ADHESIVE COMPOSITIONS AND THEIR APPLICATIONS

Abstract

A method of adhering a substantially cured or fully cured silicone based material to a substrate surface is provided. The silicone based material is obtained by curing a condensation curable composition. The condensation curable composition comprises: (I) at least one condensation curable silyl terminated polymer having at least one hydrolysable and/or hydroxyl functional group(s) per molecule; (II) a cross-linker selected from the group of silanes having at least two hydrolysable groups per molecule; and/or silyl functional molecules having at least two silyl groups, each silyl group containing at least one hydrolysable group; and (III) a condensation catalyst selected from the group of titanates and zirconates. The method includes applying a reactive interlayer to the substrate surface and applying pressure to sandwich the reactive interlayer between a surface of the silicone based material and the substrate surface, thereby causing chemical bonding of the silicone based material to the substrate.

Claims

1. A method of adhering a substantially cured or fully cured silicone based material to a substrate surface, said method comprising: applying a reactive interlayer to the substrate surface; and applying pressure to sandwich the reactive interlayer between a surface of the silicone based material and the substrate surface, thereby chemically bonding the silicone based material to the substrate; wherein the substantially cured or fully cured silicone based material is obtained by curing a condensation curable composition comprising: (i) at least one condensation curable silyl terminated polymer having at least one; hydrolysable and/or hydroxyl functional group(s) per molecule; (ii) a cross-linker selected from the group consisting of silanes having at least two hydrolysable groups per molecule; and/or silyl functional molecules having at least two silyl groups, each silyl group containing at least one hydrolysable group; and (iii) a condensation catalyst selected from the group consisting of titanates and; zirconates; and wherein the molar ratio of hydroxyl and/or hydrolysable group(s) in polymer (i) to hydrolysable groups from cross-linker (ii) is between 0.1:1 and 4:1, and the molar ratio of M-OR functions to the sum of moisture present in the formulation and hydroxyl and/or hydrolysable group(s) in polymer (i) is between 0.01:1 and 0.6:1, where M is titanium or zirconium.

2. A method of rendering a substantially cured or fully cured, tacky silicone based material non-adhesive or non-tacky), said method comprising: applying a reactive interlayer to a surface of the silicone based material; and allowing the same to interact such that upon interaction between the surface and the reactive interlayer, a silky smooth and non-adhesive surface is generated; wherein the silicone based material is obtained by curing a condensation curable composition comprising: (i) at least one condensation curable silyl terminated polymer having at least one; hydrolysable and/or hydroxyl functional group(s) per molecule; (ii) a cross-linker selected from the group consisting of silanes having at least two hydrolysable groups per molecule; and/or silyl functional molecules having at least two silyl groups, each silyl group containing at least one hydrolysable group; and (iii) a condensation catalyst selected from the group consisting of titanates and; zirconates; and wherein characterized in that: the molar ratio of hydroxyl and/or hydrolysable group s) in polymer (i) to hydrolysable groups from cross-linker (ii) is between 0.1:1 to 4:1, and the molar ratio of M-OR or tin (II) functions to the sum of moisture present in the formulation and hydroxyl and/or hydrolysable group(s) in polymer (i) is between 0.01:1 and 0.6:1, where M is titanium or zirconium.

3. The method in accordance with claim 1, wherein the condensation curable composition is stored in two parts having cross-linker (ii) and optionally polymer (i) in one part and polymer (i) and catalyst (iii) in the other part or in two parts having a first polymer (i) and cross-linker (ii) in one part and a second polymer (i) and catalyst (iii) in the other part.

4. The method in accordance with claim 3, wherein the two parts of the condensation curable composition are intermixed and cured.

5. The method in accordance with claim 1, wherein the silicone based material is a substantially cured or fully cured elastomer or a substantially cured or fully cured gel.

6. The method in accordance with claim 1, wherein the reactive interlayer is chemically reactable with the substrate surface and/or the surface of the silicone based material.

7. The method in accordance with claim 1, wherein the reactive interlayer is a coating composition material or a layer of an uncured sealant composition which can chemically interact with both the substrate surface and/or the surface of the silicone based material.

8. The method in accordance with claim 1, wherein the reactive interlayer is applied in a wet and/or uncured state onto a cleaned surface of a substrate and then a facing surface of the silicone based material is brought into contact with the substrate surface by the application of pressure such that the reactive interlayer is sandwiched between the surface of the silicone based material and the substrate surface and chemical adhesion develops.

9. The method in accordance with claim 1, wherein the reactive interlayer is a coating composition comprising a titanate or zirconate ingredient and/or a tin (II) and tin (IV) based ingredient and optionally silanes having groups which will chemically interact with excess silanol groups in the silicone based material.

10. The method in accordance with claim 9, wherein the chemically interactive groups are present and selected from the group consisting of amines, thiol, epoxy, alkoxy, acetoxy, and oximino to enhance adhesion on various substrates.

11. The method in accordance with claim 1, wherein the reactive interlayer is a coating composition comprising: from 0.01 to 90% by weight of a titanate, zirconate, tin (II) or tin (IV) catalyst; from 0 to 90% by weight of one or more silanes having at least two hydrolysable groups and optionally one or more alternative functional groups to create chemical bonds with substrate surfaces; and from 5 to 90% by weight of a silicone solvent or an organic solvent; with the total weight % of the coating composition being 100 weight %.

12. The method in accordance with claim 7, wherein the reactive interlayer is a moisture curable sealant composition comprising: at least one condensation curable silyl terminated polymer having at least one hydrolysable and/or hydroxyl functional group(s) per molecule (ai); a cross-linker (aii); and a condensation catalyst (aiii).

13. The method in accordance with claim 1, wherein the reactive interlayer is allowed to dry and/or cure on the substrate surface onto which it was first applied and then subsequently the silicone based material surface is brought into contact with the substrate surface and pressure applied to sandwich the reactive interlayer.

14. The method in accordance with claim 1, wherein the silicone based material is a tile adhesive which is chemically bonded to a tile and has a release paper preventing unwanted adhesion until in its correct position.

15. The method in accordance with claim 1, for producing a laminate in which the reactive interlayer is strongly adhered to the silicone based material and a surface of a plastic film substrate.

16. The method in accordance with claim 1, wherein the substrate is a construction panel, glass sheets for flat panel displays, glass panels for facades or cars, or metal, plastic, wood, concrete or stone plates for construction, automotive, or electronics.

17. The method in accordance with claim 1, wherein the cured silicone material is a pre-cured spacer of a transparent device.

18. An article made by the method in accordance with claim 1.

19. (canceled)

20. (canceled)

21. (canceled)

22. (canceled)

23. (canceled)

Description

EXAMPLES

Example 1 Formulation A

[0136] A float glass substrate was treated with DOW CORNING? 1200 OS PRIMER CLEAR a commercial Primer from Dow Corning Corporation of Michigan, USA, which has been used according to the manufacturer's instructions and used as reactive interlayer.

[0137] Strips of pre-cured formulation A material (approx. 1 cm width, 5-6 cm in length and 2 mm thick were attached to above described substrate at different times after the application of OS1200.

[0138] The adhesion of the strips to the float glass substrate was examined after approximately one hour and Table 3 summarizes the results.

Y means that a strip was well adhered to the glass plates and that attempts to remove it resulted in a cohesive failure within the strip
N means that the strip was easily removable (peeled off)-adhesive failure) from the glass substrate.

TABLE-US-00003 TABLE 3 Time upon treatment with OS1200 Result <1 min Y 5 Y 10 Y 15 20 N/Y 30 N COMPARATIVE Example 1(no Does not stick and reactive interlayer on substrate) removed adhesively

Example 2

[0139] Cured materials were prepared from compositions A, B and C as depicted in Tables 1 and 2. Strips of approx. 12 cm length by 2 cm width and 2 mm thickness were adhered to glass plates. Half of the surface of these plates was pre-treated with DOW CORNING? 1200 OS PRIMER CLEAR, which serves as reactive interlayer. The DOW CORNING? 1200 OS PRIMER CLEAR was used according to the manufacturer's instructions. The strips were brought into contact with the glass substrate within 2 minutes of the application of DOW CORNING? 1200 OS PRIMER CLEAR thereon.

[0140] Upon inspection it was noticed that the strips peel adhesively from the part which has not been coated with DOW CORNING? 1200 OS PRIMER CLEAR (i.e. adhered by physical adhesion). In contrast, it was impossible to detach the strips from the part treated with the reactive interlayer without breaking the strip itself (i.e. adhered by chemical adhesion).

Example 3

[0141] Elastomer/gel materials of formulation D as well as a Sn-cure elastomer formulation E (comparative example) were cured in moulds to form circular 1-cm thick articles. These articles were adhered to stainless steel plates (substrates). Half the surface of these plates was pre-treated with DOW CORNING? 1200 OS PRIMER CLEAR, which served as a reactive interlayer. The articles were attached to the steel plates within 2 minutes of the application of DOW CORNING? 1200 OS PRIMER CLEAR Results are summarized in table 4.

TABLE-US-00004 TABLE 4 E Sn IV based elastomer Cured material (comparative example) D Adhesion to Adhesive failure, Adhesive failure, untreated substrate does not stick does not stick surface (no reactive interlayer) Adhesion to Adhesive failure, Adhesion, substrate treated does not stick cohesive failure with reactive interlayer

Example 4

[0142] The experiment described in example 3 was repeated using an aluminum substrate. The cured material used was a 5 cm by 1 cm cured strip of composition C as depicted in Tables 1 and 2 above. Upon inspection it was determined that the strip did not adhere to the part of the aluminum substrate surface which had not been pre-treated with the reactive interlayer and as such due to physical nature of the adhesion these were easily detached (peeled off). In contrast, it was impossible to detach the strip from the part of the aluminium substrate surface pre-treated with the reactive interlayer (DOW CORNING? 1200 OS PRIMER CLEAR). The strip itself broke cohesively due to the chemical nature of adhesion to the substrate surface.

Example 5

[0143] The surface of a stainless steel plate (approx. 10?15 cm) was divided in three areas. The three areas were treated as follows: [0144] (1) no treatment [0145] (2) DOW CORNING? 1200 OS PRIMER CLEAR (3) primer DOW CORNING? OS 3 in 1 primer/cleaner.

[0146] The two primers were used as reactive interlayers and were applied according to the manufacturer's instructions.

[0147] A strip of pre-cured composition B, as depicted in Tables 1 and 2, which was the same size as the steel plate and a thickness of about 2 mm was cut and carefully placed on the plate. After approximately 70 hours attempts were made to remove the elastomer strip from the plate. Only physical adhesion (clean peel) was observed on the part of the plate not treated with primer. The other two parts of the plate were strongly bound (chemically) to formulation B and a clean detachment was impossible. The strongest adhesion was observed for the part of the surface primed with DOW CORNING? 1200 OS PRIMER CLEAR.

Example 6

[0148] Cured materials were prepared by mixing the two components of the composition together in a Base:curing agent weight ratio of 1:1. The base component was: [0149] a 2,000 mPa.Math.s (at 25? C.) silanol terminated polydimethyl siloxane. The curing agent components were: [0150] 100 weight parts of a 2,000 mPa.Math.s trimethoxysilyl terminated polydimethylsiloxane (at 25? C.) and 0.2 weight parts of tetra-n-butyl titanate.

[0151] The material was mixed in a speedmixer 4 times 30 seconds at a speed of 2300 rpm. The material was poured into a PVC U-shaped profile with internal dimension 18?5 mm.sup.2 and was allowed to cure for 7 days. The resulting cured material was applied on glass panes which had been primed several minutes earlier using Dow Corning? 1200 OS primer.

[0152] An example of this is provided as FIG. 1 which depicts two panes of glass separated by a continuous ribbon of the cured material adhered to the periphery of the of each glass panes effectively functioning as spacer between the two panes of glass. The upper surface of the lower glass pane depicted and the lower surface of the upper glass pane were coated around their peripheries with Dow Corning? 1200 OS primer which was allowed to dry for approximately 30 minutes.

[0153] A pre-measured ribbon of cured material as hereinbefore described was applied to the periphery of the upper surface of the lower glass pane and subsequently the lower surface of the upper pane of glass was adhered to the cured material in the regions previously primed. Almost immediately after construction the glass unit depicted in FIG. 1 could be moved and handled without impairing the structure of the construction because of the strength of the bonds formed as described herein.

Example 7

[0154] H-shaped samples of the pre-cured silicone, based on the composition in example 6, were moulded in a 2 meter long PVC U-shaped profile with internal dimension 18?5 mm.sup.2 and allowed to cure at room temperature for 7 days. 50 mm long sample pieces of this moulded product were prepared (approximate dimensions: 50?18?5 mm.sup.3). Glass pieces having 50?70?4 mm.sup.3 were primed on one surface with Dow Corning? 1200 OS primer and left for about 30 minutes. The H-shaped samples of the pre cured silicone were then applied on the primed glass alongside the 50?5 mm.sup.2 surface area on both surfaces of the pre cured silicone, leading to tensile H-pieces units.

[0155] H-piece samples were also applied to the unprimed glass surfaces following the above process excepting the application of primer. As previously explained, without the use of the primer the H shaped sample pieces showed minimal or no adhesion to the glass surface because they have no structural strength to adhere to the glass part.

[0156] Unlike the above, H-shaped samples of the pre-cured silicone material adhered to the primed glass surface were adhered to the primed glass surface almost immediately after application. Such sample pieces were tested for physical characteristics using a Zwick tensiometer.

[0157] It was noted that H-shaped samples, tested 20 minutes after application to a primed glass surface as described above, exhibit an immediate green strength of about 0.02 MPa but adhesive failure is observed, while H-shaped samples tested 7 days after application gave comparatively higher tensile strength results and exhibited cohesive failure. The results of these physical tests are provided in Table 5 below.

TABLE-US-00005 TABLE 5 H pieces on glass cured after 7 days Tensile Elongation Modulus at Time after Mode of Strength at break 12.5% application failure (MPa) (%) elongation 20 minutes Adhesive 0.02 6 after failure application 20 minutes Adhesive 0.03 8 after failure application 20 minutes Adhesive 0.04 11 after failure application 7 day after Cohesive 0.08 26 0.04 application failure 7 day after Cohesive 0.06 26 0.04 application failure 7 day after Cohesive 0.05 22 0.04 application failure

Example 8

[0158] H-shaped samples of the pre-cured silicone, based on the composition in example 6, were molded in a 2 meter long PVC U-shaped profile with internal dimension 18?5 mm.sup.2 and allowed to cure at room temperature for 7 days. 50 mm long sample pieces of this molded product were prepared (approximate dimensions: 50?18?5 mm.sup.3). Pieces of Plexiglass (PMMA), Polyethylene terephthalate (PET), Polystyrene (PS), Polyvinylchloride (PVC), aluminum mill finished (Al MF), anodized aluminum (Al AN) having 50?70?4 mm.sup.3 were primed on one surface (to be contacted by the product) with Dow Corning? 1200 OS primer and left for about 30 minutes. The H-shaped samples of the pre cured silicone were then applied on the primed glass alongside the 50?5 mm.sup.2 surface area on both surfaces of the pre cured silicone, leading to tensile H-pieces units. The H-pieces were left for 7 days at 23? C. 50% relative humidity prior to be tested

As previously explained, without the use of the primer the pieces showed minimal or no adhesion to the substrates surface.
Unlike the above, as can be seen from Table 6 below, H-shaped samples of the pre-cured silicone material adhered to the primed surfaces were adhering almost immediately after application. Such sample pieces were tested for physical characteristics using a Zwick tensiometer.

TABLE-US-00006 TABLE 6 Tensile Elongation Modulus at Mode of Strength at break 12.5% Specimen failure (MPa) (%) elongation PMMA sp1 Cohesive failure 0.105 38 0.043 PMMA sp2 Cohesive failure 0.085 28 0.044 PMMA sp3 Cohesive failure 0.105 40 0.041 PET sp1 Cohesive failure 0.11 44 0.037 PET sp2 Cohesive failure 0.103 38 0.039 PET sp3 Cohesive failure 0.097 36 0.036 PS sp1 Cohesive failure 0.089 33 0.038 PS sp2 Cohesive failure 0.103 40 0.038 PS sp3 Cohesive failure 0.096 41 0.035 PVC sp1 Cohesive failure 0.097 38 0.038 PVC sp2 Cohesive failure 0.106 40 0.039 PVC sp3 Cohesive failure 0.092 36 0.038 Al MF sp1 Cohesive failure 0.095 38 0.035 Al MF sp2 Cohesive failure 0.097 41 0.03 Al MF sp3 Cohesive failure 0.09 40 0.032 Al AN sp1 Cohesive failure 0.098 32 0.047 Al AN sp2 Cohesive failure 0.097 38 0.041 Al AN sp3 Cohesive failure 0.101 38 0.043
As it can be seen, this technique can be used to bond various substrates, not only glass, but also plastics and metals.

Example of the Second Embodiment

[0159] DOW CORNING? 1200 OS PRIMER CLEAR was applied onto the surface of cured samples of compositions A, B and C as depicted in Tables 1 and 2 above. As seen above one would expect these silicone based materials would at least physically stick to most substrates because of their naturally tacky nature. Immediately after its application, the surface of the material is observed to become non tacky to the touch and the resulting coated material does not stick anymore to any substrates even when applying pressure on the silicone based materials.