OBSH Blowing Agent Guide for Rubber, PVC, and EVA Foaming Applications

OBSH blowing agent is a chemical foaming agent commonly used to create fine, relatively uniform cellular structures in rubber, PVC, EVA, and other polymer compounds. Its full chemical name is 4,4'-oxybis(benzenesulfonyl hydrazide), and it releases gas when activated by heat during processing. I recommend selecting OBSH according to the polymer, processing temperature, target density, cell structure, odor requirements, and the supplier’s technical data rather than using one dosage for every formulation.

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For most B2B buyers, the correct approach is to define the product target first, confirm the material’s processing window, and then run a controlled laboratory trial. A typical starting dosage may be expressed in phr or percentage by weight, but the actual level must be established through formulation testing. At Shitong, I support buyers by discussing application conditions, product specifications, packaging, sampling, and batch-to-batch supply requirements before commercial purchasing.

Key Takeaways for OBSH Selection

• OBSH generates gas through thermal decomposition and is used to reduce compound density or create a cellular structure.
• It can be considered for rubber, PVC, and EVA, but the suitable grade and dosage depend on the complete formulation.
• A commonly reviewed processing range is approximately 150–160°C, although the effective activation behavior must be confirmed for the specific grade and compound.
• Buyers should evaluate decomposition behavior, gas yield, particle size, purity, moisture, dispersion, odor, packaging, and technical support.
• Laboratory trials should measure density, cell size, surface quality, compression behavior, and dimensional stability before scale-up.

What Is OBSH Blowing Agent?

OBSH is an organic chemical blowing agent used in polymer and elastomer processing. When exposed to sufficient heat, it decomposes and releases gas, helping expand a polymer compound when the material has enough melt strength or elasticity to retain the generated cells. The final result depends not only on OBSH, but also on compound viscosity, curing or fusion behavior, mold design, pressure, heating rate, and cooling conditions.

OBSH is often selected when a processor needs a fine-cell foam and controlled expansion in a relatively broad range of industrial materials. It may be supplied as a powder or in another prepared form depending on the manufacturer and application requirements. Because commercial grades can differ, I advise buyers to compare the certificate of analysis, technical data sheet, particle characteristics, and application guidance rather than relying only on the chemical name.

How OBSH Functions in Different Materials

Rubber Foaming

In rubber compounds, OBSH must work together with the vulcanization system and the compound’s rheological behavior. The decomposition and gas-release timing should be compatible with the stage at which the rubber can retain the expanding gas without excessive collapse. If gas evolves too early, the compound may lose cells during mixing or molding; if it evolves too late, expansion may be incomplete.

For rubber, I recommend checking the relationship between OBSH activation, cure onset, cure rate, and mold temperature. Buyers should evaluate density, compression set, rebound, tensile properties, tear strength, and permanent deformation after foaming. The correct formulation may require a co-agent, activator, or processing adjustment, but these changes should be validated through controlled trials rather than assumed to improve performance.

PVC Foaming

In PVC, the blowing agent must be compatible with the fusion and processing behavior of the resin system. OBSH may be considered for cellular PVC products where density reduction, insulation, cushioning, or a particular surface structure is required. The formulation must also control thermal stability because excessive heat history can affect color, degradation, and surface quality.

For PVC applications, I suggest reviewing resin type, plasticizer level, stabilizer package, processing temperature, shear history, and residence time. A trial should compare expansion ratio, skin formation, cell uniformity, surface defects, and dimensional stability. A supplier’s guidance is useful, but the final selection should be based on the customer’s actual extruder, mixer, mold, and production speed.

EVA Foaming

EVA foam is commonly used in footwear components, mats, sports products, seals, packaging, and cushioning applications. OBSH can be evaluated when the compound requires controlled gas generation during heating and a fine cellular structure. However, EVA foam quality is strongly influenced by vinyl acetate content, melt strength, crosslinking system, molding pressure, and cooling conditions.

When evaluating OBSH in EVA, I recommend monitoring expansion ratio, cell size distribution, shrinkage, hardness, resilience, compression set, and color. The blowing agent should be selected together with the crosslinking and activator system because gas release and polymer network formation need to be sufficiently coordinated. A formulation that produces attractive expansion in a small mold may not provide the same result in continuous extrusion or larger production tooling.

Important Technical Specifications to Compare

OBSH selection should begin with technical data, not only price. The most important documents are the technical data sheet, certificate of analysis, safety documentation, packaging specification, and available sample information. If a supplier cannot clearly explain the grade’s decomposition behavior, purity range, moisture control, and recommended storage conditions, I would treat that as a sourcing risk.

Processing temperature deserves special attention. Many OBSH discussions refer to an approximate activation range of 150–160°C, but this range should be treated as a technical reference rather than a universal production setting. Actual gas release can shift with heating rate, compound ingredients, pressure, particle size, and measurement method, so I recommend using the supplier’s data together with differential scanning or practical processing trials when the application is sensitive.

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A Practical Selection Framework for B2B Buyers

Step 1: Define the Product Requirement

First, I identify the required density, hardness, expansion ratio, cell structure, color, odor level, and mechanical performance. A flexible rubber seal, an EVA cushioning component, and a rigid PVC profile do not have the same priorities. I also ask whether the product will be molded, extruded, calendered, or processed through another method.

Step 2: Map the Processing Window

Next, I review mixing temperature, melt or compound temperature, residence time, mold temperature, pressure, curing conditions, and cooling time. The blowing agent should release gas when the polymer can expand and retain the desired structure. If the process window is narrow, the buyer should request more detailed technical support and consider a small-scale compatibility study before placing a large order.

Step 3: Select a Trial Level

A laboratory trial can begin with several dosage points rather than one fixed formula. For example, a development team may compare 1 phr, 3 phr, and 5 phr as screening levels, where phr means parts per hundred parts of resin or rubber; these are trial points, not universal recommendations. The best dosage depends on gas yield, desired density, polymer strength, and the behavior of the full additive package.

Step 4: Measure More Than Expansion

Expansion alone does not prove that the formulation is suitable. I recommend recording density in grams per cubic centimeter, cell uniformity, surface quality, shrinkage after cooling, hardness, compression set, tensile behavior, odor, and color change. Where possible, repeat the trial and compare results from more than one production batch to identify whether the result is stable.

Common Mistakes to Avoid

One common mistake is choosing OBSH only by nominal price per kilogram. A lower purchase price may not provide better value if the grade has inconsistent dispersion, unsuitable activation behavior, excessive moisture, or inadequate technical documentation. Buyers should compare cost per finished part, process stability, waste, packaging, and quality-control requirements.

Another mistake is changing the blowing agent dosage without reviewing the cure or fusion system. In rubber and EVA, the timing between gas release and network formation is especially important. In PVC, thermal stability and processing history can change the result, so I recommend changing one major variable at a time and documenting the complete formulation.

A further risk is scaling directly from a laboratory sample to mass production. Mixing equipment, heating rate, pressure, mold geometry, and cooling capacity can all change foam structure. Before commercial production, I suggest a pilot run that confirms density, dimensions, surface quality, mechanical properties, and packaging performance under realistic conditions.

Pricing, MOQ, Lead Time, and Supplier Evaluation

Commercial pricing for OBSH depends on grade, purity, order quantity, packaging, destination, and current raw material and logistics conditions. Minimum order quantity and lead time should be confirmed for both standard and customized requirements because production planning may differ between regular stock and made-to-order material. I recommend requesting a written quotation that separates product price, packaging, shipping terms, sample policy, and payment conditions.

When I evaluate a supplier, I look for stable product identification, consistent batch documentation, clear storage guidance, responsive technical communication, and export experience. Shitong supports B2B buyers seeking OBSH blowing agent for rubber, PVC, and EVA applications by discussing intended use, trial requirements, packaging, and supply planning. We do not replace the customer’s formulation laboratory, but we can help organize the information needed for a more efficient evaluation.

Who Should Use This Guide?

This guide is intended for compounders, polymer processors, purchasing managers, product engineers, distributors, and manufacturers developing cellular rubber, PVC, or EVA products. It is particularly useful when a buyer is comparing suppliers or moving from a small trial toward regular production. It should not be treated as a substitute for process validation, safety review, or the supplier’s current technical documentation.

Conclusion: How to Choose OBSH Blowing Agent

The best OBSH blowing agent is not simply the product with the lowest price or the highest stated gas yield. It is the grade whose activation behavior, dispersion, purity, moisture control, and supply consistency match the buyer’s polymer and processing conditions. For rubber, PVC, and EVA, I recommend selecting through a documented trial that measures both expansion and final product performance.

Your next steps should be to define the target product, share the polymer and processing details with the supplier, request current technical and safety documents, and compare controlled samples. Shitong can discuss your application, provide commercial information, and support the evaluation of OBSH blowing agent for your production plan. Contact our B2B team with your material, process, target density, estimated annual volume, and packaging requirements so we can prepare a more relevant recommendation.

Contact us to discuss your requirements of OBSH blowing agent. Our experienced sales team can help you identify the options that best suit your needs.