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Everwide Newsletter-No.66

Experiment § 2K PU elastic paint application

PU materials have been widely used in life, such as PU runways, elastic cement paint, PU waterproof paint, leather, foam materials, PU infusion, etc. Still, the application of soft PU materials in the market is rare, so synthetic soft PU elastic paint has become our goal. The problems encountered in the research and development process are often 1. How to test the softness 2. The addition of PU soft fluff powder 3. The factor control of the spraying process.

To test the softness, because the customer's substrate is hard PU, before the test, spray a layer of hard PU as a primer, let the solvent evaporate at room temperature for more than 30 minutes, and then spray the synthetic PU elastic paint. However, the NCO functional group's reaction rate in the elastic paint often causes misjudgment, so the test piece needs to do a simple ring test to confirm the softness. In addition, the addition of PU soft fluff powder can also increase the softness, and it is also a knowledge to choose the particle size of fluff powder. From experience, if the thickness of the sprayed film is 30um, the particle size of the fluff powder will be larger than 30um so that the particles of the fluff powder have the opportunity to pile up with each other so that the soft fluff powder can be touched when the hand touches the film. And make the whole film soft.

─Author: Mr. Rong-xin, Lin, Assistant R&D Engineer, Everwide Chemical


Process § Filling and packaging

After grinding and defoaming, filling and packaging follow.

(7) Filling: the defoamed product will be further filled into appropriate containers for products with large quantities and small packing weight. A semi-automatic filling machine is used for packing, and products with small packing quantities and large packing weight are filled by manual packing.

(8) Packaging: The filled product needs to be labeled, bagged, packaged, bundled, boxed, etc., so that the product can enter the stage of storage and wait for shipment.


Knowledge § Reaction mechanism of epoxy resins and amines

As shown in the figure above, a primary amine can undergo a ring-opening reaction with two epoxy groups to generate two hydroxyl groups; a secondary amine can undergo a ring-opening reaction with one epoxy group to create a hydroxyl group. The structure of active hydrogen can accelerate the rate of this type of reaction, such as alcohols, phenols, and weaker organic acids.

Generally, epoxy resins and polyamine hardeners are designed in an equivalent proportion to obtain the best mechanical properties. However, in the epoxy resin and polyamine hardener system, it is common to have excess amine groups to get better toughness and flexibility.


Living § How much do you know about temperature (5)

After the experimental class, we have half an hour of picture book sharing time. The children prepare their own stories to share with their classmates and spend a fulfilling weekend. Chenggong Elementary School is a beautiful mini-school located on the mountain. Several families grow tea on the campus. There are also horses nearby. After school, the children go to the fence to feed the horses. Everyone had a good time and fully enjoyed the natural scenery.

I often wonder: how to keep children away from the harm of TV and computer? I think the company of adults and nature is very important. The proudest thing about living in the countryside of Pingtung since I was a child is that my childhood life was so rich. I naively thought that pretending to be a scarecrow in the field could avoid my mother's sight to play for a longer time. I also watched the snake peeling while eating watermelon, and I was so frightened that I couldn't move. As for the secret to catching frogs with earthworms? Let me tell everyone secretly, tie the earthworm to a long thin wire; when the frog slowly gets close to the earthworm, it will swallow it, and it will easily get stuck in the throat at that moment. Open the plastic bag, shake it a few times and let the frog fall into the bag and you're done. I don't encourage everyone to catch frogs, but I just think that the children learning process must be with the good friend of nature.

─Author: Ms. Miao-ling, Lin, R&D Engineer, Everwide Chemical


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