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Cationic Photoinitiator for Light-Initiated Reactions

Cationic Photoinitiator for Light-Initiated Reactions

Cationic photoinitiators are a class of catalysts that, upon exposure to light, absorb light energy and transition into an excited state. They then undergo a series of decomposition reactions, ultimately generating superstrong proton acids, which in turn initiate chemical reactions. These superstrong proton acids exhibit extremely high reactivity; as active centers, they can initiate and accelerate cationic polymerization reactions. The superstrong proton acids can react with nucleophilic sites in monomer molecules such as epoxides, vinyl ethers, lactones, acetals, and cyclic ethers, forming cationic intermediates. These cationic intermediates further trigger chain-growth polymerization reactions, causing monomer molecules to continuously add to the growing polymer chain, ultimately yielding high-molecular-weight polymers.

05

2024

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08

Free-radical photoinitiators among photoinitiators

Free-radical photoinitiators among photoinitiators

A free-radical initiator is a catalyst that can decompose or break down under relatively mild conditions, thereby promoting the generation of free radicals. Free radicals are highly reactive molecular or atomic fragments that contain one or more unpaired electrons, giving them exceptional reactivity. In polymer synthesis, free-radical initiators play an especially critical role: they can initiate chain-growth polymerization reactions, enabling monomer molecules to continuously add onto each other and form high-molecular-weight polymers. The choice of free-radical initiator is crucial for controlling the rate, temperature, molecular weight distribution, and ultimate properties of the polymer. Different initiators have varying decomposition temperatures and rates, which directly influence the reaction rate and temperature control during polymerization. Moreover, the type and amount of initiator used also affect the polymer’s molecular weight distribution and degree of branching, among other properties.

01

2024

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08

The core of light-curing technology: photoinitiators.

The core of light-curing technology: photoinitiators.

Photoinitiators, also known as photosensitizers or light-curing agents, are the core components of light-curing technology. They possess the ability to absorb specific wavelengths of light within the ultraviolet or visible light spectrum. After absorbing light energy, these photoinitiators undergo a series of chemical transformations—such as cleavage or electron transfer—resulting in the generation of reactive species like free radicals or cations. These reactive species are highly active and can rapidly react with surrounding monomers, thereby initiating the polymerization process. As the polymerization reaction progresses, monomer molecules link together via covalent bonds to form polymeric chains, ultimately leading to crosslinking and curing of the entire system. This crosslinked, cured structure imparts outstanding physical and chemical properties to light-cured materials, including high strength, wear resistance, and resistance to chemical corrosion.

30

2024

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07

UV Skin-Feel Resin: B-241

UV Skin-Feel Resin: B-241

B-241 is a bifunctional polyurethane acrylate that can serve as the main resin in excimer-finish coatings. It cures via 395nm LED—254nm or 172nm excimer-mercury lamps. This resin boasts several notable properties, including rapid matting speed, excellent skin-feel performance, and superior resistance to yellowing under QUV exposure.

30

2024

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07

Method for Determining the Direction of Paper Grain

Method for Determining the Direction of Paper Grain

As the primary material used in printing, paper’s performance plays a crucial role in determining print quality and the success of post-printing processes. Among the many properties of paper, the direction of grain—also known as the fiber direction—is a particularly important physical characteristic. The grain direction refers to the predominant alignment of fibers within the paper. This direction significantly influences the paper’s physical properties, including but not limited to tear resistance, curling, and dimensional stability. Here, we will introduce several methods for detecting the grain direction of paper. Each of these methods has its own unique characteristics and is suited to different applications and precision requirements.

29

2024

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07

How to reduce the impact of paper fiber flow

How to reduce the impact of paper fiber flow

As the primary substrate material in printing production, the quality of paper directly determines both the print quality and the feasibility of post-printing processes. Among the many properties of paper, the direction of grain is a critically important factor. The grain direction not only affects the physical characteristics of the paper but also directly influences the accuracy of image and text registration during the printing process, the stability of paper feed, and the final quality of post-printing products. Therefore, a thorough understanding and mastery of the characteristics of paper grain direction and its impact on printing and processing are of great significance for enhancing print quality and improving production efficiency.

27

2024

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07

The impact of silk flow on paper properties

The impact of silk flow on paper properties

The grain direction of paper refers to the predominant orientation of paper fibers on the sheet. During the manufacturing process of machine-made paper, as the pulp is spread onto the moving wire mesh to form the paper web, the fibers tend to align in a general direction dictated by the flow of the pulp. This directional alignment is known as the grain direction. The grain direction is an important characteristic in the paper-making process, significantly influencing the paper’s performance, print quality, and post-printing processing.

26

2024

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07

The concept of wire marks on printed paper

The concept of wire marks on printed paper

The grain of paper, simply put, refers to the predominant orientation of fibers within the paper. During mechanical papermaking, pulp is evenly sprayed onto a continuously moving wire mesh. As moisture gradually evaporates from the pulp and fibers interweave with one another, a sheet of paper with sufficient strength and toughness is ultimately formed. In this process, the direction of pulp flow determines the general alignment of the fibers; this directional alignment is known as the grain direction of the paper.

25

2024

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07

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