DE2107188A1 - Cyanacrylate adhesive stabiliser - consisting of sulphuryl chloride,giving easier and more accurate control of proportions - Google Patents

Abstract

Adhesives are based on easily polymerisable monomeric substd. olefins of formula: CH2 = (in which X is -CN or -COOR, Y is -CH, halogen, - SO3R, or -COOR and R is 1-20C alkyl, cycloalkyl or phenyl) esp. alpha-cyanacrylate esters, with addition of sulphuryl chloride as stabiliser. The controlled amount of additive necessary to stabilise the monomer without affecting the adhesive power is more easily added as sulphuryl chloride than as the usual SO2 gas.

Description

SCHERING AG
Pat ent department
Ax / Bu

Stabilized adhesives

The invention relates to stabilized adhesives based on anionic, easily polymerizable monomers substituted olefins of the general formula I.

CH ₂ = C ^ (I),

where X can be -CN or -COOR and Y can be -CN, -Halogen, -SO ^ R or -COOR and where R is an alkyl group with 1 to 20 carbon atoms, a cycloalkyl group or the phenyl radical, in particular of monomeric esters of a-cyano-acrylic acid, represented by, the general. Formula II

CN 0

CH ₂ = C - C - OR (II),

wherein R has the above meaning, which adhesives by, an addition of a stabilizing effective amount of Sulfuryl chloride are labeled.

A particular embodiment of the adhesives stabilized according to the invention is due to an additional content of Free radical polymerization inhibitors.

The invention also relates to a method for stabilizing of adhesives based on easily anionically polymerizable monomeric substituted olefins of the general formula I.

JSL

CH ₂ = C (I),

-2-

209835/1002

SCHERING AG.

Patent department

Axen / Bu "" -2-

WQ for X can be -CH or -COOR and Y can be -CH, -Halogen, -SO ^ R or -COOR and where R is an alkyl group with 1 to 20 carbon atoms, a cycloalkyl group or the Can be phenyl radical, in particular of monomeric esters of a-cyano-acrylic acid, represented by, the general Formula II

0
CH ₂ = C - C - OR (II),

wherein R has the above meaning, which method is characterized in that a stabilizing effective amount of sulfuryl chloride is added to the adhesive.

A particular embodiment of the method according to the invention is characterized in that an additional content of inhibitors of the free radicals to the stabilized adhesive Polymerization is added.

It is known that monomeric cyanoacrylic acid esters are stabilized against polymerization by small amounts of acidic gases, for example SO ₂ and radical scavengers, for example hydroquinone, as claimed in US Pat. No. 2,794,788 and 2,765,332 will.

Sulfur (IV) oxide, SO ₂ , is the most frequently used stabilizer to date, which suppresses anionic polymerization, ie one that is catalyzed by bases. However, the use of SO _{2 has} a number of serious disadvantages:

A concentration of 0.001 to 0.01% by weight must be adhered to will. At higher SOg concentrations, the

209835/1002

SCHjSRING AG

Patent department

Ax / Bu -3-

Rapid setting speed of the cyano-acrylates. away. at The cyanoacrylates are not adequately stabilized at lower concentrations. Because of the gaseous state of the stabilizer and the low concentration of the same, the amount can be adjusted very poorly and analytically capture.

The monomeric cyanoacrylates are usually obtained by depolymerizing polycyanoacrylates. At this In preparation, more of the acidic stabilizer gas is expediently added in the gas phase than for stabilization is necessary. After cooling down, excess SOp must be removed by means of time-consuming operations, to obtain a product with the required balance in stability and setting speed. Ongoing provisions the SOp content are unavoidable.

Finally, the monomers stabilized in this way give off gas (SOp) under certain conditions, which is often a nuisance and is undesirable.

The known, non-gaseous stabilizers either only have a moderately stabilizing effect or else they deteriorate the setting speed so much that such adhesives are of little practical use Are interested.

In order to avoid the disadvantages mentioned, the German Offenlegungsschrift 1 807 895 describes the use of Propane sulton claimed as a stabilizer.

According to the Shell AG leaflet, this stabilizer is dated

-4-

209835/1002

SCHERING AG

Patent department

Ax / Bu -4-

July 1968 a strong carcinogen, so that the use of a suiton as a stabilizer is extremely questionable technical area is dangerous and forbids surgical use.

It has now surprisingly been found that, while avoiding the deficiencies mentioned, the monomeric cyano-acrylic acid esters be stabilized by adding sulfuryl chloride.

The monomeric esters of cyanoacrylic acid used as adhesives are produced by the depolymerization of polycyanoacrylic acid esters won. The polycyanoacrylic acid esters are by known methods by condensation of Formaldehyde and cyanoacetic acid esters in the presence of catalysts, e.g. piperidine.

The monomeric esters of α-cyano-acrylic acid are used individually or used in combinations as an adhesive. For this purpose, cc-cyano-acrylic acid esters of the general type are preferred Formula II, in_der R is an alkyl group with 1 to 5 C atoms or_die cyclohexyl group, which are particularly the methyl ester of a-cyano-acrylic acid (R = methyl) is advantageous.

The superiority of the stabilizer according to the invention comes from the following properties and handling options to expression:

The sulfuryl chloride, which is used for the stabilization of the adhesives according to the invention, is a liquid substance and can be added to the monomer in a simple manner. Time-consuming operations, such as those required for the removal of excess S0 ₂ ~ quantities, and on-

—5—
209835/1002

SCHERING AG

Patent department

Ax / Bu -5-

there is no need for agile analysis methods.

The curing rate of the cyanoacrylates in practical use is only insignificantly affected.

In general, when the monomeric ester is formed in the manner described above, via distillation of the monomer is produced, the practical work in it, the stabilization 'serving active amount of sulfuryl chloride di-. to be added straight to the container in which the condensed, monomeric ester is collected. The ester is made this way stabilized immediately, possible polymerisation is prevented.

The active amount of sulfuryl chloride added to the cyanoacrylates can be varied depending on the intended use of the adhesive and the required storage stability. In most cases an addition of about 0.001 - 1 wt .- ^ sulfuryl chloride is sufficient, 0.1-0.5% by weight of sulfuryl chloride is preferred.

In summary, it can be seen that the stabilizers according to the invention considerably more reliable, versatile, simple and safe than the previously known stabilizers can be used for the stabilization of cyano-acrylates.

Without being absolutely necessary, it is generally desirable to use the cyanoacrylates as an inhibitor for the radicals Add polymerization, since the cyano-acrylates are also capable of free-radical polymerization. Such Inhibitors are, for example. Quinone, hydroquinone, p-methoxyphenol. You can use these inhibitors in concentrations of

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SCHERING AG

Patent department

Ax / Bu -6-

add about 0.001 to 1 fo of the weight of the adhesive mass.

Modifications of the adhesives to achieve certain properties such as increasing the viscosity through the Use of a thickener can of course also be carried out. These possibilities are in the literature adequately described.

-7-209835 / 1002

SCHERING AG

Patent department

Ax / Bu -7-

example 1

100 g of the through. $> Hydroquinone, v / ground treated with 0.1 g of sulfuryl chloride - depolymerization of Polycyan-aerylsäuremethyl-ester prepared oc-cyano-acrylic acid methyl ester, 0.01 wt..

The liquid provided with sulfuryl chloride proves to be an effective, stabilized one in the following tests Adhesive.

To test the setting speed, one wears a on the cut end of a profile rubber (iTitrile rubber) Drops of glue on, then attaches a second cut end to the treated end and holds the two ends roughly 5 seconds with their surfaces pressed together. After this time has elapsed, the rubber parts are firmly connected to one another.

The long-term stability of the adhesive is tested by storing a sample of the stabilized product in an oven heated ^{to 55 ° C.} The adhesive stabilized according to the invention retains the form of a clear liquid even after a storage time of more than 60 days and quickly gives firm bonds when the above-described test of the setting speed is carried out.

Comparative example to example 1

The cyanoacrylic ester originating from the same batch, but which was stored without a stabilizer, showed ^{a stability of only a few hours at 55 °} C. and a stability of 3 days at room temperature.

-8th-

209835/10 02

S CHERIITG AG

Patent department

Ax / Bu -8-

Example 2

100 g of methyl cyanoacrylate with a hydroquinone content of 0.01% by weight are mixed with 0.5 g of sulfuryl chloride.

The adhesive obtained shows the same properties like that described in Example 1.

Example 5

The methyl cc-cyanoacrylate is used analogously to Example 1 wholly or partially by a Cp- to C-w- ~ hexyl-, phenyl or cyclohexyl esters of cyanoacrylic acid or a mixture such ester replaced. Essentially similar results are obtained; the resulting adhesives are stable at room temperature for at least 5 months and deliver on rubber, metal and numerous other surfaces fast solid connections.

-9- 209 835/10 02

Claims (4)

SCHjSRIITG AG patent department Axen / Bu ~ 9- patent claims 1. Stabilized adhesives based on anionic easily 'polymerizable monomeric substituted Olefins of the general formula I CH ₂ = C ^ (I), where X can be -CN or -COOR and Y can be -CIT, -Halogen, -SO, R or -COOR and where R is an 'alkyl group with 1 to 20 carbon atoms, a cycloalkyl group or the phenyl radical, in particular of monomeric esters of a-cyano-acrylic acid, represented by the general formula II CI 0 CH ₂ = C - C - OR (II), where R has the abovementioned meaning, characterized by the addition of a stabilizing active amount Sulfuryl chloride * 2. Stabilized adhesives according to claim 1, characterized by an additional content of inhibitors of radical polymerization. 3 «Process for stabilizing adhesives based on easily anionically polymerizable monomers substituted olefins of the general formula I. CH ₂ = C (I), -10- 209835/1002 SCHERING AG Patent grant Ax / Bu -10- - where X can be -CH "or -COOR and Y can be -CIT, -halogen, -SO ₇ R or -COOR and where R is an alkyl group with 1 to 20 carbon atoms, a cycloalkyl group or phenyl -Rest can be, in particular of monomeric esters of cc-cyano-acrylic acid, represented by the general formula II CIT 0
IR
CH ₂ = C - C- OR (II), wherein R has the abovementioned meaning, characterized in that that a stabilizing effective amount of sulfuryl chloride is added to the adhesive. 4. A method for stabilizing adhesives according to claim 3j characterized in that an additional content of inhibitors to the stabilized adhesive the radical polymerization is added. 209835/1002