DE1293374B - Process for the production of self-adhesive silicone rubber tapes - Google Patents

Description

1 2

The present invention relates to a method provided that the in

for the production of self-adhesive silicone rubber mixture, the amount of alkyl borate present is large tapes whose self-adhesive layer made of silicone rubber is larger than previously known.

consists of boron compounds, organic peroxide from British patent specification 887 441 is one and optionally fillers, which are also reinforcing 5 mixture of a polysiloxane with two organic can act contains. This method is thereby substituent, an inorganic filler, one characterized in that one contains the said additives alkoxy group-containing silicon compound and containing silicone rubber, known as boron, a boron-containing substance for connection an alkyl borate and / or alkenyl borate in turn for the production of silicone elastomers, used in such an amount that 0.6 to 1.5 Ge io This patent does not describe the weight percent boron based on the weight of the mixture containing the large amount of boron as an alkyl borate Organopolysiloxane of the silicone rubber, which are present for the purposes of the invention are, in the form of a dispersion or solution, is inherently essential. It was also found that the As is known, the presence of an alkoxy group-containing silicon on glass fabric as a carrier material brings and after the application of the coating 15 reconnection is in no way an essential component Partly vulcanized self-adhesive layer. part of the mixes used for making It is known that the addition of small amounts of boron to self-adhesive silicone rubber tapes with backings such as boric acid, boric anhydride or an alkyl borate can be used, and indeed it is preferable the processing for organopolysiloxane rubbers is not available in the present mixtures, properties of rubbers improved. It was 20 In U.S. Pat. No. 2,851,439, the also found that by adding 0.015 to using 0.01 to 3 weight percent alkyl-0.5 Percentage by weight of boron as alkyl borate to organoborate in a solution of a siloxane resin, polysiloxane rubbers these silicone rubbers which the purpose of this compound is to prevent The properties of self-adhesive are imparted by the resin when coating an object. that is, the rubber produced in this way sticks after the 25 drips before it has hardened. If you add that to it Vulcanize on itself but not on any other amount used from 0.01 to 3 percent by weight Materials such as metal or glass. Self-adhesive alkyl borate on the boron content, so it emerges Silicone rubbers made in this way only contain 0.3% boron if the alkyl borate is trimethyl borate are, in British patent specification 859,284, or even less boron if the borate is organic as well as the production of self-containing 30 groups with more than 1 carbon atom. It is adhesive silicone rubber tapes without a carrier, which are known that silicone resins are not self-adhesive can be used as electrical insulation. and are not vulcanizable. They are different In an article in "Kunststoffe", 1960, p. 433, that is, of the silicone bis used according to the invention 436, it is stated that boric acid can be used as filler rubbers in their properties and uses for dimethylpolysiloxane elastomers 35 purpose.

can and the mixtures obtained under certain silicone rubbers are a defined class of

Ratios with organic peroxide as Kataly- Organopolysiloxanes, in which the ratio

to vulcanized silicone rubber with self-R to Si 1.9 to 2.1 and which has a high molecular

adhesive properties can be used. True, it will have a weight of approximately 100,000 to 2,000,000

said that there is a possibility of fiberglass ranging from 40 and usually around 750,000. they are

To coat with the help of a silicone rubber dispersion, vulcanizable, while the silicone resins are not vulcanized

but it is stated that the elastomer blend are sable and are organopolysiloxanes that are a

cannot be vulcanized at all if the R to Si ratio is from about 1.0 to about

contains more than one boron atom per 100 silicon atoms, has 1.7 and a molecular weight of less than

and that it can only be cured satisfactorily, 45 about 10,000.

if the mixture contains less than one boron atom per The teaching of U.S. Patent 2,851,439 under-

Contains 200 silicon atoms. It is also stated that it differs from the invention both in the

that the best vulcanizates with the cheapest self-composition of the silicone compound as well as in

Shafts relating to self-adhesive are obtained if their properties and these are differences

the ratio of boron atoms to silicon atoms in 50 is so great that a lesson for technical action

the elastomer blend is from 1: 300 to 1: 400. from the field of silicone resins not to the field

Rubber straps with straps are also available as the silicone rubbers can be transferred

electrical insulation useful. Usually the borate used in the present invention is a

in the manufacture of tapes with carriers or trialkyl or trialkenyl borate. The organic

Both sides of the support, such as glass fabric, with a 55 groups can be saturated or unsaturated and

Dispersion of an organopolysiloxane rubber in may contain substituents. Usable borates

coated with a suitable solvent. Attempts for the use according to the invention are, for. B.

self-adhesive tapes with carriers using triethyl borate, triallyl borate, tributyl borate or tri-

of the mixtures of British Patent Specification 859 284 hexyl borate and, if desired, mixtures

produced little success, since there are obviously 60 of these borates used

is that the self-adhesive property is lost if the type of

the organopolysiloxane mixture used from a dispersion of Tschuk's organopolysiloxane is not

is applied in a solvent. critical provided it is vulcanizable. the

It has now been found that it is possible to use preferred organopolysiloxanes for the invention However, self-adhesive silicone rubber tapes with 65 proper use are those with the

Manufacture carriers if the organopolysiloxane general formula

mixture on the carrier material from a dispersion d c

or dissolve in an organic solvent *

3 4

in which R is a hydrocarbon group and / or mixture which represents 0.6 to 1.5 percent by weight of boron in a substituted hydrocarbon group in the form of alkyl borate, based on the weight of the and η has a value of 1.0 to 2.1. It has been found that silicone rubber contains, from a solution or that particularly good results are obtained, dispersion in an organic solvent, e.g. B. if the organopolysiloxane contains a small amount of 5 toluene, benzene or other hydrocarbons to the silicon-bonded vinyl groups, solvents, on the glass fabric, which vorzugsz. B. 0.05 to 0.2% vinyl groups, based on the way in the form of a tape is applied. To total number of groups R in the general formula the removal of the solvent during the

to facilitate later vulcanization stage, it is

M. io wishes to use a solvent whose boiling point

⁸ point is low enough for sufficient evaporation

Allow the others present in the organopolysiloxane at the vulcanization temperature. Even though Substituents can be monovalent hydrocarbon; it is preferable that the organic solvent residues or monovalent substituted hydrocarbons - contains a larger proportion of hydrocarbons, be leftovers. In addition to the small 15 mentioned above, it has been found that it is often advantageous if the The organopolysil solutions or dispersions can contain small amounts of vinyl groups, for example oxane z. B. contain alkyl radicals as substituents, such as 2 to 15 percent by weight, based on the Methyl, ethyl or propyl radicals, alkenyl radicals, such as total solvents, of an aliphatic alcohol Allyl or propenyl radicals, aryl radicals such as phenyl or contain, e.g. B. ethanol or butanol. Naphthyl residues, halogenated hydrocarbon residues, 20 The application of the solution or dispersion on such as trifluoropropyl radicals, or substituted radicals, such as the carrier material can be carried out by the usual methods, Cyanoalkyl radicals. If appropriate, the organo- such as dipping, spraying or brushing on, by polysiloxanes also a small amount of to be passed on. The most convenient way to do this is through silicon Bound reactive groups are abducted by the carrier material through the dispersion hold, such as hydroxy, acetoxy or alkoxy groups. as is passed through. The vulcanization of the

The dispersions used according to the invention can then be added by the application of heat, for. B. or solutions of the silicone rubbers can all be carried out in a vulcanization oven. Contain fillers that are normally used in the manufacture. Although a single vulcanizing agent is used to vulcanize

position of silicone rubber can be used. If the self-adhesive examples applied according to the invention are suitable fillers, a layer of silicic acid can be used, a preferred filler, such as diatomaceous earth and fumed silica, is the embodiment of the invention using titanium oxide, zirconium oxide, zinc oxide and carbon black. Preferred of two organic peroxide compounds as VuI-wise, at least part of the filler content is a canizing agent, the vulcanization temperatures of which are non-reinforcing fillers, such as finely divided silica. about 20 ⁰ C or more apart, z. B. will

The vulcanization of the inventively applied 35 a mixture of 2,4-dichlorobenzoyl peroxide and The self-adhesive layer made of silicone rubber uses dicumyl peroxide. In these cases it will due to the fact that it is normally used for vulcanization after the coating has been applied to the carrier material used by silicone rubbers heated to a temperature high enough organic peroxide compounds as a vulcanizing agent to activate one of the vulcanizing agents and medium, such as benzoyl peroxide, dicumyl peroxide, tert-40 to partially vulcanize the silicone rubber. In Butyl perbenzoate, dichlorobenzoyl peroxide or di- a later process stage, generally during tert-butyl peroxide achieved. Mixtures of org- the production of the object in which the niche peroxide compounds, as tape is used later, the tape becomes another described, preferably used. Exposed to heating time, namely to a temperature

If necessary, the temperature according to the invention which is high enough for the second vulcanization can be used To activate dispersions or solutions of the silicone agents and the vulcanization of the silicone rubbers to complete other additives, such as pigments, anti-rubber coating, oxidants, additives for permanent deformation or to ensure a good bond between the silicone

Contain anti-structure additives. to create rubber coating and the carrier material,

In addition, according to the invention, the carrier material itself can optionally be used before the deten dispersions or solutions also additives application of the dispersion coating with a contain, which the hydrolysis of the alkyl borate binders for glass fabrics, z. B. a silane, such as delay or prevent. To the delay vinyltriethoxysilane, are coated, Agents suitable for hydrolysis include metal- According to the process of the invention with silicone alkoxides and titanium or zirconium esters such as n-butyl rubber-coated glass fabric represent coated titanate, triethanolamine zirconate or tetra-2-ethyl materials that stick together and are good hexyl zirconate. It has been found that these additives have electrical insulation properties. This overpowering when they are in quantities of roughly drawn glass fabrics are therefore particularly in the form of 10 percent by weight, based on the existing self-adhesive tapes for a large number of iso-alkyl borate, are present in the mixture, although useful for lation purposes, e.g. B. to the surrounding area Quantities can also be varied if this is to wind tap rods and coils outdoors, is required. The use of additives for The following examples illustrate the invention.

Delaying the hydrolysis is particularly beneficial. All quantitative ratios given relate to each other when these mixtures are stored for long periods by weight.

have to. 65 Example 1

For the production of the self-

adhesive silicone rubber tapes with glass fabric 125 parts of silicone rubber compound, the 100 parts of a

the built-up elastomeric dimethylpolysiloxane is used as a carrier material, which is approximately 0.07%

has vinyl groups bonded to the silicon, 25 parts of silica as a reinforcing filler and 10 parts of a hydroxylated low molecular weight dimethylpolysiloxane have been based on a conventional

Example 2

A common rubber mixer was used to mix a rubber composition accordingly

Good looks could be made when following the procedure of Example 1 on glass cloth was applied.

Example 4

In place of the triethyl borate of Example 1, triisopropyl borate and tributyl borate were used in an amount

To produce rubber mixing device with 4.5 parts of dicumyl-5 of the formulation in Example 1, but this one peroxide, 1.8 parts of 2,4-dichlorobenzoyl peroxide (in Mal an additional part was triethanolamine form a paste in silicone oil) and 10 parts of triethyl zirconate are used. The built-up mass was borate mixed, with the triethyl borate 0.7 Ge exposed to the atmosphere for several days, and on weight percent boron based on the weight of the end of this period has been found to be the Organopolysiloxane. 20 parts of the free surface of the mass obtained in this way are relatively free of the Tenen mixture were then in 80 parts of toluene, hydrolysis product of triethyl borate was. which is free of water and hydrocarbon- Satisfactory self-adhesive tapes were obtained, residues is dissolved to form a dispersion. One if the above mass was used to make woven glass Glass fabric tape with a thickness of 0.13 mm, which fabric tapes according to the one described in Example 1 previously treated with silane, was then coated by 15 procedures. Dip coated by putting it through the dispersion

was conducted. Then, the coated material of Example 3 was passed through a vulcanization furnace in which

the temperature of 115 ⁰ C to a temperature according to the recipe of Example 1, a ranged from about 150 ° C, but the latter is not prepared rubber composition 20 and the internal solution has been exceeded. medium dispersed, which 10 parts of ethyl alcohol and

The coated glass fabric then contained 90 parts of toluene, as much as was

dipped twice and vulcanized to a tape of mass used that a dispersion was obtained,

a total thickness of 0.3 mm. which contained 15 percent by weight of this mass. It

A measure of the self-adhesive properties of the 25 was found to be the dispersion on storage

Coating was obtained in that a 25 mm wide remained clear and that with it self-adhesive tapes with strips of the tape around a core of 25 mm
Diameter was wound. At the free end
of the wound tape became a weight of

4.5 kg attached and the core determined so that 30 he didn't turn. The weight was removed after a period of 3 minutes. The core became free left and a 450 g weight attached to the free end of the tape. When the core

rotates, the rate of fall of the 450 g weight 35 is used, which is 0.7 weight percent based on boron

was measured and found to be about the weight of the organopolysiloxane.

Was 50 mm per minute. In both cases, usable self-adhesive

To maintain the bond strength of the coated tape tapes when the dispersions of the masses

To measure, a 25 mm wide strip was applied according to the method described in Example 1

a core with a 25 mm diameter is wound and the 40 glass fabric is applied and vulcanized.

Sample heated in an oven to 250 ° C for 30 minutes. - _r,. ,,

Comparative experiments

Adhesive strips were produced according to Example 1 of the present invention, but with 45 the difference that the content of triethyl borate gradually increases from 0 to 20 percent by weight (based on to 100 parts by weight of dimethylpolysiloxane) increased. According to the example! specified experimental set-up were the self-adhesive properties

Values for the dielectric strength of the 50 of the coating of the individual tapes were examined. The dry band received between 32,000 and first. The series of tests was varied immediately after the 40,000 volts / mm (800 and 850 volts / mil) varied. Production of the self-adhesive strips carried out while the dielectric strength, which was obtained with the second test series after a 56-day sample, which was ^{immersed in distilled water for 24 hours at 25 0} C storage of the adhesive strip in rolled form, fluctuated 55, with the Self-adhesive layer was protected by a between 10 000 and 14 000 volts / mm (250 and cellophane strips. The table ver-350 volts / mil). averages the results.

Parts by weight trialkyl borate

. 1.5

Unwind speed (cm / min.) Immediately after the

Manufacture of the tape * 6.35 11.4 13.35 3.81 5.59 0.63 2.03

Unwind speed (cm / min.) After 56 days

Storage of the tape * * * 10.16 6.35 10.16 11.4 7.62

After cooling, it was found that the load necessary to the wound Cutting tape at a rate of 50 cm per minute weighed 4.5 kg.

The dielectric strength of the coated tape was determined using Electrodes with a diameter of 6.25 mm and a continuous increase in voltage measured. There were

2 Parts by weight trialkyl borate 6th 8th 10 15th Weight percent boron of the trialkyl borate 0.3 0.45 0.6 0.75 1.13 0 4th 0.15 11.4 13.35 3.81 5.59 0.63 6.35 * 10.16 6.35 10.16 11.4 0 * * *

* Pie unrolled so quickly that a measurement was not possible.

The results show that the tapes with a boron content according to British patent specification 859,284 have quite good initial self-adhesive properties, which, however, decrease with increasing boron content. After 56 days of storage of the tapes, measurable take-off speeds were only possible with one such tape, which had a relatively high boron content, can be detected. In contrast, show Surprisingly, those tapes that have a boron content according to the present invention, far better initial self-adhesive properties than prior art tapes Technique, whereby it should be emphasized that even after 56 days of storage of the tapes an excellent Self-adhesive ability can be determined.

Claims (5)

Patent claims: 1. Process for the production of self-adhesive silicone rubber tapes, their self-adhesive layer consists of silicone rubber, the boron compounds, organic peroxide and optionally Contains fillers, which can also have a reinforcing effect, characterized in that the silicone rubber containing the additives mentioned, the boron compound being an alkyl borate and / or alkenyl borate is used in an amount such that 0.6 to 1.5 percent by weight Boron is present based on the weight of the organopolysiloxane of the silicone rubber are in the form of a dispersion or solution in a manner known per se on glass fabric as a carrier material and you apply the self-adhesive layer after applying the coating partially vulcanized. 2. The method according to claim 1, characterized in that there is a solution or dispersion used, which additionally contains a hydrolysis retarder for the borate. 3. The method according to claim 1 or 2, characterized in that two organic peroxide compounds are used in the solution or dispersion, the vulcanization temperatures of which are not less than 2O ⁰ C apart. 4. The method according to any one of the preceding claims, characterized in that for the Solution or dispersion an organic solvent is used that has a larger proportion of a hydrocarbon and a minor proportion of an aliphatic alcohol. 5. The method according to any one of the preceding claims, characterized in that as Silicone rubber an organopolysiloxane is used that a smaller proportion of to that Contains silicone bonded vinyl groups. 909517/576