With the enhancement of people’s environmental awareness and the improvement of environmental regulations, waterborne polyurethane has developed rapidly due to its advantages of being non-toxic, non-flammable, non-polluting, energy-saving, safe and reliable, and the surface of the coating surface not easily being scratched. Successfully applied to leather finishing, paper coating, steel rust prevention, fiber processing, plastics and wood coating, glass coating, etc. In this paper, a series of waterborne polyurethane emulsions were synthesized by the prepolymer method and their properties were evaluated. Research and discussion. 1. Test section 1.1 Main raw materials: polyester polyol (Mn=2000, commercially available), isophorone diisocyanate (IPDI import), dimethylol propionic acid (DMPA import), triethylamine (TEA, analysis Pure, commercially available), Diamine (Analytical Pure, Commercially available), Acetone (Analytical Pure, Commercially Available), Catalyst (T9 Analytical Pure, Commercially available), N-Methylpyrrolidone (NMP, Analytical Pure, Commercially Available) . 1.2 Raw Material Pretreatment: DMPA is dried before use. 1.3 Test procedure: In a four-necked flask equipped with an electric stirrer, reflux condenser, thermometer, and nitrogen inlet and outlet, polyester polyol, IPDI, DMPA, and T9 are reacted under a dry nitrogen atmosphere at a certain temperature. When the NCO content reached the theoretical value, a prepolymer was obtained, and then TEA was neutralized to form a salt. After adding water, emulsification, diamine was added again to extend the chain to obtain an anionic aqueous polyurethane dispersion. Finally, acetone was distilled off under reduced pressure. 2. Performance Test 2.1 Determination of Water Absorption: The emulsion was dried to form a film, weighed after constant weight, immersed in distilled water at room temperature for 24 hours and then removed. The water mark was blotted dry with a filter paper and weighed. 2.2 Determination of Viscosity: The emulsion was formulated into a solid content and measured at room temperature using a NXS-11A rotational viscometer. 2.3 Determination of average particle diameter: The average diameter of milk particles was measured by light scattering method. The main instruments used were: 723 spectrophotometer and Abbe refractometer. 2.4 Determination of mechanical properties: The emulsion was filmed on a glass plate, dried in a 60-degree oven to constant weight, and then the film-forming material was made into a dumbbell-shaped standard sample, and measured on an XLL-50 tensile testing machine. Stretching speed is 250mm/min. 2.5 Determination of stability: Accelerated settling test by centrifugation to simulate the storage stability of the emulsion. After centrifugation at a speed of 3000 r/min in a centrifuge for 15 min, a storage stability of 6 months can be considered without precipitation.
Outdoor sunshade umbrella is a common outdoor product used to block sunlight and rain, providing people with a comfortable outdoor resting environment. According to different functions and materials, outdoor sunshades can be divided into various types, which will be classified and introduced below.
Umbrella: Mainly used to block sunlight, prevent ultraviolet radiation, and protect people's skin from harm. Umbrellas are generally made of materials with anti ultraviolet coatings, which can effectively block the penetration of ultraviolet rays.
1. Classified by material
1. Polyester umbrella cloth: Polyester is a synthetic fiber material with good waterproof performance and durability. Polyester umbrella fabric is often used for umbrella protection and is suitable for various outdoor environments.
2. Nylon umbrella cloth: Nylon is a synthetic fiber material that is lightweight, wear-resistant, and waterproof. Nylon umbrella cloth is often used for rain and wind umbrellas, and is suitable for outdoor sports and travel.
3. UV resistant coating: Some outdoor sunshades use special UV resistant coatings, which can effectively block the penetration of ultraviolet rays and protect people's skin from harm.
2. Sort by size
1. Small umbrella: The diameter of the umbrella surface is generally below 60 centimeters, suitable for single person use or small spaces.
2. Medium Umbrella: The diameter of the umbrella surface is between 60 centimeters and 80 centimeters, suitable for 2-3 people to use.
3. Large Umbrella: Umbrella with a diameter of over 80 centimeters, suitable for use by multiple people or in larger spaces.