快速回答： buyers formulating 2K polyurethane topcoats usually get a cleaner shortlist when they separate three different first-screen jobs instead of treating every silicone additive as the same surface tool. CHLUMIFE® 3370 should move first when the real target is a reactive topcoat route 为了 leveling, gloss, and smoothness inside a two-component polyurethane crosslinking system. CHLUMIFE® 3166 deserves earlier review when the buyer needs a broader balance of dry feel, anti-blocking, surface smoothness, gloss, and substrate wetting, especially when the project is still crossing several formulation windows. CHLUMIFE® 3307X belongs earlier when the coating already lays down acceptably but the cured film still needs stronger scratch or abrasion resistance 和 recoatability still matters.
That is the commercially useful split. This page is not another broad leveling or scratch-additive overview. It is a 2K PU topcoat application page for buyers who already know the project lives inside the CHLUMICRYL® coating-additives branch and need a faster first shortlist.
Why 2K polyurethane topcoats deserve their own additive page
Longchang already has broader live pages for 找平添加剂, scratch-resistant additives, 缺陷驱动的添加剂选择, and the more general PU leather and polyurethane additive page. Those pages help buyers decide which function lane they are in.
A 2K polyurethane topcoat project creates a narrower question after that: should the first additive screen focus on reactive topcoat appearance control, a broader feel and anti-blocking balance, or stronger cured-film scratch resistance? That decision changes sampling order, addition logic, and risk checks. It deserves its own page because the buyer job is more specific than a broad polyurethane overview and less repetitive than another generic function page.
What makes these three routes different in 2K PU topcoats
The overlap is real, but the first-screen role is different.
- CHLUMIFE® 3370 is positioned by Longchang as a reactive hydroxyl polyester-modified polysiloxane that reacts with isocyanate and is suitable for two-component polyurethane crosslinking systems. The company page also frames it around surface leveling, higher gloss， 和 better smoothness.
- CHLUMIFE® 3166 is positioned around surface-tension control 和 excellent dry feel, with supported gains around substrate wettability, 表面光滑度, scratch resistance, anti-blocking, leveling， 和 光亮度, but with explicit watchpoints around pinholes, whitening， 和 foam stabilization.
- CHLUMIFE® 3307X is the more specific post-film scratch and abrasion route. Longchang explicitly ties it to improving abrasion resistance and scratch resistance after film formation, while still supporting 表面光滑度, leveling，以及一个 recoatability-first position.
That is enough separation to build a real buyer-selection page instead of sending everyone back to a broader additive hub.
Quick comparison table: which route deserves the first screen?
| Buyer priority in 2K PU topcoats | Best first route | Why it belongs first | 主要观察点 |
|---|---|---|---|
| Reactive topcoat appearance control with leveling, gloss, and smoothness inside a 2K polyurethane crosslinking route | CHLUMIFE® 3370 | Longchang positions it for two-component polyurethane crosslinking systems and ties it directly to leveling, gloss, and smoothness | Best treated as a 2K PU reactive topcoat route, not as a general drop-in additive for every water-based project |
| Broader balance of dry feel, anti-blocking, smoothness, gloss, and wetting, especially when the project may still cross more than one system window | CHLUMIFE® 3166 | Longchang supports it across UV, solvent, and water-based systems with a wider surface-performance balance | Pinhole, whitening, and foam-stabilization risk should be screened early |
| Cured film still marks, scratches, or abrades too easily after formation and recoating still matters | CHLUMIFE® 3307X | Longchang explicitly positions it around scratch and abrasion resistance after film formation, with recoatability priority | Not for water-based systems, and solvent pre-dilution is recommended before use |
When CHLUMIFE® 3370 is the better first move
3370 should move to the front when the buyer is working on a true 2K PU topcoat appearance problem, not only a broad surface-aid question. Longchang’s current company wording is unusually helpful here. The product is described as a reactive hydroxyl polyester-modified polysiloxane that reacts with isocyanate so organosilicon can combine with the resin system in the form of block or graft structures. Longchang also states that it is suitable for two-component polyurethane crosslinking systems and can also work with several other crosslinkable base-material systems.
That matters because some buyers are not just trying to make the coating feel slightly different. They are trying to improve how the topcoat lays down, looks， 和 holds a refined surface in a reactive PU route.
- Supported strengths: leveling, gloss increase, and surface smoothness
- Recommended dosage: 0.05% to 3% of total formulation
- Addition logic: can be added at any stage of production or later
- System fit: supported in UV and solvent systems, not a water-based route on the current company page
In short, 3370 is the cleaner first benchmark when the lab wants a reactive 2K PU topcoat route rather than a broader multi-system compromise.
When CHLUMIFE® 3166 is the better first move
3166 belongs earlier when the topcoat project is still balancing more than one surface KPI at the same time. Longchang positions it as a polyether-modified polyorganosiloxane for controlling surface tension, and the company page highlights excellent dry feel as its most notable feature. The same supported product description also includes substrate wettability, 表面光滑度, scratch resistance, anti-blocking, leveling, gloss improvement， 和 Bénard-vortex prevention.
That makes 3166 commercially useful when the project is not only about one narrow defect. It is often the better first screen when the buyer wants one route that can help the topcoat feel better, stay smoother, stack more safely, and still improve laydown quality.
- Supported system fit: 紫外、溶剂和水基
- Recommended dosage: 0.05% to 1.0% of total formulation
- Addition logic: can be added at any stage; it may be diluted first for easier addition
- Main risk notes: may cause pinholes or whitening, may stabilize foam, and may need defoamer planning during formulation testing
So 3166 is the stronger first screen when the buyer needs a broader 2K topcoat surface-balance route rather than a narrowly reactive or purely post-cure-durability route.
When CHLUMIFE® 3307X is the better first move
3307X becomes more relevant when the topcoat already looks acceptable at application, but the final cured film still scratches, rubs, or abrades too easily. Longchang’s positioning is explicit: this product is designed to improve abrasion resistance and scratch resistance of resin films after formation. The company page also supports 表面光滑度, leveling, and states that recoatability is prioritized.
That is an important commercial split. Many topcoat teams do not fail at first on leveling. They fail later when the panel looks fine but cannot handle handling, stacking, or service wear well enough.
- Recommended dosage: 总配方量为 0.1% 至 1.0%
- Preparation note: pre-dilute to 12.5% with solvent before use
- System fit: UV and solvent systems, not water-based
- 主要观察点： if recoatability is not the main concern and the buyer is only chasing smoothness, another comparison route may be more appropriate
That makes 3307X the better first screen when the buyer is judging the cured film, not only the liquid formula.
How buyers should choose before asking for samples
1. Start with the real stage of failure
If the topcoat problem is primarily about initial laydown, gloss, and smoothness inside a 2K PU crosslinking route, start with 3370. If the surface still needs a broader balance of feel, blocking control, and wetting, move 3166 earlier. If the pain point shows up after cure, 3307X should move up.
2. Keep system fit visible
3370 and 3307X are not presented on the company pages as water-based routes, while 3166 is supported across UV, solvent, and water-based systems. That alone can save time when the project portfolio is broader than one line.
3. Do not confuse broad overlap with identical selection logic
All three products touch appearance or surface performance. That does not make them interchangeable. The supported first-screen job is different for each one.
4. Use the real watchpoint, not only the headline benefit
3370 is best treated as a reactive 2K topcoat route. 3166 needs early pinhole, whitening, and foam-risk screening. 3307X needs solvent pre-dilution and belongs in non-water-based systems. These practical details often decide the better first sample.
5. Keep the first round short
For most buyers, one reactive appearance-control route， 一 broader surface-balance route，以及一个 post-cure scratch route teaches more than a crowded first panel with too many overlapping additives.
本页推荐的龙昌路线
- 集群概览： CHLUMICRYL® 涂层和油墨添加剂
- 相关功能页面： 如何选择涂料和油墨的流平助剂
- Related durability page: How to Choose Scratch-Resistant Additives for Coatings and Inks
- Related polyurethane page: How to Choose Surface Additives for PU Leather and Polyurethane Coatings
- 3370 product page: CHLUMIFE® 3370
- 3166 product page: CHLUMIFE® 3166
- 3307X product page: CHLUMIFE® 3307X
常见问题
Which additive should I screen first in a 2K PU topcoat that needs better leveling and gloss?
Start with CHLUMIFE® 3370 when the project is clearly a reactive 2K polyurethane topcoat route and the main target is better leveling, gloss, and surface smoothness.
When is 3166 a better first route than 3370?
3166 is usually the better first route when the project needs a broader balance of dry feel, anti-blocking, smoothness, gloss, and wetting, or when the work may still cross UV, solvent, and water-based systems.
When should 3307X move ahead of the other two?
3307X should move ahead when the final cured film still scratches or abrades too easily and recoating still matters. That is a more specific post-cure-durability problem than the broader appearance or surface-balance jobs of 3370 and 3166.
Can I treat these three additives as direct substitutes in every polyurethane topcoat?
No. Their supported system fit, stage-of-failure logic, and risk profile are different enough that buyers should not treat them as interchangeable without a tighter shortlist.
Need a faster shortlist for 2K PU topcoats?
If your team is stuck between better reactive appearance control, broader topcoat feel and anti-blocking balance， 和 stronger post-cure scratch resistance, define the real first-screen job before requesting samples. That usually shows much faster whether CHLUMIFE® 3370, 3166, or 3307X deserves the first round.