DE102005030580B3 - Producing glass-mica tape useful for insulation comprises impregnating mica paper and/or glass cloth with a silicone composition and laminating with mica paper and/or glass cloth and curing - Google Patents

Abstract

Producing glass-mica tape comprises impregnating mica paper and/or glass cloth with a silicone composition and laminating with mica paper and/or glass cloth and curing at 150-250[deg]C. The silicone composition comprises a hydroxy-terminal polydimethylsiloxane with a viscosity of 100-100000000 mm2>/sec at 25[deg]C, a MQ silicone resin, a catalyst and a solvent.

Description

Glass mica ribbons exist from a composite of mica paper and glass silk. They connect the excellent insulating properties of mica with the very good mechanical properties of glass fabrics. For a successful one Combining both materials, the binder plays a crucial Role. This has one in view of the planned area of application Set of requirements.

Glass mica tapes are used to insulate electrical conductors in essentially two different areas:
Depending on the insulation system, so-called "resin-rich" or "resin-poor" tapes are used for the insulation of windings in electric rotating machines (eg motors, generators) whose binder consists of an organic (eg epoxy resin) or a silicone resin ( see, eg, EP 1086479 B1 ). These are still flexible during processing (the conductors of generally rectangular cross-section need to be wrapped), but not after the final cure.

For the insulation fire-resistant Cables ("safety cables") become permanently elastic Binder in the form of so-called "silicone PSA" s (= "pressure-sensitive adhesives ") used. Although these glue mica paper and glass silk, their permanent stickiness however, presents a problem in that the glass mica tapes too Rolls are made and during the subsequent storage time the Layers should not stick together. Therefore, must the commercial adhesive formulations to be adapted to the specific application requirements.

task The invention is to improve the state of the art, in particular To prevent the layers of glass mica ribbons being made into rolls are while the subsequent Bond storage time.

• (A) OH-endständiges Polydimethylsiloxan mit einer Viskosität von 1000–100 000 000 mm²/sec bei 25°C
• (B) MQ-Siliconharz
• (C) Katalysator
• (D) Lösungsmittel

zur Imprägnierung von Glimmerpapier und/oder Glasgewebe verwendet wird und darauf folgender Laminierung mit Glimmerpapier und/oder Glasgewebe und Härtung bei einer Temperatur von 150 °C bis 250 °C, gegebenenfalls anschließendes Pressen.The invention relates to a process for the production of glass-mica tapes, characterized in that a composition comprising:

• (A) OH-terminated polydimethylsiloxane having a viscosity of 1000-100,000,000 mm ² / sec at 25 ° C
• (B) MQ silicone resin
• (C) catalyst
• (D) solvent

for the impregnation of mica paper and / or glass fabric is used and subsequent lamination with mica paper and / or glass fabric and curing at a temperature of 150 ° C to 250 ° C, optionally followed by pressing.

The composition consists of a mixture consisting of at least one OH-terminated high molecular weight polydiorganosiloxane having a viscosity of preferably 1,000 to 100,000,000 mm ² / sec, preferably 100,000 - 50,000,000 mm ² / sec, particularly preferably 1,000,000 - 20,000,000 mm ² / sec, a silicone resin consisting essentially of units of at least one R ₃ SiO _1/2 unit and of SiO _4/2 units, each R independently being a C ₁ to C ₂₀ alkyl or alkenyl radical or an aryl radical.

Examples for R are Alkyl radicals, such as the methyl, ethyl, n-propyl, iso-propyl, 1-n-butyl, 2-n-butyl, iso-butyl, tert-butyl, n-pentyl, iso-pentyl, neo-pentyl, tert-pentyl; Hexyl radicals, such as the n-hexyl radical; Heptyl radicals, such as the n-heptyl radical; Octyl radicals, such as the n-octyl radical and iso-octyl radicals, such as the 2,2,4-trimethylpentyl radical; Nonyl radicals, such as the n-nonyl radical; Decyl radicals, such as the n-decyl radical; Dodecyl radicals, such as the n-dodecyl radical; Octadecyl radicals, such as the n-octadecyl radical; Cycloalkyl radicals, such as Cyclopentyl, cyclohexyl, cycloheptyl and methylcyclohexyl radicals; Alkenyl radicals such as the vinyl, 1-propenyl and 2-propenyl radicals; Aryl radicals, such as the phenyl, naphthyl, anthryl and phenanthryl radicals; Alkaryl radicals, such as o-, m-, p-tolyl radicals; Xylyl radicals and ethylphenyl radicals; and Aralkyl radicals, such as the benzyl radical, the α- and the β-phenylethyl radical.

This mixture according to the invention also contains a solvent with a proportion of preferably 30-95% by weight, preferably 50-90% by weight, particularly preferably 60-80% by weight. Hydrocarbons, especially aromatic hydrocarbons such as toluene, xylene, are preferred as solvents. The solvent content is chosen depending on the capacity of the mica paper so that the resin content in the dried glass-mica tape is generally in the range between 10 wt.% And 30 wt.%. In addition, alkali-reacting (such as, for example, hydroxide or amine-containing compounds) and / or metal-containing catalysts (such as metal octoates), which accelerate the condensation of silanol groups, are necessary, preferably amine-containing (such as tetramethylguanidinium salts) and / or metal octoates (such as aluminum). , Zinc or lead octoate), more preferably tetramethylguanidinium octoate and / or lead octoate. These crosslinking accelerators are added in such a concentration that even during the short drying time available in the industrial production process, complete crosslinking of the silicone resin takes place, for example in amounts of from preferably 0.1 to 2% by weight, preferably 0.1 to 1% by weight, more preferably 0.2 to 0.5. As further optional crosslinking aids peroxides such as dibenzoyl peroxide or dicumyl peroxide can be used.

The OH-terminated Polydimethylsiloxane to MQ-silcon resin is used in the composition of the invention in relation to from 1: 3 to 3: 1, preferably in the ratio 5: 5 to 7: 3 especially preferably 5: 5 to 3: 7 is used.

Of the Fixed content amounts 4% by weight to 70% by weight.

The Mica paper is made from calcined muscovite, vermiculite phlogopite or synthetic mica or a compound thereof produced, with the generation of phlogopite is preferred.

Of the costly condensation step in the production of Si-PSAs does not apply the PSA precursor mixture has a significant because of the lower viscosity improved impregnation behavior on, wherein the surface tackiness by Adjustment of the mixing ratio Polydimethylsiloxane / MQ resin can be optimally adjusted.

The Composition according to the invention can optionally after setting an optimal active ingredient content by additional Dilute with solvent by dipping, spraying or applied by roller application. The impregnation can be used before lamination to mica paper and / or glass fleece or after lamination on both components together respectively.

Then done evaporation of the solvent and crosslinking of the silicone components at 150-220 ° C for 5 to 15 minutes.

sufficient cohesion within the binder is used only in networked systems and achieved sufficiently high molecular weight. It was surprising that analogous or even better mechanical values of the glass-mica tapes result, if you let the crosslinking reaction take place in the laminate instead as per stand the technique under well-defined conditions in a chemical Reactor takes place.

example 1

It is a homogeneous mixture consisting of 100 g of an OH-terminated polydimethylsiloxane having a viscosity of about 12,000 Pa s (corresponding to a chain length of about 5000), 185g of a silicone resin of the composition (Me3S101 / 2) 0.4 (SiO412) 0 , 6 and 2500 g of toluene. Before impregnation, 10 g of tetramethylguanidinium octoate are admixed thereto. Mica paper of uncalcined phlogopite with a basis weight of 120 g / m ^{2 is} immersed in this mixture. After dipping, excess binder solution is drained and then laminated with glass cloth having a basis weight of 23 g / m ² .

The drying of the laminate takes place in the drying oven in 2 temperature stages. First, at 120 ° C, 2 min, the solvent was evaporated, then at 200 ° C, 10 min, cured:
This gives highly flexible glass-mica tapes (according to DIN EN 60371-3-8), which have a non-sticky surface, so that no layer bonding takes place when stored on the roll.

Example 2

It is a homogeneous mixture consisting of 100 g of an OH-terminated polydimethylsiloxane having a viscosity of about 12,000 Pa s (corresponding to a chain length of about 5000), 185 g of a silicone resin of the composition (Me3SiOii2) 0.4 (SiO412) 0.6 and 2500 g of toluene. Before impregnation, 10 g of tetramethylguanidinium octoate and 3 g of lead octoate are admixed thereto. Mica paper of uncalcined phlogopite having a basis weight of 120 g / m ^{2 is} immersed in this mixture. After dipping, excess binder solution is drained and then laminated with glass cloth having a basis weight of 23 g / m ² .

The Drying of the laminate takes place in the drying oven in 2 temperature stages. First is at 120 ° C, 2 min, the solvent evaporated, then at 180 ° C, 5 minutes, cured. You get highly flexible Glass mica tapes (in accordance with DIN EN 60371-3-8), which have a non-sticky surface, so that no layer bonding takes place when stored on the roll.

Claims (3)

Process for producing glass mica tapes, characterized in that a composition comprising: (A) OH-terminated polydimethylsiloxane having a viscosity of 1000 - 100 000 000 mm ² / sec at 25 ° C (B) MQ silicone resin (C ) Catalyst (D) Solvent for impregnation of mica paper and / or glass cloth is used and subsequent Lamination with mica paper and / or glass cloth and at a temperature of 150 ° C to 250 ° C is cured. Method according to claim 1, characterized in that that afterwards to the hardening is pressed. Method according to claim 1 or 2, characterized that the polydimethylsiloxane to MQ silicone resin in the ratio of 1: 3 to 3: 1 is used.