In the synthesis of polyurethane acrylate, hydroxyl acrylate reacts with NCO groups to introduce acryloyloxy groups, which are generally present at the chain ends of polyurethane prepolymers.
Suitable hydroxy acrylates can be divided into the following categories according to the number of functional groups:
1. Monofunctionality: hydroxyethyl acrylate (HEA), hydroxyethyl methacrylate (HEMA), hydroxypropyl acrylate (HPA), hydroxypropyl methacrylate (HPMA), hydroxybutyl acrylate (HBA);
Generally speaking, monofunctional UV monomers have greater odor, volatility, and irritation, such as HEA and HPA. Hydroxyl methacrylate has an additional methyl group on the carbon of the double bond, so its odor and skin irritation are reduced, but its reactivity is also reduced. The polyurethane acrylates made with hydroxy methacrylate end-capping is slightly higher in hardness than hydroxy acrylates, but the curing rate is worse. Compared with HEA and HPA, HBA is much less irritating. HBA has two structures: 2-HBA and 4-HBA. In comparison, the performance of 4-HBA is better.
Since the photocuring rate of acrylate is much faster than that of methacrylate, most of them use hydroxy acrylate. The reactivity of isocyanate and alcohol hydroxyl group is: primary alcohol > secondary alcohol > tertiary alcohol, so most of them use HEA (primary alcohol) to react with isocyanate, while HPA and HBA are rarely used.
2. Difunctionality: trimethylolpropane diacrylate (TMPDA);
TMPDA is a difunctional TMPTA, in which one of the acrylic double bonds of TMPTA is converted into a hydroxyl group. This monomer is almost impossible to find a manufacturer on the market. Generally, manufacturers with monomer production qualifications will produce it for their own use. And because it is difficult to accurately control the reaction of the hydroxyl group, the final TMPDA is not pure, but a mixture containing TMPTA. TMPDA can be used to synthesize tetrafunctional, hexafunctional, or even higher-functional polyurethane acrylates.
3. Trifunctionality: pentaerythritol triacrylate (PET3A);
PET3A is generally used to produce high-functionality polyurethane acrylates. The resulting high-functionality resins have the characteristics of fast curing rate, high hardness and high wear resistance.
4. Dipentaerythritol pentaacrylate (DPHA);
In the esterification process of DPHA, a part of hydroxyl groups can be reserved by controlling the degree of esterification. Due to the different processes of different manufacturers, the final DPHA also exists in the form of a mixture. DPHA can be used to synthesize polyurethane acrylates with ten or higher functionalities. The products have higher cross-linking density and better wear resistance. However, due to the large double bond content, the cured film is prone to cracking during light curing.
The above are the commonly used hydroxyl acrylates in the synthesis process of polyurethane acrylates. As a manufacturer of photocurable resins, Bossin specializes in the research and development, production, sales and technical services of new photocurable materials. New and old customers are welcome to call for consultation.
Guangdong Bossin Novel Materials Technology Co., Ltd. is a hi-tech enterprise specializing in the R&D, production, sales and technical services of UV/EB curable materials, with honors of National Hi-Tech Enterprise, Contract-honoring & Trustworthy Enterprise in Guangdong Province, etc. Standing on the forefront of UV/EB curable material industry, Bossin has successfully applied for dozens of invention patents. “Customer priority and quality optimization” are our consistent service concept.
B-251 is a difunctional Polyurethane Acrylate (PUA) with medium molecular weight. It offers excellent flexibility of the cured film, fast curing speed, and good wetting properties on black ink.
In summary, the anti-peeping principle of anti-spy films relies on the internal micro-louver structure to control light propagation. This ensures that screen content can only be clearly seen within a certain front-facing angle, while it becomes blurred or invisible from the side due to light obstruction, thus protecting the screen content from being peeped at by others.
A privacy screen protector is a specially designed protective film for mobile phone screens. Its primary function is to prevent others from peeking at your screen by limiting the viewing angles. When applied to the phone screen, only the person viewing it directly from the front can see the content clearly. From side angles or wider perspectives, the screen appears darkened or blurred, thereby achieving the effect of privacy protection.
In the photo-curing formulation system, apart from UV resins and photoinitiators, UV monomers also serve as a vital component. UV monomers not only adjust the viscosity of the system but also impart or enhance different properties of the cured film, such as enhancing adhesion, improving flexibility, and increasing wear resistance. Therefore, the rational use of various monomers is also an important link in formulation design.
As the name suggests, bifunctional UV monomers are molecules containing two reactive functional groups that participate in photopolymerization reactions. These functional groups are typically acrylates or methacrylates, with acrylates dominating the current market due to their superior reactivity and cost-effectiveness. Compared to their monofunctional counterparts, bifunctional UV monomers offer several advantages: Faster curing speed,Higher crosslinking density in the cured film,Good dilution properties,Reduced volatility and lower odor.
Monofunctional UV monomers refer to those containing only one group capable of participating in the curing reaction per molecule. The types of functional groups include acrylates, methacrylates, vinyls, vinyl ethers, epoxies, etc.
LCD photocuring 3D printing technology, also known as Mask Stereolithography (MSLA), is an emerging additive manufacturing technology. Similar to SLA and DLP technologies, LCD photocuring also solidifies liquid resin via light exposure, but its uniqueness lies in the use of an LCD screen to control the light source. This technology utilizes the imaging principle of liquid crystal displays, where computer programs provide image signals to generate selective transparent regions on the LCD screen. Under UV illumination, the light passing through these transparent areas forms UV image regions, solidifying the liquid resin exposed to them, while areas blocked by the LCD remain uncured. This process is performed layer by layer based on the predefined 3D model, with cured resin layers accumulating to build the final three-dimensional object.
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