Adhesive for Plastic

offroader

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I have an ML430. In common with most modern cars does not have bumpers as older cars, it just has plastic fairings. The rear fairing/bumper is cracked where I backed into a wall. The cost of a new plastic moulding from M-B, sprayed to match the car, would frightening and out of proportion to the extent of the damage. I tried to do a repair using epoxy resin and glass fibre mat on the inside of the bumper. It was fine for a couple of months but eventually it peeled off. I think that is because the repair is more rigid than the plastic and because the bond between epoxy and the plastic is not strong enough. I need a flexible adhesive with a strong bond to the plastic used on M-B moulded parts.

What adhesive is used for this type of repair? Have any members had experience and success in repairing plastic mouldings?
 

television

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If you do a google search" plastic bumper repairs" there are lots of firms out there with several techniques from welding to gluing. If it is possible to get behind the damaged part then I often put an alli plate behind and use countersunk self tapping screws, and then fill,flat and spray.

Watching my local man he uses a glue that uses a catalyst, you put the glue on and spray the catalyst on and thats it. It is approved be insurance companies
 

Xtractorfan

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The spray on catalyst/ glue Malc is used by the Kitchen and wood guys, its really a bit hard for plastics,it will eventually crack, as said most motor factors do sell the bumper kits now, but the price is way over the top.. try online and check out whats available... there is an excellent glue available from diy stores that the plastic drain pipe guys use, but it will only work on some plastics, I will do a check tomorrow on the ML type of plastic and post again OK..

The ali plate and rivets or screws will seep moisture past the screw and the filling over the screw heads will bubble up..
 

Rappey69

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the stuff for plastic pipes is solvent weld and does not work on plastic motorbike and car fittings... I have tried!
Fibreglass will not stick to a smooth surface unless it is roughed up but plastic is a no-no.
the only sucess i have had is using a soldering iron on the reverse surface and melting the crack together.
Is car plastic parts some sort of polypropelene ?
 

television

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the stuff for plastic pipes is solvent weld and does not work on plastic motorbike and car fittings... I have tried!
Fibreglass will not stick to a smooth surface unless it is roughed up but plastic is a no-no.
the only sucess i have had is using a soldering iron on the reverse surface and melting the crack together.
Is car plastic parts some sort of polypropelene ?

Its all one form of ABS but there are many
 

Rappey69

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this thread is going well, soon we will have 100 solutions that dont work ! lol
 

Xtractorfan

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I have repaired bumpers with the drain pipe solvent..
Some bumpers, fords and jaguars cant even be hot welded,
fibre glass will stick if you roughen up the surface and use a plastic primer..
The melt together with the soldering iron/hot screwdriver works well on most bumpers

There used to be a test, cut of a small piece of the bumper, matchstick size and drop it into some water, if it floated it couldn't be welded, and if it sank it could....or was it the other way round...........
 

Rappey69

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Im quite amazed that you have found a plastic on a car that solvent weld will bond.
I have tried motorbike plastics, quad plastics, lots of car plastics and boat plastics but it wont melt any of them to form a bond.
Most of the above are soft plastics (flexible) whereas waste pipe and such is quite hard and will crack rather than bend so the solvent bonds them together by melting.
Stelmax is another glue which is superb for pvc as it melts it to form a bond but yet again i have failed to glue car plastics with it.

PS, television - Empty your pm box,, its full ;)
 

FIBAMAN

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Plastic?

This word covers a wide range of materials and all the replies are correct in some way.
Polypropylene (PP) cannot be glued, or fibreglassed, it can only be welded.
ABS can usually be bonded with epoxy or polyester based systems, however just gluing or brushing on resin is not enough as they are unreinforced and will crack. You need to prepare your surface by light abrasion (assuming it is ABS) SOLVENT WIPE TO REMOVE DUST AND DIRT VERY IMPORTANT, DO NOT USE ANY WITH RESIDUAL LUBRICANT eg WD40). Prime with resin mix and then do hand lay up GRP.
If you pm me with your address, I will send you some of our ready to use UV cured grp to try.
 

television

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I use a 3m adhesive flexible(ish) backing pad and a two pack adhesive. I think it is relativly new on the market and works very well. I have had no problems so far, touch wood!


That sounds a good idea :D
 

FIBAMAN

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That sounds a good idea :D

By sheer coincidence I was speaking with the manufacturer of that material yesterday (3m market it but do not make it). The subject came up during discussion about some other materials I am involved with.
The manufacturer told me that they did indeed get a good bond to PP, so it may well be worth a go also.
 

bigasotonuk

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I use a 3m adhesive flexible(ish) backing pad and a two pack adhesive. I think it is relativly new on the market and works very well. I have had no problems so far, touch wood!

Hi,
Any idea where one might be able to get some of this stuff?
 

giuseppe

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sealant for whatever

Hi, I used to use an Adhesive Sealant at work for glueing rubber to aluminium, i have used it to glue almost anything to anything, once it had cured over night it bacame very difficult to separate, and the good thing was it remained flexible but very tough, it is made by Dow Corning, I believe you can get it in Travis Perkins,or maybe B&Q, I believe it costs about £30, but definately worth it.
Its called DOW CORNING 3145 RTV MIL-A-46146 ADHESIVE/SEALANT.
It is a clear sealant.
 


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