Cleaning with the commercial aqueous systems caused immediately corrosion of the mild steel parts. After cleaning, the metal parts were dipped for at least 30 s in the silane coupling agent solutions and blown dry by air. In some experiments the metal parts were dipped in a second solution for at least 30 s, immediately after drying, and blown dry by air. Reported results use the average of three tests.
Prior to testing of the bond strength at least 16 h conditioning at room temperature was allowed. Three tests parts of every four runs were used for initial tests and six parts for the aging tests. The tests were carried out as described above. After 70 h the stainless steel chambers were taken out off the oven and some test parts were allowed to cool down to reach room temperature, still soaked in the fuel.
K L Mittal Silanes and Other Coupling Agents, Volume 3 | Chemical Substances | Chemistry
After this cool down period, the test pieces were taken out of the, fuel, dried with a tissue and immediately tested to avoid evaporation of the fuel. Tables 1 and 2 show the effect of various silanes by themselves on the adhesion strength for aluminum and brass. As references the cleaned metal parts no adhesive layer and sodium silicate were used. From Tables 1 and 2 it is clear that silane coupling agents by themselves are useful for bonding of fluorosilicone rubber to metals. A sodium silicate-layer does not have any organofunctionality.
Therefore during the vulcanization of rubber no bonds can be formed across the silicate-rubber interface. This co-vulcanization did not take place when methyltriethoxysilane was used. Vinyl moieties are known for their reactivity during vulcanization and therefore the adhesion improved radically when vinyltrimethoxysilane was used. Further it was surprising that BTSE, BDMSE and n-propyltrimethoxysilane, known as non-functional silanes, were able, to a certain extent, to bond fluorosilicone rubber to metals.
These results demonstrate that by adding VS, interfacial bonds are formed during the vulcanization of the rubber. Not always a nice homogeneously layer is obtained when a silane is applied to a substrate. Surface wetting and chemistry can lead to deficiencies in the silane layer and disorientation of the silane at the substrate interface. This phenomena has been demonstrated for y-aminopropylsilane. The amino group could be oriented towards the substrate or from the substrate depending on the pH.
Therefore it could be beneficial to apply first a layer of a silane which shows strong interaction with the substrate forming thus a homogeneous and a dense layer on the substrate followed by applying a silane which adheres very well to the first silane layer and which will be oriented in the right direction. In this way good adhesion can be obtained between two substrates. Bis- trimethoxysilyl ethane has twice as many silanol groups as other commonly used silanes.
BTSE has six silanol groups when it is completely hydrolyzed and more common silanes have three silanol groups. Therefore BTSE should react readily with the hydroxyl groups on the metal surface forming a homogeneously and dense layer. In these experiments a variety of two layer systems was compared. Concentration and pH were varied.
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Brass surfaces look to be very sensitive to applying conditions and the solutions have to be fine tuned. Not only the rubber will be affected by the fuel mixture but also the silane coupling agent layer and the interfaces.
The stress at those interfaces and in the silane layer will be increased during swelling of the elastomer. The resistance of the layer against the fuel will be determined by the layer thickness, the crosslink density of the layer, the interactions between the silane and the metal substrate on one side and the interaction of the silane with the elastomer on the other side.
A possible loss in adhesion will maybe not be observed after immersion of the test parts in the fuel. The rubber is then completely swollen and the strength of the rubber is decreased. However, after dry out and evaporation of the solvents the rubber will regain its strength back and a possible loss in adhesion will be observed. The adhesion is not affected by the aging test. The rubber strength is affected as can be seen from the decrease two thirds of the maximum force for failure after immersion in the fuel. After dry-out, the rubber regained its strength back and the maximum force is close to the initial force for failure.
However, after dry-out a substantial decreased is observed in rubber retention suggesting that the adhesion is affected by the fuel immersion and the dry-out process. In Tables the results are given for the adhesion of the four tested metals to FVMQ using a variety of silane treatments. Initial results were for stainless steel also good for a variety of silane treatments.
However, after fuel immersion and dry-out adhesion dropped for a number of treatments suggesting that the adhesion with these silane treatments was affected by the fuel aging. However, with the one step processes of only vinylsilane and a mixture of VS and BTSE also good results were obtained. Aluminum is very easy to bond to FVMQ using silanes.
Brass is most difficult to bond to FVMQ.
Similar results were obtained with these solutions. With only vinylsilane also reasonable adhesion was obtained. After dry-out the maximum force for failure is comparable with the initially measured force. Some silane layers in combination with a type of metal are very sensitive to this aging test.
This is probably due to differences in silane layer thickness, the crosslink density of the layer, the interactions between the silane and the metal substrate on one side and the interaction of the silane with the elastomer on the other side. On aluminum a nice homogeneous and dense layer with good interactions with the metal surface can be easily obtained. Several silane solutions were also evaluated on the ability to adhere other elastomer types to stainless steel and aluminum:. For all compounds the vulcanization time was set at 6 min and the ram pressure was 60 bars. After molding the test pieces were post cured for variable amounts of time depending on the elastomer type to stabilize final properties and to remove volatile peroxide decomposition products:.
The same procedure was followed as described for the fluorosilicone parts.
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The test pieces were subjected to this environment for 22 h. The parts were cooled to room temperature and tested as described above. The same procedure was followed as described for the EPDM parts. Only the parts were immersed in distilled water. Table 13 shows the results when EPDM is adhered to stainless steel and aluminum using silane coupling agents. This environment is slightly acidic pH5 and the aluminum pars are possibly affected by this environment. Table 14 gives results of durability tests in other environments.
In the citric acid environment both the rubber and the stainless steel parts seemed attacked but the adhesion was unaffected citric acid solution was colored black with the EPDM and the metal parts looked corroded. Two types of FKM compounds were tested. These compounds differ significantly in rheologic properties see Table With compound FKM-1 problems arose with processing of the compound. Therefore mold filling was not optimal and adhesion was negatively influenced.
Table 16 shows the results for the siloxane compounds. In case of VMQ-2 failure occurs not in the bulk of the rubber but in a layer very close to the silane layer.
It is clear that failure has occurred in the rubber phase. Closer observations of the failure surface showed only a few minor cracks in the rubber layer.
EDX-analysis learned that the metal surface could be seen in these cracks but that the metal was covered with the silane coupling agent layer and probably also siloxane rubber. One disadvantage of vinyltrimethoxysilane is that in contact with water, methanol can be formed. When vinyltriethoxysilane would be used this problem would be solved.
Table 17 shows the results of vinyltriethoxysilane. After hydrolysis the presolution can be adjusted to the desired concentration of silane and ethanol. Maybe hydrolysis time and presolution composition have to be reconsidered to complete hydrolysation. Two types of silicon wafers were tested: 1 a silicon wafer with a silicon oxide surface and 2 a silicon wafer with a nitride coating. Wetting of the silanes on the nitride coating was poor.
While this invention has been described with respect to particular embodiments thereof, it is apparent that numerous other forms and modifications of this invention will be obvious to those skilled in the art. The appended claims and this invention generally should be construed to cover all such obvious forms and modifications which are within the true spirit and scope of the present invention. All rights reserved. A SumoBrain Solutions Company.
Login Sign up. Search Expert Search Quick Search. Rubber to metal bonding by silane coupling agents. United States Patent Adhesion of rubber to a variety of metals aluminum, stainless steel, mild steel and brass is effectively achieved by the application of an organofunctional silane I and a non-organofunctional silane II to the requisite surface. Preferably, the organofunctional silane I is a vinyltrialkoxysilane with the non-organofunctional silane II preferably comprising an alkoxylated substituted alkyl silane.
Van Der, Aar Cornelis P. Fairfield, OH. Click for automatic bibliography generation.
Vernay Laboratories, Inc. CAA EP Steel sheet with enhanced corrosion resistance having a silane treated silicate coating. Plueddemann, E. Chen, R. Pape, P. Walker, P. Mauerer, F. Buchwalter, L. Park, J. Drown, E. Allen, K. Collier, B. Sabata, A. Coast, R. What is claimed is: 1. Method as recited in claim 1 wherein said non-organofunctional silane is a member selected from the group consisting of 1,2bis triethoxysilyl ethane BTSE ; bis methyl dietboxysilyl ethane BDMSE ; 1,2-bis trimethoxysilyl ethane TMSE ; 1,6-bis trialkoxysilyl hexanes and 1,2-bis trimeothoxysilylpropyl amine.
Method as recited in claim 2 wherein said non-organofunctional silane is BTSE. Method as recited in claim 2 wherein said organofunctional silane I is vinyltrimethoxy silane. Method as recited in claim 1 wherein said contacting comprises dipping one of said substrates in a solution containing said adhesive treatment. Method as recited in claim 6 wherein said adhesive treatment is present in solution at a pH of about Method as recited in claim 7 wherein said pH is about 4. Method as recited in claim 6 wherein said adhesive treatment is present in said solution in an amount by volume of about 0.
Method as recited in claim 1 wherein said organofunctional silane I is a vinylsilane selected from the group consisting of vinyltrimethoxysilane, vinyltriethoxysilane and vinyltriacetoxysilane. Method as recited in claim 10 wherein said contacting comprises coating said metal substrate with said non-organofunctional silane II and then providing a coating of said organofunctional silane I over said non-organofunctional silane II coating and wherein said step of placing comprises placing said rubber substrate along said coating formed by said organafunctional silane I so that said organofunctional silane can bond thereto.
Method as recited in claim 15 wherein said non-organofunctional silane is a member selected from the group consisting of 1,2bis triethoxysilyl ethane BTSE , bis methyl diethoxysilyl ethane BDMSE ; 1,2-bis trimethoxysilyl ethane TMSE ; 1,6-bis trialkoxysilyl hexanes and 1,2-bis trimethoxysilylpropyl amine.
K L Mittal Silanes and Other Coupling Agents, Volume 3
Methd as recited in claim 16 wherein said non-organofunctional silane is BTSE. Surface photografting of unsaturated alkoxysilanes onto polyolefins with excimer-UV lamps Surface functionalization of textile fibers with reactive silanes Localization of octadecyltrimethoxysilane self-assembled monolayers by a combination of bottom-up and top-down approaches Self-assembled monolayers of omega-functional silanes: A platform for understanding cellular adhesion at the molecular level Stability enhancement of polystyrene thin films on aminopropyltriethoxysilane ultrathin layer modified surfaces Electrodeposition of aromatic bis-silanes for pretreatment of aluminum alloys Performance of silanes in protecting metals from corrosion: Effect of substrate cleaning Improved water-based silane pretreatment for hot-dip galvanized steel substrates Integral epoxy resin—silane primer system for hot-dip galvanized steel Corrosion inhibitors for silane systems on aluminum alloys A novel low-VOC, chromate free, one-step primer system for corrosion protection of metals and alloys An ultra-flexible, chromate-free, low-VOC, silane-based finishing and coating system for corrosion protection of aluminum alloys Part 3: General Papers Incorporation of the macrocyclic ligand cucurbituril into a silica matrix Effect of the post-application of polysiloxanes on plasma-treated wool fabrics Comparative studies of hydrophobic surface treatments for TiO2: n-octylphosphonic acid and n-octyltriethoxysilane Show More Customer Reviews Average Review.
See All Customer Reviews. Shop Textbooks. Add to Wishlist. USD Sign in to Purchase Instantly. Temporarily Out of Stock Online Please check back later for updated availability. Overview This book chronicles the proceedings of the Fifth International Symposium held on this topic in Toronto.