Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1996-06-06
1999-03-09
Seidleck, James J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
523506, 523509, 524492, 524297, 524313, C08K 334, C08L 6700
Patent
active
058801812
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/EP94/04249 filed Dec. 21, 1994.
The present invention relates to gels of organic peroxides and the use of said gels in the curing of thermoset resins.
The application of organic peroxides in thermoset resins was attended with some problems in the past when mixing small quantities of a liquid or powdered organic peroxide or formulations thereof into the resins. These problems led to the development of organic peroxide paste formulations.
In the past, these organic peroxide paste formulations were packaged in tubes. Such packaging would enable a skilled man to meter small quantities into thermoset resins. However, the dispensing still remained troublesome and inaccurate. The introduction of the cartridge some 15 years ago was a breakthrough in this respect. Nowadays, these cartridges comprising an organic peroxide paste formulation vary from very simple hand-operated types to automatically controlled dispensers adjusting the organic peroxide dosing level to regulate the curing speed.
The use of these cartridges requires certain properties of the organic peroxide paste formulations, such as no separation of liquid from the formulation and consequent leakage from the cartridge and no unwanted discharge of the paste from open cartridges.
It has now been found that the presently known organic peroxide paste formulations do not perform as required in cartridges.
Netherlands patent application 70 06273 discloses a transparent paste comprising an organic peroxide, a phlegmatizer, and a gel-forming agent, e.g., hydrogenated castor oil. U.S. Pat. Nos. 3,806,477 and 3,859,240 disclose pastes comprising a ketone peroxide, a phlegmatizer, and a gel-forming colloid, e.g., a cellulose ester or a silica aerogel. No mention is made of mixtures of the exemplified gel-forming colloids. U.S. Pat. Nos. 3,795,630 discloses stable peroxide compositions comprising an organic peroxide, a phlegmatizer in which the organic peroxide is not soluble, and a hydrophobic, alkyl groups containing silicon dioxide. U.S. Pat. No. 3,507,800 discloses compositions comprising organic peroxides, water, and a mutual solvent, which may be, among others, a phlegmatizer or a gel-forming material. German patent 1,567,857 discloses coloured pastes comprising organic peroxides, phlegmatizers, gelling agents, such as cellulose ethers, and a pigment. Finally, U.S. Pat. No. 3,182,026 discloses also a coloured organic peroxide composition comprising organic peroxides, phlegmatizer, pigment, and a gel-forming colloid, such as alkyl cellulose or finely divided silica.
These known pastes either are storage unstable, i.e., liquid separation occurs, and/or their thixotropic behaviour is such that dosing small quantities from a cartridge is difficult if not impossible.
Accordingly, one object of the present invention is to provide a composition comprising an organic peroxide which is storage stable. Another object is to provide a composition which has thixotropic properties.
The present invention relates to a gel comprising phlegmatizer, in solution A, and fumed silica.
These gels offer the advantages of essentially no phase segregation during storage and easy metering into thermoset resins because of their thixotropic behaviour. Furthermore, the organic peroxide is essentially solubilized. So, essentially no solid crystals are present in the composition and there is no crystal growth on storage.
Examples of organic peroxides to be used in the compositions of the present invention include hydroperoxides, such as cumene hydroperoxide; diacyl peroxides, such as, optionally substituted, dibenzoyl peroxide; peroxyester, such as tert-butyl peroxy benzoate and tert-butyl peroxy 2-ethylhexanoate; peroxyketals, such as 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane; and ketone peroxides, such as cyclohexanone peroxide, acetone peroxide, acetyl acetone peroxide, methyl ethyl ketone peroxide, and methyl isobutyl ketone peroxide. Preferred are ketone peroxides.
The phlegmatizers to be used in the compositions of the present invention ha
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Eijmans Jacobus Johannes Antonius
Torenbeek Reinder
Akzo Nobel nv
Mancini Ralph J.
Rajguru U. K.
Seidleck James J.
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