Mixtures containing at least one functionalized low-molecular rubber A, at least one cross-linking agent B having groups which are reactive with respect to the functional groups of the rubber A, accelerators/catalysts C for the cross-linking reaction between A and B, possibly reactive diluents D, vulcanization chemicals E, and also fillers F and auxiliary substances G, with at least one of the average functionalities of the constituents A and B being at least 2, and their use as anti-corrosive coating agents.

The invention relates to hard-rubber coatings for protection against corrosion.
Hard-rubber coatings or rubberlinings have been used for decades as protection against corrosion for steel surfaces and concrete surfaces. For this purpose, unvulcanised or pre-vulcanised rubber sheets are traditionally glued on to the surface to be protected and subsequently, so far as required, vulcanised at an elevated temperature. With so-called factory rubberlinings, this last step takes place, as a rule, in an autoclave under excess pressure. A decisive cost factor in the case of this method is the high expenditure on time and work that is required for the lining of the often geometrically demanding structural components.
It is therefore desirable to find a system which can be applied by simple methods (such as spraying or rolling, for example) and, apart from this, does not have to rely on the additional use of adhesives.
For some years, so-called xe2x80x9cliquid hard rubbersxe2x80x9d with a content of low-molecular polybutadienes have been known, which, in contrast to conventional rubber mixtures, are viscous liquids. After vulcanisation, the coatings produced therewith have the properties of a hard rubber.
A system described in DE-A 37 40 181 is based on a low molecular 1,4-cis-polybutadiene, to which, in addition to fillers and vulcanisation chemicals, is also added a highly aromatized polybutadiene, partly in combination with a copolymer of isobutylene and isoprene, in order to improve resistance to chemicals and mechanical properties. A similar system, likewise based on linear 1,4-cis-polybutadiene, was described by O. Figovsky et al. (Proceedings of International Conference: Corrosion in Natural and Industrial Environments: Problems and Solutions, Grado, 1995).
The use of epoxidized low-molecular polybutadienes as a base for liquid hard rubbers is suggested in WO-A 98/22225. In this case, in addition to the vulcanisation process by means of sulphur, a cross-linking as a result of reaction of the epoxide groups with amines is also to take place. An improvement in the mechanical properties is achieved by the addition of a high-molecular butadiene-nitrile rubber.
The flow processes which occur during heating are a fundamental problem in the use of liquid rubbers. Above all in the case of comparatively thick layers, they lead to not yet cross-linked or vulcanised mixture running off non-horizontal surfaces. Mixtures described hitherto, which are adjusted by admixtures or other mixing ratios in such a way that this problem is slightly less pronounced, can be processed only with difficulty because of their high viscosity.
It is therefore the object of the present invention to make available a liquid hard-rubber coating agent which has a low viscosity suitable for spray application and which displays no run-off from non-horizontal walls, or as little run-off as possible, in the case of the subsequent heating required for vulcanisation.
Surprisingly, it has been discovered that this requirement can be fulfilled if a coating agent based on liquid rubbers, optionally in combination with a reactive diluent of low viscosity, is, immediately after application, solidified to such an extent as a result of a prepolymerization or pre-cross-linking preceding the vulcanisation that a run-off is substantially or completely prevented. In order to do this, functionalised rubbers are used having those reactive groups that react with an added chain extension agent or cross-linking agent, forming preferably covalent bonds, and thereby forming lengthened or branched molecules.
Therefore, mixtures containing the indicated mass fractions of the following constituents are the subject-matter of the invention:
wherein the sum of the mass fractions in the mixture must always be 100%, and at least one of the average functionalities of the constituents A or B is at least 2. xe2x80x9cMass fractionxe2x80x9d denotes the ratio of the mass of an individual component to the total mass.
Preferably, the mass fraction of A amounts to 15 to 60%, in particular 20 to 50%; that of the cross-linking agent B amounts to 1.5 to 45%, in particular 2 to 40%; that of the accelerators C amounts to 0.02 to 7%, in particular 0.05 to 5%; that of the reactive diluents D amounts to 2 to 55%, in particular 5 to 50%; that of the vulcanisation chemicals E amounts to 2 to 45%, in particular 5 to 40%, and finally the sum of the mass fractions of fillers and auxiliary substances F and G amounts to 7 to 45%, in particular 10 to 40%.
The presence of the cross-linking agent B is required for the pre-cross-linking or pre-polymerization (=chain lengthening) of the low-molecular rubber. The expression cross-linking agent is used in the following for reasons of simplification; in this connection, however, it can also be, in principle, a compound (chain-lengthening agent) which in combination with a rubber A leads only to the formation of a linear polymer.
The functionalised low-molecular rubber A and the cross-linking agent B for this rubber are contained separately from each other in different components of a two-component system, while the other constituents C to G can be distributed between the two components in any desired way. The accelerator C for the pre-cross-linking or the pre-polymerization is advantageously also separated from the cross-linking agent B if its stability is impaired thereby.
The functionalised low-molecular rubber A is preferably one or more of (co)polymerizates of monomers selected from doubly saturated or multiply unsaturated hydrocarbons, in which case singly olefinically unsaturated monomers, such as styrene, acrylic ester and acrylonitrile, for example, can additionally be present in the monomer mixture if appropriate. The rubbers A have olefinic double bonds along the main chain and/or in side chains, which double bonds are accessible to the usual vulcanisation with sulphur. Additionally, these functionalised low-molecular rubbers A also have reactive groups at the chain ends (terminal) and/or in side chains (lateral), which groups react with the cross-linker B forming oligomers or partially cross-linked systems. In this connection, the reactive groups of the cross-linking agent B are such that they react with the reactive groups of the rubber A, preferably forming covalent bonds. The functional groups of the low-molecular rubber A and those of the cross-linking agents B are therefore selected in each case from the group consisting of hydroxyl groups, epoxide groups, carboxylic acid anhydride groups, carboxyl groups, amine groups and isocyanate groups, and A and B are combined in such a way that upon the reaction of A and B, their functional groups react, forming a urethane bond xe2x80x94NRxe2x80x94COxe2x80x94Oxe2x80x94, an ester bond xe2x80x94COxe2x80x94Oxe2x80x94, a urea bond xe2x80x94NRxe2x80x94COxe2x80x94NRxe2x80x94, a xcex2-hydroxyamine bond xe2x80x94CR(OH)xe2x80x94NRxe2x80x94, or an acid amide bond xe2x80x94COxe2x80x94NRxe2x80x94. The radical R in these formulae can be the same or different and signify hydrogen, linear, branched or cyclic aliphatic radicals with preferably 1 to 20 carbon atoms or aromatic radicals with preferably 5 to 16 carbon atoms.
In this connection, those mixtures in which the rubber A is hydroxy-functional and the cross-linking agents B have functional groups selected from isocyanate groups, acid anhydride groups and epoxide groups are preferred.
It is advantageous that the average functionality of the rubbers A is 1.5 to 5.5 and that the average functionality of the cross-linking agents B is 5.0 to 1.9. In particular, those combinations in which the average functionality of A is 1.8 to 2.3 and that of the cross-linking agents B is 4 to 2.0 are advantageous. By xe2x80x9cfunctionalityxe2x80x9d is understood here and in the following the (average) number of the functional groups in one (polymer) molecule.
The reaction which starts immediately after the mixing of A and B or after heating of the mixtures of A and B and also the further additives that have been applied to the substrate, effects an increase in viscosity by a factor of at least 3, preferably to more than the 10-fold, with respect to the mixture which has not yet reacted. This can be shown, for example, by putting the mixture in a rotation viscosimeter and recording the viscosity as a function of the time (and optionally of the temperature).
The low-molecular rubbers A are preferably selected from the group consisting of polybutadiene, polyisoprene, polybutadiene copolymers (for example copolymers of 1,4-butadiene with styrene or acrylonitrile) or polyisoprene copolymers, which are functionalised with reactive groups such as hydroxyl groups, epoxide groups, carboxylic-acid anhydride groups, carboxyl groups, amino groups, isocyanate groups or a combination of these. On average, there are more than one, preferably two or more functional groups per molecule (in the case of the amines and carboxylic-acid anhydride groups, this relates to the xe2x80x94Nxe2x80x94Hxe2x80x94 group and xe2x80x94COOHxe2x80x94 group respectively, a primary amine thus producing two reactive xe2x80x94Nxe2x80x94Hxe2x80x94 groups and a carboxylic-acid anhydride group producing two reactive acid groups).
The polybutadiene or polybutadiene copolymers can be either linear or branched polymers. The proportion of 1,4-trans-, 1,4-cis- and vinyl configuration in the butadiene units can vary and offers an additional possibility of controlling the viscosity of the polymer and the properties of the (vulcanised) end product. The polyisoprene or polyisoprene copolymer can be either linear or branched polymers. The proportion of 1,4-trans- or 1,4-cis-configuration in the isoprene units can vary. In all of the above-mentioned rubbers, the preferred number average molar mass (Mn) lies between 500 and 10,000 g/mol. The functionalised polybutadienes, polyisoprenes, butadiene copolymers and isoprene copolymers which are used can also be hydrogenated or partially hydrogenated.
Particularly preferred are mixtures in which a homopolymer or copolymer of butadiene or isoprene with functional groups selected from hydroxyl groups, carboxylic-acid anhydride groups and epoxide groups is used as the rubber A.
In another preferred variant, the rubber A is selected from the group consisting of partially hydrogenated polybutadiene, partially hydrogenated copolymers of butadiene, partially hydrogenated polyisoprene, partially hydrogenated copolymers of isoprene, with functional groups selected from hydroxyl groups, carboxylic-acid anhydride groups and epoxide groups.
Also suitable, for example, are functionalised low-molecular butyl rubbers, bromobutyl rubbers, chlorobutyl rubbers, polyocteneamers or EPDM rubbers.
All of these rubbers are used alone or also in combination with each other, provided that the combination does not lead to an unwanted pre-cross-linking.
The cross-linking agents B for the functionalised rubber are compounds which are functionalised with
hydroxyl groups (B1) or
epoxide groups (B2) or
carboxylic-acid anhydride groups (B3) or
carboxyl groups (B4) or
amine groups (B5) or
isocyanate groups (B6)
or a combination of these (in so far as the different reactive groups do not already react with each other). On average, there are more than one, preferably two or more functional groups per molecule (in the case of the amines and carboxylic-acid anhydride groups, this relates, as explained above, to the xe2x80x94Nxe2x80x94Hxe2x80x94 group and xe2x80x94COOHxe2x80x94 group respectively). The cross-linking agents can also be polymeric or oligomeric compounds. The decisive factor is that the cross-linking agent can enter into a reaction with the functional groups of the low-molecular rubber, which reaction leads either to the formation of a three-dimensional network or to the formation of a polymer with a viscosity which is clearly increased with respect to the mixture of the educts (A and B).
The cross-linking agent B can also be a mixture of different suitable compounds. Polymeric cross-linking agents B might, for example, be chosen from the above-described functionalised rubbers, which can enter into a reaction with functionalised rubbers A, in which case the functional groups of B and A must be chosen in such a way that the two kinds can react with each other (for example, functional groups of A are epoxide groups and the functional groups of B are amino groups; or a hydroxy-functionalised polybutadiene as low-molecular rubber A and a maleinated polybutadiene as cross-linking agent B or vice versa).
All alcohols which contain more than one hydroxyl group per molecule are suitable hydroxyl-group-containing cross-linking agents B1. They can be both saturated and unsaturated, as well as aliphatic, cycloaliphatic, polycyclic, aromatic or heterocyclic and can also additionally have other functional groups, such as amino groups, for example. Polymers which contain terminal or lateral hydroxyl groups, such as polyglycol ether, polyester, copolymers of hydroxyl-functionalised methacrylates or acrylates, copolymers of hydroxyl-functionalised olefines, hydroxyl-functionalised rubbers or hydroxyl-functionalised polyolefines, for example, are also mentioned among these compounds. The polymers can have a linear, branched, hyper-branched or dendritic structure.
Examples of polyhydric alcohols are 1,2-dihydroxyethane, 1,2-dihydroxypropane, 1,3-dihydroxypropane, 1,4-dihydroxybutane, 1,5-dihydroxypentane, neopentyl glycol, 1,6-dihydroxyhexane, 4,8-bis-(hydroxymethyl)-tricyclo[5.2.1.02,6 ]decane, 1,4-dihydroxycyclohexane, diethylene glycol, dipropylene glycol, higher polyoxyalkylene glycols, glycerine, trimethylol propane, trimethylol ethane, pentaerythritol, sorbitol, oxalkylated polyols (such as oxalkylated trimethylol propane, oxalkylated pentaerythritol, among others, which can be obtained by reacting polyols with 1,2-epoxy alkanes in a known manner), cyclohexane dimethanol, bis-(4-hydroxycyclohexyl)methane, bis-(4-hydroxycyclohexyl)propane, N-methyldiethanolamine, N-butyldiethanolamine, N,N-(dihydroxyethyl)aniline, N,N-bis-(hydroxyethyl)toluidine, 1,4-bis-(hydroxyethyl)piperazine, triethanolamine or triisopropanolamine. The alcohols can be used both in pure form and in the form of mixtures.
All epoxide resins which contain more than one epoxide group per molecule can be used as epoxide-functional cross-linking agents B2. They can be both saturated and unsaturated, as well as aliphatic, cycloaliphatic, aromatic or heterocyclic and can also have other functional groups, such as hydroxyl groups, for example. Suitable epoxide resins are, for example, those which are obtained from diphenylol alkanes or higher polyphenylol alkanes, such as novolaks and epichlorohydrin or dihalohydrins, preferably epichlorohydrin, by the so-called Taffy reaction. The known epoxide resins based on bisphenol A or bisphenol F, in particular liquid resins, or mixtures thereof, are particularly preferred. Apart from this, those epoxide resins which are produced by reaction of epihalohydrins with polyhydric alcohols or polyether glycols (for example epoxide resins derived from polypropylene glycols) or by epoxidation of double-bond-containing compounds, for example by epoxidation of unsaturated fatty oils or unsaturated hydrocarbons such as dicyclopentadiene, butadiene, polybutadiene etc, can be used. Furthermore, poly-(N-glycidyl) compounds come into question, which compounds can be obtained by dehydrohalogenation of the reaction products of epichlorohydrin and aliphatic, araliphatic or aromatic mono-functional or poly-functional primary amines. Likewise, those compounds which are derived from isocyanuric acid, from cyclic ureas or from aminoplast formers such as melamine or guanamines are also mentioned among the poly-(N-glycidyl) compounds. Apart from this there can also be used polyglycidyl esters or polycarboxylic acids, which are obtained by reacting epichlorohydrin or similar epoxide compounds with aliphatic, cycloaliphatic or aromatic polycarboxylic acids. Further suitable compounds are glycidyl-ester-group-containing copolymers, which are obtained by copolymerization of, for example, glycidyl methacrylate with other methacrylic-acid esters or acrylic-acid esters or by copolymerization with styrene. Adducts of an epoxy resin with an amine or amino-functionalised oligomer or polymer are also suitable. The epoxides can be used both in pure form and also in the form of mixtures.
All carboxylic-acid anhydrides which are derived from dibasic or polybasic carboxylic acids are suitable carboxylic-acid-anhydride-functional cross-linking agents B3. They can be both saturated and unsaturated, as well as aliphatic, cycloaliphatic, aromatic or heterocyclic and can also additionally have other functional groups. Polymers which contain terminal or lateral carboxylic-acid anhydride groups, such as maleinated rubbers, maleinated oils or fats or maleinated polyolefines, for example, are also mentioned among these compounds. The polymers can have a linear, branched, hyper-branched (with branches on lateral branches) or dendritic structure. Examples of carboxylic acid anhydrides which can be used are hexahydrophthalic acid anhydride, phthalic acid anhydride, trimellitic acid anhydride, dodecenyl succinic acid anhydride, methyl-norbonene dicarboxylic acid anhydride, anhydrides of other carboxylic acids listed under B4 or maleinated polybutadiene or maleinated polybutadiene copolymers. The carboxylic acid anhydrides can be used both in pure form and also in the form of mixtures.
All carboxylic acids which contain more than one carboxyl group per molecule can be used as carboxyl-functional cross-linking agents B4. They can be both saturated and unsaturated, as well as aliphatic, cycloaliphatic, aromatic or heterocyclic and can also have other functional groups, such as hydroxyl groups, for example. Polymers which contain terminal or lateral carboxyl groups, such as polyesters, polyamides, polymers or copolymers of acrylic acid, polymers or copolymers of methacrylic acid, carboxyl-functionalised rubbers or carboxyl-functionalised polyolefines are also mentioned among these compounds. The polymers can have a linear, branched, hyper-branched or dendritic structure.
Alkane diacids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid or sebacic acid, and phthalic acid, terephthalic acid, isophthalic acid, cyclohexane dicarboxylic acid, tetrahydrophthalic acid, maleic acid, tartaric acid, trimesic acid or trimellitic acid, for example, can be used. The carboxylic acids can be used both in pure form and also in the form of mixtures.
All amines which contain more than one Nxe2x80x94Hxe2x80x94 functionality per molecule are suitable amino-functional cross-linking agents B5. They can be both saturated and unsaturated, as well as aliphatic, cycloaliphatic, aromatic or heterocyclic and can also have other functional groups, such as hydroxyl groups, for example. Polymers which contain terminal or lateral amino groups, such as polyamides, polyamidoamines, polyalkylene amines or copolymers of amino-functionalised acrylates or methacrylates, for example, are also mentioned among these compounds. The polymers can have a linear, branched, hyper-branched or dendritic structure.
Examples of amines which can be used are methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, tridecylamine, isopropylamine, sec.-butylamine, tert.-butylamine, 2-ethylhexylamine, trimethylhexamethylenediamine, cyclopentylamine, cyclohexylamine, 2-phenylethylamine, 1-phenylethylamine, benzylamine, m-xylylenediamine, aniline, toluidine, xylidine, ethoxyethylamine, ethoxypropylamine, methoxyethylamine, 3-(2-ethylethoxy)propylamine, (methoxyethoxy)propylamine, ethylenediamine, 1,3-propanediamine, 1,4-diaminobutane, hexamethylenediamine, 1,2-propanediamine, neopentanediamine, methylpropanediamine, diaminodicyclohexylmethane, dimethyldiaminodicyclohexylamine, diaminodiphenylmethane, isophoronediamine, 3-(cyclohexylamino) propylamine, piperazine, 1-diethylamino-4-aminopentane, 2-(diethylamino)-4-aminopentane, 3-(diethanolamino)propylamine, 3-(dimethylamino)propylamine, N-(2-aminoethyl)morpholine, 1,12-diamino-4,9-dioxadodecane, 1,13-diamino-4,7,10-trioxatridecane, polyetheramines derived from polyethylene glycol or polypropylene glycol as well as mixed polymers thereof, diethylenetriamine, dipropylenetriamine, N-(2-aminoethyl)piperazine, N-(3-aminopropyl)-N-methylpropanediamine, N,N-dimethyldipropylenetriamine. Polynuclear amines which are derived from diaminodicyclohexylmethane or diaminodiphenylmethane, polyamidoamines based on diethylenetriamine or similar amines and fatty acids, amine-epoxide-resin adducts or polyamide-epoxide-resin adducts, for example, can also be used. Examples of suitable amines with hydroxyl groups are 2-aminoethanol, 2-aminopropanol, aminopentanol, isopropanolamine, (aminoethoxy)ethanol, (aminoethyl)ethanolamine, N-ethylethanolamine, N-butyl-ethanolamine, N-(2-hydroxyethyl)aniline, 1-(2-hydroxyethyl)piperazine, N-(2-hydroxyethyl)propane-1,3-diamine, diethanolamine, diisopropanolamine, and 3-(2-hydroxyethylamino)-1-propanol. The amines can be used both in pure form and also in the form of mixtures.
All aliphatic, aromatic, cycloaliphatic or mixed aromatic-aliphatic isocyanates with more than one isocyanate group per molecule are suitable as isocyanate-functional cross-linking agents B6. m-Phenylene diisocyanate, 2,4-toluylene diisocyanate, 2,6-toluylene diisocyanate, mixtures of 2,4- and 2,6-toluylene diisocyanate (TDI), hexamethylene diisocyanate (HDI), tetramethylene diisocyanate, trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate (H12-MDI), tetramethylxylylene diisocyanate (TMXDI), naphthalene-1,5-diisocyanate or 4,4xe2x80x2-diphenylmethane diisocyanate (MDI), for example, can be used. Furthermore, all isocyanurates, polyisocyanurates, polyisocyanates, pre-polymers, biurets, uretdiones and adducts which contain isocyanate groups or were produced on the basis of isocyanates such as the ones mentioned above can also be used. The isocyanates can be used both in pure form and also in the form of mixtures.
The pre-cross-linking reaction can be accelerated by suitable accelerators or catalysts C. The selection of the accelerators or catalysts which are used is directed according to the type of the pre-cross-linking reaction.
All accelerators which are used in the conversion of epoxides or a mixture of these are suitable accelerators for the pre-cross-linking by way of epoxide groups. These preferably include tertiary amines and imidazoles such as, for example, dimethylbenzylamine, dimethylcyclohexylamine, monoethanoldimethylamine, triethanolamine, trimethylaminoethylamine, tetramethylethylenediamine, Mannich bases (for example of phenol, dimethylamine and formaldehyde), 1-methylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole or N-alkylpiperidine. However, hydrogen donors such as salicylic acid or benzyl alcohol can also be used.
All catalysts which are used in the preparation of polyurethanes or a mixture of these are suitable catalysts for the additive reaction of the isocyanates. These include tertiary aliphatic, cycloaliphatic or mixed aromatic-aliphatic amines and organometallic compounds such as, for example, triethylenediamine, N-methyl morpholine, N-ethyl morpholine, diethyl ethanolamine, 1-methyl-4-dimethylaminoethylpiperazine, bis-(N,N-dimethylaminoethyl)ether, 3-methoxypropyldimethylamine, N,N,Nxe2x80x2-trimethyl-Nxe2x80x2-isopropylpropylenediamine, 3-diethylaminopropyldiethylamine, dimethylbenzylamine, as well as organic compounds of lead, iron, mercury, titanium, bismuth and tin.
All accelerators which find use in the conversion of carboxylic-acid anhydrides or a mixture of these are suitable accelerators for the pre-cross-linking by way of carboxylic-acid anhydride groups. These include, for example, tertiary amines and imidazoles, as are also used for the conversion of the isocyanate and epoxide groups, secondary amines such as dimethylamine, diethylamine or n-dibutylamine, as well as organic acids such as p-toluene sulphonic acid or alkylbenzene sulphonic acid.
The reactive diluents D are preferably compounds of low viscosity (i.e. with dynamic viscosities of 2 Paxc2x7s or below), which, upon vulcanisation at the latest, are bound into structures which are preferably polymeric and are not capable of migration. However, it is also possible that the compounds already react fully or partially with the cross-linking agent B or the liquid rubber A before the vulcanisation.
These reactive diluents can also be substances which are crystalline at room temperature, which dissolve in the overall mixture and thus effect a lowering of the viscosity. In this connection, the olefinically unsaturated compounds which contain one or more double bonds, such as, for example, styrene and its derivatives (for example vinyl toluene, divinyl benzene), unsaturated (cyclic) aliphatics (for example cyclododecatriene, terpenes, dicyclopentadiene), low-molecular rubbers (for example low-molecular polybutadienes or polybutadiene copolymers or polyisoprenes or polyisoprene copolymers preferably with a number average molar mass Mn of between 500 and 3000 g/mol), low-molecular acrylates or methacrylates (for example trimethylolpropane trimethacrylate, diurethane dimethacrylate, butanediol dimethacrylate, hexanediol dimethacrylate, dodecanediol dimethacrylate, glycerine di- and trimethacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, n-butyl methacrylate, i-butyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, benzyl methacrylate, tetrahydrofurfuryl methacrylate, methacrylic acid ester of longer-chained aliphatic alcohols with 7 to 40 carbon atoms, hydroxyl-functionalised methacrylates, amine-functionalised methacrylates, as well as the corresponding acrylates), allyl esters (for example diallyl diglycol carbonate, diallyl phthalate, diallyl isophthalate, triallyl cyanurate) or allyl ethers of monohydric or polyhydric aliphatic alcohols with 2 to 40 carbon atoms form an important group of compounds which can be used.
Epoxy resins of low viscosity can also be used, such as, for example, butanediol diglycidyl ether, hexanediol diglycidyl ether, 2,4-epoxycyclohexane carboxylic-acid-3xe2x80x2,4xe2x80x2-epoxycyclohexylmethyl ester, bis-(3,4-epoxycyclohexylmethyl)-adipate), N,N-diglycidyl aniline, p-tert.-butylphenol gylcidyl ethers or longer-chained aliphatic glycidyl ether resins. Furthermore, polyvalent alcohols or amines can also be used as reactive diluents, such as for example, are also listed as cross-linking agents B1 and B5.
The different compounds can be used both individually and in a mixture with each other as reactive diluent. The precise amount and composition of the reactive diluent is chosen according to the desired viscosity of the mixture, the required properties of the vulcanisate and the functional groups of the rubbers A of low viscosity and of the cross-linking agents B. Large amounts of reactive diluents lead to a very low viscosity, but can clearly impair the mechanical properties of the vulcanisate. On the other hand, the addition of the correct amounts of reactive diluent lead, in addition to a lowering of the viscosity, also to an improvement of the chemical and mechanical properties. The amounts used depend on the system of rubber and reactive diluent that is chosen in each case.
In the case of rubbers which are cross-linked by way of olefinic double bonds, the vulcanisation chemicals E are sulphur and/or one or more vulcanisation accelerators or activators, as also used in the production and vulcanisation of conventional rubber webs. Examples are thiazolesulphenamides, thiurams, dithiocarbamates, guanidines, metal oxides (preferably zinc oxide), stearic acid or stearate of zinc. The use of phenolic resins is also possible, however.
If double-bond-free rubbers such as silicone rubber, EPM-rubber, acrylic rubber, CSM (chlorosulphonated polyethylene) are used, then peroxides or metal oxides such as MgO or ZnO are used as vulcanisation agents.
Suitable, in general, as fillers F, are all substances which are also used for this purpose in conventional rubber mixtures and all mixtures of these. These are, above all, carbon blacks, coal dust, graphite, hard-rubber dust, silicic acids (with and without surface modification), polymer powders (for example PE, PP, PVC, PS, PTFE, solid-rubber powders or dispersions) or barium sulphate. However, fillers and pigments which are usually used in the field of coatings, such as layer silicates, glass flakes, organic and inorganic fibres, or even solid resins such as cyclic rubber, for example, can also be used.
Those mineral fillers or pigments which give the composition blocking-layer properties are particularly suitable. These are, in particular, plate-like (oblate) mineral fillers and pigments, such as, for example, layer silicates (talcum, mica, pyrophyllite), graphite, glass flakes, micaceous iron ore (haematite) and phthalocyanine pigments. If such pigments are used in the compositions in accordance with the invention, the diffusion at right angles to the layers formed from these fillers is impeded. With the same mass fraction of filler, compositions modified in this way display better resistance to chemicals than those with fillers, the shape of which is more spherical (globulate) or prolate (cigar-shaped).
Furthermore, auxiliary substances G can be used, the composition of which is selected according to the other constituents. Antioxidants, stabilisers (for example for PVC fillers or reactive diluents), de-aerators or adhesion promoters, for example, are mentioned among the auxiliary substances.
The mixing of the individual constituents of a component can take place by way of a mixing unit such as a dissolver, for example.
Advantageously, the two components of the two-component system are not added together and mixed with each other until shortly before or during application. The pot life depends substantially on the accelerators which are added. The mixing during application can preferably take place by means of simultaneous spraying of the two components via separate nozzles or combining nozzles. In the case of this type of application, there is no problem because of short pot life.
As a result of the application of the above-described mixtures on to substrates and subsequent pre-cross-linking (rise in viscosity) and finally vulcanisation, the substrates can be coated in a simple way, even in the case of complicated geometries, and protected against corrosive influences.
Particularly advantageous is a method for the coating of substrates, in which the above-described mixtures are applied to the surface of the substrates and in the first step, as a result of reaction of the component A with the component B, as a result of a suitable selection of the type and amount of the components in the mixture and selection of the temperature, the viscosity of the coating agent is increased within a short time, a maximum of 30 minutes, to at least the three-fold value, and subsequently the viscous coating is vulcanised by heating to a temperature of 120xc2x0 C. to 160xc2x0 C. If, for example, vessels or tanks are coated from the inside in this way, the layer which is applied does not run off from the perpendicular surfaces and also does not run off from overhanging surfaces.
A method in which the coating agent is applied with a two-component nozzle, one of the components being free of amounts of the rubber A and the other component being free of amounts of the cross-linking agent B, has proven particularly advantageous. Application by means of painting, rolling, casting, immersion or application by means of a spatula is also possible, however.
After the pre-cross-linking or pre-polymerization, the rubber coating layer, in the case of suitable adjustment (i.e. mass fraction of rubber preferably more than approximately 50%, depending on the type and amount of a reactive diluent which is possibly used), can be mechanically loaded, or even walked on, to a limited extent. This facilitates, for example, the application of a further layer. The time required depends on the combination of the components A and B, type and amount of the further additives and the temperature selected for the pre-cross-linking and the wet-film layer thickness, with suitable selection of the materials or mixtures of A and B and use of catalysts or accelerators for the reaction of the two component or mixtures, in the case of a wet-film layer thickness of approximately 750 xcexcm or above and a temperature of up to 60xc2x0 C., there is already no run-off from vertical walls after only a few minutes.
The vulcanisation of the rubber coatings can be carried out both at normal pressure and also under elevated pressure. Elevated pressure is recommended for completely pore-free coatings. Ideal vulcanisation temperatures lie between 120 and 160xc2x0 C. In this connection, a completed pre-cross-linking is not absolutely a prerequisite for avoiding a run-off from inclined surfaces during the vulcanisation process. Heating to the vulcanisation temperature that is not too fast is generally sufficient, because the corresponding reactions that lead to the increase in viscosity or cross-linking are also accelerated by the rise in temperature.
A further subject of the invention is the use of the above-mentioned formulations for protection against corrosion, predominantly the corrosion-resistant lining of a structural component consisting of a metal, in particular steel, such as containers, pipelines or suchlike, in which the hard-rubber coating is applied to the exposed surface of the structural component. These can be components in rubbish incineration plants, sewage treatment plants, process containers, supply containers and storage containers in the chemical industry as well as various structural steel elements in different branches of industry.
The following examples explain the invention:

Coating with functionalized rubber, crosslinker, accelerator/catalyst and vulcanizer


An identification bracelet which is adjustable so as to allow the user to continue to use the bracelet even if his wrist size changes is provided. The present invention comprises a chain and a clasp. The clasp, which provides a panel for engraving a name or message, may be opened so that the chain may be adjusted to make the bracelet larger or smaller. The clasp provides a plurality of anchor locations so that numerous different sizes of bracelet may be made. The clasp is generally made in two sections which are rotatably connected so that they may pivot apart, to provide access to the anchor locations, and pivot together to lock the end of the chain within the clasp. The clasp may subsequently be pivoted open again to adjust the size of the chain or for removal of the bracelet.

The present invention concerns a novel identification-type bracelet which may be adjusted to fit wrists of varying sizes.
Identification-type bracelets are a very popular type of jewelry, worn by men, women and children. Typically, an identification bracelet includes an elongated panel, generally made of precious metal, or plated with a precious metal, onto which a name or message may be engraved. Further, identification bracelets, in the form of Medic Alert(copyright) bracelets and others, are also used to speak for a wearer when the wearer cannot speak for himself. For example, persons having a disabling condition or medical allergies may wear identification bracelets so that in case of difficulties, in which the person is unable to communicate, medical help may be administered correctly. Also, a young child may be given a bracelet so that the child may be returned home if lost.
Identification bracelets generally also comprise a chain, or other supporting means such as a strap, used to hold the elongated panel on the wearer""s wrist. Typically the chain or strap is made of the same material as the elongated panel and is of a fixed length. Such chains generally are broken apart, with one part of the chain attached to each end of the elongated panel. The identification bracelet generally also comprises a clasp, generally having one part of the clasp on each of the free ends of the chain, for fixing the ends of the chain together on the wearer""s wrist. Generally, identification bracelets are worn loosely on the wrist, allowing the engraved panel to float to different positions, so as to be comfortable for the wearer and to lessen wear on the engraved panel.
Because of the name or message on the elongated panel, and the ceremony often associated with giving such a bracelet to a child or young adult, identification bracelets often have more meaning, and sentimental value, than other types of jewelry. Often times these types of bracelets are given to a child to celebrate a special occasion or accomplishment, and, unfortunately, the child eventually outgrows the bracelet. Once outgrown, these bracelets become unwearable keepsakes or are misplaced and maybe forgotten. Further, a busy lifestyle may distract the wearer of a medical type bracelet from ordering a replacement when the bracelet becomes tight; leading to non-use of this crucial informative device.
Often times, because of the special significance of the bracelet, the bracelet is worn long after the bracelet no longer comfortably fits the wearer such that it becomes tight on the wrist. The tight fit may cause stress on the chain and clasp elements of the bracelet and may cause extra wear on the elongated panel (which, as noted above, is designed to be worn loosely on the wrist). Such wear may cause deterioration of the panel, including wear on the inscribed portion (both when the inscribed portion is inadvertently inverted and rubs against the wearer""s skin and as a result of the panel not being able to float away from outside contact due to the tight fit). Strain on the chain and/or clasp may lead to the breaking of the chain and the subsequent loss of the bracelet.
It would be desirable to have a bracelet that could be worn by a child, or by a person who has a small wrist diameter, and then adjusted, as the diameter of owner""s wrist changes, so that the bracelet may, potentially be worn throughout the owner""s life.
It is therefore an object of the present invention to provide an identification bracelet that is adjustable such that it maybe worn by the owner as a child and throughout the owner""s life.
It is a further object of the present invention to provide a bracelet which may be adjusted so that the bracelet may fit comfortably whether the diameter of ones wrist increases or decreases.
It is a further object of the present invention to provide a bracelet that fits all sizes without needing special fitting by a jeweler or other skilled technician.
Other objects and advantages of the present invention will become apparent as the description proceeds.
In accordance with the present invention an adjustable bracelet is provided. The bracelet comprises a clasp having a top section and a bottom section, each comprising a first end and a second end. The top section of the bracelet being removably attachable to the bottom section. The bracelet further comprises a chain, having a first and a second end, the first end being attached to the clasp and the second end of the chain comprising an anchor.
The bottom section of the clasp further comprises a plurality of anchor attachments, such that when the top section is removed the anchor may be first releasably attached in the bottom section to a first attachment and may subsequently be releasably attached to another of the attachments, so as to adjust the length of the bracelet. The attachment of the anchor chain within the clasp forms a bracelet when the top and bottom sections are subsequently attached together and the anchor is thereby held onto an anchor point.
In the preferred embodiment of the present invention, the base of the clasp is a rectangular box having a base, at least two parallel walls and an open top. The anchor is a toggle bar and the anchor points are a series of generally parallel pairs of heads soldered onto the bottom section of the clasp. The heads generally extend from the base of the bottom section to generally the height of the parallel walls of the bottom section. The toggle bar may be placed adjacent one pair of heads such that the toggle bar is held against the pair of heads, generally perpendicularly to the walls of the base section, with the chain extending, generally axially with the walls, between the remaining pairs and out of the clasp. The top section of the clasp may then be attached to the bottom section, such that the top section is placed adjacent to the walls and generally the pairs of heads, so as to provide a compartment for the toggle bar and prevent it from rising above the heads. In this manner the toggle bar is held inside the clasp. When a change in size is desired, the top of the clasp may be opened and the toggle bar may be moved adjacent to another pair of heads; the top of the clasp may then be replaced, once again restraining the toggle bar in its new position.
In the preferred embodiment of the present invention, the top and bottom of the clasp are rotatably connected together by a hinge at a first end of the clasp. Generally, the first end of the chain will be attached near the hinge portion of the clasp and the second end of the chain, comprising an anchor, may hang freely. It will be noted that with one end of the two parts of the clasp rotatably connected, the other ends will pivot relative to each other. Locking means, such as friction fit teeth, or a hasp and knob may be provided to releasably attach the second ends of the clasp parts together, holding the anchor in place within the clasp as described above.
In order to provide a more finished appearance to the bracelet of the present invention, the preferred embodiment provides walls along all four sides of the clasp, with the walls, on the top and bottom portions opposed to the hinge having openings to allow the chain to extend neatly therefrom.
A more detailed explanation of the invention is provided in the following description and claims and is illustrated in the accompanying drawings.

Adjustable bracelet and method of adjustment


The present invention relates to new pharmaceutical formulations for aerosols with at least two or more active substances for administration by inhalation or by nasal route. Specifically, the invention relates to pharmaceutical preparations for propellant-driven metered dose aerosols using a fluorohydrocarbon (HFC) as propellant, which contain a combination of active substance of two or more active substances, wherein at least one active substance is present in dissolved form together with at least one other active substance in the form of suspended particles.

The present invention relates to new pharmaceutical formulations for aerosols with at least two or more active substances for use by inhalation or by the nasal route.
In propellant-driven metered dose inhalers (MDI) the active substances can be formulated as solutions or suspensions. The vast majority of aerosol formulations for MDI""s are prepared as suspensions, especially if the preparation contains more than one active substance. Formulations in the form of solutions are used only to a limited extent. In these cases, the formulations normally contain only one active substance.
As a rule, in a suspension, the chemical stability of the active substances is noticeably higher than in a solution. Additionally, in a suspension the active substance can be more highly concentrated than in a solution, with the result that suspension type formulation enable higher doses to be administered.
A major disadvantage of suspension-formulations is the fact that over time (e.g. during storage) the suspended particles clump together to form bigger, more or less stable agglomerates or form loose flakes, sediments or floating layers, or in the worst case, particle growth, which significantly impairs the pharmaceutical quality of the product. The size of the particles formed or the speed of particle growth are influenced by the solubility features of the liquid phase. Thus, ingress of humidity during storage or a desired increase in polarity, e.g. achieved by adding co-solvents, can have a devastating effect on the quality of the medical end product, particularly if the suspended particles have polar structure elements. The suspension can be physically stabilised by the addition of surfactants, by reducing the harmful effects of moisture and/or particle growth so that suspended particles can be held in suspension for longer.
Natural solution-type formulations are not affected by the problems of increasing particle size or de-mixing processes such as sedimentation or flocculation. However, in this case there is a serious risk of chemical degradation. A further disadvantage is the fact that the limited solubility of the ingredients can prevent administration in high doses. In the past, the chlorofluorohydrocarbons TG 11 (trichlorofluoromethane), TG 12 (dichlorodifluoromethane) and TG 114 (dichlorotetrafluoroethane) have proved particularly suitable as solvents. The solubility of the ingredients can be increased by the addition of co-solvents. In addition, it is usually necessary to take additional measures to chemically stabilise the dissolved components.
Up till now, CFCs such as the above-mentioned TG 11, for example, have often been used as propellants. However, since CFCs have been linked with the destruction of the ozone layer, their manufacture and use are being phased out. The intention is to replace them with special fluorohydrocarbons (HFC) which are less destructive to the ozone layer but have completely different solubility features. The toxicological profile and physico-chemical properties such as the steam pressure, for example, determine which HFCs are suitable for MDIs. The most promising representatives at present are TG 134a (1,1,2,2-tetrafluoroethane)and TG 227 (1,1,1,2,3,3,3-heptafluoropropane).
For inhalative treatment it may be desirable to have aerosol formulations with two or more active substances. In such cases the active substances are formulated in the necessary concentrations as solutions or suspensions, frequently giving rise to problems regarding the chemical stability of the individual substances or the degree of concentration which can be attained. Major problems are encountered if one of the active substances cannot be suspended or is unstable in a suspension-type formulation of this kind or if one of the active substances is chemically unstable or will not dissolve in a solution-type formulation of this kind, particularly when HFC is used as the propellant.
It is therefore one object of the present invention to develop a formulation for metering aerosols having two or more active substances which overcomes the above-mentioned disadvantages.
Surprisingly, it has been found that a plurality of active substances can be formulated as a solution and a suspension combined in one formulation.
The invention relates to stable aerosol formulations with fluorohydrocarbons as propellants, particularly TG 134a and/or TG 227, consisting of two or more active substances, wherein at least one active substance is formulated as a solution and at least one active substance is formulated as a suspension. The pharmaceutical preparation according to the invention is used for inhalative treatment, particularly for treating diseases of the pharynx and respiratory tract, e.g. asthmatic diseases and COPD.
In one embodiment a medicinally useful combination of two or more active substances is used, containing beclometasone, budesonide, cromoglycinic acid, fenoterol, flunisolide, fluticasone, ipratropium bromide, nedocromil, orciprenaline, oxitropium bromide, reproterol, salbutamol (albuterol), salmeterol, terbutalin, N-[[2,2-dimethyl-4(2-oxo-2H-pyridin-1-yl)-6-trifluoromethyl-2H-1-benzopyran-3-yl]methyl]-N-hydroxy-acetamide, the esters, salts and/or solvates thereof. Which of the above-mentioned active substances is formulated as a solution and which as a suspension in the preparation according to the invention depends on the particular combinations of active substance and can be determined relatively quickly by solution and suspension trials.
In a preferred embodiment, one or more of the following active substances are suspended: budesonide, cromoglycinic acid, nedocromil, reproterol and/or salbutamol (albuterol) or the esters, salts and/or solvates derived from these compounds and one or more of the following substances are dissolved: beclomethasone, fenoterol, ipratropium bromide, orciprenaline and/or oxitropium bromide, N-[[2,2-dimethyl-4-(2-oxo-2H-pyridin-1-yl)-6-trifluoromethyl-2H-1-benzopyran-3-yl]methyl]-N-hydroxy-acetamide or the esters, salts and/or solvates derived from these compounds. Embodiments having two different active substances are preferred.
A particularly preferred embodiment contains dissolved ipratropium bromide, particularly combined with salbutamol sulphate (albuterol sulphate) as the suspended active substance.
In all the embodiments, the active substances are used in a therapeutically effective quantity, i.e. in a quantity that can induce a successful treatment. The concentration of the active substances and the volume per stroke of spray are adjusted in such a way that the quantity of active substance which is medically necessary or recommended is released by a single spray or by a few sprays.
One embodiment relates to formulations in which the suspended particles are stabilised by the addition of surfactant substances (surfactants) or other suspension-stabilising agents to stabilise the suspended particles against physical changes. The benefit of this is that the particle size will remain pharmaceutically acceptable even over lengthy periods, e.g. during storage. Preferred particle sizes are up to 20 xcexcm, whilst particularly preferred particle sizes are between 5 and 15 xcexcm, best of all not exceeding 10 xcexcm. The advantage of these particle sizes is that the particles are small enough to penetrate deeply into the lungs but not so small as to be breathed out again with the exchanged air.
Suitable surfactants and suspension-stabilising agents include all pharmacologically acceptable substances which have a lipophilic hydrocarbon group and one or more functional hydrophilic groups, especially C5-20 fatty alcohols, C5-20 fatty acids, C5-20 fatty acid esters, lecithin, glycerides, propyleneglycol esters, polyoxyethylenes, polysorbates, sorbitan esters and/or carbohydrates. C5-20 fatty acids, propyleneglycol diesters and/or triglycerides and/or sorbitans of the C5-20 fatty acids are preferred, whilst oleic acid and sorbitan mono-, di- or trioleates are particularly preferred. Alternatively, toxicologically and pharmaceutically acceptable polymers and block-polymers can be used as suspension-stabilising agents. The surfactants used are either non-fluorinated or partially fluorinated or perfluorinated, the term fluorinated referring to the exchange of hydrogen radicals bound to the carbon for fluorine radicals. The quantity of surfactant may be up to 1:1 based on the proportion by weight of the suspended active substances; amounts of 0.0001:1 to 0.5:1 are preferred, whilst amounts of from 0.0001:1 to 0.25:1 are particularly preferred.
A further advantage of the above surfactants is that they can also be used as valve lubricants. Therefore, one embodiment relates to formulations in which said surfactants are added as valve lubricants.
In another embodiment the solubility of at least one active substance to be dissolved is increased by the addition of one or more co-solvents. This has the advantage that the active substance or substances to be dissolved can be formulated in higher concentrations. The addition of co-solvent must not exceed the critical threshold of polarity of the liquid phase at which one of the disadvantages described above begins to affect the suspended particles of active substance.
Suitable co-solvents are pharmacologically acceptable alcohols such as ethanol, esters or water or mixtures thereof; ethanol is preferred. The concentration of the co-solvent in relation to the total formulation may be from 0.0001 to 50 wt.-%, preferably 0.0001 to 25 wt.-%. In another embodiment a concentration of 0.0001 to 10 wt.-% is preferred whilst particularly preferred embodiments are those wherein just enough alcohol is added to dissolve the active substance which has to be dissolved.
In another embodiment, other common propellants are added to the HFC propellant. These added propellants may be, beside other HFCs, saturated lower hydrocarbons such as propane, butane, isobutane or pentane provided that the mixture is pharmacologically acceptable.
In one embodiment, stabilisers are added to the formulation, with a beneficial effect on the pharmaceutical stability of the active substances even over lengthy periods, e.g. during storage. In the context of the invention, stabilisers denotes those substances which prolong the durability and usability of the pharmaceutical preparation by preventing or delaying chemical changes in the individual ingredients, particularly the active substances, e.g. caused by subsequent reactions or degradation, or those which prevent biological contamination. Stabilisers which are preferred for this purpose are those which influence the pH of the liquid phase, such as acids and/or the salts thereof, particularly suitable substances are hydrochloric acid, sulphuric acid, nitric acid, phosphoric acid, ascorbic acid, citric acid and the salts thereof. In addition, preferred bactericides, fungicides etc. are benzalkonium chloride or ethylene diamine tetraacetate. Citric acid is most preferred. The concentration of the stabilisers may be up to 1000 ppm, preferably up to 100 ppm and most preferably 20 to 40 ppm.
One particularly preferred embodiment comprises suspended salbutamol sulphate (albuterol sulphate), dissolved ipratropium bromide, ethanol as co-solvent and citric acid as stabiliser.

Pharmaceutical formulations for aerosols with two or more active substances

Boehringer Ingelheim Pharmaceuticals, Inc.


Active ingredient combinations comprising tris(2-ethylhexyl) 4,4xe2x80x2,4xe2x80x3-(1,3,5-triazine-2,4,6-triyltriimino)trisbenzoate and one or more esters of branched-chain carboxylic acids and branched-chain alcohols.

The present invention relates to cosmetic and dermatological light protection formulations, in particular skincare cosmetic and dermatological light protection preparations.
The harmful effect of the ultraviolet part of solar radiation on the skin is generally known. While rays with a wavelength of less than 290 nm (the so-called UVC region) are absorbed by the ozone layer in the earth""s atmosphere, rays in the range between 290 nm and 320 nm, the so-called UVB range, cause erythema, simple sunburn or even burns of varying severity.
The maximum given for the erythema activity of sunlight is the narrower range around 308 nm.
Numerous compounds are known for protecting against UVB radiation; these are usually derivatives of 3-benzylidenecamphor, of 4-aminobenzoic acid, of cinnamic acid, of salicylic acid, of benzophenone and also of 2-phenylbenzimidazole.
It is also important to have available filters for the range between about 320 nm and about 400 nm, the so-called UVA region, since its rays can likewise cause damage. Thus, it has been found that UVA radiation leads to damage of the elastic and collagenous fibers of connective tissue, causing premature aging of the skin, and that it is to be regarded as a cause of numerous phototoxic and photoallergic reactions. The harmful effect of UVB radiation can be intensified by UVA radiation.
However, UV radiation can also lead to photochemical reactions, in which case the photochemical reaction products intervene in the skin""s metabolism.
Such photochemical reaction products are predominantly free-radical compounds, e.g. hydroxyl radicals. Undefined free-radical photoproducts which form in the skin itself can also display uncontrolled secondary reactions because of their high reactivity. However, singlet oxygen, a non-radical excited state of the oxygen molecule, can also arise during UV radiation, as can short-lived epoxides and many other species. Singlet oxygen, for example, differs from the normal triplet oxygen (free-radical ground state) by virtue of its increased reactivity. However, excited reactive (free-radical) triplet states of the oxygen molecule also exist.
Furthermore, UV radiation is a type of ionizing radiation. There is therefore the risk that UV exposure may also produce ionic species which then, for their part, are capable of oxidative intervention in the biochemical processes.
An advantageous UVB filter is tris(2-ethylhexyl) 4,4xe2x80x2,4xe2x80x3-(1,3,5-triazine-2,4,6-triyltriimino)trisbenzoate, also known as 2,4,6-tris-[anilino(p-carbo-2xe2x80x2-ethyl-1xe2x80x2-hexyloxy)]-1,3,5-triazine.
This UVB filter is sold by BASF Aktiengesellschaft under the trade name UVINUL7 T 150 and is notable for its good UV absorption properties.
The main disadvantage of this UVB filter is its poor solubility in lipids. Known solvents for this UVB filter can dissolve a maximum of about 15% by weight of this filter, corresponding to about 1-1.5% by weight of dissolved, and therefore active, UV filter substance.
It was nevertheless surprising, and could not have been foreseen by the person skilled in the art, that active ingredient combinations comprising tris(2-ethylhexyl) 4,4xe2x80x2,4xe2x80x3-(1,3,5-triazine-2,4,6-triyltriimino)trisbenzoate and one or more esters of branched-chain carboxylic acids and branched-chain alcohols, or the use of one or more esters of branched-chain carboxylic acids and branched-chain alcohols as solvent, solubility promoter or solubilizer for tris(2-ethylhexyl) 4,4xe2x80x2,4xe2x80x3-(1,3,5-triazine-2,4,6-triyltriimino)trisbenzoate, in particular for the use in light protection compositions, would overcome the disadvantages of the prior art.
The esters of branched-chain carboxylic acids and branched-chain alcohols according to the invention can advantageously be chosen from the group of substances of the general formula
in which R1 and R2, independently of one another represent mono- or polybranched alkyl radicals having 3 to 30 carbon atoms.
R1 is advantageously a mono- or polybranched alkyl radical having up to 10 carbon atoms.
In addition, R2 is advantageously a mono- or polybranched alkyl radical having 5 to 20 carbon atoms.
It is particularly advantageous to use neopentanoic esters as carboxylic esters used according to the invention.
It is very particularly advantageous to use isodecyl neopentanoate as carboxylic ester used according to the invention. It has the chemical structure
and is entered in the Chemical Abstracts under the registry number 60209-82-7. It is sold, for example, by Stearinerie Dubois under the name DUB VCI 10. As is known, it may be used in cosmetic and dermatological preparations as oil component.
It was nevertheless surprising that the addition of one or more esters of branched-chain carboxylic acids and branched-chain alcohols effects stabilization of solutions of tris(2-ethylhexyl) 4,4xe2x80x2,4xe2x80x3-(1,3,5-triazine-2,4,6-triyltriimino)trisbenzoate, since the latter substance not only has poor solubility, but also readily crystallizes out again from its solution. The invention therefore also provides a method of stabilizing solutions of tris(2-ethylhexyl) 4,4xe2x80x2,4xe2x80x3-(1,3,5-triazine-2,4,6-triyltriimino)trisbenzoate, which comprises adding an effective content of one or more esters of branched-chain carboxylic acids and branched-chain alcohols to such solutions.
The total amount of tris(2-ethylhexyl) 4,4xe2x80x2,4xe2x80x3-(1,3,5-triazine-2,4,6-triyltriimino)trisbenzoate in the finished cosmetic or dermatological preparations is advantageously chosen from the range 0.1-10.0% by weight, preferably 0.5-6.0% by weight, based on the total weight of the preparations.
The total amount of one or more esters of branched-chain carboxylic acids and branched-chain alcohols in the finished cosmetic or dermatological preparations is advantageously chosen from the range 0.1-25.0% by weight, preferably 0.5-15.0% by weight, based on the total weight of the preparations.
It is advantageous to choose weight ratios of tris(2-ethylhexyl) 4,4xe2x80x2,4xe2x80x3-(1,3,5-triazine-2,4,6-triyltriimino)trisbenzoate and one or more esters of branched-chain carboxylic acids and branched-chain alcohols from the range 1:10 to 10:1, preferably 1:4 to 4:1.
Cosmetic and dermatological preparations according to the invention also advantageously comprise inorganic pigments based on metal oxides and/or other metal compounds which are sparingly soluble or insoluble in water, in particular the oxides of titanium (TiO2), zinc (ZnO), iron (e.g. Fe2O3), zirconium (ZrO2), silicon (SiO2), manganese (e.g. MnO), aluminum (Al2O3), cerium (e.g. Ce2O3), mixed oxides of the corresponding metals and mixtures of such oxides. Pigments based on TiO2 are particularly preferred.
For the purposes of the present invention, it is particularly advantageous, although not imperative, if the inorganic pigments are present in hydrophobic form, i.e. they have been surface-treated to repel water. This surface treatment can consist in providing the pigments with a thin hydrophobic layer by processes known per se.
One such process consists, for example, in producing the hydrophobic surface layer by the reaction according to:
nTiO2+m(RO)3Sixe2x80x94Rxe2x80x26nTiO2(surf.)
where n and m are arbitrary stoichiometric parameters and R and Rxe2x80x2 are the desired organic radicals. Hydrophobicized pigments prepared analogously to DE-A 33 14 742, for example, are advantageous.
Advantageous TiO2 pigments are available, for example, under the trade names MT 100 T from TAYCA, also M 160 from Kemira and T 805 from Degussa.
The cosmetic and/or dermatological light protection formulations according to the invention can have the conventional compositions and can be used for cosmetic and/or dermatological light protection, and also for the treatment, care and cleansing of the skin and/or hair and as make-up products in decorative cosmetics.
For use, the cosmetic and dermatological preparations according to the invention are applied to the skin and/or hair in sufficient amount and in the manner conventional for cosmetics.
Particularly preferred cosmetic and dermatological preparations are those which are in the form of a sunscreen. Advantageously, these can additionally comprise at least one further UVA filter and/or at least one further UVB filter and/or at least one inorganic pigment, preferably an inorganic micropigment.
The cosmetic and dermatological preparations according to the invention can comprise cosmetic auxiliaries such as those customarily used in such preparations, e.g. preservatives, bactericides, perfumes, antifoams, dyes, pigments which have a coloring effect, thickeners, moisturizers and/or humectants, fats, oils, waxes, or other customary constituents of a cosmetic or dermatological formulation, such as alcohols, polyols, polymers, foam stabilizers, electrolytes, organic solvents or silicone derivatives.
An additional content of antioxidants is generally preferred. According to the invention, favorable antioxidants which can be used are all antioxidants suitable or customary for cosmetic and/or dermatological applications.
The antioxidants are advantageously chosen from the group consisting of amino acids (e.g. glycine, histidine, tyrosine, tryptophan) and derivatives thereof, imidazoles, (e.g. urocanic acid) and derivatives thereof, peptides, such as D,L-carnosine, D-carnosine, L-carnosine and derivatives thereof (e.g. anserine), carotenoids, carotenes (e.g. xcex1-carotene, xcex2-carotene, lycopene) and derivatives thereof, chlorogenic acid and derivatives thereof, lipoic acid and derivatives thereof (e.g. dihydrolipoic acid), aurothioglucose, propylthiouracil and other thiols (e.g. thioredoxin, glutathione, cysteine, cystine, cystamine and glycosyl, N-acetyl, methyl, ethyl, propyl, amyl, butyl and lauryl, palmitoyl, oleyl, xcex3-linoleyl, cholesteryl and glyceryl esters thereof) and salts thereof, dilauryl thiodipropionate, distearyl thiodipropionate, thiodipropionic acid and derivatives thereof (esters, ethers, peptides, lipids, nucleotides, nucleosides and salts) and sulfoximine compounds (e.g. buthionine-sulfoximines, homocysteine-sulfoximine, buthionine-sulfones, penta-, hexa-, heptathionine-sulfoximines) in very low tolerated doses (e.g. pmol to xcexcmol/kg), and also (metal) chelating agents (e.g. xcex1-hydroxyfatty acids, palmitic acid, phytic acid, lactoferrin), xcex1-hydroxy acids (e.g. citric acid, lactic acid, malic acid), humic acid, bile acid, bile extracts, bilirubin, biliverdin, EDTA, EGTA and derivatives thereof, unsaturated fatty acids and derivatives thereof (e.g. xcex3-linolenic acid, linoleic acid, oleic acid), folic acid and derivatives thereof, furfurylidenesorbitol and derivatives thereof, ubiquinone and ubiquinol and derivatives thereof, vitamin C and derivatives (e.g. ascorbyl palmitate, Mg ascorbyl phosphate, ascorbyl acetate), tocopherols and derivatives (e.g. vitamin E acetate), vitamin A and derivatives (vitamin A palmitate) and coniferyl benzoate of benzoin resin, rutinic acid and derivatives thereof, xcex1-glycosylrutin, ferulic acid, furfurylideneglucitol, carnosine, butylhydroxytoluene, butylhydroxyanisole, nordihydroguaiacic acid, nordihydroguaiaretic acid, trihydroxybutyrophenone, uric acid and derivatives thereof, mannose and derivatives thereof, zinc and derivatives thereof (e.g. ZnO, ZnSO4), selenium and derivatives thereof (e.g. selenomethionine), stilbenes and derivatives thereof (e.g. stilbene oxide, trans-stilbene oxide), and the derivatives (salts, esters, ethers, sugars, nucleotides, nucleosides, peptides and lipids) of said active ingredients which are suitable according to the invention.
The amount of the abovementioned antioxidants (one or more compounds) in the preparations is preferably from 0.001 to 30% by weight, particularly preferably from 0.05 to 20% by weight, in particular from 1 to 10% by weight, based on the total weight of the preparation.
If vitamin E and/or derivatives thereof are used as the antioxidant or antioxidants, their respective concentrations are advantageously chosen from the range 0.001-10% by weight, based on the total weight of the formulation.
If vitamin A or vitamin A derivatives or carotenes or derivatives thereof are used as the antioxidant or antioxidants, their respective concentrations are advantageously chosen from the range 0.001-10% by weight, based on the total weight of the formulation.
The lipid phase can advantageously be chosen from the following group of substances:
mineral oils, mineral waxes
oils, such as triglycerides of capric or of caprylic acid, but preferably castor oil;
fats, waxes and other natural and synthetic fatty substances, preferably esters of fatty acids with alcohols of low carbon number, e.g. with isopropanol, propylene glycol or glycerol, or esters of fatty alcohols with alkanoic acids of low carbon number or with fatty acids;
alkyl benzoates;
silicone oils such as dimethylpolysiloxanes, diethylpolysiloxanes, diphenylpolysiloxanes and mixtures thereof.
For the purposes of the present invention, the oil phase of the emulsions, oleogels and hydrodispersions or lipodispersions is advantageously chosen from the group of esters of saturated and/or unsaturated, branched and/or unbranched alkanecarboxylic acids having a chain length of from 3 to 30 carbon atoms and saturated and/or unsaturated, branched and/or unbranched alcohols having a chain length of from 3 to 30 carbon atoms, from the group of esters of aromatic carboxylic acids and saturated and/or unsaturated, branched and/or unbranched alcohols having a chain length of from 3 to 30 carbon atoms. Such ester oils can advantageously be chosen from the group consisting of isopropyl myristate, isopropyl palmitate, isopropyl stearate, isopropyl oleate, n-butyl stearate, n-hexyl laurate, n-decyl oleate, isooctyl stearate, isononyl stearate, isononyl isononanoate, 2-ethylhexyl palmitate, 2-ethylhexyl laurate, 2-hexyldecyl stearate, 2-octyldodecyl palmitate, oleyl oleate, oleyl erucate, erucyl oleate, erucyl erucate and synthetic, semi-synthetic and natural mixtures of such esters, e.g. jojoba oil.
The oil phase can also advantageously be chosen from the group of branched and unbranched hydrocarbons and hydrocarbon waxes, of silicone oils, of dialkyl ethers, from the group of saturated or unsaturated, branched or unbranched alcohols, and also fatty acid triglycerides, namely the triglycerol esters of saturated and/or unsaturated, branched and/or unbranched alkanecarboxylic acids having a chain length of from 8 to 24, in particular 12-18, carbon atoms. The fatty acid triglycerides can advantageously be chosen, for example, from the group of synthetic, semi-synthetic and natural oils, e.g. olive oil, sunflower oil, soybean oil, groundnut oil, rapeseed oil, almond oil, palm oil, coconut oil, palm kernel oil and the like.
For the purposes of the present invention, any mixtures of such oil and wax components can also advantageously be used. When required, it can also be advantageous to use waxes, for example cetyl palmitate, as the sole lipid component of the oil phase.
The oil phase is advantageously chosen from the group consisting of 2-ethylhexyl isostearate, octyldodecanol, isotridecyl isononanoate, isoeicosane, 2-ethylhexyl cocoate, C12-C15-alkyl benzoate, caprylic/capric triglyceride and dicaprylyl ether.
Mixtures of C12-C15-alkyl benzoate and 2-ethylhexyl isostearate, mixtures of C12-C15-alkyl benzoate and isotridecyl isononanoate and mixtures of C12-C15-alkyl benzoate, 2-ethylhexyl isostearate and isotridecyl isononanoate are particularly advantageous.
For the purposes of the present invention, of the hydrocarbons, paraffin oil, squalane and squalene can advantageously be used.
The oil phase can advantageously also contain cyclic or linear silicone oils or can consist entirely of such oils, although it is preferable to use an additional content of other oil phase components in addition to the silicone oil or silicone oils.
Cyclomethicone(octamethylcyclotetrasiloxane) is advantageously used as silicone oil to be used according to the invention. However, other silicone oils can also be used advantageously for the purposes of the present invention, for example hexamethylcyclotrisiloxane, polydimethylsiloxane, poly(methylphenylsiloxane).
Mixtures of cyclomethicone and isotridecyl isononanoate and mixtures of cyclomethicone and 2-ethylhexyl isostearate are particularly advantageous.
The aqueous phase of the preparations according to the invention may advantageously comprise
alcohols, diols or polyols of low carbon number, and also ethers thereof, preferably ethanol, isopropanol, propylene glycol, glycerol, ethylene glycol, ethylene glycol monoethyl or monobutyl ether, propylene glycol monomethyl, monoethyl or monobutyl ether, diethylene glycol monomethyl or monoethyl ether and analogous products, and also alcohols of low carbon number, e.g. ethanol, isopropanol, 1,2-propanediol, glycerol, and in particular one or more thickeners which can advantageously be chosen from the group consisting of silicon dioxide, aluminum silicates, polysaccharides and derivatives thereof, e.g. hyaluronic acid, xanthan gum, hydroxypropylmethylcellulose, and particularly advantageously from the group of polyacrylates, preferably a polyacrylate from the group of the so-called Carbopols, for example Carbopol grades 980, 981, 1382, 2984, 5984, in each case individually or in combination.
The cosmetic or dermatological light protection preparations advantageously comprise inorganic pigments, in particular micropigments, e.g. in amounts of from 0.1% by weight to 30% by weight, preferably in amounts of from 0.5% by weight to 10% by weight, but in particular from 1% by weight to 6% by weight, based on the total weight of the preparations.
It is advantageous according to the invention to use, apart from the combinations according to the invention, oil-soluble UVA filters and/or UVB filters in the lipid phase and/or water-soluble UVA filters and/or UVB filters in the aqueous phase.
The light protection formulations according to the invention can advantageously comprise further substances which absorb UV radiation in the UVB region, the total amount of filter substances being e.g. from 0.1% by weight to 30% by weight, preferably from 0.5 to 10% by weight, in particular from 1 to 6% by weight, based on the total weight of the preparations, in order to provide cosmetic preparations which protect the skin from the entire range of ultraviolet radiation. They can also be used as sunscreens.
The further UVB filters can be oil-soluble or water-soluble. Examples of advantageous oil-soluble UVB filter substances are:
3-benzylidenecamphor derivatives, preferably 3-(4-methylbenzylidene)camphor, 3-benzylidenecamphor;
4-aminobenzoic acid derivatives, preferably 2-ethylhexyl 4-(dimethylamino)benzoate, amyl 4-(dimethylamino)benzoate;
esters of cinnamic acid, preferably 2-ethylhexyl 4-methoxycinnamate, isopentyl 4-methoxycinnamate;
derivatives of benzophenone, preferably 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-4xe2x80x2-methylbenzophenone, 2,2xe2x80x2-dihydroxy-4-methoxybenzophenone;
esters of benzalmalonic acid, preferably di(2-ethylhexyl) 4-methoxybenzalmalonate.
Examples of advantageous water-soluble UVB filter substances are:
salts of 2-phenylbenzimidazole-5-sulfonic acid, such as its sodium, potassium or its triethanolammonium salt, and also the sulfonic acid itself;
sulfonic acid derivatives of benzophenones, preferably 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid and salts thereof;
sulfonic acid derivatives of 3-benzylidenecamphor, such as e.g. 4-(2-oxo-3-bornylidenemethyl)benzenesulfonic acid, 2-methyl-5-(2-oxo-3-bornylidene-methyl)sulfonic acid and salts thereof.
The list of said further UVB filters which can be used in combination with the active ingredient combinations according to the invention is of course not intended to be limiting.
It can also be advantageous to combine the combinations according to the invention with further UVA filters which have hitherto been customarily present in cosmetic preparations. These substances are preferably derivatives of dibenzoylmethane, in particular 1-(4xe2x80x2-tert-butylphenyl)-3-(4xe2x80x2-methoxyphenyl)propane-1,3-dione and 1-phenyl-3-(4xe2x80x2-isopropylphenyl)propane-1,3-dione. These combinations and preparations which contain these combinations are also provided by the invention. The amounts which may be used are as for the UVB combination.
It is further advantageous to combine the active ingredient combinations according to the invention with further UVA and/or UVB filters.
It is also particularly advantageous to combine the active ingredient combinations according to the invention with salicylic acid derivatives, some of which, as is known, can also absorb UV radiation. Customary UV filters include
The invention further provides a process for the preparation of the cosmetic and/or dermatological light protection preparations according to the invention, which comprises suspending and, if desired, homogenizing tris(2-ethylhexyl) 4,4xe2x80x2,4xe2x80x3-(1,3,5-triazine-2,4,6-triyltriimino)trisbenzoate in one or more esters of branched-chain carboxylic acids and branched-chain alcohols or an oil phase containing one or more esters of branched-chain carboxylic acids and branched-chain alcohols with uniform stirring and if necessary with warming, where appropriate combining the mixture with further lipid components and optionally with one or more emulsifiers, then mixing the oil phase with the aqueous phase into which a thickener has optionally been incorporated and which is preferably at the same temperature as the oil phase, if desired homogenizing the mixture, and allowing it to cool to room temperature. After the mixture has cooled to room temperature, homogenization may be repeated, particularly if volatile constituents are still to be incorporated.

Cosmetic and dermatological light-protective formulations containing triazine derivatives one or several esters of branched-chain carboxylic acids and branched-chain alcohols


The present invention relates to a method of increasing the concentration of dilute brine in NaCl electrolysis plants using the membrane process, wherein the NaCl required is stored in a mass flow silo with supernatant liquid and is fed continuously from there to the quick dissolver.

In the production of chlorine and sodium hydroxide by the membrane process, virtually saturated NaCl solution (brine) is fed to the electrolysis cell. There, the desired products chlorine, sodium hydroxide and hydrogen are produced by means of direct current. The salt concentration in the brine is at the same time reduced by 80-130 g/l. In addition, the amount of brine present in the electrolysis cell is decreased during the electrolysis process by 3-4 mol of H2O per mole of NaOH produced.
In order to maintain the electrolysis process, these cells have to be continually supplied with sufficient concentrated brine for the salt concentration in the dilute brine (anolyte) leaving the cell not to drop below the minimum concentration specified by the membrane manufacturer. This is about 170 g of NaCl per litre. The depletion of the brine is usually restricted to from 200 to 220 g of NaCl per litre.
Thus, about 40% of the amount of salt introduced with the brine into the electrolysis cell is utilized. The dilute brine leaving the cell is recycled for economic and ecological reasons, i.e. after dechlorination, its concentration is increased again by means of solid salt and after appropriate purification it is fed back to the electrolysis cell. Before addition of crystalline salt to increase the concentration, the missing am amount of water is added to make up for the amount of liquid escaping through the membrane.
In conventional plants to increase the concentration of brine, the brine is customarily passed from the bottom upward through containers (quick dissolvers) containing crystalline salt. In this way, the concentration of the brine is increased. The salt is continuously introduced into the quick dissolver by means of mechanical feed devices. In an alternative method, the dilute brine is introduced into open salt storages and its concentration is increased there (Ullmann Encyclopxc3xa4die der technischen Chemie; Chapter Chlor und Natriumchlorid; Scouce, Chlorine, Reinhold Publishing Corp.; USA; 1962).
In such plants, salt is taken from an appropriate dry salt storage either using automatic conveyor units or by means of bucket-wheel loaders.
The methods known from the prior art suffer from a series of disadvantages.
If possible, the quick dissolver is supplied directly, without intermediate storage, from the salt transport path. However, the salt used here has to be doped with anticaking agents (e.g. potassium hexacyanoferrate) to enable it to be stored, which leads to a poorer current yield in the electrolysis process (cf. W. Versteegen, report from Akzo Nobel, title: Decomposition of Ironhexacyanides in alkaline Brine of Chlorin-Caustic Plants during dissolution and Brine treatment, Author: J. H. G. van der Steegen, Mar. 26, 1990).
Open dissolution pits lead to formation of salt-containing mists, which in turn causes considerable corrosion damage to surrounding installations. In addition, an unnecessarily large amount of heat is lost as a result of the escape of steam and this has to be replaced afterwards by heating.
In addition, mechanical feed devices for supplying quick dissolvers are subject to continual wear, have a high maintenance requirement and need corresponding labour-intensive supervision and attention.
It is an object of the present invention to provide a method of increasing the concentration of dilute brine, which avoids the abovementioned disadvantages and:
automatically increases the concentration of the dilute brine from a storage (silo),
does without addition of anticaking agents to enable the salt to be stored,
has low heat losses,
keeps large amounts of salt at the ready,
does without mechanical transport devices.
However, dry or almost dry NaCl having a residual moisture content of 1-3% is not able to be stored in a silo: it tends to suffer from bridge formation and caking and makes reliable metering impossible.
It has surprisingly been found that NaCl without addition of anticaking agents can be stored in a silo and metered without problems from there if the NaCl is admixed with water in such a way that some supernatant liquid is always ensured. The height of liquid above the salt varies depending on the silo size and its geometric configuration. It should be selected so that the salt does not become dry. If necessary, water has to be added during the dispensing procedure.
The present invention accordingly provides a method of increasing the concentration of dilute brine in NaCl electrolysis plants using the membrane process, which is characterized in that the salt is stored in a mass flow silo with supernatant liquid and is fed continuously from there to the quick dissolver or preferably directly to the dilute brine stream.
According to the present invention, the salt is stored in the silo in such a way that the salt bed is covered with saturated brine or water. Since the height of liquid above the salt bed is reduced when water/NaCl mixture is taken out, additional water has to be introduced so as to ensure that a minimum height of liquid above the salt of 20 cm is maintained.
The supernatant brine is used to suppress bridge formation and to flush the crystalline salt from the outlet pipe of the silo. Relatively small amounts of liquid are sufficient to discharge the salt.
The dimensions of the silo need to be such that the filter resistance caused by the salt produces a liquid flow which is able to dispense the desired amount of salt. Preferred silos are mass flow silos. In general, silos of this type have the following dimensions: diameter: 5 to 12 m, height: 10 to 25 m.
The amount of liquid seeping through the contents of the silo can be checked and its order of magnitude estimated on the assumption of a stationary solid in the silo, e.g. with the aid of known calculation procedures, e.g. for groundwater flow.
The mathematical calculation shows that in a customary mass flow silo, sufficient seepage liquid to discharge the amount of salt required in a membrane electrolysis is available even in the case of finely divided salt.
On the other hand, experiments show that the proportion of liquid in the discharge is smaller than the amount of additional water required in the brine circuit. This proves to be advantageous for the NaCl membrane process, since it allows the amount of water added to be controlled as required.

Method of increasing the concentration of dilute brine in NaCl electrolysis plants using the membrane process


An radially expandable stent-graft and method of making the same, including at least one a stent member encapsulated between at least two longitudinally expanded polytetrafluoroethylene (ePTFE) coverings. The at least one stent member has openings through wall surfaces of the stent to permit radial expansion. The at least two longitudinally expanded ePTFE coverings are circumferentially applied over the at least one stent member in their unsintered state, and sintered during application of a circumferential pressure to bond the ePTFE around and through the wall surfaces of the stent. The sintered ePTFE forms a substantially continuous, monolithic and integral encapsulation of the at least one stent. Upon radial expansion of the stent-graft, the stent and the ePTFE node-fibril microstructure radially deform. Radial deformation of the ePTFE encapsulation results in nodal elongation in the axis of radial expansion. After radial expansion of the stent-graft, a substantial bonded area remains intact and maintains the encapsulation of the stent in vivo.

The present invention relates generally to an encapsulated endoluminal stent comprising a stent inseparably encased between at least two polytetrafluoroethylene grafts. In accordance with the preferred embodiments of the present invention, the grafts are tubular grafts are longitudinally expanded polytetrafluoroethylene tubular extrudates (ePTFE) and the stent is a pressure-expandable stent. The present invention also provides a method for making the inventive ePTFE encapsulated stent and a method for endoluminal delivery of the inventive ePTFE encapsulated stent. More particularly, a first preferred embodiment of the present invention relates to a radially balloon-expandable encapsulated stent for endovascular delivery which comprises a balloon-expandable tubular stent member interdisposed between two radially balloon-expandable tubular ePTFE grafts. The two radially balloon-expandable tubular ePTFE grafts are made by extruding a PTFE-lubricant mixture through a ram extruder into a tubular shaped extrudate and longitudinally expanding the tubular extrudate to yield a uniaxially oriented node-fibril microstructure in which substantially all of the fibrils in the ePTFE microstructure are oriented parallel to one another in the axis of longitudinal expansion. ePTFE tape or sheet materials may be substituted for the tubular ePTFE grafts.
The method of making the encapsulated stent generally includes the steps of providing a first tubular ePTFE graft member about a mandrel, concentrically positioning a pressure-expandable stent over the first ePTFE graft member such that the first tubular ePTFE graft member covers at least a substantial extent of the luminal surface of the stent, and concentrically positioning a second tubular ePTFE graft member over the stent such that the second tubular ePTFE graft member covers at least a substantial extent of the abluminal surface of the stent, applying an external positive circumferential pressure or an internal radial pressure to assembly to cause a physical interaction and adhesion between the node-fibril microstructure of the first and second ePTFE graft members through wall openings in the stent, and fully sintering the stent-graft assembly to create a substantially monolithic encapsulation of the stent.

Endoluminal encapsulated stent and methods of manufacture and endoluminal delivery