DESC:FIELD OF INVENTION
This disclosure is related to methods for sealing holes including covers/plugs for holes.
BACKGROUND OF THE INVENTION
During the manufacturing of a four wheel automobile, a BIW (Body in White) with holes is initially assembled where the holes provide, inter alia, a drain for paint during cathodic electro-deposition (CED) process, access points for application of anti-corrosive coating (e.g. wax), access to components during assembly, methods for placing additional special features (cables) and part locator pin and other manufacturing processes. Though the holes are essential during the production, it is equally imperative the holes be sealed properly with suitable grommets or plugs in the subsequent processes so as to avoid water and air leakage and dust entry in the cabin during operation of the vehicle, and reduction of engine noise and outside noise entering cabin during operation of the vehicle. Currently, a typical process adopted by manufacturers for closing the holes is the use of rubber/ or plastic grommets.
However, the use of rubber or plastic grommets has certain limitations. To install or fix grommets in a body shop during the BIW build stage requires that the plug or grommet withstand and be compatible with pretreatment alkali or acid solutions, CED processes, withstand high temperature paint curing processes (e.g., temperatures up to 200 oC) and effectively mitigate corrosion as well. These limitations render the process for installation of grommets in a body shop during body build impractical.
Further, the manufacturing of rubber or plastic plugs or grommets requires special metal dies for molding different geometries which leads to complexity in defining material specifications.
In addition, the current processes require high storage volumes which lead to increased costs and complex logistics.
There are also other drawbacks such as complex technical construction, high investment costs for new molding tools, requiring investments for every new dimension and process miss-outs (plugs not fitted in vehicle), and improper sealing especially at contour surfaces which allows entry of air, water and noise leading to customer complaints.
In addition, there is no diagnostic checkup possible for uncovered holes in complex vehicle construction, and it is difficult to achieve optimum noise, vibration, and harshness (NVH) insulation and consequent optimum acoustic performance.
There is a need in the field for readily adaptable seals, hole covers which can be used ubiquitously.
SUMMARY OF THE INVENTION
Provided herein are reinforced adhesive based hole covers that are designed to be compatible with post BIW-build pretreatment and CED processes and temperatures. The reinforced flexiseal hole covers described herein comprise a combination of polymeric materials, glass fiber, adhesives, and adhesive release papers which allow for easy handling on factory floors, and also in paint and body shops.
In one aspect, provided herein is a flexible seal for a hole comprising:
a first silicone coated release layer;
an inner layer comprising a rubber-based compound;
a middle glass fiber layer;
an outer epoxy layer; and
a second silicone coated release layer.
In some embodiments, the seal is placed so that it covers a hole, or the seal is placed around a plug or grommet placed in the hole.
In one group of embodiments, the rubber-based compound comprises chlorosulfonated polyethylene (CSPE) synthetic rubber, neoprene synthetic rubber, or styrene-butadiene rubber. In some of such embodiments, the layer comprising a rubber-based compound comprises a 75:25 mixture of toluene: (CSPE) synthetic rubber.
In further embodiments, the layer comprising a rubber-based compound further comprises one or more than one rubber modifiers. In some of such embodiments, the one or more than one rubber modifiers are selected from the group consisting of trimethylolpropanettrimethacrylate/propylidynetrimethyl trimethacrylate (TMPTMA); [(1R,4R,6R)-1,7,7-trimethyl-6-bicyclo [2.2.1] heptanyl] 2-methylprop-2-enoate (IBOMA); zinc di-methacrylate (ZDMA); lauryl methacrylate; methyl methacryalte; tetrahydrofurfuryl methacrylate and 2-hydroperoxypropan-2-ylbenzene.
In a group of embodiments, the layer comprising a rubber-based compound further comprises one or more than one stabilizers. In some of such embodiments, the one or more than one stabilizers is2,5 di – tert butyl hydroquinone.
In additional embodiments, the layer comprising a rubber-based compound further comprises one or more than one accelerators.
In a group of embodiments, the glass fiber layer comprises aluminum borosilicate glass fiber.
In a group of embodiments, the epoxy is a multifunctional expoxy resin. In some of such embodiments, the epoxy is an epoxy phenol novolac resin, a bisphenol A diglycidyl ether resin; a bisphenol A epoxy resin, or a bisphenol F epoxy resin.
In certain instances, the epoxy layer comprises an epoxy phenol novolac resin and an epoxy curing agent in a weight ratio of 60:5. In some cases, the epoxy curing agent is an amine adduct dicyandiamide complex.
In a specific embodiment, the hole being sealed is in the body of an automobile.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
Figure 1: shows the four layers of a seal for a hole described herein.
DETAILED DESCRIPTION OF THE INVENTION
All materials used herein were commercially purchased or prepared from commercially purchased materials as described herein.
Currently used plugs or grommets in the automobile industry which are used for sealing holes are made by molding a single material in a desired design shape and size. Such customized seals are not compatible with post BIW-build processes and temperatures. There is a need in the field for readily adaptable seals which can be used in multiple settings and by multiple users.
Accordingly, described herein are readily adaptable flexiseals / flexiseal holecovers which are design friendly and can be used in any shop (e.g., factory floor or paint shop / body / assembly shop); allow for design and tool standardization (no need for separate tools for different hole dimensions); are highly conformable (can take any shape); are process friendly (easy to apply - peel and paste); are durable (have good air and water leakage resistance); confer improved acoustic insulation (NVH); have high temperature resistance (including CED processing oven temperatures); reduce complexity in logistics due to standardization; have superior corrosion resistance properties; are compatible with automobile paints and paint application systems (can be applied in aesthetically important areas of vehicle); are compatible with PVC coatings and can be used for under-body holes sealing; confer stone chip protection; and confer improved puncture resistance and aging resistance (water/humidity).
Accordingly, the flexible seals / hole covers described herein provide a one point solution that meets multiple manufacturing requirements and further reduces the development cost, time, and complexities of developing, procuring and logistics because the same flexible seal / plug / hole cover can be used in multiple settings / shops / locations.
Advantageously, the flexiseals / hole covers described herein lower storage volume and costs because one size fits many holes and shapes; they are compatible with any process automation with no additional costs required for new models; and further, the flexiseal hole covers can be adapted for any desired geometry. In addition, the seals are durable, cost effective and user friendly.
In one aspect, provided herein are hole covers comprising a first layer comprising silicon coated release liner (A); a second layer comprising a rubber based compound (B); a third layer comprising a glass fabric (C); a fourth layer comprising an expoxy based compound (D) and a fifth layer comprising silicon coated release liner (E).
The silicon coated release liner facilitates the handling of uncured material placed on hole to be sealed.
In some embodiments, the rubber based compound is MyTBond Rx. In some embodiments, the glass fabric is E-glass fabric. In some embodiments, the epoxy based compound is MyTBond Ex.
As used herein, “epoxy based compounds” refers to polyepoxides, a class of reactive prepolymers and polymers which contain epoxide groups. Epoxy resins may be cross-linked (cured) either with themselves through catalytic homopolymerisation, or with co-reactants (e.g., hardeners/curing agents) including polyfunctional amines, acids (and acid anhydrides), phenols, alcohols and thiols.
As used herein, “rubber based compounds” refers to natural or artificial rubber. Natural rubber substantially comprises polymers of isoprene, along with other compounds (additives) in minor amounts. Synthetic rubbers comprise polymers of isoprene or other monomers and may also comprise additional rubber modifiers that affect properties of the rubber.
As used herein, a rubber modifier is any agent which modifies the properties of the base polymer. For example, a rubber modifier may be a cross-linking agent, or a curing agent or any other agent (e.g., antioxidants, anti-ageing agents, accelerators, and the like) which modifies the properties of the native polymers in the rubber. In some instances, a rubber modifier may be a polymer which enhances adhesive properties of rubber.
Examples of rubber cross linking agents/curing agents include and are not limited to sulfur, sulfur monochloride, tellurium, selenium, polysulphide polymers, p-quinonedioximes, metallic oxides, organic peroxides, di-isocyanates, trimethylolpropanettrimethacrylate / propylidynetrimethyl trimethacrylate (TMPTMA); [(1R,4R,6R)-1,7,7-trimethyl-6-bicyclo [2.2.1] heptanyl] 2-methylprop-2-enoate (IBOMA); zinc di-methacrylate (ZDMA); lauryl methacrylate; methyl methacryalte; tetrahydrofurfuryl methacrylate, and 2-hydroperoxypropan-2-ylbenzene, N- acetyl N- phenyl hydrazine and saccharin.
The rubber based compound forms a layer which provides an acoustic barrier and improves sound dampening, thereby acting as a sound barrier. The rubber based material is cross-linked during the paint shop baking process and forms a strong bond with a metal substrate such as mild steel or aluminum (either bare or cathodic electrodeposition (CED) coated) thereby forming a good seal. The glass fabric layer is formed of knitted glass fiber fabric and provides tear strength to the hole cover and also acts as a carrier for the rubber and epoxy based curable materials. The epoxy layer, after curing, forms a strong outer layer that provides strength against chipping and abrasion.
Although the flexi-seal hole covers provided herein are described in the context of the automobile industry, it will be appreciated that such hole covers / seals have utility in other settings. By way of non-limiting examples, such seals can be used for repairing holes or cracks in plumbing fixtures, or holes or cracks in rain gutters and the like. All such equivalents are contemplated within the scope of embodiments presented herein.
EXAMPLES
Materials used:
Chemical IUPAC Name Cas No.
Toluene Methylbenzene 108-88-3

SiO2 Silicon dioxide 7631-86-9

TMPTMA Trimethylolpropane Trimethacrylate / Propylidynetrimethyl Trimethacrylate 3290-92-4
IBOMA [(1R,4R,6R)-1,7,7-trimethyl-6-bicyclo [2.2.1] heptanyl] 2-methylprop-2-enoate 7534-94-3
ZDMA Zinc Di-methacrylate 13189-00-9
CHP 2-hydroperoxypropan-2-ylbenzene 80-15-9

Saccharin 2H-1?6,2-Benzothiazol-1,1,3-trione 81-07-2

NANPH N'-phenyl aceto hydrazine 114-83-0
Lapox 238 Formaldehyde, oligomeric reaction products with 1-chloro-2,3-epoxypropane and phenol
MyTBond Rx/Ex are rubber or epoxy based adhesive compounds purchased from M/s Metlok Adhesives Pvt. Ltd.
Example 1:
MyTBond EX - Epoxy based compound:
Ingredient Weight ratio
Epoxy Novolac Resin 60
Toluene 10
Ajicure Dicy AH 154 5

In this example, Ajicure Dicy AH 154 is a curing agent for the epoxy resin. As used herein, “weight ratio” means that for any given unit of weight measurement, the ratio of the weights of the listed ingredients is as shown herein. In this example, the epoxy novolac resin : toluene : Ajicure Dicy AH 154 weight ratio will be 60 : 10 : 5, and where the unit of measurement is grams, the composition will comprise 60 g of epoxy novolac resin, 10 g of toluene and 5 g of Ajicure Dicy AH 154.

MyTBond RX – Rubber based compound:
Ingredient Weight ratio
Mix. Toluene and Hypalon 30 (a chlorosulfonated polyethylene (CSPE) synthetic rubber) (75:25 mixture was weighed) 90
SiO2 10
TMPTMA 5
IBOMA 5
ZDMA 2
CHP 2
Saccharin 0.1
N- Acetyl N- Phenyl Hydrazine 0.2
2,5 Di – Tert Butyl Hydroquinone 0.02

In this example, TMPTMA and IBOMA act as rubber modifiers / cross linkers, CHP acts as a rubber modifier / curing agent, N- acetyl N- phenyl hydrazine and saccharin act as rubber modifiers / accelerators, and 2,5 di – tert butyl hydroquinone acts as a rubber modifier / stabilizer and / or an anti-ageing agent.
The invention has been described in detail with reference to preferred embodiments thereof. However, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

,CLAIMS:
1. A flexible seal for a hole comprising:
a first silicone coated release layer;
an inner layer comprising a rubber-based compound;
a middle glass fiber layer;
an outer epoxy layer; and
a second silicone coated release layer.
2. The flexible seal of claim 1, wherein the seal is placed on a hole, or around a plug or grommet placed in the hole.
3. The flexible seal of claim 1, wherein the rubber-based compound comprises chlorosulfonated polyethylene (CSPE) synthetic rubber, neoprene synthetic rubber, or styrene-butadiene rubber.
4. The flexible seal of claim 3, wherein the layer comprising a rubber-based compound comprises a 75:25 mixture of toluene: (CSPE) synthetic rubber.
5. The flexible seal of claim 1, wherein the layer comprising a rubber-based compound further comprises one or more than one rubber modifiers.
6. The flexible seal of claim 5, wherein the one or more than one rubber modifiers are selected from the group consisting of trimethylolpropanettrimethacrylate/propylidynetrimethyl trimethacrylate (TMPTMA); [(1R,4R,6R)-1,7,7-trimethyl-6-bicyclo [2.2.1] heptanyl] 2-methylprop-2-enoate (IBOMA); zinc di-methacrylate (ZDMA); lauryl methacrylate; methyl methacryalte; tetrahydrofurfuryl methacrylate and 2-hydroperoxypropan-2-ylbenzene.
7. The flexible seal of claim 1, the layer comprising a rubber-based compound further comprises one or more than one stabilizers.
8. The flexible seal of claim 7, wherein the one or more than one stabilizers is 2,5 di – tert butyl hydroquinone.
9. The flexible seal of claim 1, wherein the layer comprising a rubber-based compound further comprises one or more than one accelerators.
10. The flexible seal of claim 1, wherein the glass fiber layer comprises aluminum borosilicate glass fiber.
11. The flexible seal of claim 1, wherein the epoxy is a multifunctional epoxy resin.
12. The flexible seal of claim 1, wherein the epoxy is an epoxy phenol novolac resin, a bisphenol A diglycidyl ether resin, a bisphenol A epoxy resin, or a bisphenol F epoxy resin.
13. The flexible seal of claim 1, wherein the epoxy layer is prepared from an epoxy phenol novolac resin and an epoxy curing agent in a weight ratio of 60:5.
14. The flexible seal of claim 13, wherein the epoxy curing agent is an amine adduct dicyandiamide complex.

15. The flexible seal of claim 1, wherein the hole being sealed is in the body of an automobile.