HiSiaddi is an innovative foreign trade service provider driven by both technology commercialization and export business. We have established a "1+2+3+4=1" service system and can supply DTDM sourced from multiple well-known original manufacturers. As a tech-enabled foreign trader with independent R&D capabilities, HiSiaddi has repeatedly resolved customized DTDM product demands for clients through technical cooperation with manufacturers and precise market insight. The following case illustrates how HiSiaddi delivered a tailored DTDM solution.
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The buyer is RubberSpain S.L. based in Barcelona, Spain, a long-established Tier 2 supporting enterprise on the Iberian Peninsula. Its core products include EPDM sealing components for new energy vehicle battery housings, oil-resistant NBR oil seals for construction machinery, and silicone rubber accessories for white goods. Its products supply SEAT and Renault’s Spanish manufacturing plants, complying with EU REACH, RoHS, LFGB food contact standards, IATF16949 automotive factory access requirements, and DIN rubber physical & chemical testing specifications.
The enterprise has long purchased refined DTDM grades originally manufactured by AkzoNobel of the Netherlands. However, European raw material production capacity has contracted in the past two years with continuous price hikes, and sea freight lead times have extended from 40 days to 92 days. Consequently, the client launched a localization substitution project for DTDM, with an annual rigid demand of 215 tons.
Conventional industrial-grade DTDM available in China will thermally decompose and release sulfur-containing small molecules during internal mixing at high temperatures, leading to blooming and whitening of finished products and pungent odors generated during vulcanization. The resulting excessive vehicle interior VOC fails whole-vehicle factory acceptance standards. Most domestic DTDM manufacturers adopt fixed synthesis and recrystallization processes for mass production of generic off-the-shelf goods. Custom process modifications would raise production costs, so most factories refuse to invest in R&D adjustments. The client entrusted HiSiaddi, a technology-focused fine chemical foreign trade firm, to fully undertake customized development, lab trials, pilot tests, and mass production rollout.
HiSiaddi has specialized in exporting rubber vulcanization accelerators for over a decade. We have secured two leading DTDM manufacturers equipped with continuous synthesis and negative-pressure recrystallization facilities upstream. Our in-house team includes rubber formulation engineers and accelerator synthesis specialists. Unlike generic resale traders, we deliver full-process customization covering raw material selection, catalytic synthesis adjustment, solvent recrystallization refining, pre-dispersion pelletization, and rubber compound compatibility testing, alongside full sets of export compliance documentation.
1. Free sulfur content ≤0.18% (generic domestic DTDM typically ranges from 0.5% to 0.9%) to eliminate blooming during high-temperature mixing and control vulcanization odors and finished product VOC levels;
2. Loss on heating ≤0.22%, initial melting point ≥122.5°C, compatible with one-stage internal mixing at 160°C to prevent premature thermal decomposition and failure during processing;
3. Inorganic insoluble impurities ≤0.07% to avoid particle voids inside sealing rubber and guarantee finished product compression set performance;
4. Two customized formulations: ① High-purity crystalline powder DTDM (for white silicone rubber and light-colored EPDM applications) with APHA color ≤42; ② EPDM carrier pre-dispersed DTDM-70 pellets (for black oil seals and automotive sealing parts), active component content 69.5%~70.5%, dust-free, no caking after six months of ambient storage.
Conventional domestic DTDM adopts aqueous-phase synthesis and crude water-washing recrystallization processes, making it difficult to simultaneously achieve low free sulfur, low impurities, and low color value. Most manufacturers declined targeted reformulation evaluations.
Combining the client’s three formulation systems (NBR/EPDM/silicone rubber), HiSiaddi engineers collaborated with manufacturers to optimize and improve three core process segments:
1. Synthesis Section: Adjust material feed ratios for morpholine disulfide synthesis, adopt a low-temperature composite catalytic system, and precisely control reaction conversion rates to reduce by-product elemental free sulfur at the source;
2. Refining Section: Abandon conventional industry water-washing impurity removal and adopt closed organic solvent secondary negative-pressure recrystallization to remove inorganic salt impurities and colored by-products, while optimizing crystallization rates to boost product whiteness;
3. Formulation Differentiation: High-purity powder adopts low-temperature negative-pressure hot air drying; pre-dispersed pellets use food-grade EPDM raw rubber as the carrier and undergo low-temperature twin-screw extrusion pelletization to avoid yellowing risks for light-colored rubber associated with ordinary SBR carriers.
The factory deployed a 50kg small-scale test line. After four rounds of adjustments to solvent ratios and crystallization temperatures, the final customized DTDM achieved the following test results: free sulfur 0.15%, melting point 123.2°C, loss on heating 0.19%, insoluble impurities 0.05%, APHA color 39 – all exceeding the client’s customized threshold limits. The active content of pre-dispersed pellets stabilized at 70.2% with qualified dispersion performance.
HiSiaddi uniformly packaged samples and airfreighted them to the client’s laboratory in Spain for internal mixing evaluation within the original vulcanization system. Vulcanization rate, scorch time, and mechanical properties matched AkzoNobel’s original imported products.
A complete standardized production SOP was finalized, and an independent pilot production line was commissioned to produce a 1.2-ton pilot batch shipped to Spain by sea. The client conducted 72-hour non-stop continuous production trials across three mass production lines. Light-colored silicone rubber showed no yellowing, black sealing components exhibited no blooming, and no pungent odors were generated during vulcanization. Third-party incoming material testing by Renault passed in one go.
1. The manufacturing factory allocated an exclusive customized production line with fixed raw material specifications and process parameters, separated from generic industrial-grade DTDM production lines to guarantee consistent batch indicators;
2. HiSiaddi compiled unified bilingual Chinese-English COAs, full SVHC test reports, bilingual CLP RoHS-SDS documents, and LFGB compliance statements to support client warehouse acceptance reviews and EU customs clearance inspections.
1. Order Split & Scheduling: The full-year 215 tons were shipped evenly monthly, including 95 tons of high-purity refined powder DTDM and 120 tons of EPDM pre-dispersed DTDM-70 pellets;
2. Procurement Cost Optimization: Comprehensive procurement cost of customized domestic DTDM dropped by 30.2% compared to original AkzoNobel Dutch imports, and sea freight lead times were reduced to 27 days;
3. Extended Incremental Cooperation: The client launched a new special sealing rubber project for energy storage equipment the following year. HiSiaddi collaborated with the factory to develop a hydrolysis-resistant modified DTDM grade, adding an annual procurement volume of 68 tons;
4. Long-Term After-Sales Quality Control: HiSiaddi conducts pre-shipment sampling inspections of key physical and chemical indicators for every batch, and provides dedicated processing instruction manuals for customized grades alongside shipments.
Domestic DTDM manufacturers focus on mass production of generic industrial goods centered on cost compression. High-investment advanced recrystallization technical upgrades deliver low per-unit product margins, and manufacturers lack downstream rubber formulation technical support, so most refuse to undertake niche high-end customization. European mid-to-high-end specialty rubber enterprises adopt highly refined formulations; generic off-the-shelf domestic DTDM fails to meet stringent low-precipitation and low-VOC specifications, while independent in-house sample testing incurs high material loss and time costs.
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