On Thursday, 22 October 2026, two representatives of an Indian PVC coir mat manufacturer visited Shandong Changxing Plastic Additives and our Wansheng plant in Jining. Their sourcing question was narrow: the PVC backing of a coir mat needs DOTP plasticizer, but which grade: superior, first or qualified grade? The visit was set up to answer that on the line and in the laboratory, not only on a specification sheet.
Key Takeaways
- ✅ Date: Thursday, 22 October 2026.
- ✅ Visitors: two representatives of an Indian PVC coir mat manufacturer.
- ✅ Sites: Changxing headquarters and the Wansheng plant, Jining. The plant photos below were taken at Wansheng.
- ✅ Product: qualified-grade DOTP (CAS 6422-86-2), colour ≤450 APHA, ester content ≥98%.
- ✅ Why qualified grade: the PVC backing is the hidden underside of a mat, so colour tolerance can be relaxed before mechanical performance is touched.
- ✅ Follow-up: the sales team will confirm grade, specification and sample arrangements after the audit.
Why Qualified-Grade DOTP Fits PVC Coir Mats
Qualified grade is the right DOTP for a PVC coir mat because the backing is hidden and usually dark, so colour can be traded away while plasticizing performance stays the same. A coir mat is made of two materials: coir fibre on the face that scrapes shoes, and a PVC backing that holds the fibre, adds weight and keeps the mat flat at a doorway. That backing has to stay flexible through foot traffic, sunlight and rain, and the PVC mat backing plasticizer is one of the largest cost items in it.
The backing is also the part nobody looks at. It is usually black or dark brown, and it sits face-down on the floor. Colour is the only thing that separates our three DOTP grades. Plasticizing performance is the same in all three.
The Three DOTP Grades, Side by Side
The three grades carry the same ester content at ≥98% and differ in one figure only, the colour ceiling: 150, 230 or 450 APHA.
| Grade | Colour (APHA) | Ester content | Typical use |
|---|---|---|---|
| DOTP superior | ≤150 | ≥98% | Light-coloured or transparent PVC goods |
| DOTP first grade | ≤230 | ≥98% | General flexible PVC where slight colour is acceptable |
| DOTP qualified grade | ≤450 | ≥98% | Dark or hidden parts such as mat backing |
Density, acidity, water content, flash point and volume resistance are the same across the three grades. The colour ceiling is the only figure a mat maker can trade away. A darker DOTP still plasticizes PVC. It only tints the compound, and in a black backing that tint is gone.
The Visit: Changxing Headquarters and Wansheng
The visit covered two sites: Changxing headquarters for the commercial and technical discussion, Wansheng for the physical audit. At the Changxing headquarters the agenda was grade selection, monthly volume, packaging, documents and the specification the customer would put into its purchase contract. At Wansheng the two visitors walked the DOTP production area themselves.
Wansheng is our wholly owned subsidiary in the Wenshang Chemical Industrial Park, Jining. It is also where the photographs in this article were taken. The plant runs a recycled-PET route to DOTP, so the visitors could follow the feedstock from the yard through reaction and distillation to the finished-product tanks.
Wansheng Capacity: What Is Running and What Is Coming
Wansheng runs 80,000 tonnes/year of plasticizer today. A 100,000 tonnes/year Phase II is under construction with planned commissioning in May 2027, which takes the site to 180,000 tonnes/year and the group to 230,000 tonnes/year once that phase is running.
| Item | Status |
|---|---|
| Wansheng Phase I | 80,000 tonnes/year of plasticizer, in operation since June 2024 |
| Wansheng Phase II | 100,000 tonnes/year under construction, planned commissioning May 2027 |
| Wansheng upon full completion | 180,000 tonnes/year (Phase I 80,000 + Phase II 100,000) |
| Group upon full completion | 230,000 tonnes/year, including the Changxing headquarters site |
Wansheng Phase I capacity of 80,000 tonnes/year was the number that mattered to this customer. A mat backing line runs at a steady rate and needs the same grade month after month. Capacity already in operation, plus batches that repeat, answers that. A headline figure for a plant still under construction does not.
Inside the Wansheng Laboratory
A DOTP batch is released on seven tests: colour, ester content, acidity, water content, density, flash point and volume resistance. Our QC team walked the visitors through them in the order they are run, including instrument calibration, out-of-spec handling and batch traceability.
What Each Test Means for a Mat Backing
The qualified-grade release specification carries seven limits. The table sets each limit against its effect on a mat backing.
| Test | Qualified-grade limit | Why it matters in a backing |
|---|---|---|
| Colour (APHA) | ≤450 | Sets the tint of the compound; irrelevant under a black backing |
| Ester content | ≥98% | Less inert material means the same phr behaves the same way |
| Acidity (as terephthalic acid) | ≤0.035% | Keeps PVC from degrading during hot compounding |
| Water content | ≤0.1% | Moisture causes bubbles and weak adhesion to the coir |
| Density | 0.980–0.985 g/cm³ | Keeps dosing and charge weight consistent |
| Flash point | ≥210 °C | Handling and storage margin at the customer's plant |
| Volume resistance | ≥2×10¹² Ω·cm | Not critical for mats, but part of the same release specification |
A CoA from a recent batch can be matched to its production record. That is the check a mat maker actually needs. One good sample proves little. A document trail that repeats with every delivery is the thing being tested. We issue a CoA with each batch, and SGS reports on phthalates, PFAS and EN 71-3 are available on request.
DOTP Packaging and Delivery to India
DOTP reaches India in one of three formats, and the choice follows the discharge point at the customer's factory. A plant with a bulk tank can take a flexitank, which carries 20–24 tonnes in a 20ft container. A plant that stores material in totes or drums cannot.
| Format | Payload per 20ft container | Best for |
|---|---|---|
| Flexitank | 20–24 tonnes | Regular volume with bulk discharge and storage on site |
| 1000L IBC tote | About 20 tonnes (20 totes) | Plants without a bulk tank; easy to store and move |
| 200L drum | About 16 tonnes (80 drums) | Trial orders and sites that cannot handle a tank |
For India, the usual entry ports are Nhava Sheva (JNPT), Mundra and Chennai. Ocean transit from Qingdao is typically 18–25 days, depending on whether the service is direct or transships. The full import sequence, from IEC code to customs clearance, is set out in our DOTP import guide for India.
What Happens Next
The technical step that follows this audit is a qualified-grade sample in the customer's own backing formulation.
If the darker colour disappears in the customer's backing compound, qualified grade can replace first grade and cut the plasticizer cost per mat. If their backing is lighter than we assumed, first grade remains the safer choice.
Either way, the specification will be fixed before the first order: grade, colour ceiling, ester content and packaging. Indian buyers comparing DOTP suppliers can start with our DOTP product page or book a visit through the contact form.
"A mat backing does not need our best grade. It needs a grade we can repeat, batch after batch, with the paperwork to prove it."
Frequently Asked Questions
When did the Indian customers visit?
The two representatives visited on Thursday, 22 October 2026. The itinerary covered the Changxing headquarters and the Wansheng plant in Jining, Shandong.
Which plant is shown in the photos?
The outdoor plant photos and the laboratory photo were taken at the Wansheng plant, the wholly owned subsidiary in the Wenshang Chemical Industrial Park, Jining.
What product did the customers come to buy?
Their main purchase item was qualified-grade DOTP (dioctyl terephthalate, CAS 6422-86-2) for the PVC backing compound of coir mats.
Why choose qualified grade instead of superior grade for a coir mat?
The three DOTP grades differ mainly in colour ceiling: superior is ≤150 APHA, first grade ≤230 APHA and qualified grade ≤450 APHA. The mat backing is the hidden underside and is usually black or dark, so a darker plasticizer does not show. Ester content stays at ≥98% and the other routine specifications are the same.
What does the laboratory test on each qualified-grade DOTP batch?
Colour (APHA), ester content, acidity as terephthalic acid, water content, density, flash point and volume resistance. A Certificate of Analysis is issued against the batch number.
How is DOTP shipped to India?
Flexitanks in 20-foot containers carry 20–24 tonnes and suit plants with bulk discharge tanks. 1000L IBC totes and 200L drums are alternatives for sites without bulk storage. Common entry ports are Nhava Sheva (JNPT), Mundra and Chennai, with typical ocean transit of 18–25 days from Qingdao.
Ready to Source Qualified-Grade DOTP?
Shandong Changxing Plastic Additives Co., Ltd. is an ISO 9001 / 14001 / 45001 / 50001 certified manufacturer with 230,000 tonnes of group plasticizer capacity upon full completion. We supply DOTP, DCP, MEG and 2-octanol to overseas buyers, including PVC mat and flooring producers in India.
Request a Free Quote + Technical Data Sheet- ✓ Qualified, first and superior DOTP grades from one production system
- ✓ Certificate of Analysis with every batch; SGS phthalate, PFAS and EN 71-3 reports on request
- ✓ ISO 9001 / 14001 / 45001 / 50001 certified
- ✓ National High-Tech Enterprise and Shandong Gazelle Enterprise
- ✓ Flexitank, IBC and drum supply to Nhava Sheva, Mundra and Chennai
Shandong Changxing Plastic Additives Co., Ltd.
October 2026
