For PVC foam products, buyers should not choose a blowing agent dosage from a fixed percentage alone. The appropriate dosage depends on the target density, foam thickness, processing temperature, extrusion equipment, cell structure and the gas output of the selected blowing agent. For a manufacturer moving from laboratory trials to continuous production, dosage should therefore be validated together with decomposition temperature, gas generation and final foam density rather than evaluated only by additive cost.
Shitong supplies chemical blowing agents for rubber and plastic processing, including NC, AC, OBSH and RA grades. Our product selection can be matched to the customer's material system and processing conditions rather than treating every PVC foam application as the same formulation.
Blowing agent dosage directly affects the amount of gas available during processing, but the relationship between dosage and final density is not perfectly linear.
When dosage increases, more gas may be generated and the polymer melt can potentially expand further. However, excessive gas generation can exceed the melt strength of the formulation, producing oversized cells, cell rupture, surface defects or dimensional instability.
For purchasing teams, this means that “higher dosage” should not automatically be interpreted as “lighter product.”
A practical evaluation should consider at least five variables:
| Buyer parameter | Why it matters | Typical purchasing concern |
|---|---|---|
| Blowing agent type | Determines decomposition behavior and gas generation | Is it compatible with the processing temperature? |
| Dosage | Controls available gas | Can the target density be achieved without cell collapse? |
| Decomposition temperature | Determines when gas is released | Does it match the extrusion profile? |
| Gas generation | Affects expansion potential | Is the gas output sufficient for the target density? |
| Melt strength | Determines whether cells remain stable | Will the foam structure collapse during cooling? |
The correct dosage is therefore a formulation parameter rather than a simple purchasing specification.
Neither parameter should be considered independently.
For example, Shitong's RA blowing agent has a reported thermal decomposition temperature of 225–235°C and gas generation of 140–150 ml/g, making it relevant to higher-temperature plastic and rubber foaming systems.
By comparison, the company's OBSH blowing agent has a reported decomposition temperature of 150–160°C and gas evolution of 120–130 ml/g.
This difference matters when the same additive is considered for different production lines. A blowing agent with high gas output may not perform efficiently if its decomposition window does not match the actual processing conditions.
For procurement, the better question is:
“Does the blowing agent release gas at the right stage of my process?”
rather than simply:
“Which blowing agent produces more gas?”
Different products require different starting points because their geometry and performance requirements are different.
For a thin PVC foam sheet, excessive gas generation can create surface instability or oversized cells. A thicker board may require sufficient gas generation to achieve the target density through the entire cross-section, while still maintaining adequate melt strength.
For PVC foaming boards, Shitong identifies white blowing agents as suitable for PVC white foaming products, including extruded PVC advertising boards and bathroom boards. The company also notes that white and yellow blowing agents may be used together depending on the formulation.
Buyers should therefore provide the following information before requesting a dosage recommendation:
PVC resin type and K-value
Target product density
Product thickness
Extrusion temperature range
Extruder type and screw configuration
Existing blowing agent
Current dosage
Required cell size
Surface appearance requirements
Whether recycled material is used
This information gives the supplier enough context to recommend a starting formulation instead of quoting an isolated dosage number.
Low dosage generally limits gas generation and can leave the product heavier than the target specification.
Typical production symptoms may include insufficient expansion, higher density, low thickness and poor material utilization. However, simply increasing the blowing agent is not always the correct correction because poor expansion can also originate from insufficient melt strength, unsuitable processing temperature or inadequate additive compatibility.
A useful troubleshooting sequence is:
Confirm the actual dosage.
Verify the blowing agent's decomposition temperature.
Check the extrusion temperature profile.
Measure actual product density.
Inspect cell size and cell uniformity.
Check melt strength and processing aid balance.
Conduct a controlled dosage trial.
This approach helps prevent a production team from compensating for an unrelated processing problem by continuously increasing blowing agent dosage.
Excessive dosage can generate more gas than the polymer melt can retain.
Possible results include large or irregular cells, cell rupture, surface roughness, dimensional instability and reduced mechanical performance. In continuous extrusion, the problem may become more visible because small formulation deviations are repeated over long production runs.
The failure risk is especially important for buyers purchasing additives for automated production. A formulation that works during a short laboratory trial may behave differently when extrusion speed, cooling conditions and throughput increase.
There is no single grade that applies to every PVC foam process. Selection should begin with the processing window and final product requirements.
| Application condition | Main concern | Selection direction |
|---|---|---|
| White PVC foam board | Whiteness, fine cells, controlled expansion | Consider NC/white blowing agent systems |
| Low-odor rubber/plastic foam | Odor and cell uniformity | Consider OBSH where compatible |
| Higher-temperature processing | Thermal stability | Consider a high-temperature grade such as RA |
| Conventional PVC foaming | Gas output and decomposition balance | Compare suitable grades against actual process temperature |
| Customized formulation | Multiple variables | Request supplier formulation support |
Shitong's product range includes NC, AC, OBSH and RA blowing agents, allowing buyers to compare grades according to application rather than purchasing solely on price.
For more information, buyers can review the Blowing Agent product range and the PVC Foaming Board application.
A controlled trial is more useful than comparing supplier quotations alone.
The buyer should keep the resin, stabilizer, lubricant and processing conditions as consistent as possible, then change only the blowing agent or dosage during the trial. Density, thickness, cell structure, surface quality and production stability should be recorded.
A suitable trial can use three dosage levels around the proposed starting formulation. The objective is not simply to identify the lowest dosage, but to identify the operating range that provides stable production.
A purchase specification should contain more than the product name.
At minimum, buyers should confirm:
Product grade
Appearance
Active content
Decomposition temperature
Gas generation
Moisture limit
Particle size where relevant
Packaging
Batch identification
Inspection documentation
Storage requirements
Recommended application
Technical support availability
For example, Shitong's published RA specifications include ≥98% content, 225–235°C thermal decomposition temperature, 140–150 ml/g gas generation, moisture ≤0.5%, and average grain diameter of 8–10 μm.
These measurable parameters give procurement teams a more useful basis for supplier comparison than price per kilogram alone.
There is no universal dosage because the required level depends on resin, product density, thickness, processing temperature and blowing agent characteristics. A dosage should be confirmed through controlled trials using the actual production formulation.
No. Excessive dosage can generate gas faster than the melt can retain it, resulting in cell rupture or unstable expansion. Density should therefore be evaluated together with cell structure and melt strength.
Gas generation is important, but it should not be considered alone. The decomposition temperature must also match the actual processing window so that gas is released at an appropriate stage.
Yes. We can evaluate the material, processing temperature, target density, product structure and application requirements and then recommend a suitable blowing agent or formulation direction.
Provide the PVC material, product type, thickness, target density, extrusion temperature, current formulation and required production volume. More process information allows us to evaluate both product grade and dosage instead of quoting an unsuitable standard grade.
For manufacturers planning a new PVC foam product or replacing an existing blowing agent, Shitong can provide blowing agent selection and formulation support based on actual processing requirements. Contact cindy@stgaocai.com with your product specifications, current formulation and target performance to discuss a suitable additive solution.
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