Brief introduction and application of polyurethane catalyst

Brief introduction and application of polyurethane catalyst
Catalyst description:
Catalysts are promoters of many chemical reactions. Catalyst is an important assistant for the synthesis of resin, and polyurethane is no exception. It can shorten reaction time, improve production efficiency, selectively promote positive reaction and inhibit side reaction. In the production of many polyurethane products, catalyst is a commonly used auxiliary agent, with small amount and great effect.
Although there are few inorganic salt compounds, organophosphorus oxides and other catalysts that can be used as catalysts for polyurethane, the catalysts commonly used in the synthesis of polyurethane and its raw materials are mainly tertiary amine catalysts (including their quaternary ammonium salts) and organometallic compounds.
Catalyst classification:
Tertiary amine catalysts can be divided into aliphatic amines, alicyclic amines, aromatic amines, alcohol amines and their ammonium salts.
Aliphatic amine catalysts include N, N, N, N, N-pentamethyldiethylenetriamine, N, N-dimethylcyclohexylamine, bis (2-dimethylaminoethyl) ether, triethylenediamine, triethylenediamine, tetramethylhexanediamine, tetramethylenediamine, triethylamine, N, N-dimethylbenzylamine, N, N-dimethylhexadecylamine, etc.
Alicyclic amines include triethylenediamine, N-ethylmorpholine, N-methylmorpholine, N, N-diethylpiperazine, N, N-diethyl-2-methylpiperazine, N-2-hydroxypropyldimethylmorpholine, etc.
Ethanolamine compound catalysts include triethanolamine, N, N-dimethylethanolamine, etc. Alcoholic amine is a kind of reactive catalyst, which can be used together with other highly active catalysts. Triethanolamine is also a crosslinking agent for molding foam.
Application of catalyst in polyurethane:
Tertiary amine and quaternary ammonium salt are generally used as catalysts in polyurethane foam. In addition, stannous octoate is a common catalyst for continuous block foaming polyurethane soft foam. Potassium hydroxylate is mostly used for polyisocyanurate modified polyurethane rigid foam. Organic tin compounds such as dibutyltin dilaurate can be used for a few rigid foam, semi rigid foam and high resilience foam formulations. The common amine trimer catalysts for rigid polyurethane foam include 2,4,6 – (dimethylaminomethyl) phenol, DMP-30, TMR-2, POLYCAT 41, etc.
Among the formulations of polyurethane elastomers such as adhesives, coatings, sealants, waterproof coatings and paving materials, dibutyltin dilaurate and other organic metal catalysts are most commonly used. They are very effective in promoting the reaction of isocyanate and hydroxy, but they also have a certain acceleration effect on the reaction of water and isocyanate in the formula with water, so special catalysts such as organic lead can be used in the formula of plastic track. Tertiary amines with strong gel properties (mainly promoting the reaction between isocyanate group and hydroxyl group) such as triethylenediamine can also be used in some elastomer polyurethane formulations.
Common catalysts for molded high resilience foam:
The traditional additive catalysts mainly used in the production of soft molded high resilience foam are: bis (dimethylaminoethyl) ether, triethylenediamine, triethanolamine, diethanolamine, dimethylethanolamine, etc. For better production process and faster production efficiency, a lot of functional delayed catalysts have been derived, which can shorten the release time and improve production efficiency while delaying the early opalescence time. For example, delayed catalysts 8154, A300, A400, C-225, MP602, 1027, 1028
Commonly used reactive amine catalysts for polyurethane:
Reactive amine catalyst is a catalyst with OH hydroxyl functional group in the molecular structure, which can react with isocyanate-based NCO and eventually become part of polyurethane. These commonly used reactive amine catalysts mainly include 2 – (2 – (2-dimethylaminoethoxy) – ethylmethylamino) – ethanol, N, N, N- Trimethyl-N-hydroxyethyl-diaminoethyl ether, dimethylaminoethoxyethanol, bis (dimethylaminopropyl) urea, tetramethyldipropylenetriamine, 1,3-bis [3 – (dimethylamino) propyl] urea, trimethylhydroxypropylethylenediamine, DPA, NP15, 3,3 ‘- iminobis (N, N-dimethylpropylamine), N, N-dimethyl-N’, N ‘- bis (2-hydroxypropyl) – 1,3-propylamine, N (3-dimethylaminopropyl) – N, N, diisopropylamine, bis (3-dimethylaminopropyl) aminoisopropanol Bis – (3-dimethylpropylamine) amine, N, N-dimethyl-1,3-propanediamine, N, N-dimethylethanolamine, etc. The use of these low odor reactive amine catalysts greatly reduces the odor and VOC volatilization of polyurethane foam products, and is an environmentally friendly polyurethane catalyst. At present, it is mainly used in automotive interior products, such as car seats, headrests, NVH sound insulation pads and car ceilings.
Summary:
The selection of catalyst suitable for polyurethane and its raw materials should not only consider the catalytic activity and selectivity of the catalyst, but also consider the physical state, ease of operation, mutual solubility with other components, stability, toxicity, price in the mixed raw material system, and whether the catalyst residue in the product has a detrimental effect on the polymer performance.