Robin,
Excellent summary.
Thanks,
Rick
-----Original Message-----
From:
Homebrew_PCBs@yahoogroups.com [mailto:
Homebrew_PCBs@yahoogroups.com] On Behalf Of Robin Whittle
Sent: Tuesday, July 30, 2013 10:30 PM
To:
Homebrew_PCBs@yahoogroups.comSubject: [Homebrew_PCBs] DIY laser labels and toner bonding to metals, plastics etc.
In the absence of a mailing list devoted to DIY self-adhesive labels and the like, I suggest that this subject is probably on-topic for Homebrew PCB. Firstly some or many folks doing PCBs at home may also want to make labels. Secondly, the two goals may involve some common processes.
This is a fresh subject line to make this material easier to find in the archives. In "RE: [Homebrew_PCBs] Re: Easy Fast Laser Print DIY Circuit Boards - Dave's toner-transfer freezing technique", Rick Sparber wrote:
> I'm not sure people on this BBS have seen this old article:
>
> http://rick.sparber.org/ttm.pdf
This looks like one of the highly informative PDF files which are linked to from:
http://rick.sparber.org/electronics/el.htmexcept that it is not mentioned there. This file is entitled:
Laser Printing to Clean, Smooth Surfaces, version 5
By R. G. Sparber
and the date within the PDF file is 2011-08-23.
The three techniques described in this file involve laser printing black toner to a variety of kitchen non-stick baking paper known as "parchment paper". Rick states that this is coated on both sides with silicone and that it can handle up to 400F = 190C.
I guess that a good alternative to this would be, as discussed in "Easy Fast Laser Print DIY Circuit Boards - Dave's toner-transfer freezing technique", the (dib-bid) "Heat Toner Transfer Paper" such as:
http://www.ebay.com/itm/170900415631 http://myworld.ebay.com/shcfstoreThe first technique (I will call it TLRS1 - Toner Label Rick Sparber) involves bonding the toner to a metal surface by first applying a thin coating of glue. The toner is left stuck to the glue and the glue on the metal which has no toner can then be removed with care. A spray sealant "Rust-Oleum ® Crystal Clear Spray Enamel." is used to make the final toner transfer more robust.
I think a limitation of this would be the relatively weak bonding between the metal and the toner. Another, as Rick mentions, is the propensity of the sealing enamel to dissolve the toner.
The second technique TLRS2 involves picking the toner off the parchment paper with matte or clear self-adhesive tape and then sticking this onto the surface of interest. Here the tape acts as a complete transparent label. I think this would be fine for small black areas, where the label is not subject to a great deal of wear at the edges, moisture or high temperature. However, a large black area version of this would suffer from there being no adhesion between the toner and the base material - metal, plastic or whatever.
The third technique TLRS3 is to melt the toner so it bonds to the metal substrate. Rick uses a serious-looking hot air gun. I think this would be good if care was taken with the distance to get the right temperature.
An alternative might be to use a large metal electric frypan, with a non-contact infra-red thermometer to check its temperature. I recently bought a large rectangular shallow electric frypan for these sorts of purposes. The thermostat has a wide temperature range but quite a high hysteresis, so it was difficult to get a consistent temperature such as 140C. I observed 20 to 30C temperature variations. I solved this to some extent by running it from a big variac (variable toroidal transformer). The frypan is 2000 watts and the variac is 1250 watts, but that is OK since I run the frypan at less than half its 230V rated voltage, which results in less than 1/4 the power dissipation. This means that there is more On time with less power for the thermostat at these low temperatures, so there is less overshoot to higher temperatures. It may be best to use the thermostat as some kind of safety limit, or turn it fully up, and then use the variac to control the temperature manually. Big variacs like this are expensive and hard to obtain. An alternative might be a suitably powerful phase-angle variable triac/thyristor motor speed controller - which I think is like a big incandescent lamp dimmer.
Here are some further techniques, all based on using a laser printer on some kind of transfer paper. I did my experiments with a Brother colour HL-4040CN 600DPI laser printer.
Technique TLRW1 is to run the printed transfer paper through a laminator with one layer of conventional laminating film. The laminating film, I understand, is typically Mylar/BoPET/PET/Polyester (all four terms seem to be valid for the same material, though Mylar is a trade name):
http://en.wikipedia.org/wiki/BoPETI understand that the glue on the laminating film is essentially the same as that used in hot-melt glue guns sticks - Ethyl Vinyl Acetate (EVA).
I removed my transfer paper with water soaking through the paper/card so that it softened the "gum"-like glue (Poly Vinyl Alcohol = PVA != Poly Vinyl Acetate - real gum is dextrin starch, which is totally different).
Then I could wash off the remaining PVA with warm water.
Once the transfer paper is removed, I have laminating film with the toner very firmly bonded to its EVA layer. This does not require temperatures high enough to melt the toner. Just 100C to 140C will do the trick - to melt the EVA. The areas of laminating film without toner can now be bonded to a substrate with heat and pressure.
I experimented with doing this onto the Mylar/BoPET/whatever top surface of a 3M brushed silver self-adhesive label material. I don't know where to buy this except in huge rolls or bulk quantities of sheet. It is flat gloss on the top and the back surface is embossed with a textured pattern, to which aluminium has been sputtered. Then a self-adhesive has been applied to the aluminium and "waxed paper" (really polyethylene-impregnated paper) is applied to the back, to make a peel-off paper layer. I used 3M 7214SA:
http://www.tekra.com/content/3m/performanceThis worked reasonably well for small black or colored areas. The limitation is that the toner has no adhesive bond with the substrate.
This won't work at all for a label with a black or colour printed edge, since there is no bond there. The solutions to this is quite tricky, but I did get them to work.
Here is technique TLRW2. It may be possible to transfer some EVA onto the bottom of the bonded toner by this method. Run the printed laminating film through a laminator with an fresh piece of laminating film facing its adhesive side. This would, on its own, produce a clear "laminated nothing except laser toner" material. This could be useful as a phototool, or a transparent label or tag.
The variation on this is to peel the two films apart as they come out of the laminating rollers. This requires taking the top off the laminator, exposing yourself to threats of DEATH etc. due to exposed mains wires and of course to BURNS. By peeling them apart while the EVA is still melted, it may be possible to get some EVA to transfer from the fresh film to the EVA of the original printed film, including transferring EVA to the toner bonded there. I think that by repeating this several times it is possible to create an EVA layer over the bottom of the whole original piece of lamination film. Then this can be bonded to almost any surface with heat. This may be useful, if it can be made reliable, since the label could be trimmed and applied with heat, leaving no messy bits of glue.
Here is a somewhat related technique TLRW3 for black on clear laser toner based silvery-background self-adhesive labels. It does not involve laminating film. It relies on a particular Mylar etc.
laser-printable film which comes from Canada, but for which there is an Australian eBay seller here in Melbourne:
http://screenprinting.asc365.com/index.asp?ID=TT1029This is from ASC365.COM in Toronto (with an office in Miami).
In Melbourne (Australia) there is an eBay seller who is evidently associated with the above company:
http://myworld.ebay.com.au/printingsupplies2009/ http://stores.ebay.com.au/ascscreenprintingThis has a slightly matte side which my Brother printers print quite well on. This includes the 600DPI color HL-4040CN, but initially I will explain just the black approach.
I print the design in mirror image of how I want it to be on the slightly matte side. The gloss side will be the top surface of my label. The toner melts and bonds very strongly to this material.
I held the 3M 7214SA material glossy face up on a hot surface - now I would use the flat shallow rectangular electric frypan at about 120C, I think. At the time I used a flat solid object I preheated in a gas oven.
I then used a hand-held (with tissues or cloth) low temperature hot-melt glue stick, sideways, to smear the top surface of the 3M material with melted glue, as thinly as I could.
Then I applied the laser printed film, toner down, starting at one end with the film held up and out of the way, pressing it very firmly with a rubber roller (a shorter piece of aluminium-cored firm foam rubber roller from the innards of a scrapped laser printer).
I did not achieve a totally thin layer of hot-melt glue, so the surface was not entirely flat. EVA is quite viscous unless it is heated to a much higher temperature. I think this process could be refined with practice to give a consistently thin hot-melt glue stick EVA layer. It bonded both the Canadian laser transfer film and the bottom surface this film with toner to the 3M material ∗really∗ well.
I then cut the label to size and used a 1/8" corner rounder (Cropodile - but I think there are probably better ones) to make the final label.
You can see the result in the 5th photo here:
http://www.firstpr.com.au/rwi/tr-808/This has colour, which I will explain below. I am generally happy with the result. However, there are limitations.
For black or single colour (if you can make the printer do this) magenta, cyan or yellow text or small lines on an unprinted background, with unprinted edges, I think this is a very good technique.
For black-background labels like the one above, it can work fine if the letters etc. have no printing. If the requirement is for colored text, then the limitations of laser printing become important. There will be screening dots by which different densities of toner are accomplished.
Technique TLRW4 solves the registration problem:
There will be imperfect registration between the black, magenta, cyan and yellow toner layers. As far as I know there's no way of telling the printer to print a larger area of "red" (magenta and yellow) or magenta, or any other colour, so that when the black covers it, the whole non-black area will be filled with red or whatever. In the graphic arts, this is called "trapping".
For this label, with only part of it in red, I printed the Canadian laser film twice. The first printing was just for black. (The HL-4040CN prints in this order: black, yellow, magenta and cyan.)
The second printing was for red, with the outlines (this was with vector graphics - Illustrator or Inkscape) trapped - made thicker so the red went beyond the proper edge of the characters. This involved two different design files.
An alternative might be to print only black and then use a permanent marker of some kind to color in the clear areas I want to be red text.
Multiple pure colours could then be used on the one label. However, I am concerned about red dye in the markers fading with time. For some reason I don't feel such concern about the laser printer toner magenta and yellow dye.
The result on the final label, starting at the top, is:
1 - The Mylar/PET/whatever Canadian laser film.
2 - Below that is the black toner, or the red (magenta and yellow)
where there is no black. Where there is black around this text,
the next layer below the black toner is the "red" toner.
3 - Next is the hot-melt glue stick EVA glue, which is ideally very
thin but in my work so far not necessarily so thin or consistently
thin.
4 - Then there is the top gloss surface of the 3M material. The bottom
edge of this is embossed with the brushed texture and this has
aluminium sputtered onto it.
5 - Then there is the self-adhesive material, and this is what is
sticking to the actual substrate - in the photo above the ABS side
of a drum machine.
I haven't tried this, but I suggest a technique TLRW5: Coat the substrate itself - which must be metal or a high temperature plastic, with the hot-melt glue stick EVA. Then heat it up (hot air gun, electric frying pan or gas/electric oven) and roll the laminating film with toner already bonded to its EVA underside, onto this layer of now molten EVA. TLRW6 is the same, except use the reverse printed Canadian laser film as in TLRW4.) Either in this process, or later, heat the whole thing up to EVA melting temperature - 100C or more, perhaps lower for low-temperature glue sticks - and try to squeeze as much of the EVA out as possible, leaving a thin, even, bonding layer of hot-melt EVA, together with a little of the EVA from the laminating film, holding the laminating film and toner to the substrate.
However . . . this would leave a flash of EVA around the label area.
There label would need to have been previously cut to size.
As far as I know, nothing in the Universe acts as a solvent for EVA. If anyone can find such a solvent, this would be a major breakthrough, because it may then be possible to thinly coat EVA onto arbitrary surfaces without heat.
I have not been able to find out how it is coated in a thin later onto lamination film. I have tried water, glycerine, ethanol, isopropyl alcohol, acetone, turpentine, "Shellite" (like petrol or gasoline but without the additives, AKA cigarette lighter fluid), Tetra Hydra Furan (excellent ABS solvent, can be used as an ABS glue), MEK (Methyl Ethyl Keytone - a major component of lacquer thinners) and Elmer's Sticky Out, which contains 1-propoxy-2-propanol, alkyl benzenesulphonic acid, ethoxylated alkyl (C9-11) alcohol and sodium metasilicate.
I am interested in these laser, EVA and laminating film techniques, but am more interested in an inkjet (Epson ultrachrome pigment ink) technique involving an inkjet printable Japanese self-adhesive matte silvery label material, with laminating film over the top. I will write that up in a separate message.
- Robin
http://www.firstpr.com.au/pcb-diy/------------------------------------
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