CA1180483A - Compositions obtained by treating a rubbery polymer with a reactive silane, an epoxy resin and a reactive silane - Google Patents

Compositions obtained by treating a rubbery polymer with a reactive silane, an epoxy resin and a reactive silane

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Publication number
CA1180483A
CA1180483A CA000395362A CA395362A CA1180483A CA 1180483 A CA1180483 A CA 1180483A CA 000395362 A CA000395362 A CA 000395362A CA 395362 A CA395362 A CA 395362A CA 1180483 A CA1180483 A CA 1180483A
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stage
reactive silane
rubbery polymer
process according
silane
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CA000395362A
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French (fr)
Inventor
Yasukazu Shinada
Daniel E. Nerinckx
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ExxonMobil Technology and Engineering Co
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Exxon Research and Engineering Co
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Priority to CA000395362A priority Critical patent/CA1180483A/en
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Abstract

ABSTRACT

Rubbery Polymer Compositions with Improved Adhesion Rubbery polymer compositions, e.g. based on chlorobutyl rubber, having improved adhesion to mineral substrates such as glass or metal, are produced by a stepwise reaction sequence. In a first stage the rubbery polymer is reacted with a reactive silane such as an amino trialkoxy silane, in a second stage the product is mixed with an epoxy resin, and in a third stage a further amount of reactive silane is reacted with the epoxy containing compound.

Description

l Rubbery Polymer Compositions with Improved Adhesion The present invention relates to a process ~or producing rubbery polymer compositions, particularly but not exclusively those based on butyl polymers, which have improved adhesion to mineral substrates such as glass and metals. In particular the invention relates ~ product compositions which may be used as sealants in double glazing.
Currently sulphonated rubbers are generally supplied as solutions which need drying and furthermore they tend to be decomposed by moisture which can come from condensation.
Thus it is desirable to provide an adhesive or sealant composition that can be applied by ext^rusion and which has improved resistance to moi~ure.

It is well known that it is difficult to achieve good adhesion between mineral substrates such as glass and metals, and rubbery polymers such as butyl polymers including halobutyl polymers such as chlorobutyl rubber and bromobutyl rubber. Some commercial adhesives are available for bonding butyl polymers to substrates, but these have been found to 20be uns~1itable for certain applications. For example, ~nited States Patent 3,366,612 relates to the rendering of halogen containing polymers such as chlorinated butyl rubber adhesive to substrates such as glass or metal by reacting them with a silane. It has been found that although this method improves the adhesion, it does not result in adequate adhesion for certain applications.

1 In accordance with Ur-~ited States Patents 4073776 and 4073826, the reaction products of novolac resins with various epoxides are used as tackifiers for elastomers such as chlorobutyl, however there is no sugyestion also to use silanes in such compositions.

It has been proposed to use combinations of amino silanes with epoxy compc,unds as adhesion promoters in a variety of systems. For example United States Patent 3,850,872 relates to the use of epoxy compounds and resins, along with lo amino silanes, to improve glass fibre-elastomer adhesion.
In particular in this patent document the elastomer is blended with an oily epoxy compound and then compounded with silane treated glass fibres.

The previously proposed techniques for improving the adhesion between rubbers and mineral substrates have proved unsatisfactory where ~s is particularly important that the bond be water resistant such as with butyl sealants for double glazing.

We have now found that significantly improved adhesion may be achieved if a rubbery polymer such as a halobutyl rubber 20 is subjected to a stepwise reaction sequence in wh-ch it is first reacted with a silane, the silane containing rubber is subsequently mixed with an epoxy resin, and this product then reacted with further silane.

863~

1 Accordingly the present invention provides a process for producing a composition having improved adhesion to mineral substrates characterised in that it comprises in a first stage reacting a rubbery polymer with a reactive silane (as hereinafter defined) at elevated temperature; in a se~ond stage mixing the product of the first stage with an epoxy resin as wetting agent;
and in a third stage reacting the epoxy containing product of the second st~age with a f~rther amount of a reactive silane (as hereinafter defined) to form the desired composition.

10 The scope of the invention, it will be appreciated, also extends to the compositions produced by the defined process, and to their use as a mastic or a component of a mastic.
.~oreover the invention includes glazing systems which incorporate such compositions or mastics as sealants.

The term reactive silane as used herein is meant to include silanes having a first group attached directly or indirectly to the silicon atom which is reactable with the rubbery ~olymer, and at least one other group attached directly or indirectly to the silicon atom which is hydrolysable and 20 which, on hydrolysis in contact with the surface of a mineral substrate such as glass, concrete or metal will give a strong bond thereto~

.. . . .

1 The reactive silane used in the first reaction stage is preferably the same as that used in the third stage, althouyh they may be different if required. The silane may be for example a mercapto-, epoxy~ or vinyl-silane in which the specified functiona] groups react with the rubbery polymer, in the presence of free radical initiator if necess~ry.

However it is particularly preferred that the reactive silane used is an amino silane such as the commercially available product Z-6020, N-beta-(aminoethyl) gamma~amino propyl trimethoxy silane.

The amount of reactive silane used in the first stage of the process is preferably from 50 to 100%, more preferably from 60 to 75~ of that stoichometrically re~uired to combine with the rubbery polymer. For example some two thirds of the stoichometric amount may be used in order to avoid the reticulation which could take place under certain conditions if the stoichiometric amount or more is employed.

The rubbery polymer used in accordance with the invention may be for example EPR, EPDM or an EV~ copolymer. However 20the process has been found to be particularly useful when the rubbery polymer is a halobutyl rubber such as chlorobutyl rubber. Bromobutyl rubbers may also be employed, but they ~nera' ly tend to be too react vc for convenience.

1 In the case where the reactive silane is an amino silane and the rubbery polymer is chlorobutyl rL~bber, the first staye reaction between the amino grouping and the alkyl chloride of the chlorinated butyl is believed to proceed by N-alkylation or the formation of a quaternary ammonium salt, as set out in ~he following reaction schemes:

p- G~ f H~ )3 - ,- p~ R- s~--(R')3 t H C~

P CL fl~ R~ R'J ~ p_ ~ ~R

P- ce ~ ~--R- S~ )7, ~ R~ ~ R
k~" C,~

In the above, P represents a polymer; R represents a divalent radical such as an alkylene group eg propylene; R" and R"', which may be the same or different, represents a monovalent radical such as an alkyl group e.g. methyl or ethyl; and the silicon substituents R' may independently be hydrogen or a hydrolyzable radical with the proviso that at least one 20 R' must be hydrolyzable. By way of example the hydrolyzable radical may be acetoxy, halo~en, or alkoxy having from 1 to 20, preferably 1 to 10 and most preferably 1 to 3 carbon atoms. Amino trialkoxy silanes of the formula NH2~CH2)n Si~ORiV~3 where Riv is alkyl ~nd '- ~

l ~ is a number from 1 to 8 have been found to be particularly useful as reactive silanes in the process of the invention, especially when the rubbery polymer is chlorobutyl rubber.

A particularly preferred embodiment of the invention therefore provides a process for producing a composition having improved adhesion to mineral substrates characterised in that in a first stage a chlorobutyl rubber is mixed with an aminosilane having at least one hydrolyzable radical attached to the silicon atom; in a second stage the product of the first stage is mixed :Lo with an epoxy resin; and in a third stage epoxy containing product of the second stage is mixed with a further amount of an aminosilane having at least one hydrolyzable radical attached to the silicon atom, to form the desired composition.

Generally with respect to the silane, the primary amine is preferred. Also, as stated previously, at least one of the groups on the silane atom should be readily hydrolyzable, but it is preferred that three of these be hydrolyzableO
The amounts of functional silane to be used will vary to some extent depending on the degree of hydrolyzable silane 20 functionality required to produce a vulcanized network.

The reactive silane e.g. amino silane is reacted with the rubbery polymer eg chlorobutyl rubber during the normal compounding conditions for the rubber; for example reaction may be achieved by incorporating the silane into the compounding, at elevated temperatur~s of from 135 to 150C, say at 140C
for about half an hour.

::
... . _ , , .

~ny epoxy resin may be usecl in the second stage of the process.
It is preferred however to use epoxy compounds derived from bis-phenols and epichlorhydrin, those sold under the Registered Trade Mark "Epikote", e.g. Epikote 1007, being particularly preferred.
The epoxy resin may conveniently be mixed with the silane treated rubber with heating, ag2ain preferably at temperatures in the range 135 to 150C.
The epoxy resin serves as a wetting agent with regard to the rubber polymer, and so to an extent the amount incorporated is arbitrary. However it has been found that added amounts of 10 to 50 wt %, partic~llarly 25 wt ~, based on the weight of rubbery polymer are effective.
The second charge of silane may then be reacted with the epoxy treated material in the third process stage, if required under similar conditions to those used for the first process stage.
The amount of silane used is preferably at least that stoichiome-trically required to combine with the epoxy groups present. The use o an excess amount of silane is even preferred since this will enhance the formation of chemical bonding between the rubber and the substrate.
We have found that the compositions produced according to the present invention have significantly improved adhesion to mineral substrates, particularly when the modified rubber is chloro-butyl rubber, compared with unmodified butyl rubbersO On contact between the substrate and the composition, the alkoxy groups or other hydrolyzable groups pxesent in the silane attached to the polymer chains will be ~ - 7 -1 hydrolyzed by traces of water on the mineral s~bstrate surface to give a strong bond thereto. Frequently in the use of such compositions there will be sufficient water present to give a strong bond but if necessary the surface may be deliberately wetted. It is believed that through the effect of moisture the alkoxysilane or other hydrolyzable groups form silanols which can react both among themselves (thus crosslinking the rubbery polymer and the epoxy resin) and with e.g. OH groups on the glass surface. The adhesion can be developed under normal atmospheric conditions or at elevated temperatures or by immersing the surfaces to be bonded in hot water~ The compositions are particularly useful in bonding glass, especially as sealants for double glazing. It is believed that the presence of the epoxy resin improves the extent to which the glass is wetted by the rubber, and that the process technique gives improved internal bonding and adhesion. It has also been found that the compositions such as are exemplified hereinafter undergo crosslinking with time at room temperature. Thus once 20 applled the composition will provide increasingly cohesive strength.

1 The compositions, especially modified chlorobutyl rubbers produced by the process of the present invention are particu-larly useful as sealants for double ylazing between the glass and the metal, generally aluminium , spacer. The compositions will generally be used as a component in a hot flow mastic which may contain other conventional components such as polyisobutylene and petroleum resin tackifiers;
fillers such as carbon black and whiting; and other additives such as stabilisers, antioxidants and pigments. Thus in one lo embodiment the process of the invention includes incorporating a filler or other conventional additive at any stage. By way of example the final composition may have the overall ingredients, based on the composition or as whole, of 7.5-12.5~ rubbery polymer; 2-5~ epoxy resin; 0.5-1.5%
silane: 15-20% polyisobutylene; 10-15% carbon black; 25-30 whiting; 25-30~ plasticiser/tackifier. The handling and service properties (tem~perature and viscosities) of such compositions may be adjusted by controlling the ratio of rubbery polymer and additive e.g. polyisobutylene, or by 20 controlling the molecular weight of the polyisobutylene.

The mastic may then be extruded at elevated temperatures between the surfaces to be adhered. The temperatures vary, depending on the viscosity of the mastic composition and may be in the range 150-180C. -Alternatively the composition may be in the form of a tape.

The following Examples illustrate, but in no way limit, the invention.

.

- l o -1 Example 1 A rubber composition in the form of a mastic was prepared by mixing the components in the manner described below, the composition having the ingredients in the proportions (parts by weight)indicated in Table 1 in which:~
Chlorobutyl 1068 is a chlorobutyl rubber; Vistanex MML-140 is a polyisobutylene of molecular weight 1900 000 - 2350 Q00; Vistanex LM-MS is a ~clyisobutylene (molecular weight about 55000); silane Z-6020 is commercially available 10 N-beta-~aminoethyl) gamma-amino propyl trimethoxy silane;
Epikote 1007 is a solid bisphenol A-epichlorohydrin epoxide resin; Omya BL is a whiting; Escorez 1304 is a petroleum resin tackifier, and FEF ls a carbon black.

Thus 40 parts of chlorobutyl rubber and 20 parts of car~on black were mixed in a Banbury internal mixer at 140C to make a masterbatch. Half of this masterbatch was placed in a kneader mixer at 110'~C with 30 parts polyisobu~ylene and 15 parts car~n black and after 15 minutes mixing the remainder of the masterbatch~ the remainder of the polyisobu-~o tyiene and the remainder of the carbon black were added.
Afte-f a further 15 minutes mixing 33.33 parts tackifier and 50 parts whitiny were added and mixing was continued for another 15 minute period. Thereafter the remainder of the tackif~er and whiting was added and the temperature was ~D~

. .

increased with mixing over 30 minu~es to 135-140C. ~t this point
2 parts of silane were added and reacted with the chlorobutyl for 30 minutes with mixing. Subsequently the epoxy resin was added and mixed for 15 minutes at 145-150C, and thereafter the remaining 1.5 parts of silane were added and reacted with the epoxy for 30 minutes prior to dumping the composition from the kneader.
The mastic composition was tested using a sandwich techni-que. Thus two aluminium spacers (wrapped with release paper) were sandwiched between two glass plates which had been cleaned and dried with acetone, and the cavity was filled to a contact area of 25 x 50 x 7,5 mm with the mastic delivered from a hot gun having a body temperature of about 180C. The set was then tested by pulling at 5 cm/min in shear; the Mooney viscosity was also measured. These measurements, which were made on the fresh composition and on com-position which had been aged for one year, are given in Table 2.
Adhesion values marked more interfacial values, to other val.ues reflect cohesive failure.
Examples 2 and 3, and Comparison Example 4 Example 1 was substantially repeated but using ingredients such that the overall compositions produced had the formulation shown in Table 1.

l Table I

Example1 ___ 2 3_ _ _4 Chlorobutyl 1068 40 30 40 40 Vistanex LM~MS 60 70 30 60 Vistanex MML-140 - - 30 Omya BL 100 100 100 100 Escorez 1304 100 100 100 100 Silane Z-6020 2+1.51.5~1.5 2~1.5 2 lO Epikote 1007 - 10 10 10 Table 2 Example 1 1 2 3 4 _ _ Unaged Aged Unaged Unaged Una Adhesion (kg) Temperature 34 41 26 32 ~ 24 65C 3.1 80C - 2.2~ 1.0 2.3~ 1.7 Mooney Viscosity ML (1~14) 20 50C 69 89 ~7 75 63 90~C 15 18 ~ 18 10 _. . . . . .. . . .

1 As may be concluded from the above resultsf the presence of the epoxy resin in the formulation improves the adhesion and has a low effect on cohesion. Moreover the viscosity and cohesion of the mastic composit:ion decrease as the ratio of chlorobutyl to polyisobutylene is decreased (a decrease in hot viscosity being a means of improving the contact surface and hence adhesion). Furthermore it may be deduced that increasing the molecular weight of the polyisobutylene which is admixed with the composition produced according to 1~ the invention leads to an increase in the hot cohesion.

Claims (10)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for producing a composition having improved adhesion to mineral substrates which comprises in a first stage reacting a rubbery polymer with a reactive silane at elevated temperature; in a second stage mixing the product of the first stage with an epoxy resin as wetting agent; and in a third stage reacting the epoxy containing product of the second stage with a further amount of a reactive silane to form the desired composition.
2. A process according to claim 1 wherein the rubbery polymer comprises a halobutyl rubber.
3. A process according to claim 2 wherein the halobutyl rubber is a chlorobutyl rubber.
4. A process according to claim 1 wherein the rubbery polymer is selected from the group consisting of ethylene propylene rubber (EPR), ethylene propylenediene monomer (EPDM) and ethylene vinyl acetate copolymer (EVA).
14 A process according to claim 1 wherein the reactive silane used in the first stage is the same as that used in the third stage.
6. A process according to claim 1 wherein the reactive silane is an aminosilane.
7. A process according to Claim 1 wherein the reactive silane is selected from the group consisting of mercapto-, epoxy- and vinyl silanes.
8. A process according to claim 1 wherein in the first stage an amount of reactive silane is used corresponding to from 50 to 100% of that stoichiometrically required to combine with the rubbery polymer.
9 A process according to claim 8 wherein the amount of reactive silane used in the first stage corresponds to from 60 to 75% of that stoichiometrically required to combine with the rubbery polymer.

A process according to claim 1 wherein in the third stage an amount of reactive silane is used corresponding to at least that stoichiometrically required to combine with the epoxy groups present.

11 A process according to claim 1 wherein an additive selected from fillers, pigments and processing aids is incorporated at any stage.

12 A process for producing a composition having improved adhesion to mineral substrates which comprises in a first stage mixing a chlorobutyl rubber with an aminosilane having at least one hydrolyzable radical attached to the silicon atom; in a second stage mixing the product of the first stage with an epoxy resin;
and in a third stage mixing the epoxy containing product of the second stage with a further amount of an aminosilane having at least one hydrolyzable radical attached to the silicon atom, to form the desired composition.

13 An improved mastic comprising a tackifier, a filler and other additives selected from stabilisers, antioxidants and pigments, the improvement comprising, as a rubbery component, a composition produced in accordance with the process of claim 1.

14 An improved mastic as claimed in claim 13 wherein the composition comprises from 7.5 to 12.5% by weight of a rubbery polymer of the composition produced in accordance with the process of claim 1;
from 2 to 5% of epoxy resin, from 0.5 to 1.5% of silane; from 15 to 20% of polyisobutylene; from
10 to 15% carbon black; 25 to 30% whiting; and from 25 to 30% plasticiser or tackifier.
A glazing system which includes, as sealant a composition produced in accordance with the process of claim 1.
CA000395362A 1982-02-02 1982-02-02 Compositions obtained by treating a rubbery polymer with a reactive silane, an epoxy resin and a reactive silane Expired CA1180483A (en)

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CA000395362A CA1180483A (en) 1982-02-02 1982-02-02 Compositions obtained by treating a rubbery polymer with a reactive silane, an epoxy resin and a reactive silane

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CA000395362A CA1180483A (en) 1982-02-02 1982-02-02 Compositions obtained by treating a rubbery polymer with a reactive silane, an epoxy resin and a reactive silane

Publications (1)

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CA1180483A true CA1180483A (en) 1985-01-02

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