Looking For A Special Glue

[oldcarfan]

The local Walmart has been clearing out their diecast cars of various scales at a good price. I got a ton of them to break down for the wheels and tires.

Now for the question, a lot of these toys have some cool body parts and details that would be nice for model kits. The plastic on the chassis and interior is a slightly bendable black plastic.

Could it be a type of ABS? I've tested use a Tamiya liquid cement, and super glue, but neither really touches it. I do have a generic Bondic but haven't tried it yet. Has anyone ever glued this stuff together and if so what works? I couldn't find any markings on the pieces saying what kind of plastic it is.

[StevenGuthmiller]

Epoxy works on everything.

It’s pretty much all that I use on models now.

Saves having to keep 15 different glues on hand.

 

 

 

 

Steve

[peteski]

If it is one of those slippery plastics, no glue will produce strong bond.  By slippery plastics I mean something like the waxy plastics used for Tupperware. Polypropylene or Polyethylene.  Also, if the plastic is difficult to glue, paint will likely not stick to it.

[Mike 1017]

I would experiment sanding the part to give the glue and paint something to stick to.  I agree epoxy is the way to go.

Mike

[Ace-Garageguy]

On 2/27/2024 at 11:11 PM, peteski said:

If it is one of those slippery plastics, no glue will produce strong bond.  By slippery plastics I mean something like the waxy plastics used for Tupperware. Polypropylene or Polyethylene.  Also, if the plastic is difficult to glue, paint will likely not stick to it.

True, but there are adhesion promoters and special adhesives made for use in the autobody industry that will do an OK job on many "difficult to bond" plastics. However, they're not cheap, and rarely come in modeler-friendly packaging.

In general, epoxy does stick reasonably well to everything but PP and PE and their derivatives, but the 5-minute stuff is a complete waste of time.

The rule-of-thumb is that the longer an epoxy takes to reach "full cure", the stronger the bond will be.

Roughing the surfaces to be bonded is also very necessary to get decent bonds with non-solvent gloos.

 

Edited February 29, 2024 by Ace-Garageguy

[Muncie]

3M Plastic Emblem and Trim Adhesive.  It's a tube glue, no mixing.  I've seen it available at some auto parts stores, (maybe even Walmart?) but an auto body supply shop would definitely have it.  It's like a high-performance contact cement. Buy the smallest size that you can get - It will stick the cap to the tube rendering the remaining glue in the tube hard to get. Reasonable price in the smaller tubes. It takes a couple of days to dry to full strength but seems to stick to anything. Strong enough for any abuse that I could give it.

Edited February 29, 2024 by Muncie

[peteski]

The other thing I mentioned in my original post was that pain adhesion.  even if you can get the part to stick. what good is it of the paint will not adhere well?

As far as I understand adhesion promoters, those are designed for using automotive paints on polyurethane (urethane) parts, not polypropylene or polyethylene.  But I would be happily proven wrong.

[stitchdup]

if the parts you want to use are fitted to the diecast using pegs or clips you could try copying those parts in styrene so you dont need to worry about glue. On the diecast i've taken apart most seem to be either pegs or slots for the smaller parts so if you got a good friction fit you should get away without glue. If its a screw on part the centre of where the screw goes should give you a decent enough area to glue keyed pegs to, even if the glue aint the best, if you really glob the glue in as it would be holding onto a ribbed area and in effect you've sorta made a screw out of glue.

If all else fails theres always double sided tape for fixing cell phone screens, which i'm going to try on some alfa-model windshields. Its not cheap but if it holds a phone together in our pockets its should work for models. I got the 1mm black stuff but its available in clear too. I think I paid about £20 for 1 roll. The clear stuff is near invisible once its on phones. My friend that does phone repairs suggested it to me and said not to cheap out on it and to get the tena brand and to use it a warm area as it doesn't stick well when the parts are cold. It comes with decent free needle point tweezers too which i assume is to take the backing off

[Muncie]

1 hour ago, peteski said:

The other thing I mentioned in my original post was that pain adhesion.  even if you can get the part to stick. what good is it of the paint will not adhere well?

As far as I understand adhesion promoters, those are designed for using automotive paints on polyurethane (urethane) parts, not polypropylene or polyethylene.  But I would be happily proven wrong.

Just kicking out an idea here ...  SEM makes an aerosol paint for upholstery vinyl and other flexible plastics.  Not cheap, but not bad if it works. it's available at some auto detail supply or some auto paint supply shops.  Probably should be confirmed by testing a sample for compatibility and to see if it will work.

Color Coat™ Aerosols | SEM Products

[peteski]

Vinyl (PVC) and Polypropylene or Polyethylene are different types of plastic. 

But feel free to experiment.

[Muncie]

Long ago, I recoated some hard flexible molded trim panels and seat upholstery made of different plastics with a paint made for upholstery - very little plastic knowledge so I don't know what plastics they were.  The upholstery paint that I used seemed to get it's adhesion by "melting" into the top surface of the plastic.  It actually softened the plastic until it dried. Probably not only to stick to the part but to be more durable little by getting the color into the plastic so it would not wear off so easily.  Strange stuff, it probably would have turned kit plastic into a putty consistency.  Like I say, just an idea and the SEM rattle can appeared easy to use.

[peteski]

10 minutes ago, Muncie said:

The upholstery paint that I used seemed to get it's adhesion by "melting" into the top surface of the plastic.  It actually softened the plastic until it dried.

You hit the nail on the head.  Polypropylene and Polyethylene plastics are not attacked by any of the strong solvents (like acetone or similar) used in paints. So paint will not fuse into them.

 

But then we don't even know for certain what type of plastic we are dealing with. I'm just speculating.  It could possibly be nylon or  POM ( Polyoxymethylene  ) which is pretty much impossible to glue or paint.

Edited February 29, 2024 by peteski

[Ace-Garageguy]

3 hours ago, peteski said:

The other thing I mentioned in my original post was that pain adhesion.  even if you can get the part to stick. what good is it of the paint will not adhere well?

As far as I understand adhesion promoters, those are designed for using automotive paints on polyurethane (urethane) parts, not polypropylene or polyethylene.  But I would be happily proven wrong.

The adhesion promoters I was referring to are this sort of thing from 3M, designed for TPO-type plastics.

3M™ Polyolefin Adhesion Promoter is a specially formulated adhesion promoter for use when repairing low surface energy plastics such as thermopolyolefin (TPO). Use the adhesion promoter with 3M brand adhesives. 3M™ Polyolefin Adhesion Promoter is designed specifically for polyolefin and ethylene propylene plastic identified by the marks PP, EP, TPO or EPDM on the back of the part.

NOTE: These adhesion promoters will work differently on specific PE and PP blends, and may not do much at all on some...like the garden-variety yellow bondo spreaders. They are a totally different product than what's marketed for urethane-based plastics.

TPO-type plastics are defined as:

 

TPO compounds are resin blends of polypropylene (PP) and un-crosslinked EPDM rubber and polyethylene. They are characterised by high impact resistance, low density and good chemical resistance.

They are used in applications where there is a requirement for increased toughness and durability over the conventional PP copolymers, such as automotive bumpers and dashboards. The properties are restricted to the high end of the hardness scale, typically >80 Shore A and with limited elastomeric properties.

 

 

 

 

 

[peteski]

I didn't know that Polyolefin Adhesion Promoters existed.  Thanks for your educational post Bill.  Never too old to learn new things.

Edited March 1, 2024 by peteski

[Ace-Garageguy]

33 minutes ago, peteski said:

I didn't know that Polyolefin Adhesion Promoters existed.  Thanks for your educational post Bill.  Never too old to learn new things.

It doesn't work on everything PP or PE, again depending on the specific compound, but it can be a real bacon-saver these days when insurance companies are cutting every last nickel out of what they'll pay to repair older vehicles.

We're often forced to use LKQ parts (like kind and quality...which is newspeak for "junkyard"), many of which are non-urethane, and most of which need some repairs to be presentable.

It's a handy product to know about.

https://www.3m.com/3M/en_US/p/d/b40065456/

PS EDIT: If you like chemisery, this is an interesting rabbit-hole to go down...

https://www.mdi.org/blog/post/what-is-the-difference-between-polyethylene-and-polypropylene/#:~:text=Polyethylene's monomer unit is ethylene,by polymerizing propylene monomer units.

Edited March 1, 2024 by Ace-Garageguy

[oldcarfan]

Reading the replies made me think and I went out and checked. I have a couple of Bondo spreaders and they feel and flex like plastic I'm talking about. The plastic doesn't take cutting or sanding well at all. I tried some epoxy on a roughed up area and it doesn't adhere very well either. 

Edit: Come to think of it the plastic feels similar to the plastic that Super glue comes in.

Edited March 1, 2024 by oldcarfan

[Bugatti Fan]

What about Plastic Weld liquid cement by Plastruct? I find it a good all around adhesive for ABS, Polystyrene and Acrylics. I discovered it years ago when using some of the Plastruct ABS extrusions for industrial and architectural model makers that polystyrene adhesives would not work on. It is my 'go to' liquid cement for most of my modelling work.

The plastic innards from die cast toys/models is usually a hard type of plastic that is less britt!e than polystyrene. Plastic Weld might be worth a try on it.

The flexible polythene types of plastic as used for Tupperware tend to be resistant to any adhesives. I used to curse Airfix for moulding their figure sets in the stuff as they were just impossible to clean up mould lines from or cut up to adapt. As for painting, their flexibility made them pretty useless in that respect too.

Edited March 1, 2024 by Bugatti Fan

[stitchdup]

would the resin on its own for glassfibre work? when i've worked with it it always seemed to stick to stuff it shouldn't

[NOBLNG]

Screw it if ya can’t glue it.??

 

Edited March 1, 2024 by NOBLNG

[Ace-Garageguy]

13 hours ago, stitchdup said:

would the resin on its own for glassfibre work? 

That would be either a polyester or an epoxy resin system, and neither will stick particularly well to "low surface energy" plastics like PE and PP without an adhesion promoter...if at all.

There are options, but they aren't cheap or generally available to modelers.

https://multimedia.3m.com/mws/media/755526O/innovations-in-bonding-to-low-surface-energy-white-paper.pdf

The OP needs to do some experimenting on his own.

As I said at the beginning, without knowing exactly what his particular problem-plastic is, speculation is a total waste of time.

Edited March 1, 2024 by Ace-Garageguy

[oldcarfan]

Reading the replies made me think and I went out and checked. The plastic does indeed have a sort of waxy feel to it not unlike Teflon in some ways.  I have a couple of Bondo spreaders and they feel and flex like plastic I'm talking about. The plastic doesn't take cutting or sanding well at all. Out of curiosity, I tried an experiment. I scuffed up the leftover chassis of a parts kit and tried various things on it. I tried super glue, Bondo spot putty, two part epoxy, ketone, and some other solvent based cleaners. They had no effect on the plastic. It didn't bond the plastic and it didn't even distort it. 

 

[Ace-Garageguy]

6 minutes ago, oldcarfan said:

Reading the replies made me think and I went out and checked. The plastic does indeed have a sort of waxy feel to it not unlike Teflon in some ways.  I have a couple of Bondo spreaders and they feel and flex like plastic I'm talking about. The plastic doesn't take cutting or sanding well at all. Out of curiosity, I tried an experiment. I scuffed up the leftover chassis of a parts kit and tried various things on it. I tried super glue, Bondo spot putty, two part epoxy, ketone, and some other solvent based cleaners. They had no effect on the plastic. It didn't bond the plastic and it didn't even distort it. 

 

Good job.

Nothing within the usual modeler's repertoire is going to stick to it then.

Best figure out some way to pin the parts together, or find some other mechanical fastening method...small screws, etc.

 

[Bugatti Fan]

If the die casts were toys rather than models then they were designed to be played with, hence the plastic that was used probably.

We are modellers, right!  Why not do some scratch building and copy those underside parts with plastic card instead. Thinking a bit laterally, it could be a neat way of solving this problem plus you can use the adhesives you already have!

Edited March 2, 2024 by Bugatti Fan

[peteski]

If the slippery plastic parts you found could be very useful, you could make RTV rubber molds from them and then make urethane reins copies (which then could be handled like other resin cast parts), Urethene resin is glueable and paintable.

[Bugatti Fan]

Depends on how many identical ones you need to justify it Pete.       RTV and all that is a bit pricey.    If they all differ then using the plastic card would be more viable.