Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-07-13
2003-07-29
Lovering, Richard D. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C433S217100, C433S228100, C522S025000, C522S908000, C525S533000, C525S939000, C528S089000, C528S090000, C528S091000, C528S092000, C528S095000
Reexamination Certificate
active
06599960
ABSTRACT:
This application is the national phase under 35 U.S.C. §371 of PCT International Application No. PCT/EP98/07830 which has an International filing date of Dec. 2, 1998, which designated the United States of America.
The invention relates to storage-stable, cationically polymerisable preparations which have improved curing behaviour. The preparations are based on compounds containing epoxy groups and/or N-alkyl aziridino groups and/or vinyl ether groups.
It is well known that the polymerisation of cationically polymerisable compounds may be initiated by substances with acid properties (H.-G. Elias, “Makromoleküle”, Hüthig u. Wepf Verlag (1990)).
It is thus known from U.S. Pat. No. 3,842,019 that sulfonic acid salts such as, for example, CF
3
SO
3
Ag may be used as latent catalysts for the curing or polymerisation of cationically sensitive monomers, such as, for example, epoxides, vinyl ethers, N-vinyl compounds, aziridines, ethylenically unsaturated hydrocarbons and acetals.
Moreover, curable epoxy compositions are known from EP-A-0 083 130 which contain a metal salt catalyst corresponding to the formula M(XF
n
)
p
as hardener, wherein M is lithium or a metal of group II, X means boron, arsenic, antimony or phosphorus, n is equal to 4 if n means boron and n is 6 if X means arsenic, antimony or phosphorus, and p is 1 if M means lithium and 2 if M is a metal of group II. The metal salt catalysts are incorporated in the curable composition in a pre-prepared catalyst composition.
Finally, curable epoxy resins are known from JP-A-52080399 which contain imidazolium salts and anion acceptors, such as, for example, metals, carboxylic acid salts of metals, etc., for improving curing.
It is important for the use of cationically polymerisable preparations that polymerisation begins at the desired time and is ended with a curing pattern that depends on the application in question.
For the production, storage and use of cationically polymerisable preparations, it is necessary to prevent unwanted premature polymerisation and to obtain the desired pattern of the degree of conversion/time curve after initiation.
The object is achieved by cationically polymerisable preparations which are characterised in that they contain 0.0005 to 50 wt. % of soluble and/or fine-particle organic and/or inorganic alkaline earth and/or alkali metal compounds.
Surprisingly, it was ascertained that the retarding effect of the soluble and/or fine-particle organic and/or inorganic alkaline earth and/or alkali metal compounds is greatly reduced as polymerisation proceeds. This retarding effect at the beginning of cationic polymerisation and its reduction as polymerisation proceeds may be utilised both to prolong the pot life once initiation has taken place and to produce storage-stable cationically polymerisable preparations without the disadvantage of a reduced degree of conversion. The use according to the invention of the above-mentioned alkaline earth and/or alkali compounds permits the production of storage-stable cationically polymerisable preparations and, moreover, adjustment of the curing pattern and, more particularly, of the pot life of the initiated preparation at ambient temperature and of the time required to achieve further processability of the cured material.
The cationically polymerisable compounds according to the invention are based preferably on monomers containing epoxy groups and/or N-alkyl aziridino groups and/or vinyl ether groups.
Suitable monomers containing epoxy groups are aromatic, aliphatic and cycloaliphatic epoxy compounds. Typical representatives of said monomers are the glycidyl ethers of bisphenols or novolaks and of aliphatic alkanols, alkane diols or polyether diols.
The monomers containing cycloaliphatic epoxy groups are selected preferably from the group (1) comprising the diepoxides of cycloaliphatic esters having the general structure
wherein the substituents R
1
to R
18
may be the same or different and independently of one another mean H, alkyl with 1 to 12 carbon atoms or aryl with 6 to 15 carbon atoms, (2) comprising products of the reaction of epoxidised cyclohexane derivatives of the alcohol and acid type with aliphatic dicarboxylic acids or diols and (3) comprising cycloaliphatically substituted dioxyspiro alkanes.
Cycloaliphatic diepoxy compounds used in particular preference are 3,4-epoxycyclohexylmethanol-3′,4′-epoxycyclohexylcarboxylate and 3-(3′,4′-epoxycyclo-(hexyl)-8,9-epoxy-2,4-dioxyspiro(5,5)undecane.
These and other cycloaliphatic diepoxides which may be used according to the invention are described, for example, in EP-B-0 119 425.
The production and cationic polymerisation of N-alkylaziridino compounds is by no means new and is summarised by H. Bestian in “Methoden der Organischen Chemie” (Houben Weyl) XII/1 (1958). DE-C-17 45 810 describes the synthesis of aziridino polyethers and the production of moulded articles on the basis of cationic polymerisation of said aziridino polyethers. Aziridino polyethers are used in dental preparations and, more particularly, in impression materials.
The cationic polymerisability of vinyl ethers is by no means new and is utilised nowadays for surface treatment, for example, in coating compounds with very high reactivity. Typical representatives of monomeric vinyl ethers are: monovinyl ethers of aliphatic, branched and unbranched alcohols such as n-butylvinyl ether, octadecylvinyl ether, cyclohexylvinyl ether, tert.-amylvinyl ether, butane diol monovinyl ether, divinyl ethers of ethylene glycol and various oligoethylene glycols, and hexane diol and trivinyl ethers of trimethylol propane.
The types mentioned and individual representatives of cationically polymerisable monomers may be used on their own and in mixture.
When making a selection, however, both the differing reactivity and the complicating factor that cationic polymerisation may take place at different calionic centres have to be taken into account.
The preparations according to the invention also contain the compounds suitable for initiating polymerisation. Depending on the number of components into which the preparations have to be divided up in order to obtain sufficient storage stability, and depending on the properties of the monomers, various classes of compounds may be considered.
Using soluble and/or fine-particle organic and/or inorganic alkaline earth and/or alkali compounds according to the invention, it is possible to produce one-component storage-stable preparations containing both the individual monomers described or mixtures of individual types of monomers and individual representatives as well as photoinitiators of the onium compound and/or metallocenium compound type—in each case with a complex anion having a weak nucleophilic effect.
Typical representatives of onium compounds which decompose on irradiation with light in a wave length from 280 to 400 nm are bisaryliodonium compounds and trisarylsulfonium compounds.
The metallocenium cation may have a variety of structures, as shown, for example, in EP-A-0 542 716. For use in the materials according to the invention, however, it is expedient to select those cations which decompose to form Lewis acids or Brönsted acids on irradiation with light in a wave length from 300 to 550 nm. This condition may be fulfilled in an industrially useful manner by metallocenium compounds with iron as the central atom.
The anions used may be, for example, the hexafluorophosphate or the hexafluoroantimonate anion. Also suitable are complex borate anions having the general structure
wherein the substituents A, E, C, D may be the same or different and mean aryl or perfluoroaryl. An anion used in preference is tetrakis(pentafluorophenyl)borate.
The compounds used as photoinitiators are used preferably in concentrations from 0.1 to 2 wt. %, particularly preferably 0.4 to 1.0 wt. %, of the preparations in question.
The one-component preparations containing alkaline earth and/or alkali compounds according to the invention are characterised by good storage stability, which may be adjusted to values
Eckhardt Gunther
Lechner Gunther
Somnitz Ursula
Wanek Erich
Birch & Stewart Kolasch & Birch, LLP
Espe Dental AG
Lovering Richard D.
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