What is a crosslinking agent?

Quick answer: For wetting, leveling, defoaming, and dispersing topics, formulators usually compare performance and side effects together because over-correcting one surface issue can easily create another.

1. Co-crosslinking agent refers to a type of auxiliary agent that improves the crosslinking efficiency of peroxides, most of which are compounds with polyunsaturated functional groups. The contribution of the auxiliary crosslinking agent to the crosslinking efficiency is generally understood as providing a higher concentration of reactive sites, inhibiting side reactions such as polymer radical disproportionation or chain scission, and helping to form more crosslinking bonds.

2. The specific use effect of the crosslinking agent is not only related to its chemical structure and added amount, but also related to various conditions such as the type of polymer and crosslinking peroxide.

1. The influence of crosslinking agent on physical properties

The use of cross-linking aids helps to increase the cross-linking density. In terms of physical properties, it is manifested as an increase in modulus, hardness, and a decrease in elongation at break and compression set. In some cases, it can also improve tensile strength, tear strength, heat resistance, abrasion resistance, or dynamic performance.
The effect of using auxiliary crosslinking agent on physical properties is mainly manifested in the following aspects: (Not all properties can be obtained at the same time, and some properties can be achieved by using specific auxiliary agents)

Reduce permanent compression set;

Increase flexibility

Increase modulus

Increase the hardness;

Reduce rubber viscosity and improve processing performance;

Improve oil resistance;

Improve heat aging resistance;

Improve the adhesion of rubber and metal products;

Increase the vulcanization speed;

Reduce the amount of peroxide;

Increase tensile strength;

Improve tearing and hot tearing performance;

Improve dynamic flexing performance;

2. The influence of the structure of the crosslinking agent on the performance of the crosslinking agent

The structure of the crosslinking agent is closely related to the performance of the crosslinking agent. The type of functional group of the crosslinking aid, the number of functional groups, the structure of the bridge bond, the polarity of the molecule, the molecular weight, etc. will all affect the performance of the crosslinking aid.

The type and number of functional groups are the primary parameters that affect the vulcanization performance of the crosslinking agent, which directly affects the activity of the crosslinking agent, the solubility in the polymer and the physical properties of the product. Common crosslinking agents are mostly bifunctional and trifunctional additives;

The structure of the bridge bond, which includes the polarity of the bridge bond, the length of the bridge bond, and the molecular structure. Although the structure of the bridge bond usually has no direct effect on the activity of the crosslinking agent, it may affect the efficiency of the crosslinking agent, the solubility in the polymer, and the strength of the crosslinking bond, which are also very important parameters. ；

The molecular weight can have an impact on the efficiency of the crosslinking agent, and it can also be used as an important evaluation parameter for the volatility of the crosslinking agent. If the molecular weight is small, the volatility may be high;
The polarity of the auxiliary crosslinking agent can directly affect its solubility in the polymer and other factors, thereby affecting the vulcanization efficiency and performance;

3. Classification of crosslinking aids

According to their contribution to vulcanization, crosslinking aids can be divided into two categories. One is to increase the degree of vulcanization while also increasing the vulcanization speed, which is also called the first type of crosslinking aid; the other is to only increase the degree of vulcanization or crosslinking density without increasing the vulcanization speed, also known as The second type of crosslinking agent.

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How buyers usually evaluate coating and ink additives

Additive selection is usually most effective when the team defines the defect first and then screens compatibility, dosage range, and process stage. That is often much more reliable than choosing only by chemistry family or by a single dramatic lab result.

• Start from the defect, not the additive name: wetting loss, crater, microfoam, and instability often need different solutions even inside the same formula.
• Check compatibility at the intended dosage: the strongest additive can still be the wrong commercial choice if it narrows the process window too much.
• Review the stage of use: some products are most useful during grind, while others matter more during let-down, filling, or final application.
• Balance cure or film quality with defect control: the right additive fixes the problem without sacrificing adhesion, gloss, or appearance.

Recommended product references

• CHLUMIAF 094: A balanced defoamer reference for waterborne coatings and many general foam-control screens.
• CHLUMIAF 3062: Useful when printing-ink and UV-ink compatibility matter in the defoaming screen.
• CHLUMIAF 3037: A stronger process-defoaming option when persistent foam survives harsher conditions.
• CHLUMIWE 3280: A strong wetting-agent reference for inks, coatings, and difficult substrate wetting.

FAQ for buyers and formulators

Why does an additive that looks powerful in a beaker sometimes fail in production?
Because shear, temperature, substrate, and the full formula can all change the way the additive performs under real process conditions.

Should the most aggressive additive always be preferred?
Not usually. The best additive is the one that solves the real defect while preserving the broadest safe operating window.