Rubber Accelerator D (DPG, CAS 102-06-7): Properties and Applications

What Is Rubber Accelerator D (DPG)?

Rubber accelerator D, also called DPG, CAS 102-06-7, chemically 1,3-diphenylguanidine, is a guanidine-type accelerator and secondary accelerator. It is a strong, fast accelerator on its own and, more often, is used as a secondary accelerator or activator with thiazole and sulfenamide accelerators, and in latex compounds.

Where the sulfenamides (CZ, TBBS, DCBS) provide controlled, delayed acceleration, DPG provides activation and speed: a small addition raises the cure rate and modulus of a thiazole or sulfenamide system. It is one of the oldest and most versatile rubber accelerators, still widely used for its ability to fine-tune a cure. PolyBlueChem supplies Rubber accelerator D (DPG) to a controlled specification with per-batch COA and SDS.

CAS number	102-06-7
Chemical name	1,3-Diphenylguanidine
Synonyms	Rubber accelerator D; DPG; diphenylguanidine; D
Molecular formula	C₁₃H₁₃N₃
Molecular weight	211.27 g/mol
Type	Guanidine accelerator / secondary accelerator
Appearance	White or grey powder

Chemistry and Structure

DPG is a guanidine: a central carbon bonded to three nitrogen atoms, two of which carry phenyl groups. The guanidine group is strongly basic, which is exactly why it is an efficient accelerator and activator:

The strongly basic guanidine group accelerates sulfur vulcanisation and activates other accelerators.
The two phenyl groups give the molecule its solid, crystalline form and its compatibility with rubber.
High nitrogen content in a small molecule makes it a powerful, fast-acting accelerator per unit weight.

Because it is so active, DPG is usually used at low levels and is typically a secondary accelerator rather than the main one – a small addition is enough to speed up a thiazole or sulfenamide system.

How DPG Works

In a sulfur cure, DPG acts in two related ways:

As an accelerator – the basic guanidine group speeds the reaction of sulfur with the rubber, forming crosslinks quickly.
As an activator/co-accelerator – with thiazoles (MBT/MBTS) and sulfenamides (CZ/TBBS), DPG raises the activity of the system, increasing cure rate and crosslink density (modulus).

This is why DPG is often described as a “booster”: a plant that finds a thiazole or sulfenamide cure slightly too slow can add a small amount of DPG to bring it up to the required rate, rather than reformulating the whole system. Like other accelerators, DPG works with the zinc oxide/stearic acid activator system and elemental sulfur.

How DPG Is Produced

DPG is made by reacting aniline with a source of the guanidine carbon, classically by heating aniline with cyanogen chloride or via the reaction of aniline with carbon disulfide and ammonia chemistry, forming the diphenylguanidine:

Aniline is reacted to introduce the central guanidine carbon, forming the diphenylguanidine.
The crude product is purified (for example by recrystallisation).
The purified DPG is dried and milled to a powder.

Because DPG is used as a fine powder and at low levels, particle size and purity matter: residual aniline and impurities affect activity, odour and colour. The specification therefore fixes melting point, heating loss, ash and a very low sieve residue.

Specifications and Quality Control

Rubber accelerator D (DPG) is supplied as a white or grey powder to the following specification:

Parameter	Specification
Appearance	White or grey powder
Initial melting point	144 °C min
Heating loss	0.30% max
Ash	0.30% max
Sieve residue (150 µm)	0.01% max

The very low sieve residue (0.01% max) reflects a finely divided, free-flowing powder – important because DPG is used at low levels and must disperse evenly to act reliably.

Parameter	What it controls
Initial melting point (144 °C min)	Purity and identity
Heating loss (0.30% max)	Moisture and volatiles
Ash (0.30% max)	Inorganic residues
Sieve residue (150 µm, 0.01% max)	Very fine particle size / good dispersion

A specification sheet and a per-batch certificate of analysis (COA) are available on request.

Key Properties

Property	Behaviour	Practical value
Class	Guanidine	Strong, fast accelerator
Role	Primary or (usually) secondary accelerator	Boosts thiazole/sulfenamide cures
Activity	High per unit weight	Effective at low levels
Form	Fine powder	Disperses evenly
Latex use	Effective in latex compounds	Common in dipping and foam

Applications

Industry / product	Function
Rubber (all types)	Secondary accelerator to raise cure rate and modulus
Latex compounds	Accelerator for dipping, foam and latex goods
Hard rubber / ebonite	High-modulus compounds
Thick goods	Used with a delayed accelerator to balance scorch and cure
General rubber	NR, SBR, BR, NBR and blends

As a secondary accelerator – DPG is most often used with a thiazole (MBT/MBTS) or sulfenamide (CZ/TBBS) to increase the speed and completeness of the cure.
In latex – DPG is a common accelerator for latex dipping (gloves, balloons) and foam, where its activity and water compatibility are useful.
Hard rubber – its ability to raise crosslink density suits high-modulus and ebonite compounds.

Rubber Accelerator D (DPG) vs Other Accelerators

Accelerator	CAS	Class	Role
DPG (D)	102-06-7	Guanidine	Secondary accelerator / activator; fast
MBT (M)	149-30-4	Thiazole	Primary accelerator; often needs a booster
MBTS (DM)	120-78-5	Thiazole	Primary / secondary accelerator
CZ (CBS)	95-33-0	Sulfenamide	Delayed primary accelerator
TBBS (NS)	95-31-8	Sulfenamide	Delayed primary accelerator

Guidance: use DPG as a secondary accelerator/activator to speed a thiazole or sulfenamide system; be careful with the level, because DPG is very active and can cause scorch if over-used. It is rarely the sole accelerator in a demanding compound, but it is an invaluable fine-tuning tool.

Dosage and Cure Systems

Use	Character
With thiazole (MBT/MBTS)	Classic fast general-purpose system
With sulfenamide (CZ/TBBS)	Raises cure rate; balanced against scorch
Latex compounds	Added at low levels for dipping and foam
Hard rubber	Higher additions for high modulus

Because DPG is so active, its level is small and is set carefully. The compound is balanced so that the added speed does not reduce scorch safety below the processing window. Confirm the level by rheometer cure curves and physical tests.

Safety, Handling and Storage

Irritation and sensitisation – DPG is an irritant and a potential skin sensitiser; avoid skin and eye contact and follow good industrial hygiene (gloves, dust control).
Dust – avoid breathing the fine powder; use local extraction where large amounts are handled.
Storage – keep sealed, cool and dry, away from acids and oxidisers.

Regulatory Status

Use	Status (as commonly cited)
Rubber (industrial)	Governed by the buyer’s specification and article requirements
Food-contact / potable-water rubber	Only where the specific accelerator is permitted; confirm the applicable regulation

Packaging, Logistics and Supply

Item	Standard options
Packaging	25 kg PP/PE bags or fibre drums
Documentation	Per-batch COA and SDS
Incoterms	FOB and CIF
Storage	Sealed, cool and dry

Price tracks the aniline feedstock and the finishing quality; buying on committed tonnage gives the best terms.

DPG as a Booster and Latex Accelerator

DPG earns its place in two roles that are worth understanding.

The booster role – a thiazole (MBT/MBTS) cure is versatile but sometimes too slow for the required cycle. Adding a small amount of DPG raises the cure rate and modulus without redesigning the system. The formulator keeps the DPG low enough that scorch safety stays acceptable.
The latex role – in latex, water-based compounding means the accelerator must work in an aqueous system. DPG performs well in latex, and is used in dipped goods (gloves, balloons) and latex foam, often with a thiazole or dithiocarbamate.

Latex product	DPG role
Dipped gloves	Cure acceleration in the latex compound
Balloons and thin goods	Controlled fast cure
Latex foam	Acceleration with good dispersion

In both roles the key is that DPG is active at low levels: it changes the result with a small addition, which is why it is described as an activator and booster rather than a bulk accelerator.

Quality: Reading a DPG Certificate of Analysis

Parameter	What it tells you
Initial melting point (144 °C min)	Purity and identity; low values suggest residual aniline or impurities
Heating loss (0.30% max)	Moisture/volatiles; consistent values keep the fine powder free-flowing
Ash (0.30% max)	Inorganic residues
Sieve residue (150 µm, 0.01% max)	Very fine particle size; essential for even dispersion at low addition

Because DPG is used at low levels, the very low sieve-residue limit is important: a coarser product would disperse unevenly and act inconsistently, so the batch COA is the practical way to keep cure results reproducible.

Building a Fast General-Purpose Cure with DPG

The classic use of DPG is to turn a thiazole cure into a fast, general-purpose system. A typical build looks like this:

Component	Role
MBT or MBTS (thiazole)	Primary accelerator
DPG	Booster / activator – raises cure rate and modulus
Sulfur	Crosslinker
Zinc oxide + stearic acid	Activator system
Antioxidant / antiozonant	Protection (see the antioxidant articles)

The thiazole-plus-DPG combination is one of the oldest and most reliable general-purpose cure systems in rubber. It is fast, uses inexpensive chemicals, and is easy to tune: increasing DPG speeds the cure and raises modulus, while the level is kept low enough to preserve scorch safety. In compounds that must be processed hot or stored a long time, the increase in speed has to be balanced against the processing window.

DPG vs Other Boosters

DPG is one of several chemicals used to boost a cure. Understanding the alternatives helps place it.

Booster	Class	Character	Notes
DPG	Guanidine	Fast, strong; raises modulus	Versatile; also latex; can scorch if over-used
TMTD / thiurams	Thiuram	Very fast; also sulfur donors	Used in EV systems; some nitrosamine consideration
Dithiocarbamates	Dithiocarbamate	Very fast (ultra-accelerators)	Latex and low-temperature cures; nitrosamine consideration
Sulfenamides (CZ/TBBS)	Sulfenamide	Delayed primary accelerators	Control scorch while raising cure speed

DPG is chosen when a plant wants a simple, cost-effective boost to a thiazole cure with good modulus, or an accelerator that works in latex. Where nitrosamine potential matters, thiuram and dithiocarbamate boosters are treated with more caution than DPG.

Scorch Management When Using DPG

Because DPG is so active, adding it always trades speed for a reduced processing window. Managing that trade-off is the main practical skill in using DPG.

Keep the level low – a small amount is enough; more is not better and quickly risks scorch.
Add a retarder if needed – where more speed is wanted but scorch becomes a risk, a retarder such as PVI can restore the processing window.
Watch processing temperature – the hotter the compound gets during mixing and forming, the less DPG it can tolerate.
Confirm on the rheometer – the cure curve shows both the scorch time and the cure rate; the level is set so both are acceptable.

In practice, DPG is often the last adjustment made to a cure system: the base accelerator sets the character of the cure, and a small amount of DPG fine-tunes the rate and modulus.

Frequently Asked Questions about Rubber Accelerator D (DPG)

What is Rubber accelerator D used for?

It is a guanidine accelerator, used mainly as a secondary accelerator / activator to speed thiazole and sulfenamide cures, and in latex compounds.

What is the CAS number of DPG?

102-06-7.

Is DPG the same as accelerator D?

Yes – DPG, D and “rubber accelerator D” refer to 1,3-diphenylguanidine.

Is DPG a primary or secondary accelerator?

It can act as a primary accelerator but is most often used as a secondary accelerator/booster with thiazoles or sulfenamides.

Can DPG cause scorch?

Because it is very active, over-use can cause scorch; its level is kept low and confirmed by test.

Is DPG used in latex?

Yes – it is a common accelerator for latex dipping and foam.

Is DPG a skin sensitiser?

It is an irritant and a potential skin sensitiser; avoid skin contact.