Experiment § Why do we need static pressure-sensitive adhesive?
The instructions for hook sold in the market often indicate "Stay for 24 hours". Why can we use it only after standing still? This is because the adhesive behind the hook is pressure-sensitive adhesive and has viscoelastic properties. At first glance, it looks like a solid, but at the microscopic level, it has the properties of a fluid. The pressure-sensitive adhesive will wet the substrate when it touches the surface of the substrate and fills up the uneven surface. The longer the standing time, the better the wetting effect, the higher the peel strength (adhesive strength), and finally it will tend to a constant value (Figure 1). From this perspective, time is an important factor in evaluating pressure-sensitive adhesives. We used a certain pressure-sensitive adhesive to make T-shaped test pieces and then tested the peel strength in 7, 14, 28 days (Figure 2). The adhesive force measured in the experiment is 1.0kg, 1.4~1.5kg, and 1.6kg respectively, showing that the strength is getting better and better. The speed of wetting is related to the formulation of the adhesive. If the tackiness of the adhesive is made higher, the surface can be wetted quickly and stable strength, but relatively, pressure-sensitive adhesives with too high viscosity and low elasticity are not too strong and have poor durability. The wetting speed is also related to the temperature. When the room temperature is high, the wetting speed becomes faster and when the room temperature becomes low, the wetting speed becomes slower. Before the pressure-sensitive adhesive is attached, use a hairdryer to slightly heat the surface and then quickly attach it to get better strength.
—Author: Mr. Dong-Qi, Pan
Activity § Occupational disaster experience event
In order to promote the concept of occupational disaster prevention and promote the concept of attaching importance to workplace safety activities, Everwide Chemical cooperated with the Labor and Occupational Safety and Health Institute of the Ministry of Labor to organize a labor occupational disaster prevention exhibition on August 13. In the afternoon of the previous day, the roving car of the Labor Safety and Health Action Museum was parked inside the company, which aroused everyone's curiosity. This small museum is well-equipped. The exhibition topics are divided into hearing protection, confined space, fire prevention knowledge, high-temperature work, high-altitude work, mechanical work hazards and chemical hazards. Colleagues listen to the introductions of the lecturers one by one and learn about various occupational disasters. During the meeting, colleagues also raised questions about "static protection" and asked how to improve. The lecturers also pointed out some industrial safety incidents that have occurred in the industrial zone, so that everyone can better understand how to avoid occupational disasters. We would like to remind everyone that while working hard, don't forget to protect yourself and avoid occupational injuries!
Knowledge § Why is the surface often sandblasted before metal adhesion?
There is often anti-rust oil on the metal surface, cutting oil will be encountered during processing, and there is often an oxide layer on the surface, which will cause the adhesion effect to be unstable. The most common method is to use a sandblasting machine to blast sand to the surface of the metal at high speed to remove the surface layer and contaminants. Through the choice of the size of the gravel, the metal surface can be roughened at the same time, so that the surface area for adhesion can be increased, and the effect of mechanical anchoring can also be created. In addition to improving the adhesion strength and stabilizing the quality of adhesion, sandblasting is also helpful for the retention of strength after environmental testing. However, there are also points to pay attention to in sandblasting. The metal surface after sandblasting is easy to oxidize again. Adhesion should be carried out as soon as possible, otherwise, surface treatment agents should be applied to protect it and another point to pay attention to is that high-shaking adhesives have poor penetrability, and sometimes they cannot completely wet the roughened metal surface, which will reduce the effect of sandblasting. At this time, choose an appropriate surface treatment agent and apply it on the surface after sandblasting to assist the adhesive to wet the metal surface, which will greatly improve the adhesive strength.
Living § Preparation for visiting Nissan
This year's employee travel plan is to visit Nissan Motor's factory in Yokohama and the company asked me to prepare some reference materials for everyone. In 1911, Hashimoto Shinjiro founded the "Quick Forward Auto Factory", and in 1915, Japan's first purely domestic car (including the engine) was released. After several organizational changes, it was named "Nissan Motor Co., Ltd." in 1934 and became an important military vehicle supplier during World War II. In the process of rebuilding Japan at the end of World War II, the Americans once mocked that Japan would only imitate assembling cars. In 1952, Nissan cooperated with the British Austin Motors to develop the DATSUN 210 to win the Australian Rally. Benefited from the oil crisis and reliable quality, Japan's auto production was the largest in the world from 1980 to 1990, and Nissan was the second-largest automaker in Japan after Toyota. A bubble economy occurred after the 1990s, and Nissan suffered losses for 7 consecutive years, with a debt of 1.4 trillion yen. In 1999, the French Renault Automobile became a shareholder, and Carlos Ghosn proposed a revival plan, layoffs 21,000 employees, closed 5 factories, and finally turned a profit. Currently, RENAULT NISSAN is the world's 4th largest automobile group. While sorting out these materials, I kept wondering why Japan was able to make cars in 1915, but others could not? Why can Japanese cars be rebuilt after the war, surpassing the United States and becoming the world's number one? Why can't the world's largest Japanese car escape the fate of recession and loss? What did Renault teach Nissan to bring it back to life? These questions are full of inspiration for us, but there are no simple answers. What can we do about it? Let us all go to the actual place and think together next month!
—Author：Mr Jin-Lie, Chen
