INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Jobs

Adhesive for bonding Polypropylene sheets

Adhesive for bonding Polypropylene sheets

(OP)
For a project (an evaporative humidifier), I want to stack some polypropylene sheets to create a unit of multiple airflow channels. So between each two sheets there should be some spacers to form those airflow channels.
in my designs these spacers are made using hot melt adhesive strips.

The process of making this unit should be done in two steps.
1. gluing sheets and forming spacer strips.
2. Reactivating glue strips and stacking sheets.

To elaborate my idea I created a graphical presentation and attached it to this message.



I think I need some kind of Reactivating Hot-Melt Adhesive, but I don't know anything about adhesives and can't figure out what adhesive I should use exactly. someone please help me and refer me to something which fits my needs.

Thanks

RE: Adhesive for bonding Polypropylene sheets

Your design is not feasible.

RE: Adhesive for bonding Polypropylene sheets

(OP)
I've made a sample already using general purpose glue and thin woods as spacers. I want replace those thin woods with adhesive.
I got the idea from a video. as you can see those strips are hot melt adhesive. in that video those adhesive strips are reactivated by hot water steam or something like that and sheets are bond to each other.
below image is from that video. Using this technique, They make kind of HMX which is more more complex than the moisturizer unit I'm trying to build.



thanks

RE: Adhesive for bonding Polypropylene sheets

(OP)
Can't use anything but Spunbond polypropylene. I've tested it before and results were great. I just need an adhesive.

RE: Adhesive for bonding Polypropylene sheets

The problem is, polypropylene is one of the most difficult materials to bond to. What about ultrasonic welding strips of polypropylene to the sheet?

RE: Adhesive for bonding Polypropylene sheets

(OP)
I can customize glue strips specification like their shapes, thickness or space between them in order to have different airflow channels, simply by changing glue applicator nuzzles. Ultrasonic welding or any other technique cant bring this much flexibility to my design.

RE: Adhesive for bonding Polypropylene sheets

"I can customize glue strips specification like their shapes, thickness or space between them in order to have different airflow channels, simply by changing glue applicator nuzzles."

Wow. I've only ever extruded blobs from hot glue guns. Good for you.

RE: Adhesive for bonding Polypropylene sheets

It is not reasonable to expect to be able to control the thickness and uniformity of a bead of hot-melt.

It is not reasonable to expect that you can selectively reactivate only the "bottom" of a previously applied bead.

It is not likely that you can uniformly heat many beads of previously applied hot melt deep within a stack of insulating material.

Consider a PSA on a strip of something so that you can control the thickness.

As noted by btrueblood, polypropylene is very difficult to bond.

RE: Adhesive for bonding Polypropylene sheets

(OP)
When I said I can simply control shape and formation of my hot-melt glue, I used the word simply to compare my method with other methods for example ultrasonic welding.
You know I can control the shape and formation with acceptable margin of error
the nozzle changing thing is a example of what can I control, sure I should control many parameters like nozzle types, PSA, cooling process and some other thing.

RE: Adhesive for bonding Polypropylene sheets

(OP)
"It is not reasonable to expect that you can selectively reactivate only the "bottom" of a previously applied bead."
"It is not likely that you can uniformly heat many beads of previously applied hot melt deep within a stack of insulating material."
this is my exact problem. I've seen something like that in a video.

RE: Adhesive for bonding Polypropylene sheets

A lot is going to depend on what kind of tolerance you can accept with the spacing after reactivation. Much will also depend on the bond requirements. Do you have peel strength requirements? Heat resistance? Solvent/water resistance? How much flexibility do you need? How many layers? Color? Cost?

Have you considered using a 3 mm plastic rod with a thin layer of heat activated adhesive coextruded around it to assure a consistent spacer?

Tom Quinn
Adherent Laboratories
www.adherentlabs.com

RE: Adhesive for bonding Polypropylene sheets

(OP)
Hi Tom

I cant use plastic rods. Each unit has 80 layers and I would need about 1600 rods between those layers, so using rods could be very time consuming. Beside that, because of layer structure of units I cant heat both side of the rods to activate them. Finally my PP sheets cant tolerate direct heat.

peel strength: Not required
Heat resistance: No
Water resistance: Yes
flexibility: Not needed
color: not important
layers: between 80
space between layers: 3mm (± 0.5mm)

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close