DE1163540B - Organopolysiloxane molding compounds that can be stored in the absence of moisture - Google Patents

Description

Organopolysiloxane molding compounds which can be stored in the absence of moisture Molding compositions which harden to form solids at room temperature are very valuable. you will be primarily for coatings, e.g. B. used as paints for wood. Resulting in elastomers Masses of this type are used in particular as coating, sealing or potting compounds used. The first compounds based on organopolysiloxanes to cure at room temperature consisted of two or more components which, when mixed, spontaneously result in the desired one Solid hardened. 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 quite apart from the fact that a mixing process always requires additional time and workload conditional.

In addition, the mixtures must be produced within a relatively short time to be used after mixing together as there is no way to get one Hardening after mixing with catalyst and crosslinkers, for example SiH compounds or alkoxysilicates.

One-component materials based on liquid organopolysiloxanes were later introduced with Sig-bonded acyloxy residues became known, which in the presence of moisture depending on the composition of the organopolysiloxanes to form resinous or solid elastomers, with elimination of a carboxylic acid, which in the case of the commercial products in general acetic acid is harden. However, there are a number of areas of application where the presence of carboxylic acid is undesirable and harmful.

The invention, in air at room temperature to form elastomers curing one-component molding compounds based on organopolysiloxanes with functional Groups and condensation catalysts and optionally fillers are in Can be stored for a long time in the absence of moisture and do not split when hardened Acid off. They contain such as organopolysiloxanes with functional groups the general average formula RySi [(OSiR2) xZSiRa-a (OR ') a] 4-y where R is a monovalent, hydrocarbon radical free of aliphatic multiple bonds, which optionally may be substituted by halogen or cyano groups, Z is a divalent, aliphatic one Multiple bonds free hydrocarbon radical with at least 2 carbon atoms and R ' an alkyl radical with 1 to 4 carbon atoms, optionally in the A, y or position may be substituted by halogen, y means 0, 1 or 2, a 2 or 3 and x is at least 3. The radicals R and Z preferably contain no more than 18 carbon atoms.

Examples of hydrocarbon radicals R are any alkyl radicals, such as methyl, ethyl, isopropyl, tert-butyl, 2-ethylhexyl, dodecyl, I-isobutyl-3,5-dimethylhexyl, Octadecyl or myricyl radicals, any cycloalkyl radicals such as cyclopentyl or cyclohexyl radicals, any aryl radicals, such as phenyl, naphthyl or xenyl radicals, any aralkyl radicals, such as benzyl, phenylethyl or xylyl radicals, or any alkaryl radicals such as toluyl or dimethylphenyl radicals.

However, R preferably denotes a methyl radical.

Examples of halogenated hydrocarbon radicals R are chloromethyl, 3,3,3-trifluoropropyl-3,3,4,4, 5,5,5-heptafluoropentyl-, perchlorphenyl-, 3,4 - Dibromocyclohexyl, a, a, a-trifluorotoluyl, 2,4-dibromobenzyl or a, ß, jB-trifluoro-a-chlorocyclobutyl radical.

In the case of the hydrocarbon radicals R it is preferably cyanoalkyl radicals, such as the S-cyanoethyl, y-cyanopropyl, w-cyanobutyl, , B-cyanopropyl, γ-cyanobutyl or rn-cyanoctadecyl radical.

If hydrocarbon radicals containing cyano groups are present, so they are preferably on at least 1 mole percent of the silicon atoms in the organopolysiloxane bound.

Examples of the radical R 'are methyl, ethyl, n-propyl or isopropyl radical or the ß-chloroethyl, A-chloropropyl, 2,2,2-trifluoroethyl, called y-bromopropyl, a-iodobutyl or 3,3,3,2,2-pentafluoropropyl radical.

However, R 'preferably denotes a methyl radical.

The following formula groupings may be mentioned as examples for the radical Z: Configurations of Z are preferred, the Si atoms linked thereby being separated by at least 2 C atoms, such as e.g. B. with the ethylene residue.

The general average formula given above includes organopolysiloxanes of the most varied configurations, which can be obtained by varying the values for y and x result. Of course, some of the terminal radicals OR 'can pass through hydrolyzed by the inevitable presence of moisture during manufacture and storage be.

The organopolysiloxanes used according to the invention have a linear structure, if y has the value 2: (R'O) aR3-aSiZ (R2SiO) xSi (R2) ZSiR3-a (OR ') a II If y, on the other hand, has the value 1 or 0, they have a branched structure: RSi [(OSiR2) rZSiRaa (OR ') aia (y = 1) III Si [(OSiR2) xZSiR3-a (OR'a] 4 (Y = O) IV The Organopolysiloxanes used according to the invention are expedient by reacting one Siloxane of the formula RySi [(OSiR2) rHh-Y V with silanes of the formula R "SiR3-a (OR ') a VI or by reacting a siloxane of the formula RySi [(OSiR) xR "} i v VII with silanes of the Formula HSiRa-a (OR ') a VIII where R, R', y, x and a have the meanings given above and R "is a monovalent hydrocarbon radical with an aliphatic or cycloaliphatic C - C double bond is, in the presence of one for the addition from compounds with aliphatic multiple bonds to compounds with Si-bonded Hydrogen conventional catalyst produced. The reaction will be beneficial at Temperatures from 30 to 150 ° C in the presence of Pt catalysts such as chloroplatinic acid, Pt / charcoal or Pt / aluminum oxide.

The organopolysiloxanes used according to the invention are benzene-soluble Substances that lead to insoluble gels, especially in the presence of a catalyst, the reaction of the Si-bonded alkoxy groups with H20 or with Si-bonded OH groups are able to accelerate hardening when mixed with water in liquid form or come into contact in the form of water vapor, already being the atmospheric Moisture is enough. The mixture of the organopolysiloxanes and the catalysts is but stable and storable in the absence of water.

The curing speed can be determined by the choice of catalyst and by the number of functional groups in the organopolysiloxane component can be set in the usual way.

It is advantageous here to use catalysts which are found in the organopolysiloxanes Are soluble or easily dispersible, which can optionally be achieved by using a common solvent can be promoted. Suitable condensation catalysts are for example organometallic compounds, such as metal salts of monocarboxylic acids, z. B. lead-2-ethylhexoate, dibutyltin diacetate, di-butyltin-2-ethylhexoate, dibutyltin dilaurate, Butyltin tri-2-ethylhexoate, iron-2-ethylhexoate, cobalt-2-ethylhexoate, magnesium - 2 - ethyl hexoate, zinc 2-ethyl hexoate, tin octoate, tin naphthenate, zirconium octoate, Antimony octoate, bismuth naphthenate, tin oleate, tin butyrate, zinc naphthenate, zinc stearate or titanium naphthenate, organic titanium esters or their partial hydrolysates, such as tetrabutyl titanate, Tetra-2-ethylhexyl titanate, tetraphenyl titanate, tetraoctadecyl titanate, triethanolamine titanate, Octylene glycol titanate or bis - acetylacetonyl diisopropyl titanate, amines such as hexylamine, Dodecylamine or di-n-hexylamine, amine salts such as hexylamine acetate, dodecylamine phosphate or hexylamine octoate, quaternary amine salts such as benzyltrimethylammonium acetate, hydroxyethyltrimethylammonium-2-ethylhexoate or tetraethylammonium butyrate, carboxylic acids such as acetic acid or formic acid, or inorganic acids such as HCI.

For the one-component composition according to the invention, the amount of catalyst is not critical, but 1 to 2 percent by weight of the catalyst is advantageous, based on the weight of the organopolysiloxane component used. For example the above defined organopolysiloxanes with 1 percent by weight of stannous octoate or 0.3 weight percent dibutyltin dilaurate are mixed.

The one-component compositions according to the invention are expediently suitable as coating, sealing or potting compounds and as impregnating agents. You can can be used very well in isolating electrical devices. For many For purposes of application, it is advantageous if the masses also contain fillers, be it as an extender or to give certain properties.

The fillers can be organic, such as phthalocyanines, copper phthalocyanines or organic fibers, or be inorganic, such as metal oxides, e.g. B. titanium dioxide, Zinc oxide, aluminum oxide, ferric oxide or magnesium oxide, silicates such as aluminosilicates, Clays, zirconium silicate or glass, silicon dioxides such as diatomaceous earth, sand, quartz powder, SiO2 obtained pyrogenically in the gas phase, dehydrated while maintaining the structure Silica hydrogels (so-called SiO2 aerogels) or precipitated SiO2, also metal powder, such as aluminum or zinc powder or types of carbon such as graphite or carbon black.

Example 1 a) Preparation of the polysiloxane used, 277 g of a dimethylpolysiloxane containing dimethylhydrogensiloxy units as terminal units with 0.12 percent by weight of Si-bonded hydrogen are mixed with 68 g of vinyltrimethoxysilane mixed. About 5 / 10-6 parts by weight based on total reactants (ppm) of platinum in the form of chloroplatinic acid are added to a quarter of the mixture added and heated to 125 to 1300C.

The remainder of the reaction mixture is then added and 1 Heated to 145 "C for one hour. After removing the up to 150 ° C / 3 to 4 mm Hg The organopolysiloxane has the formula (CH30) 3SiCH2CH2Si (CH3) 20 [Si (CH3) 20] nSi (CH3) 2CH2CH2Si (OCH3) 3 where n has an average value of about 21, in the form of a straw yellow colored Get liquid. b) Use according to the invention 10 g of this organopolysiloxane are mixed with 0.1 g of tetraisopropyl titanate. This mixture hardens in the air at room temperature in less than 24 hours to a non-sticky, solid film, while it remains unchanged in the closed vessel.

Example 2 a) Production of the Polysiloxane Used A mixture of 265.5 g of the dimethylpolysiloxane used in Example 1, a) and 53 g of vinylmethyldimethoxysilane and about 5 ppm of platinum in the form of chloroplatinic acid is taken in ethanol for 2 hours Heated to reflux. After adding a further 15 g of vinylmethyldimethoxysilane and Pt catalyst is heated to 170 to 1800C for 2 hours. After removing the low-boiling components at 150 ° C / 2 mm Hg the organopolysiloxane of the formula (CH30) 2Si (CH3) CH2CH2Si (CH3) 20 [Si (CH3) 20] Si (CH3) 2CH2CH2Si (CH3) (OCH3) 2 where n has an average value of 21, in the form of a straw yellow colored Get solution. b) Use according to the invention 20 g of this organopolysiloxane will be mixed with 0.25 g of stannous octoate. Part of this mixture is placed in a petri dish given. After 40 minutes a solid film with a non-sticky surface forms; it is completely through after 72 hours hardened. The rest of this mixture showed no change when stored in a sealed bottle. c) 10 g of the organopolysiloxane are mixed with 0.1 g of tetraisopropyl titanate. This mixture hardens in the air at room temperature in less than 24 hours to a non-sticky, solid film, while it remains unchanged in the closed vessel. d) 8 g des Organopolysiloxane are mixed with about 0.1 g of tetrakismethoxyethyl titanate. Part of this mixture hardens in a thin layer in air at room temperature to a non-tacky film within 48 hours.

Claims (1)

Claim: Storable with exclusion of moisture, under the action of atmospheric moisture at room temperature to elastomers curing molding compounds based on organopolysiloxanes with functional groups and condensation catalysts and optionally fillers containing as Organopolysiloxanes with functional groups those of the general formula RySi [(OSiR -), ZSiR3 -, (OR '), 1? -, where R is a monovalent. hydrocarbon radical free of aliphatic multiple bonds, which may optionally be substituted by halogen or cyano groups, Z is divalent hydrocarbon radical free of aliphatic multiple bonds at least 2 carbon atoms, R 'is an alkyl radical with 1 to 4 carbon atoms, which optionally in the iS- Y- or t "-position can be substituted by halogen, y 0, 1 or 2, a is 2 or 3 and x is at least 3.