Views: 0 Author: Site Editor Publish Time: 2025-11-18 Origin: Site
Carbodiimide Anti-hydrolysis Agents are the backbone of durable polymer performance—protecting PLA, PBAT, TPU, and other materials from hydrolysis-induced degradation by scavenging harmful carboxyl groups. Yet, not all carbodiimides are created equal. The manufacturing process determines their purity, reactivity, odor, and ultimately, their value in industrial applications. For decades, the industry relied on the traditional thiourea process to produce carbodiimides, but this method is plagued by sulfur impurities, inconsistent activity, and unpleasant odors. Our company has revolutionized the space with the advanced isocyanate condensation process, creating Carbodiimide Anti-hydrolysis Agents that outperform thiourea-based alternatives across every critical metric. This article breaks down the two processes, highlights their key differences, and explains how our process-driven advantages translate to better polymer protection for your applications.
To understand why our Carbodiimide Anti-hydrolysis Agents are superior, you first need to grasp the core mechanics of the two manufacturing processes. Each pathway uses distinct raw materials and reactions, leading to fundamentally different end products.
The thiourea process is a decades-old method that relies on sulfur-containing intermediates to produce carbodiimides. Its workflow is multi-step, resource-intensive, and inherently limited by its raw materials:
Raw Material Preparation: Start with lime nitrogen (calcium cyanamide, CaCN₂) and hydrogen sulfide (H₂S)—a toxic, pungent gas. These react to form thiourea (NH₂CSNH₂), the key intermediate.
Dehydrosulfurization: Thiourea is treated with oxidizing agents (e.g., lead oxide, copper sulfate) to remove sulfur, forming crude carbodiimide. This step is imprecise: over-oxidation can damage carbodiimide structures, while under-oxidation leaves residual sulfur.
Crude Purification: The crude product undergoes simple filtration or distillation to remove solid impurities (e.g., lead sulfide byproducts). However, this cannot eliminate trace sulfur compounds (thiols, unreacted thiourea) or ash from lime nitrogen.
The thiourea process’s reliance on sulfur-based raw materials and multi-step conversion creates unavoidable flaws. These flaws don’t just affect the manufacturing process—they directly limit the performance of the resulting Carbodiimide Anti-hydrolysis Agent.
Our isocyanate condensation process is a modern, one-step method that prioritizes purity and control. It uses high-quality, sulfur-free raw materials and proprietary catalysts to produce carbodiimides with unmatched consistency:
Raw Material Selection: We start with sterically hindered isocyanates (e.g., 2,6-diisopropylphenyl isocyanate)—high-purity compounds with no sulfur content. These isocyanates are chosen for their stability and reactivity, critical for forming effective Carbodiimide Anti-hydrolysis Agents.
Catalytic Condensation: Under controlled temperature (80–120℃) and pressure, the isocyanates react with our proprietary transition metal catalyst (e.g., (C₅Me₅Fe(CO)₂)₂). This catalyst drives a clean decarbonylation reaction, where two isocyanate groups (–NCO) combine to form a carbodiimide group (–N=C=N–), releasing only carbon dioxide (CO₂) as a byproduct.
Precision Purification: The crude carbodiimide undergoes multi-stage vacuum distillation and molecular sieving to remove any residual isocyanates (to <10 ppm) and trace impurities. This step ensures the final product is nearly homogeneous.
The isocyanate condensation process eliminates the sulfur-related flaws of the thiourea method. Its one-step reaction, sulfur-free raw materials, and advanced purification create a Carbodiimide Anti-hydrolysis Agent that is purer, more reactive, and more versatile.
The true difference between the two processes becomes clear when comparing their end products—our isocyanate-derived Carbodiimide Anti-hydrolysis Agents outperform thiourea-based alternatives in every metric that matters for industrial use. Below is a data-driven breakdown:
| Performance Metric | Traditional Thiourea Process (Carbodiimides) | Our Isocyanate Condensation Process (Carbodiimides) | Impact on Polymer Applications |
|---|---|---|---|
| Purity (HPLC) | 92–95% (max); sulfur impurities: 61–2030 ppm; ash content: 0.3–0.5% | ≥99.5%; sulfur impurities: <10 ppm; ash content: <0.01% | Sulfur impurities in thiourea-based agents trigger secondary polymer degradation (e.g., TPU discoloration, PLA brittleness). Our low-impurity agents preserve polymer integrity. |
| Reactivity (Carboxyl Scavenging Rate) | 0.8–1.2 mmol/g·h (slower due to competing impurities) | 1.5–1.8 mmol/g·h (30% faster; no competing reactions) | Faster reactivity means our agent stops hydrolysis sooner. In PLA tests, our agent retained 88% tensile strength after 6 months—vs. 72% for thiourea-based alternatives. |
| Odor (VOC Content) | Strong sulfuric/pungent odor; VOCs: 3–5 g/L (from residual H₂S/thiols) | Odorless; VOCs: <1 g/L (only trace CO₂ from reaction) | Thiourea-based agents contaminate food packaging/automotive interiors with odor. Our agent meets global indoor air quality standards (e.g., EU 10/2011 for food contact). |
| Batch Consistency | Purity varies ±3–5% per batch (due to inconsistent thiourea quality) | Purity varies <0.5% per batch (automated catalyst dosing) | Inconsistent thiourea-based agents cause unpredictable polymer performance (e.g., PBAT mulch films with variable lifespans). Our consistency ensures reliable results. |
| Storage Stability | Loses 15–20% activity after 12 months (sulfur compounds accelerate degradation) | Retains 98% activity after 12 months (no reactive impurities) | Our agent has a longer shelf life, reducing waste and inventory costs. Thiourea-based agents require frequent reordering and retesting. |
The superiority of our isocyanate-derived Carbodiimide Anti-hydrolysis Agents isn’t just about lab metrics—it translates to real-world benefits for your applications, compliance needs, and bottom line.
The thiourea process’s sulfur impurities and odor make its carbodiimides unusable in high-sensitivity applications. Our isocyanate-derived agents, by contrast, unlock sectors where purity and safety are non-negotiable:
Food-Contact Polymers (PLA/PBAT): Our agents meet FDA 21 CFR §177.1520 standards (no sulfur, low VOCs), making them ideal for food packaging (e.g., salad bowls, beverage cups). Thiourea-based agents are rejected here due to odor and sulfur leaching risks.
Medical-Grade Polymers (PHA/TPU): Medical devices (e.g., dissolvable sutures, TPU catheter tubes) require biocompatible, low-impurity additives. Our <10 ppm sulfur agents pass ISO 10993 biocompatibility tests—thiourea-based alternatives fail due to toxic sulfur residues.
Automotive Interiors (TPU/CPU): Car manufacturers demand odorless materials to meet cabin air quality standards (e.g., VW PV 3900). Our odorless agents are specified by Tier 1 suppliers—thiourea-based agents cause "new car smell" complaints and rejections.
The thiourea process is environmentally costly and dangerous to operate. Our isocyanate condensation process aligns with 2024’s sustainability trends and workplace safety standards:
Waste Reduction: The thiourea process generates 0.8 tons of solid waste (e.g., lead sulfide, lime ash) per ton of carbodiimide. Our process produces near-zero solid waste—only CO₂, which is captured and recycled.
Toxicity Mitigation: The thiourea process requires handling H₂S (a toxic, flammable gas), increasing workplace hazards and regulatory scrutiny. Our process uses stable, low-toxicity isocyanates and catalysts, reducing safety risks and compliance burdens.
Energy Efficiency: Our one-step reaction operates at 80–120℃—vs. 150–200℃ for the thiourea process’s dehydrosulfurization step. This cuts energy use by 40%, lowering our carbon footprint and passing cost savings to you.
Choosing a thiourea-based Carbodiimide Anti-hydrolysis Agent may seem cheaper upfront—but hidden costs erase those savings. Our agent delivers better value over time:
Lower Addition Rates: Due to higher reactivity (1.5–1.8 mmol/g·h), our agent requires only 0.5–1.0 phr (parts per hundred resin) to protect polymers. Thiourea-based agents need 1.0–1.5 phr to achieve similar results—raising raw material costs.
Reduced Rework: Inconsistent thiourea-based agents cause 15–20% of polymer batches to fail (e.g., brittle PLA films, odorous TPU). Our <0.5% batch variation cuts rework rates to <2%, saving labor and material costs.
Waste Disposal Savings: Thiourea-based agents generate hazardous waste (sulfur-contaminated byproducts) that costs $50–$100 per ton to dispose of. Our low-waste process eliminates these fees.
We don’t just use the isocyanate condensation process—we’ve optimized it with proprietary technologies to push Carbodiimide Anti-hydrolysis Agent performance even further. These innovations are exclusive to our products and create an unbeatable competitive advantage:
Our custom transition metal catalyst (e.g., modified (C₅Me₅Fe(CO)₂)₂) lowers the reaction temperature by 40℃ compared to standard catalysts. This:
Reduces thermal degradation of carbodiimide molecules, preserving reactivity.
Cuts energy use by an additional 15%, vs. generic isocyanate processes.
Enables the production of high-molecular-weight polymeric carbodiimides (e.g., our Bio-SAH™ 342Liquid) that provide longer-lasting hydrolysis protection for TPU/CPU.
Most isocyanate condensation processes stop at single-stage distillation. We add two critical steps:
Molecular Sieving: Removes residual isocyanates to <10 ppm (vs. 50–100 ppm for generic processes), eliminating irritation risks for workers and polymer discoloration.
Crystallization for Solids: Our Bio-SAH™ 362Powder undergoes controlled crystallization, creating uniform white crystals that disperse easily in dry polymer blends (e.g., PLA pellets). Thiourea-based powders are uneven and clump during mixing.
Unlike the thiourea process (which produces only low-molecular-weight carbodiimides), our optimized process lets us tailor carbodiimide structures to your polymer’s needs:
Monomeric Carbodiimides (e.g., Bio-SAH™ 362Powder): For fast-acting protection in PLA/PBAT.
Polymeric Carbodiimides (e.g., Bio-SAH™ 342Liquid): For sustained protection in high-temperature applications (e.g., TPU EV battery seals).
Water-Soluble Variants (e.g., Bio-SAH™ 342Liquid): For aqueous polymer systems (e.g., PBAT emulsions for coatings).
This customization means you get a Carbodiimide Anti-hydrolysis Agent that’s engineered for your specific use case—not a one-size-fits-all product.
The choice between the traditional thiourea process and our advanced isocyanate condensation process isn’t just a manufacturing decision—it’s a choice about the quality, reliability, and value of your Carbodiimide Anti-hydrolysis Agent. Thiourea-based agents are: they’re impure, slow-reacting, and limited to low-sensitivity applications. Our isocyanate-derived agents, by contrast, are precision-engineered to deliver:
≥99.5% purity with <10 ppm sulfur impurities,
30% faster carboxyl scavenging,
Odorless, compliant performance for food/medical/automotive sectors,
Lower total cost of ownership.
In a market where polymer durability and sustainability are non-negotiable, our process-driven Carbodiimide Anti-hydrolysis Agents give you a competitive edge. They don’t just protect your polymers from hydrolysis—they protect your brand reputation, compliance status, and bottom line.
A: Thiourea uses sulfur feedstocks with impurities; isocyanate condensation is sulfur-free, one-step, and pure.
A: ≥99.5% HPLC purity, sulfur <10ppm vs. thiourea-based’s 61–2030ppm sulfur.
A: No sulfur byproducts from isocyanate process; thiourea-based has pungent sulfur odors.
A: No—sulfur impurities and odor fail compliance; ours meets FDA standards.
A: Yes, 0.5–1.0 phr vs. 1.0–1.5 phr for thiourea-based, due to higher activity.
