Patent Grant
8030431
The invention relates to curable mixtures formed from aromatic cyanates or cyanate/epoxide mixtures, aromatic amines and optionally catalysts for the preparation of polytriazine-based thermosetting materials. It additionally relates to the thermosetting substances obtainable by curing these mixtures and to their use in the preparation of molded items.
The polytriazines obtainable from bi- or polyfunctional aromatic cyanates and the thermosetting materials obtainable from the abovementioned cyanates and epoxy resins are valuable materials because of their outstanding heat-resistance and good dielectric properties. In each case, the term polyfunctional cyanates, polyfunctional epoxides or polyfunctional amines is understood to mean, here and subsequently, compounds comprising three or more cyanate, epoxy or amino groups in a molecule.
It is true that it is also possible to cure the abovementioned starting materials by a purely thermal route but the curing is usually carried out by addition of catalytically effective transition metal compounds, such as, for example, cobalt or copper acetylacetonate or zinc octanoate (“zinc octoate”). However, because of their toxicity and/or danger to the environment (in particular in the disposal of materials prepared with them), and the possible influencing of the electrical and magnetic properties, these are per se undesirable.
It was accordingly an object of the present invention to make available alternative additives for the curing of aromatic cyanates and cyanate/epoxide mixtures which do not exhibit the abovementioned disadvantages.
This object is achieved according to the invention by the curable mixtures as of the invention. It has been found surprisingly that, by the use of aromatic amines as curing agent of bi- or polyfunctional cyanates or their mixtures with epoxides, not only can catalysts comprising heavy metals be dispensed with but also products with outstanding properties are obtained after curing. Thus, the glass transition temperature (Tg) in particular is markedly increased and the cured products exhibit an improved impact strength. In addition, the through-curing is improved and the curing pattern, in particular the latency in the curing, is improved.
The curable mixtures according to the invention comprise at least the following constituents:
Transition metal compounds are to be understood as meaning both salts and coordination compounds, the transition metals in particular being able to be first row and second-row transition metals. This includes, for example, coordination compounds, such as cobalt or copper acetylacetonate, or salts, such as zinc octanoate or zinc stearate.
Boron trihalides are in particular boron trifluoride and boron trichloride.
Use is preferably made, as bi- or polyfunctional aromatic cyanates, of those from the group consisting of the compounds of the general formulae
in which R1 is hydrogen, methyl or bromine and X is a divalent organic radical chosen from the group consisting of —CH2—, —CH(CH3)—, —C(CH3)2—, —C(CF3)2—, —O—, —S—, —SO2—, —C(═O)—, —OC(═O)—, —OC(═O)O— and
in which n is a number from 0 to 10 and R2 is hydrogen or methyl; and
in which n has the abovementioned meaning. Mixtures of these compounds, prepolymers of these compounds, prepolymers formed from mixtures of these compounds and mixtures formed from prepolymers of these compounds can likewise also be used. Prepolymers are to be understood as the oligomers obtainable by partial trimerization. These comprise both triazine groups produced by trimerization and unreacted cyanate groups. The cyanates are known compounds and are in many cases available commercially; likewise, the prepolymers are known and are in some cases available commercially or can be readily prepared from the cyanates.
Use is preferably made, as epoxy resins, of those from the group consisting of the compounds of the general formulae
in which R1 and X have the abovementioned meanings, and the corresponding oligomers;
in which n and R2 have the abovementioned meanings:
and
in which n has the abovementioned meaning. These compounds are also known and are available commercially from various manufacturers.
Use is preferably made, as aromatic amines, of those from the group consisting of the compounds of the general formulae
in which R3, R4 and R5 are, independently of one another, hydrogen, C1-4-alkyl or halogen, and
in which R6, R7 and R8 are, independently of one another, hydrogen or C1-4-alkyl. These compounds are also known and are in many cases available commercially. Compounds of the formula VII are, for example, used as chain extenders in polyurethanes and those of the formula VIII as amine component in polyureas or as starting materials for the preparation of isocyanates.
The polytriazine-based thermosetting substances obtainable by thermal curing of the mixtures described above, optionally with addition of fillers and/or auxiliaries, are likewise a subject matter of the invention. Fillers and auxiliaries are to be understood as in particular reinforcing materials in the form of fabrics, fibers or particles, colorants or other additives for obtaining particular mechanical, optical, electrical or magnetic properties or for improving the processing characteristics. These fillers and auxiliaries are known to a person skilled in the art.
The use of the thermosetting substances thus obtainable in the preparation of molded items for electronic equipment, aircraft, spacecraft, road vehicles, rail vehicles, watercraft and industrial purposes is an additional subject matter of the invention.
The following exemplary embodiments clarify the invention without a limitation to be seen therein.
Mixtures of cyanates (Primaset® PT 15 from Lonza AG; formula II, R2=H, viscosity 20-30 Pa·s at 80° C.), optionally epoxide (Dow DER 330; formula IV, R1=H, X=—C(CH3)2—), and amine (Lonzacure® DETDA from Lonza AG, formula VIII, R6=R7=Et, R8=Me, mixture of isomers) were prepared and thermally cured. The glass transition temperature (Tg) was determined from the cured test specimens by thermomechanical analysis. The mixing proportions, curing conditions and glass transition temperatures are summarized in the following table 1.
1)after complete curing (2nd measuring cycle)
Processing was carried out as described in the above examples but using Lonzacure® M-CDEA (formula VII, R3=R4=Et, R5=Cl) as amine. The results are summarized in the following table 2.
1)after complete curing (2nd measuring cycle)
Processing was carried out as described in examples 9-12 but using the cyanate Primaset® CT 90 (formula II, R2=Me, softening point >60° C.) instead of the cyanate Primaset® PT 15. The results are summarized in the following table 3.
1)after complete curing (2nd measuring cycle)
| Number | Date | Country | Kind |
|---|---|---|---|
| 01124967 | Oct 2001 | EP | regional |
This is a 371 national stage application of International Patent Application No. PCT/EP02/11662, filed on Oct. 18, 2002, that has priority benefit of both European Patent Application No. 01124967.9, filed on Oct. 19, 2001 and U.S. Provisional Application No. 60/330,424, filed on Oct. 22, 2001.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP02/11662 | 10/18/2002 | WO | 00 | 4/16/2004 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO03/035718 | 5/1/2003 | WO | A |
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| 5206321 | Hefner et al. | Apr 1993 | A |
| 5371178 | Nguyen | Dec 1994 | A |
| 5494981 | Gorodisher et al. | Feb 1996 | A |
| 20020095007 | Larock et al. | Jul 2002 | A1 |
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|---|---|---|
| 1055524 | Jan 1967 | GB |
| 93-17059 | Sep 1993 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20040254329 A1 | Dec 2004 | US |
| Number | Date | Country | |
|---|---|---|---|
| 60330424 | Oct 2001 | US |
