PU foam catalysts · Gelling versus blowing balance, TEDA and BDMAEE roles, dilution in DPG, reactive low-emission amines, rise profile testing
A polyurethane foam catalyst is a tertiary amine or metal compound, supplied neat or as a solution, added in small amounts to a polyol blend to speed the reactions of isocyanate with polyol (gelling) and with water (blowing) so the foam rises and cures on schedule. Ask three things first: which balance of gelling and blowing your foam needs, which active amines and diluents the catalyst contains, and whether low-emission (reactive) catalysts are required.
Amine and related catalysts for flexible, moulded and rigid polyurethane foams, supplied neat or as solutions. Isocyanates, polyols, silicone surfactants, blowing agents and catalysts for coatings and elastomers only are outside this page.
CNFX editorial research · Sources checked October 12, 2026 · 4 sources
US patent 6,432,864 (acid-blocked amine catalysts) explains that polyurethane foam needs a balance between the isocyanate-polyol (gelling) and isocyanate-water (blowing) reactions to give relatively uniform cells. If a catalyst promotes blowing too strongly, carbon dioxide forms before enough polymer has built up, bubbles out and the foam collapses; if it promotes gelling too strongly, much of the gas forms after significant polymerisation, giving high density and broken or poorly defined cells. A gelling catalyst and a blowing catalyst are used together. [1]
The patent notes that tertiary amines accelerate both reactions and that triethylenediamine (TEDA, 1,4-diazabicyclo[2.2.2]octane) and its derivatives are named in the patent as commercial catalysts. [1] Tosoh's technical review (2013) states that TEDA and bis(dimethylaminoethyl) ether (BDMAEE) are used in flexible foam to activate the gelling and blowing reactions respectively, and describes TEDA-L33 as a strong gelling catalyst and TOYOCAT-ET as a strong blowing catalyst; its reactive TEDA product contains 66.7% dipropylene glycol (DPG) 'in the same manner as TEDA-L33'. [2]
Editorial calculation: a TEDA solution with 66.7% DPG carries about 33.3% active TEDA, so dosing 0.30 parts per hundred polyol of the solution adds about 0.10 parts of TEDA; compare suppliers on active content, not on solution weight. [2]
Give the supplier the foam type (flexible slabstock, moulded, rigid), isocyanate (TDI, MDI) and polyol system, water and blowing agent level, target cream, gel and rise times, emission requirements, any existing catalyst package to match, packaging and storage conditions.
02
Control emissions and test the rise profile
Tosoh notes that TEDA and BDMAEE are fugitive, volatile compounds that contribute significantly to VOC emissions and odour, and that non-fugitive amines with hydroxyl or reactive amino groups bind into the polymer to reduce emissions, but have lower activity and can act as chain terminators, hurting foam properties. Its reactive TEDA was developed to keep strong gelling activity with lower emissions. [2]
In its tests catalyst levels were adjusted to give similar rise times of about 100 s or 150 s in slabstock foams, or the same gel time of about 60 s in moulded foams at 52 kg/m³ with an 8-minute demould; rise profiles were measured with a laser displacement sensor every second, physical properties after 7 days at 23 °C and 50% RH, and emissions by a chamber method used under CertiPUR. [2]
Editorial note: ask catalyst suppliers to match your current rise or gel time on your own formulation, then compare foam properties and emission results at equal reactivity, as Tosoh did.
03
Plan for amine catalyst exposure at the line
An American Chemistry Council paper (2014, authors from BASF and Air Products) reports industrial hygiene monitoring during application and trimming of high-pressure open-cell spray polyurethane foam in two Houston-area homes and a spray booth. It monitored an emissive amine catalyst, BDMAEE, and a non-emissive (reactive) catalyst, TMAEEA. It states there are no OSHA PELs for these catalysts, but ACGIH sets a TLV of 0.05 ppm as an 8-hour TWA and a STEL of 0.15 ppm for BDMAEE. [3]
The authors conclude that BDMAEE exceeded the TLV-TWA during application and during trimming of fresh and 24-hour-old foam, while the non-emissive TMAEEA was detected in only two personal samples, taken in a confined attic with no mechanical ventilation. They recommend mechanical ventilation during and after application and following PPE practice. [3] This matches the trade-off described for reactive amines: lower emissions, lower activity. [2]
Editorial calculation: the attic maximum of 4.52 ppm is about 90 times the 0.05 ppm TLV-TWA, and the 24-hour trimming result of 0.073 ppm is about 1.5 times it.
Sampling situation (BDMAEE, personal samples)
Reported concentration
Spray booth application
0.07–0.36 ppm (not full-shift)
Attic application, home with no mechanical ventilation
0.52–4.52 ppm
Trimming fresh foam
1.24 and 1.34 ppm
Trimming foam sprayed 24 hours earlier
0.073 ppm
ACGIH TLV-TWA for comparison
0.05 ppm
Ask the supplier for the catalyst's occupational exposure limit, vapour pressure or emission class, and whether a reactive (non-emissive) grade is offered for your foam.
04
Pair the amine with a metal gelling catalyst
Flexible slabstock recipes combine an amine with a metal catalyst. In a study by Cadi Ayyad University and the Spanish polymer institute ICTP-CSIC, every foam held 0.5 php of the amine PMDETA, 6 php water, 0.2 php Dabco DC 198 silicone and an isocyanate index of 100, and only the metal catalyst changed: 0.2 php stannous octoate against 0.2, 0.1 or 0.05 php bismuth triflate. Cream and rise times of the bismuth and tin foams at equal dose were similar, at about 12 s and 135 s. Trials with bismuth alone and no amine gave non-homogeneous, high-density foams with long gelling times. [4]
The authors attribute the lower density at 0.2 php bismuth to the triflate's high solubility in water, which tilts it toward the blowing reaction, and chose 0.1 php as the optimum: at the same density as the tin foam it gave a higher specific modulus with half the catalyst. [4]
Editorial calculation: halving bismuth triflate from 0.2 to 0.1 php raised density by 7.6 kg/m³ (28.2 to 35.8), about 27%, while the amine level stayed fixed, so a change of metal catalyst alone shifts the gel-blow balance. Ask for trial foams at your amine level before switching the metal catalyst. [4]
Metal catalyst (php)
Apparent density (kg/m³)
Average cell size (µm)
Specific Young's modulus (kPa per kg/m³)
Stannous octoate 0.2
35.6 ± 1.2
277 ± 83
0.42 ± 0.15
Bismuth triflate 0.2
28.2 ± 3.4
332 ± 97
0.40 ± 0.15
Bismuth triflate 0.1
35.8 ± 1.1
341 ± 99
0.61 ± 0.21
Bismuth triflate 0.05
40.2 ± 1.9
294 ± 86
1.09 ± 0.45
05
Foam catalysts sold among PU additives and raw materials
Listings include polyurethane foam catalysts among PU additives and raw materials.
06
Gelling amine, blowing amine, diluent, reactive groups and blocking acid
The active-content entry decides the dose when the amine comes as a solution: Tosoh's TEDA solution in 66.7% DPG carries about a third active TEDA. [2]
Gel time, foam density, water content, flash point and exposure limit for a catalyst order
The exposure-limit row matters at the line as well as in the warehouse: the American Chemistry Council paper measured BDMAEE up to 4.52 ppm in an unventilated attic against a 0.05 ppm TLV-TWA. [3]
1 company lists this product among what they make. Company figures are quoted from each
company's own website; every card states where the relationship came from.
Guangzhou Yourun Synthetic Material Co., Ltd.
Manufacturing site to be confirmed for the order
Lists polyurethane foam catalysts among PU additives and raw materials.
Explore company information and manufacturing capabilities, then discuss the scope of your project with a relevant supplier.
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Compiled and source-reviewed by the CNFX editorial team.
Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review
· Page last updated 13 October 2026
Buyer questions
What happens if the blowing catalyst is too strong?
Carbon dioxide forms before enough polymer has built up, bubbles out and the foam collapses, per US patent 6,432,864. [1]
Which amines are used for gelling and blowing?
Tosoh names TEDA for gelling and BDMAEE for blowing in flexible foam. [2]
Why use reactive amine catalysts?
They bind into the polymer and reduce VOC and odour, though Tosoh notes such amines have lower activity than fugitive amines. [2]
What exposure limit applies to the amine catalyst BDMAEE?
An American Chemistry Council paper cites the ACGIH TLV of 0.05 ppm (8-hour TWA) and STEL of 0.15 ppm; OSHA has no PEL for it. [3]
Can bismuth replace tin in flexible foam catalysis?
In one Polymers 2021 study, 0.1 php bismuth triflate with 0.5 php PMDETA matched the density of a 0.2 php stannous-octoate foam (35.8 vs 35.6 kg/m³) with a higher specific modulus; bismuth alone gave poor foams. [4]
Sources and what still needs a direct check
Sources checked 2026-10-12. Tosoh is an amine catalyst maker describing its own reactive catalyst work; the patent's background explains the gel-blow balance; the American Chemistry Council paper, by authors from BASF and Air Products, reports amine exposure monitoring during spray foam work; an open-access Polymers paper compares tin and bismuth co-catalysts at a fixed amine level. Catalyst choice must be confirmed in trials on your formulation.
