DE1177339B - Process for the production of compounds which harden to form elastomers at room temperature under the action of water - Google Patents

Description

Process for the preparation of at room temperature under action of water to form elastomers hardening compositions It is known that by mixing of organopolysiloxanes each having a hydroxyl group in the terminal units with silicic acid alkyl esters and alkyl titanates molding compounds are obtained, which result in elastomers harden. This known method has the disadvantage that the hardening immediately after the mixing of the ingredients begins and the mixtures after their preparation must be processed immediately.

This type of masses curable to give elastomers has therefore hitherto been the case just like numerous other compositions based on organopolysiloxanes, crosslinkers and catalysts only available in the form of two separately packaged components, one of which is the catalyst and the other is a mixture of silicic acid ester and contains organopolysiloxane; the consumer then has to mix these two components.

For many purposes, especially in factories where the processing procedures can be strictly monitored and in which the staff Admittedly, sufficient measuring devices are available, the two-component system is sufficient completely. In other cases, however, it is less advantageous, for example when the Workers are not trained accordingly or the mixing equipment is not sufficient, quite apart from the fact that a mixing process always requires additional time and Required workload. Also, the mixtures must be proportionate within be used a short time after mixing, as there is no way to to prevent hardening after mixing the two components.

There are one-component compositions based on liquid organopolysiloxanes with Sig-bonded acyloxy residues known, which in the presence of moisture elastomer solids, with elimination of a carboxylic acid, which in the case of the commercial products in general acetic acid is harden. However, there are areas of application in which the presence of carboxylic acid is undesirable and harmful.

Furthermore, one-component compositions are based on hydroxyl groups containing diorgano polysiloxanes, silicic acid esters and organic titanium compounds known that harden under the action of water to form elastomers. However, you own the disadvantage that the hardening proceeds relatively slowly. According to the invention The masses obtained, on the other hand, cure to form elastomers within a relatively short time.

The process according to the invention for the preparation of compositions which cure at room temperature under the action of water to give elastomers by reacting 1. Organopolysiloxanes of the general average formula with exclusion of the ingress of water where z on average 1 to 1.01 and y on average 1.99 to 2, the sum of z + y = 3, R is a monovalent hydrocarbon radical, optionally containing halogen atoms and / or cyano groups, with 1 to 18 carbon atoms and the value of n corresponds to a viscosity of at least 25 cSt125 "C, with 2. at least 0.5 mol of silicon compounds with organic radicals bonded to the Si atom via oxygen per mol of Si-bonded hydroxyl group in the organopolysiloxanes in the presence of 3. at least 0.10 / 0, based on the weight of the organopolysiloxanes, of organic titanium compounds in which the organic radicals are bonded to titanium via oxygen, while any titanium valences not saturated with organic radicals via oxygen are saturated by OH groups and oxygen in a TiOTi bond are, and 4. optionally fillers and other conventional additives is characterized in that as silicon compounds with oxygen to the Organic radicals bonded to Si atoms, silanes of the general formula RSi (OR ') 3, in which R has the meaning given and R' is a monovalent, optionally halogenated, aliphatic hydrocarbon radical having fewer than 5 carbon atoms can be used.

In the process according to the invention, the access of water is both in liquid form as well as in the form of water vapor, including air humidity, to exclude.

The products obtained according to the invention are to the exclusion of Water storable.

In the process according to the invention, compounds of the general formula are presumably formed by reacting the alkoxy groups of the silane or the silanes with the Si-bonded hydroxyl groups of the organopolysiloxane or the organopolysiloxanes generated with elimination of the alcohol of the formula R'OH.

Examples of hydrocarbon radicals R are alkyl radicals such as methyl, Ethyl, propyl, hexyl or octadecyl radicals, alkenyl radicals, such as vinyl, allyl, hexenyl or M ethallyl radicals, cycloaliphatic hydrocarbon radicals, such as cyclopentyl, Cyclohexyl or methylcyclohexyl radicals, aralkyl radicals, such as benzyl. 13-phenylethyl or B-phenylpropyl radicals, or aryl or alkaryl radicals, such as phenyl, xenyl, toluyl, Xylyl or naphthyl radicals. Examples of halogenated hydrocarbon radicals R are Chloromethyl, fi-chloropropyl, 3 3,3-trifluoropropyl, a, a-trifluorotoluyl, chlorophenyl, Bromxenyl, trifluorovinyl or chlorocyclohexyl radicals. As having cyano groups Hydrocarbon radicals R are cyanoalkyl radicals such as 3-cyanoethyl. j3-cyanopropyl -, - cyanopropyl or O, -Cyanoctadecylreste, preferred. R is expediently in each case a methyl radical.

Containing the Si-bonded hydroxyl groups used according to the invention Siloxanes consist essentially of diorganopolysiloxanes in those used in organopolysiloxane elastomer production usually required degrees of purity. You can according to any, to manufacture customary processes for organopolysiloxanes containing Si-bonded hydroxyl groups, z. B. according to the German patent 1 042 242 prepared. There is none decisive upper limit of the viscosity of the organopolysiloxanes used according to the invention. Their viscosity can be in the range of that of easily manoeuvrable liquids to that of non-flowing, highly viscous masses.

It depends on the purpose of the mass. So is z. B. for the best possible impregnation of porous materials a low one Viscosity; for higher demands on tensile strength and elongation at break of elastomers the compositions produced according to the invention are highly viscous organopolysiloxanes expedient.

The organopolysiloxanes containing Si-bonded hydroxyl groups can be homopolymers and / or mixed polymers, and each to a Si atom bonded radicals R can be identical or different. Depending on the value of y, you can the organopolysiloxanes can be linear or branched.

The aliphatic hydrocarbon radicals R 'can be of any kind, z. B. methyl, ethyl, propyl or butyl radicals. If they are halogenated, contain they preferably have no halogen in the a-position to the oxygen. Preferred examples for halogenated aliphatic hydrocarbon radicals are therefore the A-chloroethyl, b-chlorobutyl, 2,2-difluoro-3,3,3-trifluoropropyl, ß - bromopropyl, 3 - iodobutyl or 2,2,2-trifluoroethyl radical. Examples of the methods according to the invention Usable silanes are Ethyltrimethoxy-, Vinyltrimethoxy-, 3,3,3-Trifluorpropyltrimethoxy-, 5-cyanoethyltrimethoxy, phenyltrimethoxy, n-octadecyltrimethoxy or propyltris (b-chlorobutoxy) silane. Methyltrimethoxysilane is preferred because of its ready availability.

The upper limit of the amount of silane is not critical. Too big Quantities of silane are not appropriate because they should only dilute the mass. Preferably, however, more than 1 mole of silane is used per mole of Si-bonded hydroxyl group used to prevent gelling of the mass accidentally, e.g. B. with others Components such as fillers or stabilizing additives, incorporated or to prevent water ingress during storage.

The organic titanium compounds are preferably in the organopolysiloxanes soluble or easily dispersible in it, which may be due to its use a common solvent can be promoted.

Among the organic which can be used in the context of the process according to the invention Titanium compounds include above all the alcoholates and / or acylates.

The organic titanium compounds can be monomeric, e.g. B. correspond to the general formula Ti (OZ) 4, where Z is a monohydric radical derived from an optionally substituted alcohol and / or an optionally substituted carboxylic acid and some of the radicals Z can be replaced by hydrogen atoms, or partial condensates, i.e. polymeric and thus have an average of less than four organic groups per titanium atom. You can then z. B. of the general formula (ZO) xTiO4-x 2 in which Z has the meaning given and x is 1, 2 and / or 3 and / or in which Z has the meaning given and y is at least I. The partial hydrolyzates are expediently soluble in solvents. Such partial condensates are commercially available. They are accessible by partial hydrolysis and / or partial condensation of the corresponding monomeric titanium compounds. Polymers with the configuration - TiOZTi -II, in which Z is a divalent radical derived from an optionally substituted alcohol and / or an optionally substituted carboxylic acid, can also be used.

The radicals Z can be halogen atoms, in particular Cl, Br or F, amino, hydroxyl, carboxyl, carboxylic acid ester or ether groups.

Examples of monomeric organic titanium compounds, in which the organic radicals are bonded to titanium via oxygen, are tetraethyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetra-2-ethylhexyl titanate, tetraphenyl titanate, tetraoctadecyl titanate, tetraoctadecyl titanate, titanate tri-octadecyl titanate, tetra-12-octadecyltanate, tetra-12-octadecyltanate (HOC3H6) 2N (CH2) 3O] 2Ti [OCH (CH3) 2] 2 [(CH3CH2) 2N (CH2) 2O] 4Ti [(C6H13) 2N (CH2) 60] 2Ti [OCH2CH (CH3) 2] 2 [C4HoNH (CH2) 40] 4Ti (HOCH2CH2NHCH20) 4Ti TEtrakis-triethanolamine titanate-N-stearate, ethylene glycol titanate, octylene glycol titanate, tetra (methoxyethyl) titanate, bis (acetylacetonyl) titanium isopropyltitanium ester of the formanate [HOOCCH (CH3) 034Ti [HOOC (CH2bOJ2Ti (OH (CH3COOCH2034Ti (CH300CCH20) 4Ti) or diisopropyl diacetoxy titanate.

The size or configuration of the organic groups is not critical. The organic groups can be linear, branched or cyclic and each Contain 1 to 30 or more carbon atoms.

Examples of corresponding partial condensates are those of the formula (CH3CH2CH2O) 3TiOTi (OCH2CH2CH3) 3 Ti [OTi (OCH2CH-2NHCH2CHOH) 3li The titanium compounds can also be chelates which generally have the coordination number 6. Usually an oxygen or a nitrogen atom is bound to titanium by a chelate bond. This is particularly common with titanates of the ethanolamine titanate, alkylene glycol titanate or hydroxyacyl titanate type. Examples of such chelates are those of the formula The upper limit of the amount of organic titanium compound is not critical; however, the use of more than 10 percent by weight of titanium compound, based on organopolysiloxane, is generally of no advantage.

The process according to the invention can be carried out at any desired temperature can be carried out in the range from below room temperature to over 2000 C. The ingredients can be mixed very well at room temperature. It can however, it can sometimes be useful to heat during or after mixing to remove the alcohol formed during the mixing. The removal of the alcohol However, prior to storage from the mixture is not absolutely necessary.

The order in which the ingredients are mixed is not critical. You can mix the siloxane with the silane first and then the titanium compound admit; one can mix the siloxane with the titanium compound first and then add the silane; one can mix the titanium compound with the silane and then add the siloxane; but you can also mix all three components at the same time.

When first the titanium compound with the sig-bonded hydroxyl groups containing organopolysiloxane is mixed, there is often a considerable increase in viscosity to observe. The viscosity drops again after a few minutes, especially after the addition of the silane, strongly decreases.

The curing of the compositions produced according to the invention to give elastomers takes place within a few minutes to a few hours under the action of water, where the humidity is sufficient.

So z. B. by mixing the following siloxanes with 5 moles of silane per mole of Si-bonded hydroxyl group in the siloxane and 20/0, based on the weight of the siloxane, of the specified titanium compound with the exclusion of water, which remain unchanged with the exclusion of water, but harden in the air due to the moisture contained in it to form an elastomer. Table I. Siloxane Silane Titanium Compound G2H5 Si OO Si OH C6H5Si (OCH3h tetraoctylene glycol titanate 3 y, 1 HO SiO H C2H5Si (0C tetradiethy! Englyco1titanate I. {OOcCl7 HO SiO H CaHnSi (OCH3) 3 HO oH II eH CH-CHi CH2 C2H5 HO SiO SiO H C2HsSi (OC3H7) 3 diisopropoxytitanium dioleate CH3 CH3 5 100 -iO ~ iotaH CH3Si (OCt4) 3 (C4H90) 3TioTi (oC4Hs) 3 HO SiO 5wo H CH3Si (c4H9OiOTi (OCH9) a HO 'SiO H CIGSi (OCZ4) 3 octadecyl titanate HO0SCiHO3 CHSi (OCH octadecyl titanate HO (CHsSi (OCHsh (C, H, OhTi CH5CH5N SiO CH3 3n HOOCCI7H35 fH2 oHHs 2 HOLSiO ~ IlotloH CH3Si (OCHs) 3 ~ GH; O ~ TiOCH2CH20 ~ (oC3H7) HO SiO 10 (x> H (OCH3> C3H70 TiOCH2CH2O- Ti (OC3H?) 8 continuation Siloxane titanium bath (CI HO SiO H CHa $ 0CH2CHGI) 3 Tctra42-ethylhexylfitanate or tIj3) g7I <WH CE-ISijcCH, HO SiO) eoH H Cl8H3sSi K = HCR2CI, fs tetraisopropyl fitanate In addition to the above-mentioned essential constituents, other constituents can optionally also be used in the process according to the invention. These include fillers to e.g. B. to confer the desired tensile strength on the elastomers from the compositions produced according to the invention. Any organic fillers commonly used in siloxane elastomers, such as phthalocyanine or copper phthalocyanine, and / or inorganic fillers, such as metal oxides, e.g. B. aluminum oxide, titanium oxide, zirconium oxide, magnesium oxide or zinc oxide, inorganic silicates, z. B. aluminum silicate, mica or glass, various types of silicon dioxide, e.g. B. DW atomic earth, pyrogenic silicon dioxide obtained in the gas phase, sand, quartz powder, silicon dioxide xerogels or precipitated silicon dioxide, or types of carbon, e.g. B. carbon black or graphite can be used. The fillers can optionally have organosilyl groups on their surface.

These fillers are known commercial products.

The constituents that may be used also include others in compositions which can be hardened to give elastomers and are based on organopolysiloxanes Usual additives such as plasticizers to reduce the hardness of the elastomer, e.g. liquid, trimethylsiloxy end-blocked dimethylpolysiloxanes, agents to reduce permanent deformation, antioxidants or ultraviolet Light absorbing substances. All of these additives which can optionally be used can can be added at any time to the compositions prepared according to the invention. It Care should be taken that this does not cause any noticeable amounts of moisture to be introduced.

The masses produced according to the invention are as sealing and Potting compounds, as coating compounds, for insulating electrical devices, for Production of moldings or for the impregnation of porous materials can be used very well.

The viscosities given in the following examples were determined at 25 "C in each case.

Example 1 100 g of one hydroxyl group in each of the terminal units containing dimethylpolysiloxane with 4000 cSt were with exclusion of water with 0.5 mol of methoxyethyl titanate, d. H. the compound of the formula TitOCH2CH20CH3) 4, mixed The resulting mixture initially thickened to a paste, was however, a viscous liquid again during stirring.

A sample of the mixture was exposed to air; it wasn't Hardening observed.

The mixture was then mixed with 1.25 ml of methyltrimethoxysilane. It was then storable in the absence of water, but hardened in air 15 minutes to a body with a tack-free surface.

Example 2 100 g of one hydroxyl group in each of the terminal units containing dimethylpolysiloxane with 2000cSt were with the exclusion of water mixed with 5 g of methyltrimethoxysilane and 0.5 ml of tetrapropyl titanate. The mixture thickened but turned to a liquid after stirring for 4 or 5 minutes return. This liquid remained unchanged when stored in the absence of water, however, gelled to an elastomer in air in 4 to 5 hours.

In game 3 80 g of a 33 percent by weight solution of one in the terminal units each having a hydroxyl group containing dimethylpolysiloxane with 500,000 cSt in xylene were mixed with 5 g of methyltrimethoxysilane and 0.5 mol of tetrapropyl titanate mixed. This solution did not change its viscosity when stored in the absence of water, however, it hardened under the action of atmospheric moisture to form an elastomeric coating.

Example 4 250 g of one hydroxyl group in each of the terminal units containing 49 cSt dimethylpolysiloxane were mixed with 112 g of methyltrimethoxysilane and 1 g of tetrapropyl titanate mixed with the exclusion of water. The mixture was heated to 110 ° C initially at normal pressure and then at 1 mm pressure to remove the methanol and remove excess methyltrimethoxysilane. The product obtained contained Methoxyl groups and hardened in air without the addition of a further catalyst within 15 minutes to an elastomer with a tack-free surface.

Example 5 Mixtures of 100 parts each of one in the terminal Units each having a hydroxyl group containing dimethylpolysiloxane with 12,000 cSt, 40 parts of a dimethylpolysiloxane end-blocked by trimethylsiloxane units as a plasticizer and 28 parts of one with trimethylsiloxy groups aS Saturated silica with a surface area of about 350 qm / g were under Exclusion of water with in each case 1 part of the titanium compounds given below and with 5 parts by weight of methyltrimethoxysilane per 100 parts by weight of dimethylpolysiloxane mixed. All blends were shelf-stable, but cured to elastomers in air with the properties given in the table.

Table II Physical Properties of the elastomer after 7 days at room temperature Titanium compound Durometer tensile fracture value strength elongation kg / cm2% (CH3OCH2CH2O) 4Ti 25 14 340 (C3H70) 4Ti 28 14.70 360 Bis (acetylacetonyl) - diisopropyl titanate 26, 18.90 440 Example 6 15 g of a 3,3,3-trifluoropropylmethylpolysiloxane with a hydroxyl group in each of the terminal units and having 300 cSt were initially mixed with 1 ml of methyltrimethoxysilane. After adding 0.25 ml of tetrapropyl titanate, the mass thickened; however, it turned into a liquid after standing in a closed container for 2 hours. This liquid showed no changes in viscosity when stored in a closed container, but solidified to an elastomer in the air.

Claims (2)

Claims: 1. Process for the preparation of compositions which cure at room temperature under the action of water to give elastomers by reacting 1. Organopolysiloxanes of the general average formula with the exclusion of the ingress of water where z is on average 1 to 1.01 and y on average 1.99 to 2, the sum of y + z = 3, R is a monovalent hydrocarbon radical, optionally containing halogen atoms and / or cyano groups, with 1 to 18 carbon atoms, and the value is of n corresponds to a viscosity of at least 25 cSt / 25 ° C, with 2. at least 0.5 mol of silicon compounds with organic radicals bonded to the Si atom via oxygen per mol of Si-bonded hydroxyl group in the organopolysiloxanes in the presence of 3. at least 0.10 / 0, based on the weight of the organopolysiloxanes, of organic titanium compounds, in which the organic radicals are bonded to titanium via oxygen, while any titanium valences not saturated with organic radicals via oxygen are provided by OH groups and oxygen in TiOTi- Bond are saturated, and 4. optionally fillers and other customary additives, characterized in that as silicon compounds with via oxygen to the Si-A tom-bonded organic radicals silanes of the general formula RSi (OR'h, where R has the meaning given and R 'is a monovalent, optionally halogenated, aliphatic hydrocarbon radical with fewer than 5 carbon atoms. 2. Modification of the method according to claim 1, characterized in that that the alcohol formed during the reaction is distilled off. Documents considered: French patent specification No. 1,266,528.