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Latent Curing Agent “AJICURE”

The inquiry about this product

One-package Epoxy Resin

Epoxy resins are widely employed as electric insulating materials, various molded products, adhesives or coatings. They provide superior chemical resistance ; resistance to elevated temperature ; excellent electrical insulation as well as adhesion to metal, glass and ceramics ; low moisture absorption ; and rigidity. Generally, the epoxy resins are cured by curing agents for example aromatic or aliphatic amines, amides, polyamides, acid anhydride etc. The epoxy resin and curing agent may constitute a two part system in which the two components are stored separately and they are mixed in the correct quantity just prior to use. One part system, so-called one-package epoxy resin have considerable advantages over two part systems in that they are easier to use, can be used continuously and not suffer from the attendant difficulties associated with two part systems. One-package epoxy resins require a so-called latent curing agents which does not react with epoxy resins at room temperature, but react with epoxy resins on heating. Representative compounds which have been proposed as latent curing agent is dicyanodiamide(DICY). Formulated epoxy / DICY composition have excellent storage stability but it must be heated at high temperature, more than 180deg.C , for long time. To improve the curing conditions, various accelerators are being employed, but conventional accelerators impair storage stability. For many years in epoxy resin industry attempts have been made to ensure that one component composition possess a long pot life and at the same time a short cure time.

Latent Curing Agents and Accelerator “AJICURE”

AFT have developed various kind of latent curing agents and curing accelerators. Now, we describe the feature and use of our representative curing agent “AJICURE” PN-23 and “AJICURE” MY-24 as epoxy resin hardener and promoters for epoxy / DICY or epoxy / acid anhydride compositions. “AJICURE” PN-23 and MY-24 are both micro-ground powders which consist of amine adducts with epoxy resin, derived from the reaction of a compounds having tertiary amino group and epoxy compounds. “AJICURE”, mixed and dispersed into epoxy resin, is essentially insoluble in epoxy resins under normal condition (at room temperature) so that the mixtures, “AJICURE” and epoxy resins, are stable and provide long pot life. When the mixture is heated at 80deg.C or 100deg.C, the powder of “AJICURE” dissolve into epoxy resin and cure. This curing reaction occur very rapidly. The initiation of curing reaction depends upon a simple phase change, which is very rapid compared to dissociation reaction of any other type of latent curing agent or accelerator, DICY or urea compounds.

Applications as curing accelerators

“AJICURE” PN-23 and MY-24 are very useful as accelerators for epoxy / DICY or epoxy / organic acid anhydride systems. Although these latent epoxy systems are being widely used because they have a fairly good storage stability, they must be heated at higher temperatures for a long time to accomplish the curing reaction. To improve the curing conditions, various accelerators like aromatic tertiary amines or imidazole derivatives are being employed, but these accelerators have a clear tendency to deteriorate the latency resulting in a very short pot life or shelf life. When either “AJICURE” PN-23 or MY-24 is incorporated into any of these latent systems as accelerator in the range from 0.5 phr to 5 phr, the latency of the systems is not adversely affected and is stable over a month at 40deg.C. Nevertheless, the systems can be cured at relatively lower temperatures in a short time ; that is, 100deg.C / 60min. or 120deg.C / 30min. in curing conditions. In latent cure epoxy or one-package epoxy systems, the cured properties are apparently determined to a large degree by the accelerator used. In this viewpoint “AJICURE” PN-23 and MY-24 have been examined and no significant adverse on heat resistance and mechanical properties are observed.

Application as curing agent

In addition to the use as accelerators as mentioned above, “AJICURE” PN-23 and MY-24 can be utilized as latent curing agent for epoxy resins either solely or in combination of both materials. When “AJICURE” PN-23 or MY-24 is formulated into epoxy resin (DGEBA) at a level of 20 phr, the mixture obtained has a long pot life and is stable for a month or over even at 40deg.C In addition to the long pot life, the mixture can be cured at 80 – 120deg.C in 30 – 60 min. providing a high Tg and good mechanical properties. In conclusion, “AJICURE” PN-23 and MY-24 are characterized by providing the feature as accelerator or curing agents ;

  • Easily dispersible to resins
  • Provide high storage stability and longer pot life
  • Can be cured at lower temperature in a short time
  • Provide good cured properties
  • Lower skin irritation
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“AJICURE” product list & typical properties

ProductStructure typeParticle sizeMelting pointRecommended
usage *
Pot life**Special feature
av.
(μm)
(softening point,
deg.C)
as
hardener
as
accelerator
PN-23 Amine
adduct
10-12 100-105 15-25 1-5 1 month Low
temp. rapid cure.
Accelerator for DICY.
PN-H Amine
adduct
11-13 120-125 15-25 1-5 2 months Modified
PN-23
for longer pot life.
PN-31 Amine
adduct
10-12 115-120 15-25 1-5 2 months Modified
PN-23
for longer pot life.
PN-40 Amine
adduct
10-12 105-110 15-25 1-5 3 months Modified
PN-23
for longer pot life.
PN-50 Amine
adduct
10-13 100-125 15-25 1-5 4 months Modified
PN-23
for longer pot life.
PN-23J Amine
adduct
2-4 100-105 15-25 1-5 2 weeks Micropulverized
PN-23
Faster cure.
PN-31J Amine
adduct
2-4 115-120 15-25 1-5 3 weeks Micropulverized
PN-31
Faster cure.
PN-40J Amine
adduct
2-4 105-110 15-25 1-5 1 month Micropulrerized
PN-40
MY-24 Amine
adduct
8-10 115-120 15-25 1-5 3 months Good
adhesion
Accelerator for acidanhydride
MY-25 Amine
adduct
8-10 110-150 15-25 1-5 4 months Modified
MY-24 for
longer pot life
AH-203 Amine
adduct
complex
10-12 115-120 15-25 1-5 1 month Modified
MY-24
Faster cure
AH-154 DICY
complex
-15 200-210 9 3 months Accelerated
DICY.
Easy to disperse.
AH-162 DICY
complex
-15 200-210 11 3 months Accelerated
DICY.
Long pot life.
VDH Dihydrazide 100mesh pass
>98%
120 41 not suitable 1 month Colorless
transparent
cured product
Can be used as a crosslinking
agent for acrylic
VDH-J Dihydrazide 2-4 120 41 not suitable 1 month
UDH Dihydrazide 30mesh pass
>98%
150 48 not suitable 3 months Low calorification
High exfoliation intensity
Low elastic modulus
UDH-J Dihydrazide 2-4 150 48 not suitable 3 months
* Recommended usage : with liquid epoxy resin having an epoxy equivalent weight of 190
** Pot life : period until initial viscosity doubles
  PN,MY,AH series : 40deg.C pot life
  VDH,UDH series : 25deg.C pot life
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“AJICURE” Applications

Electric
& electronics
SMT
adhesives
Encapsulation
of relay-switch
Encapsulation
of electronic parts
Insulation
(coil)
Conductive
adhesives
Film
adhesives
Automotive Adhesives
Powder
coating
Epoxy
primer
Composites Sporting
goods etc
Other
Adhesives
Various
heat cure adhesives
Coating Acrylic emulsion crosslinking agent
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Technical Note

Technical data presented in this document are typical experimental values and do not signify any of the products’ specifications. The data may be revised without prior notice.

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The inquiry about this product
The Ajinomoto fine-techno are a company which bears the core of the fine-chemicals enterprise of Ajinomoto groups including insulating material "Ajinomoto Build-up Film"(ABF).
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