Experiment § How to improve the surface dryness of UV glue?
Oxygen will interfere with the reaction of UV glue, resulting in poor drying of the surface after hardening. There are two types of solutions:
1. Physical method: 1. Floating wax method: Paraffin is added to the formula. Paraffin is incompatible with organic resins and floats on the surface to block external oxygen. 2. Pass nitrogen: block the external oxygen. 3. Lamination method: cover the inert plastic film as an oxygen barrier (such as PE film) and tear off the film after UV light hardening. 4. Strong light irradiation method: strong light irradiation causes a large number of photoinitiators to decompose simultaneously, and a large number of free radicals are added to the monomer in an instant. The rapid increase in viscosity hinders the diffusion of external oxygen, and the increase in viscosity is conducive to the progress of free radical polymerization. 5. Two irradiation methods: first irradiate the coating with a short wave (254nm), the short wave has poor penetration in the organic layer, and the polymerization only occurs on the surface layer, forming a good oxygen barrier film; Long wavelengths penetrate the coating for deep hardening.
2. Chemical method: 1. Add oxygen scavenger: such as 3rd-grade amine, mercaptan. 2. Use type I and type II photoinitiators.
To improve the surface dryness, from the formula, equipment, manufacturing process, etc. Which method is the most appropriate? Every case is different and requires individual consideration.
─Author: Ms. Miao-ling, Lin, R&D Engineer, Everwide Chemical
Product § Adhesive for micro speakers
This series of materials are suitable for producing high-quality electro-acoustic components, mainly used in the bonding of components and the fixing and reinforcement of lead wires. They are also used in other fields, such as waterproof sealing products. For example, buzzer, horn, miniature horn, etc. We combine the latest technology and partners with professional backgrounds, using the most advanced equipment and materials suitable for the electronic industry.
*Application 1: Surrounding the sound film - bonding the sound film and the coil. Product features: ①The colloid has toughness after UV curing and has the characteristics of shock absorption and thermal shock resistance. ②Most of the resin is dyed red to facilitate identification of the gluing position (as shown by the blue arrow) and glue quantity control. ③ can harden quickly. There will be no severe shrinkage stress during the hardening process. ④Through the hot and cold cycle (-20~80℃) and high-temperature dynamic test. Recommended products are GM342 series, GM344 series, GM304.
*Application 2: Surrounding the sound film - bonding the sound film and the basin frame. Product features: ① For the connection between the outer ring of the Mylar sheet in the speaker and the black plastic PBT. ②The colloid has toughness after UV curing and has the properties of shock absorption and thermal shock resistance. ③Pass the hot and cold cycle (-20~80℃) and high-temperature dynamic test. ④ Data that does not affect the oscillation frequency. Recommended products are GN618, GM304.
*Application 3: Surrounding the sound membrane—lead fixing. Product features: ①The flexible colloid will not affect the vibration frequency. ②There are colors for identification to facilitate process control. ③It has the characteristics of shaking and will not sag. Recommended products are GN618-2, GM344-5, FP7111.
Knowledge § What is the autocatalytic reaction of epoxy resin?
In the reaction system of epoxy resin/amine hardener, substances with active hydrogen such as alcohols, phenols, etc., are the catalysts (HX in Equation 1) of the reaction above. The reaction mechanism is shown on the left: There are two sources of active hydrogen substances with catalytic ability: one is the catalyst initially placed in the formula, and the other is generated during the hardening reaction of the resin. Each epoxy resin reacts with an amine hardener; it opens a ring to create a hydroxyl group (OH group, Equation 3). This hydroxyl group can further catalyze the reaction between epoxy resin and amine. In other words, the product generated after the reactant reacts will become the catalyst of the reactant; when the reactant's concentration decreases, the catalyst's concentration increases relatively. The above characteristics are called autocatalytic reactions, and the reaction rate of this type of reaction will become faster and faster with the increase of reaction time before gelation occurs.
Living § "Xiao Ming Specification"
Xiao Ming went to the glasses shop to get shortsighted glasses, but he kept shouting that he could not see clearly. The optometrist helped him adjust it to 1.5, and he said that if it were too clear, he would get dizzy. If it is adjusted to 1.0, it would be dangerous if he couldn't see enough. So the optometrist specially ordered the lenses, and the degree was calculated to the decimal point so that he could see just 1.2, which was a little clear and would not cause dizziness because of too clear. A week later, Xiao Ming came back to see an optometrist. He said that the 1.2-degree glasses were not good. The optometrist was confused and asked that 1.5 is too clear, 1.0 is not clear enough, and 1.2 is just right! Then how do you want me to match it?
Xiao Ming said, "I take this pair of glasses out. I feel dizzy when I read a book and blurry when birdwatching, so your specially tuned degree is very difficult to use. It's costly and rotten." This Xiao Ming story gave us a lot of inspiration. Some customers' requirements for material properties and some development goals set by R&D are actually "Xiaoming specifications" that cannot be achieved. And, like this story, it often takes actual testing to uncover inconsistencies that don't work. To communicate effectively with customers, a good team must actively conduct internal research to minimize the waste of time and cost caused by "Xiao Ming specifications."
─Author: Mr. Hui-xu, Li, R&D Engineer, Everwide Chemical
