DE1028721B - Combination paints based on silicone alkyd resins and polyvinyl resins - Google Patents

Description

Combination paints based on silicone alkyd resins and polyvinyl resins The invention relates to paints based on silicone alkyd resins and polyvinyl acetal resins, which the heat resistance of the paint films of the organopolysiloxane resins and the desirable ones combine physical properties of polyvinyl acetal resins; with these Varnishes are used on electrical wires and other conductors of all thicknesses and shapes Received insulating coatings with good coating properties.

The long-used lacquers, lacquer enamels, for the insulation of Electrical conductors have both favorable and disadvantageous properties. On the one hand, the well-known organic paint resins are limited because of their Heat resistance inadequate; so polyvinyl acetal resins and with phenol aldehyde resin are suitable modified polyvinyl acetal resins not for exposure to temperatures above 105 ° C.

Organopolysiloxanes are characterized by high temperatures exceptional thermal stability, but also on the other hand due to a lack of mechanical properties, such as insufficient resistance against abrasion. Obtained from organopolysiloxane resins modified with alkyds Although more resistant films, but a wire of smaller diameter, z. B. of 0.125 mm or less, can not be satisfactory with such paint resins be coated. Furthermore, although round wires of larger diameter can be used, but do not cover angular wires with such silicone alkyd resin lacquers, as with the angular wires only the flat surfaces, but not the angular contact points the individual surfaces are covered; however, it is a discontinuous coating worthless for use in electrical insulation technology. One already has suggested mixing silicone alkyd resins and polyvinyl acetate; such combinations however, they are unsuitable as coating agents because the resins are different during film formation unmix. In addition, a resin solution must have a viscosity that is sufficient for absorption of the wire should be suitable for resin solids, a very high content of resin solids exhibit; this in turn requires little clearance in the mold, what in turn leads to frequent malfunctions, since the wire is less in shape as a result Irregularities in the wire is jammed.

Also mixtures of the heat-resistant organosiloxane resins with polyvinyl acetal resins and their modifications have been found to be inadequate and not technical Becomes important because the mixtures already at relatively low temperatures are thermoplastic and flow off the wire, leaving the latter uncovered, so that short circuits occur. In addition, lacquer coatings produced with this have have very low solvent resistance and are consistently in isolation unsuitable for magnetic wires. In order to avoid these disadvantages, it has been suggested that to provide electrical conductors with a base layer of polyvinyl acetal resins, to which a top layer of silicone resins is applied; this procedure is conditional however, in contrast to the combination according to the invention, an additional operation.

The present invention relates to mixtures which are essentially characterized by the following constituents (A) at least 40 percent by weight of a silicone alkyd resin, which is the reaction product of (1) 5 to 60 percent by weight of an organosilicon compound of the unit formula wherein R is monovalent hydrocarbon radicals and halogenated monovalent hydrocarbon radicals, X is halogen atoms, alkoxy and hydroxy radicals, n has an average value of 1 to 2 inclusive, m has an average value of 0.05 to 3 inclusive and the sum of m +, n is no more than 4, (2) 10 to 30 percent by weight of polyhydric alcohols and (3) 30 to 70 percent by weight of a dicarboxylic acid or its anhydride or lower alkyl esters; (B) up to 60 weight percent polyvinyl acetal resin. The organosilicon compounds referred to above as constituent (1) of the silicone alkyd resins (A) include monomeric silanes, furthermore polymeric partial hydrolysates of silanes, and monomeric and polymeric fully hydrolysed silanes. The polymeric partial silane hydrolysates are polysiloxanes with residual alkoxy groups or halogen atoms bonded to the silicon atoms. The fully hydrolyzed silanes are either monomeric silanols or hydroxylated polysiloxanes. The hydrolyzates listed are prepared by known processes. The organosilicon compounds (1) may contain more than one kind of R and X groups. Examples of the Organosiliciumv onnectivity (1) are dimethyldichlorosilane, Dibutyldiisopropoxysilan, Phenylmethyldiäthoxysilan, Di @ inyldibutoxysilan, Tolyltriäthoxysilaii, cyclohexyltrimethoxysilane, Phenylmethyldibromsilan, (trifluoromethylphenyl) -methyldichlorsifan, ChlorphenvItriäthoxysilan, Bromxenyltrichlorsilan, Stearylmethyldiäthoxysilan, Allylstearyloxydimethoxysilan and mixtures thereof, further and partial or complete hydrolysates or such Silanes and / or mixtures of such substances. In addition, diphenylsilanediol, phenylmethylsilanediol, di-methylsilanediol, chlorophenylmethylsilanediol, octadecylmethylsilanediol, and combinations thereof are also effective.

If desired, up to 50 percent by weight of the organosilicon compound can be used (1) be replaced by drying oils and / or drying oleic acids, for example through acids from linseed oil, sardine oil, soybean oil, tung oil, oiticica oil, perilla oil, China oil, hemp oil, poppy seed oil, saffron oil, sunflower oil and walnut oil as well as dehydrated Castor oil, also through the oils mentioned as such. The drying oils and the drying oleic acids can react with the organosilicon compounds Way to be combined.

As component (2) of the silicone alkyd resins (A) there are two, three and tetravalent alcohols. The dihydric alcohols cannot alone but only used in a mixture with trihydric and / or tetravalent alcohols be, the amount of dihydric alcohol not more than 50 percent by weight, calculated on the total weight of the alcohol mixture. According to the invention Applicable alcohols include ethylene glycol, neopentyl glycol, glycerine, Pentaerythritol, trimethylol ethane and trimethylol propane.

As constituent (3) of the silicone alkyd resins (A) according to the invention any dicarboxylic acid or mixture of such acids is effective. Examples such acids are aliphatic dicarboxylic acids, such as malonic, adipic, sebacic, Maleic and dimethyl maleic acid; cycloaliphatic dicarboxylic acids, such as cyclohexyldicarboxylic acid, and aromatic dicarboxylic acids such as methylenedisalicylic acid, phthalic acid, terephthalic acid, Isophthalic acid, naphthalic acid, stilbene dicarboxylic acid, diphenic acid, tolanedicarboxylic acid and dibenzyl dicarboxylic acid. The anhydrides of the acids mentioned can also be used and their alkyl esters, in which the alkyl radical contains fewer than 9 carbon atoms, z. B. use the methyl, ethyl, propyl and amyl esters.

The polyvinyl acetal resins (B) also used according to the invention are through Condensation of any polyvinyl esters and / or polyvinyl alcohols with any Aldehydes produced, for example with formaldehyde, acetaldehyde, propionaldehyde, Butyraldehyde or benzaldehyde. Examples of polyvinyl esters are polyvinyl acetate, Polyvinyl propionate and polyvinyl butyrate. The best known polyvinyl acetal resin is that which can be prepared by condensing a hydrolyzed polyvinyl ester with formaldehyde Polyvinyl formal. The Poly @ inylacetalharze can alone or in a mixture with a a smaller amount of a phenol aldehyde resin can be used. You can by incorporating of up to 50 percent by weight, based on the total weight of the resin mixture (B), any thermosetting phenol aldehyde resin which the aldehyde component formaldehyde, acetaldehyde, benzaldehyde, cinnamaldehyde and propionaldehyde, while the phenol component can be phenol, cresols, xylenols and the like are applicable.

The constituents of the silicone alkyd resins (A) can be in any order added or the organosilicon compound to that already reacted with dicarboxylic acid Alcohol or any other arbitrary procedure can be used. Corresponding The polyvinyl acetal resins and / or polyvinyl acetal-phenol aldehyde resins can also be used (B) can be produced as desired. The silicone alkyd resins (A) and polyvinyl acetal resins (B) can be mixed together in any desired manner.

Electrical wires or other conductors can be used according to any processes known for this purpose are coated with the combination lacquers. The viscosity, those for a successful coating of the ladder with the help of spray guns and subsequent oven curing is required, can with a solids content in the Resin solution are obtained, which is well within the practical limits, as they are applicable in the usual wire enamelling towers, moves.

The combination paints can be used in an economical manner both on fine round wires whose diameter z. B. is less than 0.125 mm than also on wires with a rectangular, hexagonal or other straight cross-section Instruct. These coatings exhibit remarkable resistance to sudden changes Exposure to heat. On the other hand, coatings made from unmodified silicone alkyd resins form Hairline cracks when the coated wire is stretched 10% of its original length, wound around a mandrel until the winding is ten times the diameter of the wire is and is heated to 200 ° C, whereas the paint films according to the invention at same treatment, but the winding is only four times the wire diameter can come, have no hairline cracks. This is extremely important for coated magnet wires, which are used, for example, for motor coils, because such wires are generally tightly wound and at relatively high temperatures get abandoned. In addition, the combination lacquers form tear-resistant films, which above all an elongation of the wire covered with them easily up to 30 ° / o withstand.

The parts and percentages given in the examples below are parts and percentages by weight, unless otherwise specified. EXAMPLE 1 An alkyd resin (A) is prepared in a known manner by converting 17% glycerol, calculated on the total weight of the subsequently produced silicone alkyd resin, 8.5 ″ ethylene glycol and 53.50 dimethyl terephthalate The mixture is heated to 230 ° C. in the presence of magnesium acetate as a catalyst in a nitrogen atmosphere until approximately the theoretical amount of methanol has been removed. The resulting polymer is diluted in cresol to a concentration of 50% solids and then diluted to 21 ° / o, calculated on the total weight of the silicone alkyd resin, of a partially hydrolyzed phenylmethylsiloxane containing 30% methoxy groups is added, the mixture is then heated to 200 ° C. until the theoretical amount of methanol has been removed, and the reaction product is then filtered.

The polyvinyl formal resin (B) used in the present invention consists of a solution of 33 parts of cresol formaldehyde resin and 67 parts of polyvinyl formal resin in a mixture of cresol and high-boiling mineral oil.

The resin solutions (A) and (B) are mixed together so that the silicone alkyd resin solid parts 80 and the polyvinyl formal resin solid parts 20% calculated on the total weight of resin solids in the solution. The combination paint obtained has a concentration of 33.3 ° o, calculated on the total amount of resin solids, and a viscosity of 6000 cP at 25'C. Copper wire with a diameter of around 1 mm is drawn through this lacquer solution and then at a speed of 670 cm / min. through a 305 cm long, vertical oven, the temperature of which is 80 to 100'C on the bottom and is in the top Oven part increases to 510 to 550'C. The solvent is driven off and the resin coating cured. The immersion and subsequent hardening is six times repeated and thus obtained a resin coating 0.08 mm thick.

The coated wire is subjected to the following standard heat shock test: It is stretched 10 per cent of its original length and more differently by mandrels Sizes wrapped. The wire-wound mandrels are placed in an oven and heated 30 minutes at 225 ° C. After this time has elapsed, the wire is checked and determined that with a wire whose winding around the mandrel is five times or more the wire diameter fraud, there are no hairline cracks; on the other hand, the unmodified silicone alkyd resin fails, whose winding around the mandrel is or forms 15 times the diameter of the wire Hairline cracks.

The heat resistance of the coating corresponds roughly to that of the pure silicone alkyd resins. The coated copper wire can be used successfully at an average temperature for wires of 165 ° C without damaging the insulating coating; even hot spots up to 180 ° C have no adverse effects on the coatings. In contrast, polyvinyl formal resin coatings cannot be used above the average wire temperature of 90 and / or 105 ° C hot spot temperature. In all other respects, too, the silicone alkyd resin-polyvinyl formal resin mixtures prove to be excellent wire enamels and are extremely suitable for use in electric motors and the like. Example 2 A mixture consisting of 95% of the silicone-modified alkyd resin and 5% of the polyvinyl formal resin , calculated on the total solids content of the resin, is prepared according to Example 1 and used as a coating for a wire about 8 mm in diameter, with equivalent results being achieved. Example 3 Using the method and resins of Example 1, a mixture of 90 % of the silicone alkyd resin and 10 % of the polyvinyl formal resin is prepared. When this resin is checked, it turns out to be extremely suitable for use as magnetic wire enamel. EXAMPLE 4 50 parts each of the silicone alkyd resin according to Example 1 and a polyvinyl formal resin which does not contain phenol aldehyde resin are mixed and dissolved in a mixture of cresol and high-boiling mineral oil to a resin solids content of 21% and a viscosity of 28,000 cP at 25 ° C. The lacquer obtained is suitable in every way as a coating for magnet wire. A wire coated with this resin according to Example 1, which is wound around a mandrel the size of the wire diameter and heated to 225 ° C. for 30 minutes, shows no heat damage.

Example 5 An alkyd resin is prepared by reacting 124 parts of ethylene glycol, 245.4 parts of glycerol and 776 parts of dimethyl terephthalate in the presence of magnesium acetate as catalyst in a nitrogen atmosphere at 230 ° C. until approximately the theoretical amount of methanol has been removed. The resulting polymer is diluted with cresol and 1338 parts of a hydroxylated organosilicon compound consisting of 51 mol percent phenylmethylsiloxane, 28 mol percent methylsiloxane, 14 mol percent phenylsiloxane and 7.5 mol percent diphenylsiloxane units, which have 3 percent by weight of silicon-bonded hydroxyl radicals, are added to the solution. The alkyd-silicone mixture is heated to 200 ° C. for 2 hours and then filtered. The filtrate is mixed with 20% of the polyvinyl formal resin prepared according to Example 1. These resin components prove to be compatible both in the solution and in the film; a product with excellent coating properties is obtained. EXAMPLE 6 A reaction product is prepared from 19% trimethylolethane, 9.7% ethylene glycol, 51% dimethyl terephthalate and 20.3% of a methoxylated partial hydrolyzate of 20 ″ diphenylsiloxane containing methoxy groups are mixed with magnesium acetate as a catalyst and heated to 230 ° C. until approximately the theoretical amount of methanol is removed. Then cresol is added until a solution with 50% solids is present. The latter is filtered and mixed with the polyvinyl formal resin according to the example 1 in a proportion of 80 % silicone alkyd resin and 20% organic resin, calculated on the total amount of resin solids, mixed.

Claims (5)

PATENT CLAIMS: 1. Combination paints based on silicone alkyd resins and polyvinyl resins, consisting essentially of mixtures of (.a) at least 40 percent by weight of a reaction product of (1) 5 to 60 percent by weight of organosilicon compounds of the formula where R is an optionally halogenated monovalent hydrocarbon radical, X is a halogen atom or an alkoxy or hydroxyl radical, n is 1 to 2, m is 0.05 to 3 and m + n is at most 4, (2) 10 to 30 percent by weight of polyhydric alcohols and (3 ) 30 to 70 percent by weight of dicarboxylic acids, their anhydrides or lower alkyl esters, and (B) up to 60 percent by weight of polyvinyl acetal resin. 2. Combination lacquers according to claim 1, containing as constituent (1) organosilanes of the formula R "SiXm, in which m is 2 to 3, or their partial or complete hydrolysates. 3. Combination paints according to Claims 1 and 2, containing three or three as component (2) tetravalent alcohols or their mixtures with up to 50 percent by weight, calculated based on the total weight of the alcohol mixture, of dihydric alcohol. 4. Combination paints according to claims 1 to 3, containing as constituent (B) mixtures of polyvinyl acetal resin with up to 50 percent by weight, calculated on the total weight of the mixture (B), on thermosetting phenol aldehyde resin. 5. Combination paints according to claim 1 to 4, consisting of the reaction product (A) of (1) a phenylmethyloxy- or alkoxysilane, (2) a mixture of at least 50 percent by weight glycerol and up to 50 percent by weight ethylene glycol and (3) dimethyl terephthalate and one Mixture (B) of at least 50 percent by weight of polyvinyl formal resin with up to 50 percent by weight of phenol-formaldehyde resin. Considered publications: German Patent Specifications No. 841 362, 853 353; Austrian Patent No. 176 935; Kunststoffe, 1953, v. 19th