Hardening accelerators, amine

Accelerator 399. [Texaco] Epoxy curing promoter for use wiA amine hardeners. 

For example, an anhydride hardener (with tertiary amine accelerator) will produce a polyester -type structure with low polarity, whereas an amine hardener will form a P-hydroxyl amine network with high polarity. Hydrogen bonding of water molecules at these sites enhances the concentration of moisture which can be absorbed. However, with catalytic curing agents, polyether stmctures of relatively low polarity will form. Since it is quite common to use mixed curing agents for composite matrices, the cured... 

By contrast, most modem composites cure by a light-activated process. The typical photoinitiator system used is based on camphorquinone (Fig. 3.4) with an aromatic tertiary amine as accelerator [13]. These are sensitive to blue light at 468 nm, and irradiation causes homolytic decomposition of the camphorquinone to form free radicals, which then initiate the polymerization and associated hardening of the composite resin. 

Chem. Descrip. Uncatalyzed mercaptan polymer Uses Epoxy hardener, accelerator tor amides, amines, and amido-amines in conventional and high-solids applies., fast-set concrete adhesives, castings, potting, laminates Features Requires amine catalyst tor activation Properties Gardner 2 max. color sp.gr. 1.15 dens. 9.6 Ib/gal vise. 100-150 poise gel time 4.5-6.5 min (30-50 g) After 7 day 25 C cure tens, str. 5900 psi elong. 3.75% flex. str. 10,000 psi 100% solids Capcure 40 sec HV [Cognis/Coatings Inks]... 

Chem. Descrip. Mercaptan polymer precatalyzed, accelerated Uses Epoxy hardener, accelerator in concrete adhesives, grouts, mortars, and coatings co-curative improves bond to glass and metal Features Fast cure eliminates induction times of polyamides and amido-amines... 

Cumylphenol derivative n. One of a group of polymer intermediates based on cumylphenol that offer higher performance at lower cost than nonylphenol competitors. The free phenol is an accelerator for amine hardeners of epoxy resins. Cumylphenyl acetate and the glycidyl ether are reactive in epoxy systems, giving enhanced strength. The benzoate of cumylphenol aids extrusion of PVC compounds. 

The hardening processes of obtained block-copolymers were carried out both in the presence of accelerator and without it. Amine type accelerator hexamethylenetetramine (HMTA) and isomer mixture of methyltet-rahydrophthalic anhydride (750-MTHA) was used as hardened activators. 

A few reports of contact allergy to non-amine hardeners have been published in the case of dicy-andiamide (Senff et al. 1988), dodecenyl succinic anhydride (Goransson 1977), methylhexahydrophthalic anhydride (Kanerva et al. 1997), hexavalent chromate, an accelerator additive (Handley and Burrows 1994 Bruze et al. 1996) and polysulfides (Bruze et al. 1996). 

Patent Number US 5684202 A 19971104 TERTIARY AMINES, A PROCESS FOR THEIR PREPARATION AND THEIR USE AS HARDENING ACCELERATORS... 

The present invention relates to novel tertiary amines derived from bisphenols, diepoxides and aromatic secondary amines, to a process for their preparation and to their use as hardening accelerators for ethylenically unsaturated cold hardenable acrylic and polyester resins. 

Chemical clusters can be obtained also with two monomers, when two reaction mechanisms are in competition, favoring formation of regions of higher and lower crosslink densities. This situation is more complex and more difficult to control. It is certainly the case for dicyanodiamide (Dicy)-cured epoxies with this hardener an accelerator is always used and a competition between step (epoxy-amine addition) and chain (epoxy homopolymerization) occurs (Chapter 2), leading to inhomogeneous networks. 

As a preliminary step in the manufacture of unsaturated polyester thermoset plastic one uses low molecular weight linear polyester (Mr 10,000) obtained by a polycondensation of polyglycols with saturated and unsaturated dicarboxylic acids. The precondensate can then be dissolved and stored in the stabilized comonomer, e.g. styrene, with which it will be crosslinked later. The crosslinking polymerization reaction between the polyester chains and the styrene bridges is initiated with the help of organic peroxides which are added dispersed in plasticizers. The reaction begins at 60-90 °C and then proceeds exothermally. In addition to this a cold hardening reaction can also be carried out. For this reaction cold accelerators are necessary, e.g. tertiary amines or cobalt naphthenate. 

The polymercaptans can also be used to accelerate the curing of epoxy resins systems blended with polyamines, amidoamines, or amines. The other curatives serve as the base to accelerate mercaptans, and the mercaptans react rapidly, generating the heat to accelerate the cure with the other hardener. 

Overview of Experimental Data. Most peroxide-amine systems impart colors to the cured polymers ranging from yellow for N,N-dimethyl-2 -toluidine to black for N,N-dimethyl-2-phenylenediamine ( ). Highly electron-donating groups in the accelerator molecule usually cause the hardened material to be esthetically unsuitable. 

The storage stability of the components of composite formulations is mainly limited by the poor shelf-life of the BP ingredient ( ). Paste formulations, containing BP, but free of accelerator prematurely harden when stored at 60°C. Formulations using powder-liquid constituents are more stable at these elevated temperatures. After extended storage at room temperature for two years, composite mixes showed delayed setting and decreased mechanical properties in the cured material. The purity of the BP and the amine selected greatly influences parameters such as reaction rate, color stability and biocompatibility (18). 

It was important to find to what extent the relationships concern the real ACECs being cured with standard hardeners in the presence of accelerators, e.g. tertiary amines and tertiary amine substituted phenols. To start with, the addition of ACECs (Table 8) with model hardeners 3-cyclohexene-l-carboxylic acid and aniline was studied. 

Accelerators. To allow the degradation of the peroxides at room temperature, the activation energy must be reduced. This is done by adding accelerators. Hydroperoxides are cleaved by heavy metal salts and acyl peroxides by tertiary aromatic amines. Up to 2% of the latter are added by the manufacturers to resins for fillers. These are known as amine-accelerated UP resins. It is common to add 0.02-0.05% cobalt (calculated as cobalt metal) in the form of cobalt naphthenate or cobalt octoate dissolved in aromatics (not white spirit) to the systems hardened with hydroperoxides. The accelerator should only be added shortly before application for reasons of storage stability and drift. 

Again this reaction is accelerated by hydroxyl groups or tertiary amines. This is also the predominant reaction with anhydrides. In fact, reactions with resin and hardener or catalyst are very much more eomplex than these idealized reactions, and both reactions as well as a number of side reaetions probably oeeur to varying extents in any cross-linking mechanism. Major suppliers of euring agents inelude Anchor Chemicals, Dow, Shell, and Cray Valley Products. 

Usually no hardeners are added during the production of wood-based panels (particle board, MDF, OSB, engineered wood products) using PMDI as adhesive. With special additives a distinct acceleration of the hardening reaction and hence shorter press times or lower press temperatures can be achieved [209]. This fact is especially interesting for coldsetting systems as well as for the production of particleboards. Possible catalysts are tertiary amines (e.g., triethanol amine, triethylamine, A,A-dimethylcyclohexylamine) and metal catalysts, based on organic compounds of tin, lead, cobalt, and mercury [208,215-218],... 

Chem. Descrip. Accelerated amine adduct Uses Epoxy curing agent/hardener for chem. resist, coatings, coatings, adhesives, and tooling compds. 

Hardeners HY830 andHY850 are aromatic amines of 90 and 350 poises respectively at21°C. HY850 also includes an accelerator. Both are made by CIBA (A.R.L.) Ltd. 

However, if the finish is to be cured at room temperature, there is no peroxide which can, on the one hand, remain relatively stable in the activator pack and, on the other, produce free radicals fast enough to give rapid hardening when activator and finish are mixed. Peroxide decomposition is accelerated by the addition of a metal salt from the drier range. The mechanism of the catalysis is as given in Chapter 12 for hydroperoxides. The combination of cobalt and either of the above ketone peroxides is widely used. Another combination is benzoyl peroxide and a tertiary amine, but this has the drawback that the films produced are prone to yellowing. 

Modified polyfunctional aliphatic amines, amidoamines and fatty polyamides are covered for both CTBN/epoxy adducts or ATBN hardener systems (42,44). Examples of systems based on selected epoxy-anhydride (45), an amine-ether (46) and Lewis acid/amine complexes (47) augment this information base. Dicyandiamide (1-cyano guanidine) containing systems alone (48) and with melamine (49) and various proprietary accelerators (50-53) are shown to serve as latent, one-component film and paste adhesives with an excellent balance of adhesive properties. 

Hexamethylenetetramine (Hexamine) - te-tr9- inen [ISV hexa- + methylene + tetra-+ amine] (1888) (HMT, methenamine, and urotropine) n. (CH2)6-N4. A bicyclic compound, the reaction product of ammonia and formaldehyde. It is used as a basic catalyst and accelerator for phenolic and urea resins, and a solid, catalytic-type curing agent (hardener) for epoxies See image). 

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