The viscosity of the sol can obviously also be adjusted to suitable values or to remove secondary products of the reaction (for example alcohols). The post-reaction stage can preferably be coupled with a reduction in the solvent content. The weight ratio of the nanocomposite in the composite material is preferably from 0.1 to 80% by weight, in particular from 1 to 40% by weight and particularly preferably from 1 to 20% by weight. The substrate and the nanocomposite or the nanocomposite sol are combined after at least the initial hydrolysis of the component (b) and in any case before the final hardening. Before the substrate is placed in contact with the nanocomposite sol, after at least the initial hydrolysis of the component (b) and in any case before the final hardening, they are combined. Before it is contacted with the substrate, the nanocomposite sol is preferably activated by the feeding of an additional amount of water. The contact can be made by any means known to a person skilled in the art and considered to be useful for the particular case, for example by means of simple mixing of the substrate and the nanocomposite sol, dipping, spraying or spraying, manual application or by rotation, pouring, spreading or application with a brush, etc., in or with the nanocomposite sun. In order to improve the adhesion between substrate and nanocomposite, it may be advantageous in many cases to subject the substrate before contact with the nanocomposite or its precursor to a conventional surface pre-treatment, for example corona discharge, degreasing, treatment with a primer such such as aminosilanes, epoxysilanes, molds made of starch or silicones, complexing agents, surfactants, etc. Before the final curing, a drying step must be carried out at room temperature or at a slightly elevated temperature (for example up to about 50 ° C). Real hardening or pre-hardening can be carried out. at room temperature, but preferably by heat treatment at temperatures above 50 ° C, preferably above 100 ° C and particularly preferably at 150 ° C or more. The maximum hardening temperature depends among other things on the melting point and / or the thermal resistance of the substrate, but is generally 250 to 300 ° C. With mineral substrates, however, significantly higher curing temperatures are also possible, for example 400 to 500 ° C and above. Hardening times are generally in the range of minutes to hours, for example 2 to 30 minutes. In addition to conventional curing by heating (for example in a furnace with air circulation), other hardening methods, for example hardening with IR or laser beams, can be used. If desired, the prepared compound can also undergo a formation process before hardening. The invention also relates to the use of the aforementioned nanocomposite for the coating and / or consolidation of the aforementioned substrates. The term "consolidation" is intended to include any measure that is adequate to provide the substrate in a consolidated and / or compact form, and thus includes, for example, impregnation of the substrate with nanocomposites, embedding the substrate in a matrix of the nanocomposite or cemented or bonding the substrates or pieces of the substrate with the nanocomposite. The term "coating" must mean in particular a partial or complete encapsulation of a substrate with a nanocomposite in order to give this substrate or parts thereof particular properties, for example oxidation resistance, fire retardancy, hydrophobic or oleophobic character. , hardness, impermeability or thermal or electrical insulation. The following examples illustrate the present invention. In the following examples the silica sol used is an aqueous silica sol of BAYER ("Levasil 300/30") with a solids content of 30% n weight and a particle size of 7 to 10 nm. The following abbreviations are used in the examples: MTEOS = Methyltriethoxysilane TEOS = Tetraethoxysilane PTEOS = Phenylthioethoxysilane E MPO l A mixture of 65 mole% of MTEOS, 15 mole% of PTEOS and 20 mole% of TEOS (or alternatively, 80 mole% of MTEOS and 20 mole% of TEOS) it vigorously shakes with silica sol and hydrochloric acid as a catalyst in order to prepare a nanocomposite sol by means of hydrolysis and condensation of the silanes. The amount of water introduced by means of the silica sol is such that 0.8 moles of water are present per mole of hydrolysable group. Approximately 5 minutes after the preparation of the sol from the above silane mixture is added to it in such a way that the total water content of the resulting mixture is 0.4 moles of water per mole of alkoxy groups. The silica sol represents approximately 14% by weight of the total solids content. After the post-reaction phase of about 12 hours at room temperature, water is added to the above mixture in an amount which results in a total water content of the sol of 0.5 moles of water per mole of alkoxy groups. After about 5 minutes the mixture is ready to be used. The ready-to-use mixture is sprayed in wet glass wool through an atomizer ring and cured for 5 to 10 minutes in a circulating air oven at approximately 200 ° C. Obtaining thus an elastic insulating material that shows improved properties against fire compared to glass wool bound with phenolic resin. EXAMPLE 2 68.7 ml of MTEOS (corresponding to 80 mol%) and 19.2 ml of TEOS (corresponding to 20 mol%) are mixed and half of that mixture is vigorously stirred with 11.7 ml of silica sol (corresponding to a ratio of 14.3). % by weight of silica sol) and 0.386 ml of concentrated hydrochloric acid. Five minutes later the second half of the silane mixture is added to the mixture after which stirring is continued for another 5 minutes. Subsequently the resulting sol is subjected to a post-reaction stage (allowing it to stand at room temperature for 2 hours). Obtaining a storage stable precondensate having a solids content of Si02 of about 300 g / l and 0.4 moles of water per mole of hydrolysable group. By concentrating in a rotary evaporator the solids content is adjusted to 60% by weight. Before application of the binder, 3.0 ml of titanium isopropylate and approximately 2.5 ml of water are added in order to reach a water content of 0.5 mol of water per mol of hydrolysable group. The mixture thus prepared is mixed with wood chips in an amount which results in 15% of the composition consisting of SiO2. Subsequently the composition is ligated in a hot press at 180 ° C for 10 minutes to form a formed body. Thus, a shaped body similar to an enameled insulated pressed board is obtained, however this body is prepared without an organic binder. The fire properties of the corresponding plate are significantly improved compared to those of a similar enamelled insulating pressboard. EXAMPLE 3 1. Preparation of the sun 172 ml of MTEOS are mixed with 48 ml of TEOS. 29 ml of silica sol and 2 ml of sulfuric acid (35%) are added with vigorous stirring. Five minutes later an opaque sun has formed which is allowed to post-react for 4 hours at room temperature. After the addition of another 3 ml of water with stirring the mixture is ready for use after about 5 minutes. 2. Application of the sun 2.1 100 g of wood chips are mixed with 60 ml of the sol and molded under a pressure of 7.1 mPa in a press mold having a diameter of 12 cm for 10 minutes. Subsequently the molding is pressed in a hot press (hot top and bottom molds) at a pressure of 2.6 mPa and at a temperature of 100 ° C for 3 hours. Obtaining a mechanically stable formed body with a content of wood chips of 82% by weight. 2.2 300 g of stone wool granules are mixed with 10 ml of the previous sol and pressed at a pressure of 4.4 mPa in a press mold with a diameter of 12 cm for 5 minutes. Subsequently the molding is exposed to a temperature of 80 ° C for 8 hours in a circulating air dryer. Obtaining a mechanically stable formed body with a content of stone wool granules of 1% by weight. It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects or products to which it refers.

Claims (17)

1. CLAIMS Having described the invention as above, property is claimed as contained in the following indications: 1. - Composite material characterized by a substrate and base to glass fibers, mineral fibers or products derived from wood and by means of a nanocompueeto that is in functional contact with the substrate and is obtained by means of the surface modification of a) inorganic colloidal particles with b) one or more silanes of the general formula (I) Rx-Si-A4.x (I) wherein the radicals A they are the same or different and hydroxyl groups or groups that can be hydrolytically removed, except methoxy, the radicals R s are the same or different and are groups that can not be hydrolytically removed and x is 0, 1, 2 or 3, where x. > 1 at least 50 mol% of the silanes; under the conditions of the sol-gel process with a sub-stoichiometric amount of water, based on the hydrolysable groups present with the formation of a nanocomposite sol, and subsequent hydrolysis and condensation of the nanocomposite sol, if desired, it is put in contact with the substrate followed by the cure.
2. 2. Composite material according to claim 1, characterized in that the surface modification has been carried out in the presence of an acid condensation catalyst at a pH of 1 to 23.
3. Composite material according to claim 1 6 2, characterized in that the nanocomposite sol has been subjected for a period of several hours to several days, to a post-reaction at temperatures from room temperature to 120 ° C.
4. 4. - Composite material according to any of claims 1 to 3 characterized in that the colloidal inorganic particles (a) are selected from the group consisting of sols and dispersible powders of SiO2, TiO2, ZrO2, A1203, Y203, CeO2, SnOa, ZnO , oxides of iron or carbon in a nano-scale.
5. 5. - Composite material according to any of claims 1 to 4, characterized in that to prepare the nanocomposite sol other additives (c) are used for example hardening catalysts, organic binders, pigments, dyes, fire retardants, compounds of glass forming elements, anti-corrosive agents and / or coating auxiliaries.
6. 6. - Composite material according to any of claims 1 to 5, characterized in that from 5 to 60% by weight, preferably from 10 to 40% by weight, and particularly from 10 to 20%, are used to prepare the nanocomposite. by weight, of component (a).
7. 7. Composite material according to any of claims 1 to 6, characterized in that from 20 to 95% by weight, preferably from 40 to 90% by weight, and particularly preferably from 70 to 90% by weight of the component (b) expressed as polysiloxane of the formula: R3CSiO (2-o.5?) have been used to prepare the nanocomposite.
8. 8. Composite material according to any of claims 5 to 7, characterized in that not more than 20% by weight, preferably not more than 10% by weight, and particularly preferred not more than 5% by weight of the other additives ( c) have been used to prepare the nanocomposite.
9. 9. - Composite material according to any of claims 1 to 8, characterized in that the radicals A in the formula (I) are alkoxy groups with 2 to 4 carbon atoms, preferably ethoxy groups.
10. 10. Composite material according to any of claims 1 to 9, characterized in that R in the formula (I) is an alkyl group with 1 to 4 carbon atoms substituted or not and / or an aryl group with 6 to 10 carbon atoms substituted or not, preferably methyl, ethyl and / or phenyl.
11. 11. - Composite material according to any of claims 1 to 10, characterized in that x in the formula (I) is 0, 1 or '2, preferably 0 * 1.
12. 12. Composite material according to any of the claims 1 to 11, characterized in that at least 60 mol% and preferably at least 70 mol% of the component (b) is silane of the formula (I) wherein x_l, and preferably x = 1.
13. 13. - Composite material according to any of claims 1 to 12, characterized in that the surface modification has been carried out using 0.1 to 0.9 mol, preferably 0.25 to 0.75 mol of water per mol of hydrolysable groups that are present.
14. 14. - Composite material according to any of claims 1 to 13 characterized in that the weight ratio of the nanocomposite is 0.1 to 80% by weight, preferably 40% by weight, and particularly preferred from 1 to 20% by weight. weight.
15. 15. - Composite material according to any of claims 1 to 14, characterized in that the hardening is performed thermally, preferably at temperatures of 50 to 300 ° C.
16. 16. - Composite material according to any of claims 1 to 15 in the form of a substrate coated with the nanocomposite, a fabric impregnated with the nanocomposite or an article formed consisting of a substrate material consolidated with the nanocomposite.
17. 17. Use of a nanocomposite as defined in claims I to 13, for coating and / or consolidating substrates based on glass fibers, mineral fibers or wood products.