Pyrogenically prepared, surface modified aluminum oxide, having the following physical chemical properties:

The present invention relates to a pyrogenically prepared, surface modified aluminum oxide and a process for the preparation thereof as well as the use thereof.
Ceramic oxide particles, particularly silica, alumina, titania, and zirconia are known to have corona resistance properties. Sub-micron alumina is often used commercially in such (corona resistance) applications.
U.S. Pat. No. 4,308,312 to Urban teaches improved corona resistance using a film coating comprising alumina particles of a type "which provide a suspension which has an acid pH when the particles are slurried in distilled water."
U.S. Pat. No. 4,760,296 to Johnston et al. teaches the use of unmodified ceramic oxide particles, organosilicates, or organoaluminates as wire insulation (corona resistant) filler and distinguishes these composite fillers from organosiloxane derivatives.
Numerous temperature-resistant polymers, including polyimides, polyetherketones, polyethersulfones and polyphthalamides, have been considered for use as high voltage wire insulation. However, ceramic oxide fillers can be difficult, if not impractical or impossible, to efficiently and economically disperse into such polymers in sufficient quantities to achieve optimal desired corona resistance.
An ineffective dispersion of (corona resistant) composite filler can result in inadequate corona resistance and/or diminished mechanical properties. A need therefore exists for a temperature resistant polymeric composition (for wire coatings or similar type applications) having excellent corona resistance and/or mechanical properties.
It is known how to prepare pyrogenic aluminum oxide by means of high temperature or flame hydrolysis from AlCl3 [Ullmann's Encyclopedia of Industrial Chemistry], 4th edition, Volume 21, page 464 (1982).
Pyrogenically prepared aluminum oxides are characterized by extremely fine particle size, high specific surface area (BET), very high purity, spherical particle shape, and the absence of pores. On account of these properties, pyrogenically prepared aluminum oxides are finding increasing interest as supports for catalysts (Dr. Koth et al., Chem. Ing. Techn. 52, 628 (1980).
It is known how to modify pyrogenically prepared aluminum oxide on its surface by means of a silane mixture (DE 42 02 694).
In accordance with the document DE 42 02 694, the modification is carried out by spraying aluminum oxide with 0.5 to 40 parts by weight of a silane mixture per 100 parts by weight of aluminum oxide, the silane mixture consisting of 1 to 99 parts by weight of a silane of Formula A
and 99 to 1 parts by weight of a silane of Formula B,
and the surface modified aluminum oxide havinga surface area of 50 to 150 m2/g,a tamped density of 50 to 90 g/L,a drying loss of less than 5%,a loss on ignition of 0.5 to 15%,a C content of 0.5 to 12% anda pH value of 4 to 8.
The object of the present invention is a pyrogenically prepared, surface modified aluminum oxide, which is characterized by:
Surface area [m2/g] 50 to 150Tamped density [g/L] 25 to 130Drying loss [%]less than 5Loss on ignition [%]0.1 to 15 C content [%]0.1 to 15 pH value3 to 9
A further object of the invention is a process for the preparation of the pyrogenically prepared, surface modified aluminum oxide, which is characterized in that the pyrogenically prepared aluminum oxide is sprayed with a surface modifying agent, except for the mixture consisting of the silanes A and B in accordance with DE 42 02 694, at room temperature and the mixture is subsequently treated thermally at a temperature of 50 to 400° C. over a period of 1 to 6 h.
An alternative method for surface modification of the pyrogenically prepared aluminum oxide can be carried out by treating the pyrogenic aluminum oxide with a surface modifying agent, except for the mixture consisting of the silanes A and B in accordance with DE 42 02 694, in vapor form and subsequently treating the mixture thermally at a temperature of 50 to 800° C. over a period of 0.5 to 6 h.
The thermal treatment can be conducted under protective gas, such as, for example, nitrogen. The surface treatment can be carried out in heatable mixers and dryers with spraying devices, either continuously or batchwise. Suitable devices can be, for example, plowshare mixers or plate, cyclone, or fluidized bed dryers.
As starting material, it is possible to employ a pyrogenically prepared aluminum oxide, such as described in Ullmann's Encyclopedia of Industrial Chemistry, 4th edition, Volume 21, page 464 (1982).
Furthermore, it is possible to employ, as starting material, a high surface area, pyrogenically prepared aluminum oxide that has a specific BET surface area of more than 115 m2/g.
This pyrogenically prepared aluminum oxide can be prepared in accordance with the flame oxidation method or, preferably, by flame hydrolysis, whereby, as starting material, a vaporized aluminum compound, preferably the chloride, is used. This aluminum oxide is described in DE 199 43 291.0-41 which is relied on and incorporated herein by reference.
As surface modifying agent, except for the mixture consisting of the silanes A and B in accordance with DE 42 02 694, it is possible to employ the following compounds and mixtures of the following compounds:
a) Organosilanes of the type (RO)3Si(CnH2n+1) and
(RO)3Si(CnH2n−1), wherein
R=alkyl, such as, for example, methyl, ethyl, n-propyl, i-propyl, butyl, and
n=1-20
b) Organosilanes of the type R′x(RO)ySi(CnH2n+1) and R′x(RO)ySi(CnH2n−1) wherein
R=alkyl, such as, for example, methyl-, ethyl-, n-propyl-, i-propyl-, butyl-
R′=alkyl, such as, for example, methyl, ethyl, n-propyl, i-propyl, butyl
R′=cycloalkyl
n=1-20
x+y=3
x=1,2, and
y=1,2
c) Halogen organosilanes of the type X3Si(CnH2n+1) and X3Si(CnH2n−1), wherein
X=Cl, Br
n=1-20
d) Halogen organosilanes of the type X2(R′)Si(CnH2n+1) and X2(R′)Si(CnH2n−1), wherein
X=Cl,Br
R′=alkyl, such as, for example, methyl, ethyl, n-propyl, i-propyl, butyl
R′=cycloalkyl
n=1-20
e) Halogen organosilanes of the type X(R′)2Si(CnH2n+1) and X(R′)2Si(CnH2n−1), wherein
X=Cl, Br
R′=alkyl, such as, for example, methyl, ethyl, n-propyl, i-propyl, butyl
R′=cycloalkyl
n=1-20
f) Organosilanes of the type (RO)3Si(CH2)m-R′
                R=alkyl, such as methyl, ethyl, propyl        m=0.1-20        R′=methyl-, aryl (for example, —C6H5, substituted phenyl residues)                    —C4F9, OCF2—CHF—CF3, —C6F13, —O—CF2—CHF2             —NH2, —N3, —SCN, —CH═CH2, —NH—CH2—CH2—NH2,            —N—(CH2—CH2—NH2)2             —OOC(CH3)C═CH2             —OCH2—CH(O)CH2             —NH—CO—N—CO—(CH2)5             —NH—COO—CH3, —NH—COO—CH2—CH3, —NH—(CH2)3Si(OR)3             —Sx—(CH2)3Si(OR)3             —SH            —NR′R″R′″(R′=alkyl, aryl; R″=H, alkyl, aryl; R″′=H, alkyl, aryl, benzyl, C2H4NR″″R′″″ with R″″=H, alkyl and
R′″″═H, alkyl)
g) Organosilanes of the type (R″)x(RO)ySi(CH2)m—R′
                R″=alkyl x+y=2                    =cycloalkyl x=1.2                            y=1.2                m=0.1 to 20                                                R′=methyl, aryl (for example, —C6H5,substituted phenyl residues)                    —C4F9, —OCF2—CHF—CF3, —C6F13, —O—CF2—CHF2             —NH2, —N3, —SCN, —CH═CH2, —NH—CH2—CH2—NH2,            —N—(CH2—CH2—NH2)2             —OOC(CH3)C═CH2             —OCH2—CH(O)CH2             —NH—CO—N—CO—(CH2)5             —NH—COO—CH3, —NH—COO—CH2—CH3, —NH—(CH2)3Si(OR)3             —Sx—(CH2)3Si(OR)3             —SH—NR′R″R′″(R′=alkyl, aryl; R″=H, alkyl, aryl; R′″=H, alkyl, aryl, benzyl, C2H4NR″″R′″″ with R″″=H, alkyl and R′″″=H, alkyl)h) Halogen organosilanes of the type X3Si(CH2)m-R′                        X=Cl, Br        m=0.1-20        R′=methyl-, aryl (for example, —C6H5, substituted phenyl residues)                    —C4F9, —OCF2—CHF—CF3, —C6F13, —O—CF2—CHF2             —NH2, —N3, —SCN, —CH═CH2,            —NH—CH2—CH2—NH2             —N—(CH2—CH2—NH2)2             —OOC(CH3)C═CH2             —OCH2—CH(O)CH2             —NH—CO—N—CO—(CH2)5             —NH—COO—CH3, —NH—COO—CH2—CH3, —NH—(CH2)3Si(OR)3             —Sx—(CH2)3Si(OR)3             —SHi) Halogen organosilanes of the type (R)X2Si(CH2)m-R′                        X=Cl,Br        R=alkyl, such as methyl, ethyl, propyl        m=0.1-20        R′=methyl-, aryl (for example, —C6H5, substituted phenyl residues)                    —C4F9, —OCF2—CHF—CF3, —C6F13, —O—CF2—CHF2             —NH2, —N3, —SCN, —CH═CH2, —NH—CH2—CH2—NH2,            —N—(CH2—CH2—NH2)2             —OOC(CH3)C═CH2             —OCH2—CH(O)CH2             —NH—CO—N—CO—(CH2)5             —NH—COO—CH3, —NH—COO—CH2—CH3, —NH—(CH2)3Si(OR)3,            wherein R=methyl, ethyl, propyl, butyl            —Sx—(CH2)3Si(OR)3, wherein R=methyl, ethyl, propyl, butyl            —SHj) Halogen organosilanes of the type (R)2X Si(CH2)m-R′                        X=Cl, Br        R=alkyl        m=0.1-20        R′=methyl-, aryl (for example, —C6H5, substituted phenyl residues)                    —C4F9, —OCF2—CHF—CF3, —C6FI3, —O—CF2—CHF2             —NH2, —N3, —SCN, —CH═CH2, —NH—CH2—CH2—NH2,            —N—(CH2—CH2—NH2)2             —OOC(CH3)C═CH2             —OCH2—CH(O)CH2             —NH—CO—N—CO—(CH2)5             —NH—COO—CH3, —NH—COO—CH2—CH3, —NH—(CH2)3Si(OR)3             —Sx—(CH2)3Si(OR)3             —SHk) Silazanes of the type
                R=alkyl        R″=alkyl, vinyll) Cyclic polysiloxanes of the type D 3, D 4, D 5, wherein        D 3, D 4 and D 5 refer to cyclic polysiloxanes with 3, 4, or 5 units of the type —O—Si(CH3)2-.
For example, octamethylcyclotetrasiloxane=D 4
m) Polysiloxanes or silicone oils of the type
                m=0, 1, 2, 3, . . . ∞        n=0, 1, 2, 3, . . . ∞        u=0, 1, 2, 3, . . . ∞        Y=CH3, H, CnH2n+1         n=1−20        Y=Si (CH3)3, Si (CH3)2H, Si (CH3)2OH, Si (CH3)2(        Si (CH3) 2 (CnH2n+1), n=1−20R=alkyl, such as CnH2n+1, where n=1 to 20, aryl, such as phenyl and substituted phenyl residues, (CH2)n-NH2, HR′=alkyl, such as CnH2n+1, where n=1 to 20, aryl, such as phenyl and substituted phenyl residues, (CH2)n-NH2, HR″=alkyl, such as CnH2n+1, where n=1 to 20, aryl, such as phenyl and substituted phenyl residues, (CH2)n-NH2, HR′″=alkyl, such as CnH2n+1, where n=1 to 20, aryl, such as phenyl and substituted phenyl residues, (CH2)n-NH2, HPreferably, as surface modifying agent, the following silanes are employed, either individually or in a mixture:dimethyldichlorosilane, octyltrimethoxysilane,oxtyltriethoxysilane, hexamethyldisilazane,3-methacryloxypropyltrimethoxysilane,3-methacryloxypropyltriethoxysilane,hexadecyltrimethoxysilane, hexadecyltriethoxysilane,dimethylpolysiloxane, glycidyloxypropyltrimethoxysilane,glycidyloxypropyltriethoxysilane,nanofluorohexyltrimethoxysilane,tridecafluorooctyltrimethoxysilane,tridecafluorooctyltriethoxysilane, aminopropyltriethoxysilane.Especially preferably, octyltrimethoxysilane and octyltriethoxysilane can be employed.
Excluded are the silanes that are employed in DE 42 02 094 in the form of a mixture.
The pyrogenically prepared, surface modified aluminum oxide in accordance with the invention can be employed as additives in high temperature polymers.
The surface modified alumina according to this invention can be used in high temperature polymeric materials useful for wire wrap type applications, including polymeric materials comprising at least 50 weight percent high temperature polymers, such as, polyimide, polyetherketone, polyethersulfone polyphthalamide and/or combinations or derivatives.
The high temperature polymeric materials comprise corona resistant composite filler, which is the alumina according to the invention, in an amount within a range between (and including) any two of the following weight percentages: 2 and 50 weight percent.
The organic component is selected according to the particular solvent system selected for dispersing the composite filler into the high temperature polymeric material (or precursor thereto). In one or more steps, the high temperature polymeric material (or precursor thereto) is solvated to a sufficiently low viscosity to allow the composite filler (also suspendable in the solvent system concurrently or in a subsequent step or steps) to be dispersed within the polymer or polymer precursor without undue agglomeration, interfacial voids or other problems that have often been associated with inorganic particle composite fillers dispersed in high temperature polymeric materials. The resulting filled polymeric material has been found to have extraordinary corona resistance, without unduly harming (and in some instances actually improving) mechanical properties.
The corona resistant high temperature polymeric materials can be suitable for wire insulation in high voltage applications. For example, wire insulated with the corona resistant compositions can be used in combination with (or as an integral part of) rotors, stators or the like found in large industrial dynamo-electric machinery or the like.
The compositions comprise: i.a. high temperature polymeric matrix and ii. a composite, corona resistant composite filler. These components will be described individually, then in combination.
High Temperature Polymeric Matrix. Useful high temperature polymeric matrices of the present invention include as a dominant component a polymer having one or more of the following moieties: amide, imide, ether, sulfone, epoxy, carbonate, ester. Preferred high temperature polymeric matrix polymers include:
1. polyimide,
2. polyester,
3. polyesteramide,
4. polyesteramideimide,
5. polyamide,
6. polyamideimide,
7. polyetherimide,
8. polycarbonate,
9. polysulfone,
10. polyether,
11. polyetherketone,
12. polyethersulfone,
13. polyphthalamide,
14. epoxy resins,
15. and the like, including derivations and combinations thereof.
In one embodiment, the polymeric matrix is a thermoset polyimide, such as a KAPTON® brand polyimide available from E.I. du Pont de Nemours and Company of Wilmington, Del., USA. As used herein, the term 'thermoplastic' polyimide is intended to mean a polyimide composition where the glass transition temperature of the material is less than 375, 350, 325 or 300° C. Conversely 'thermoset' polyimides are intended to include polyimide compositions where the glass transition temperature is equal to or greater than the above defined (upper limit) glass transition of a thermoplastic polyimide, or otherwise where the polyimide does not have a measurable glass transition temperature.
The polymeric binder is a polyimide synthesized by first forming a polyimide precursor (a polyamic acid solution) created by reacting (in a solvent system) one or more dianhydride monomers with one or more diamine monomers. So long as the corona resistant composite filler is sufficiently dispersible in the polyamic acid solution, the composite filler can be dispersed prior to, during, or after the polyamic acid solution is created, at least until polymerization, imidization, solvent removal or other subsequent processing increases viscosity beyond what is needed to disperse the composite filler within the material. Ultimately the precursor (polyamic acid) is converted into a high temperature polyimide material having a solids content of greater than 99.5 weight percent, and at some point in this process, the viscosity is increased beyond what is necessary to intermix the composite filler into the polyimide or polyimide precursor. Depending upon the particular embodiment chosen, the viscosity could possibly be lowered again by solvating the material, perhaps sufficient to allow dispersion of the composite filler into the material.
In one embodiment, the polyamic acid solution is formed from one or more aromatic and/or aliphatic diamine monomers and one or more aromatic and/or aliphatic dianhydride monomers. In an alternate embodiment the dianhydride and diamine monomers are both aromatic, optionally also including an aliphatic diamine.
Polyamic acid solutions can be converted to high temperature polyimides using processes and techniques commonly known in the art, such as heat and/or conventional polyimide conversion chemistry. Such polyimide manufacturing processes have been practiced for decades, and the amount of public literature on polyimide manufacture is legion, and hence further discussion here is unnecessary. Any conventional or non-conventional polyimide manufacturing processes are appropriate for use in accordance with the present invention, provided a precursor material is available of sufficiently low viscosity to allow composite filler particles of the present invention to be mixed therein.
As used herein, an "aromatic" monomer is either a diamine or a dianhydride having at least one aromatic ring, either alone (i.e., a substituted or unsubstituted, functionalized or unfunctionalized benzene or similar-type aromatic ring) or connected to another (aromatic or aliphatic) ring.
The term "diamine monomer" as used herein is intended to mean a monomer that reacts with (is complimentary to) a dianhydride monomer to form an intermediate polyamic acid. The polyamic acid is then cured, typically under heat, to form a polyimide.
Depending upon the context, the term "diamine monomer" can mean (i.) an unreacted monomer (i.e., a diamine monomer); (ii.) a partially reacted monomer (i.e., an oligomer or other polyimide precursor having amine functionality, whereby the precursor is derived in part from diamine monomer) or (iii.) a diamine portion of a fully reacted polymer (the portion or portions of the polyimide attributable to the diamine monomer). The diamine monomer can be functionalized with one or more moieties, depending upon the particular embodiment selected in the practice of the present invention.
Indeed, the term "diamine" is not intended to be limiting (or interpreted literally) as to the number of amine moieties in the diamine monomer. For example, (ii.) and (iii.) above include polymeric materials that may have two, one, or zero amine moieties. Alternatively, the diamine monomer may be functionalized with additional amine moieties (in addition to the amine moieties that react with a dianhydride to provide a polyimide chain). Such additional amine moieties could be used to crosslink the polymer or to provide other functionality to the polymer.
Similarly, the term 'dianhydride monomer' as used herein is intended to mean the monomer that reacts with (is complimentary to) the diamine monomer to form a polyamic acid, and then upon curing with heat and/or radiation, a polyimide.
Depending upon the context in which it is used, "anhydride" as used herein can mean not only an anhydride moiety per se, but also a precursor to an anhydride moiety, such as: (i.) a pair of carboxylic acid groups (which can be converted to anhydride by a dehydration or similar-type reaction); or (ii.) an acid-acid ester functionality (or any other functionality presently known or developed in the future which is) capable of conversion to anhydride functionality.
Depending upon, context, "dianhydride" can mean: (i) the unreacted form (i.e., a dianhydride monomer, whether the anhydride functionality is in a true anhydride form or a precursor anhydride form, as discussed in the prior above paragraph); (ii) a partially reacted form (i.e., the portion or portions of an oligomer or other partially reacted or precursor polyimide composition reacted from or otherwise attributable to dianhydride monomer) or (iii) a fully reacted form (the portion or portions of the polyimide derived from or otherwise attributable to dianhydride monomer).
The dianhydride monomer can be functionalized with one or more moieties, depending upon the particular embodiment selected in the practice of the present invention. Indeed, the term "dianhydride" is not intended to be limiting (or interpreted literally) as to the number of anhydride moieties in the dianhydride monomer. For example, (i.), (ii.) and (iii.) (in the paragraph above) include organic substances that may have one or zero anhydride moieties, depending upon whether the anhydride is in a precursor state or a reacted state. Alternatively, the dianhydride monomer may be functionalized with additional anhydride type moieties (in addition to the anhydride moieties that react with diamine to provide a polyimide). Such additional anhydride moieties could be used to crosslink the polymer or to provide other functionality to the polymer.
Examples of useful dianhydride monomers in the present invention include pyromellitic dianhydride (PMDA);
3,3′,4,4′-biphenyl tetracarboxylic dianhydride (BPDA);
3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA);
4,4′-oxydiphthalic dianhydride (ODPA); bis(3,4-dicarboxyphenyl) sulfoxide dianhydride (DSDA);
1,1,1,3,3,3,-hexafluoropropane dianhydride (6FDA); bisphenol A dianhydride (BPADA); 2,3,6,7-naphthalene tetracarboxylic dianhydride; 1,2,5,6-naphthalene tetracarboxylic dianhydride; 1,4,5,8-naphthalene tetracarboxylic dianhydride; 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride; 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride; 2,2′-bis(trifluoromethylbenzidine); 2,3,3′,4′-biphenyl tetracarboxylic dianhydride; 2,2′,3,3′-biphenyl tetracarboxylic dianhydride; 2,3,3′,4′-benzophenone tetracarboxylic dianhydride; 2,2′,3,3′-benzophenone tetracarboxylic dianhydride; 2,2-bis(3,4-dicarboxyphenyl) propane dianhydride; 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride; 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride; bis(2,3-dicarboxyphenyl)methane dianhydride; bis(3,4-dicarboxyphenyl)methane dianhydride; 4,4′-(hexafluoroisopropylidene) diphthalic anhydride; bis(3,4-dicarboxyphenyl) sulfone dianhydride; tetrahydrofuran-2,3,4,5-tetracarboxylic dianhydride; pyrazine-2,3,5,6-tetracarboxylic dianhydride; thiophene-2,3,4,5-tetracarboxylic dianhydride; phenanthrene-1,8,9,10-tetracarboxylic dianhydride; perylene-3,4,9,10-tetracarboxylic dianhydride; bis-1,3-isobenzofurandione; bis(3,4-dicarboxyphenyl) thioether dianhydride; bicyclo-[2,2,2]-octen-(7)-2,3,5,6-tetracarboxylic-2,3,5,6-dianhydride; 2-(3′,4′-dicarboxyphenyl) 5,6-dicarboxybenzimidazole dianhydride; 2-3′,4′-dicarboxyphenyl) 5,6-dicarboxybenzoxazole dianhydride; 2-(3′,4′-dicarboxyphenyl) 5,6-dicarboxybenzothiazole dianhydride; bis(3,4-dicarboxyphenyl) 2,5-oxadiazole 1,3,4-dianhydride; b is 2,5-(3′,4′-dicarboxydiphenylether) 1,3,4-oxadiazole dianhydride; their acid ester and their acid chloride derivatives.
Pyromellitic dianhydride (PMDA) is preferred.
Examples of suitable diamine monomers include: 2,2 to-(4-aminophenyl) propane; 4,4′-diaminodiphenyl methane;    4,4′-diaminodiphenyl sulfide;    3,3′-diaminodiphenyl sulfone;    4,4′-diaminodiphenyl sulfone;    4,4′-diaminodiphenyl ether (4,4′-ODA); 3,4′-diaminodiphenyl ether (3,4-ODA);    1,3-bis-(4-aminophenoxy)benzene (APB-134);    1,3-bis-(3-aminophenoxy)benzene (APB-133);    1,2-bis-(4-aminophenoxy)benzene;    1,2-bis-(3-aminophenoxy)benzene;    1,4-bis-(4-aminophenoxy)benzene;    1,4-bis-(3-aminophenoxy)benzene;    1,5-diaminonaphthalene;    4,4′-diaminodiphenyldiethylsilane;    4,4′-diaminodiphenylsilane;    4,4′-diaminodiphenylethylphosphine oxide;    4,4′-diaminodiphenyl-N-methyl amine;    4,4′-diaminodiphenyl-N-phenyl amine;    1,2-diaminobenzene (OPD);    1,3-diaminobenzene (MPD);    1,4-diaminobenzene (PPD);    2,5-dimethyl-1,4-diaminobenzene;    2,5-dimethyl-1,4-phenylenediamine (DPX);    trifluoromethyl-2,4-diaminobenzene;    trifluoromethyl-3,5-diaminobenzene;    2,2-bis(4-aminophenyl) 1,1,1,3,3,3-hexafluoropropane;    2,2-bis(3-aminophenyl) 1,1,1,3,3,3-hexafluoropropane;    benzidine;    4,4′-diaminobenzophenone;    3,4′-diaminobenzophenone;    3,3′-diaminobenzophenone;    m-xylylene diamine;    p-xylylene diamine;    bisaminophenoxyphenylsulfone;    4,4′-isopropylidenedianiline;    N,N-bis-(4-aminophenyl)methylamine;    N,N-bis-(4-aminophenyl) aniline;    3,3′-dimethyl-4,4′-diaminobiphenyl;    4-aminophenyl-3-aminobenzoate;    2,4-diaminotoluene;    2,5-diaminotoluene;    2,6-diaminotoluene;    2,4-diamine-5-chlorotoluene;    2,4-diamine-6-chlorotoluene;    2,4-bis-(beta-amino-t-butyl) toluene;    bis-(p-beta-amino-t-butyl phenyl)ether;    p-bis-2-(2-methyl-4-aminopentyl)benzene;    1-(4-aminophenoxy)-3-(3-aminophenoxy)benzene;    1-(4-aminophenoxy)-4-(3-aminophenoxy)benzene;    2,2-bis-[4-(4-aminophenoxy)phenyl]propane (BAPP);    2,2′-bis-(4-aminophenyl)-hexafluoro propane (6F diamine);    2,2′-bis-(4-phenoxy aniline) isopropylidene;    2,4,6-trimethyl-1,3-diaminobenzene;    4,4′-diamino-2,2′-trifluoromethyl diphenyloxide;    3,3′-diamino-5,5′-trifluoromethyl diphenyloxide;    2,2′-trifluoromethyl-4,4′-diaminobiphenyl;    4,4′-oxy-bis-[(2-trifluoromethyl)benzene armine];    4,4′-oxy-bis-[(3-trifluoromethyl)benzene amine];    4,4′-thio-bis-[(2-trifluoromethyl)benzene-amine];    4,4′-thio-bis-[(3-trifluoromethyl)benzene amine];    4,4′-sulfoxyl-bis-[(2-trifluoromethyl)benzene amine;    4,4′-sulfoxyl-bis-[(3-trifluoromethyl)benzene amine];and 4,4′-keto-bis-[(2-trifluoromethyl)benzene amine]. 4,4′-oxydianiline (4,4-ODA) is preferred.
Aliphatic diamines are also useful diamine monomers and are used to make the polyamic acid precursors (and then the polyimides) of the present invention. Useful aliphatic diamines are 1,4-tetramethylenediamine, 1,5-pentamethylenediamine (PMD), 1,6-hexamethylenediamine (HMD), 1,7-heptamethylene diamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine (DMD), 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine (DDD), 1,16-hexadecamethylenediamine. The preferred aliphatic diamine is 1,6-hexamethylene diamine (HMD). 1,6-hexamethylene diamine (HMD) is preferred.
In an alternative embodiment, an epoxy resin is used as the high temperature polymer matrix. In one embodiment, the epoxy resin is derived from bisphenol-A diglycidyl ether, epoxy novolac resins, cycloaliphatic epoxy resins, diglycidyl ester resins, glycidyl ethers of polyphenols or the like. These resins preferably have an epoxy equivalent weight average molecular weight of about 130-1500. Such resins are well known in the art and are described in U.S. Pat. Nos. 2,324,483; 2,444,333; 2,494,295; 2,500,600; and 2,511,913.
Catalytic hardeners, or curing agents for the above mentioned epoxy resins include aluminum acetylacetonate, aluminum di-sec-butoxide acetoacetic ester chelate or tetraoctylene glycol titanate in combination with phenolic accelerators, including resorcinol, catechol or hydroquinone and the corresponding dihydroxynaphthalene compounds. Compositions of this type have been described in U.S. Pat. Nos. 3,776,978 and 3,812,214.
The organic component of the composite filler material is chosen primarily to provide or improve dispensability of the composite filler material into a particular solvated polymer matrix or polymer matrix precursor. Generally speaking, an organic component of similar polarity (to a selected solvent) and of relatively low molecular weight will more readily disperse in the solvent than otherwise. Hence the organic component is selected in view of the particular solvent system into which the composite filler is intended to be dispersed or otherwise intermixed.
Similarly, the inorganic component of the composite filler is selected primarily to provide or improve corona resistance. Since alumina is a widely accepted corona resistant inorganic ceramic oxide, it is particularly mentioned herein, but the industry may prefer or otherwise adopt other types of corona resistant inorganic ceramic oxides, and hence the inorganic component is intended to be broadly defined.
While not intending to be bound by a particular theory, in at least one embodiment it is believed that the organic component lowers the surface energy of the inorganic component and thus allows it to be easily dispersible in organic solvents. Because the composite fillers of the present invention are more readily dispersible, often with little to no additional shearing force or filtration required, these slurries often form fewer, perhaps no (or essentially no, i.e., less than 100 per million (or "ppm"), highly undesired agglomerates in the size range of greater than 0.5 microns. Hence, the compositions of the present invention can be used to form films having highly improved dielectric strength and/or highly improved mechanical film properties.
Furthermore in some embodiments, it has been surprisingly discovered that films often have higher dielectric strength than films made without inorganic ceramic oxide particles incorporated into the polymer (i.e., pure polyimide polymer without metal oxide or silica filler). Although not intending to be bound to any particular theory, it is theorized that the composite fillers provide such an efficient dispersion of non-agglomerated small particles within the polymer matrix that the composite fillers of the present invention may be capable of diluting electric charge along a film's x-y plane, at least to a greater extent than is observed with unfilled, pure polymer (and also to a greater extent than conventional poorly dispersed, more highly aggregated ceramic oxide fillers), perhaps thereby improving electrical resistance in the z direction.
Typically, the composite fillers of the present invention generally do not require extensive milling and filtration to breakup unwanted particle agglomeration as is typical when attempting to disperse nano-sized conventional ceramic oxide fillers into a polymer matrix. Such milling and filtration can be costly and may not be capable of removing all unwanted agglomerates.
Indeed in one embodiment, the composite filler is dispersible and suspendible at 20 weight percent in a (at least 99 weight percent pure) dimethylacetamide solvent and after dispersing and suspending the filler into the solvent with a high shear mechanical force, less than 15, 10, 8, 6, 4, 2 or 1 weight percent of the filler precipitates out of solution when kept at rest at 20° C. for 72 hours.
Composite, Corona Resistant Filler: Organic Component. The organic component of the corona resistant composite filler of the present invention can be polymerization (by conventional or non-conventional techniques) using virtually any monomer, depending upon the embodiment selected. The organic component is often, at least in part, the organic portion of a (organic-inorganic) coupling agent reacted to the inorganic component. In selecting the organic component, proper attention should be given to matching the dispensability of the organic component with the particular solvent chosen for the particular high temperature polymer matrix selected.
Generally speaking, the organic component is more readily dispersible in a solvent, the more similar the polarity (or non-polarity) of the organic component with respect to the solvent; furthermore, the lower the molecular weight, generally speaking, the greater the dispensability of the organic component. Hence, the organic component should be selected in a way that optimizes the polarity of the composite filler with the polarity of the solvent, while also minimizing the surplus amount of organic component (that does little to further compatibalize polarity while thereby unduly adding bulk that is detrimental to dispensability). Ordinary skill and experimentation may be necessary in optimizing the organic component for any particular solvent system selected.
Potentially useful monomers include:    1. unsaturated aromatic compounds such as styrene, alpha-methylstyrene, halogenated styrene and divinylbenzene;    2. unsaturated esters such as vinyl acetate and vinyl propionate;    3. unsaturated nitriles, such as, acrylonitrile;    4. acrylic acid esters or methacrylic acid esters, such as methyl acrylate, methyl ethacrylate, ethyl acrylate, ethyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, ethyleneglycol diacrylate, ethyleneglycol dimethacrylate, glycidyl acrylate, glycidyl methacrylate, 2-hydroxyethyl acrylate, acryl acrylate and allyl methacrylate;    5. C2-C20 alkene or vinyl monomers, such as ethylene, propylene, butylene, butadiene, isoprene, and the like;    6. acrylic acid, methacrylic acid, and derivations thereof;    7. acrylamide, methacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, and the like;    8. monomers having one or more polymerizable reactive sites, such as, hydroxyl, epoxy, carboxyl, anhydride, amino, halide, and the like; and    9. combinations and derivations thereof.
However, the organic component must be functionalized or otherwise capable of being bonded to the inorganic ceramic oxide component of the composite filler by means of an organo-siloxane (and less preferably, an organo-metaloxane) moiety. This can be done by functionalizing the organic component with a functional group capable of reacting with the inorganic ceramic oxide component in a way that produces a siloxane (or metaloxane) linkage between the two components.
For example, the organic component can be functionalized with a —Si(R1, R2, R3), where: —Si—R1,
—S1—R2, and
—S1—R3
are the same or different and at least one of which is further defined as being —SiOR, where
R is either:
    1. hydrogen (i.e., —SiOR is —SiOH); or    2. a substituted or unsubstituted alkyl capable of undergoing hydrolysis to convert the —OR to —OH, (i.e., SiOR is a precursor to —SiOH, that is converted to SiOH upon hydrolysis).
In this embodiment, the —SiOH functionalized organic component can be reacted to the inorganic component, bonding the organic and inorganic components together and thereby forming a —Si—O—X— bond at the interface of the two components, where X is an atom of the inorganic component that is either Si or a metal, depending upon the particular inorganic component selected.
The forming of an organo-siloxane (or organo-metaloxane) bond at the interface of the two composite filler components can also be done by functionalizing the inorganic component with an R′—Si—O—X moiety (or R′—M—-O—X— moiety), where X is an atom of (and covalently bonded with and to) the inorganic component and is either Si or a metal, depending upon the particular inorganic component selected, and where R′ is an organic moiety that is either the entire organic component or a portion of the organic component that is then reacted with one or more additional organic reactants to form the organic component.
In one embodiment, the organosiloxane bond between the organic and inorganic components of the composite filler can be accomplished by using an organo-silane coupling agent, where the silane group of the coupling agent bonds (forming a siloxane linkage) to the inorganic component and the organo portion of the coupling agent is selected to bond to the organic component. Useful such coupling agents may include:    (a) vinyltrichlorsilane, vinyltris(.beta.-methoxyethoxy)silane, vinyltriethoxysilane, vinyltrimethoxysilane, gamma-methacryloxypropyltrimethoxysilane, gamma-mercaptopropyltrimethoxysilane and gamma-chloropropyltrimethoxysilane;    (b) gamma-glycidoxypropyltrimethoxysilane and gamma-glycidoxypropylmethyldiethoxysilane; and    (c) N-beta(aminoethyl).gamma.-aminopropylttimethoxysi lane, N-(beta(aminoethyl) gamma-aminopropylmethyldimethoxysilane and gamma-aminopropyltriethoxysilane.
The silane coupling agents of the present invention preferably have functional groups that can easily react with the organic component functional groups. For example, for organic components having carboxyl groups introduced therein, the silane coupling agents of (b) and (c) above with epoxy groups and amino groups are preferred. Among these, gamma-glycidoxypropyltrimethoxysilane and N-(beta-(aminoethyl) gamma-aminopropyltrimethoxysilane are particularly preferred.
A less preferred by alternative coupling agents include organo-metaloxane coupling agents, such as, acetoalkoxyaluminum diisopropylate and the like, and isopropyl triisostearoyltitanate, isopropyltridecyl benzenesulfonyltitanate, and the like. Different coupling agents may be used alone or in combinations of two or more, and coupling agents of different types may also be used together.
In one embodiment, the organo portion of the coupling agent is all or part of the organic component of the composite filler. If a commercial or otherwise available coupling agent can be found having a suitable organo portion offering excellent dispensability with respect to a particular, desired solvent system, the organic component of the composite filler is generally preferably obtained by means of the coupling agent. In such circumstances (or otherwise) a sophisticated inorganic particle supplier, such as Degussa AG of Germany, may be able to custom manufacture a suitable inorganic/organic composite filler (bonded with an organo-siloxane or organo-metaloxane) in accordance with the present invention.
Otherwise, the bonding of each coupling agent to a separate organic component can be accomplished by dispersing the coupling agent in a dispersion containing the organic component and the inorganic component. Depending upon the particular embodiment of the present invention chosen, suitable solvent systems can include water, organic solvents and water in combination with (water miscible) organic solvents, such as many alcohols. Incompatible (or multi-phase) solvent systems may also be useful, depending upon the particular embodiment selected, provided sufficient agitation or mixing is provided to allow reaction between the coupling agent and both the organic and inorganic component of the composite filler. When water is included in the dispersion medium, it is preferred to introduce hydrophilic functional groups such as hydroxyl groups, epoxy groups or carboxylic groups into the organic component in order to stabilize the organic component in the dispersion system and achieve uniform dispersion. Introduction of these functional groups can also promote easier chemical bonding and/or non-chemical bonding of the coupling agent(s). Preferred alcohols for such use include lower saturated aliphatic alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol and the like. These alcohols can be used alone or in combinations of two or more. Other organic solvents besides alcohol, such as methyl ethyl ketone and dimethylformamide may be used, and these organic solvents, water and alcohol may also be used in combination in appropriate weight ratios.
In the above described reaction to create the composite filler, the organic component content in the dispersion medium is preferably 0.0001-70 wt % (hereunder all percent values will mean weight percent, unless indicated otherwise), more preferably 0.001-50%, and especially 0.01-25%. If the content is under 0.0001%, the composite filler yield can be low, and if it is over 70%, one or more components may fall out of suspension or otherwise dispersion stability can be problematic. Further, the reaction for forming the composite filler can be promoted by heating or using a catalyst. For heating, the reaction system temperature is preferably 40-100° C. As catalysts there may be used acids, bases, aluminum compounds, tin compounds and the like. Acid catalysts and aluminum catalysts are well known for promoting organo-siloxane or organo-metaloxane reactions with inorganic oxide particles.
Incorporating the Composite Filler Into A High Temperature Polyimide Matrix. Polar aprotic solvents are particularly useful in forming polyimides. Hence, the composite fillers of the present invention are preferably designed to readily disperse in polar aprotic solvents, such as, N-methylpyrrolidinone (NMP), dimethylacetamide (DMAc), gamma-butyrolactone, N,N′-dimethyl-formamide (DMF), dimethyl sulfoxide (DMSO), and tetramethyl urea (TMU). In one embodiment, the preferred solvent is dimethylacetamide (DMAc).
Co-solvents can also be used generally at about five to 50 weight percent of the total solvent. Useful co-solvents include xylene, toluene, benzene, diethyleneglycol diethyl ether, 1,2-dimethoxyethane (monoglyme), diethylene glycol dimethyl ether (diglyme), 1,2-to-(2-methoxyethoxy)ethane (triglyme), to [2-(2-methoxyethoxy)ethyl)]ether (tetraglyme), to-(2-methoxyethyl)ether, tetrahydrofuran, "CelloSolve™" (glycol ethyl ether) and "Cellosolve™ acetate" (hydroxyethyl acetate glycol monoacetate).
The corona resistant polyimide films in accordance with the present invention can be produced by combining diamine and dianhydride monomers together, in the presence of a polar aprotic solvent, to form a polyamic acid solution (also called a polyamide acid solution). The dianhydride and diamine monomers are typically combined in a molar ratio of aromatic dianhydride monomer to aromatic diamine monomer of from about 0.90 to 1.10. Molecular weight of the polyamic acid can be adjusted by adjusting the molar ratio of the dianhydride and diamine monomers.
In one embodiment, the polyamic acid solution contains polyamic acid dissolved in a polar aprotic solvent at a concentration in a range between (and including) any two of the following percentages: 5,10, 12, 15, 20, 25, 27, 30, 40, 45, 50, 55, or 60(%). percent by weight. In one embodiment, the solvent content of the polyamic acid solution is in a range of from about 10, 12, 14, 16, 18, 20, or 22, to about 24, 26, 28 or 30 weight (%) percent solvent.
In one embodiment, nano-sized composite filler in accordance with the present invention (i.e., alumina oxide particles comprising C2-C12 alkyl organic component linked to the alumina via an organo siloxane linkage) are first dispersed in a solvent to form a slurry and then the slurry is dispersed in the polyamic acid precursor solution. The mixture is called a filled polyamic acid casting solution. The concentration of composite filler to polyimide (in the final film) is typically in the range of 5, 10, 15, 20, 25, 30, 35, or 40, to about 45, 50, 55, 60, 65 or 70(%) percent by weight. As the concentration of the composite filler increases, the corona resistance of the composite polyimide also increases.
The filled polyamic acid casting solution is typically a blend of a pre-formed polyamic acid solution and composite filler to form a slurry, where in at least one embodiment, the composite filler is present in a concentration range from about 1, 3, 5, 7, 9 or 10 weight (%) percent to about 15, 20, 25, 30, 35, 40, 45 or 50(%) weight percent. In one embodiment, the composite filler is first dispersed in the same polar aprotic solvent used to make the polyamic acid solution (e.g. DMAc). Optionally, a small amount of polyamic acid solution may be added to the composite filler slurry to either increase the viscosity of the slurry, or stabilize the slurry from unwanted particles agglomeration.
In one embodiment, a composite filler slurry is blended with a polyamic acid solution to form the filled polyamic acid casting solution. This blending operation can include high sheer mixing. Preferably, the average particle size of the composite filler in the slurry and the casting solution and final polyimide film is in a range between and including any two of the following sizes: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 125, 150, 175, 200, 250, 300, 350, 400, 450, and 500 nanometers. In one embodiment, the average particle size is from 100 to 300 nanometers.
The ratio of polyamic acid to composite filler may be represented by the ratio A:B wherein A is the weight of the polyamic acid polymer and B is the weight of the composite filler. In one embodiment, A is a range between and including any two of the following: 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 0.9 and B is 1. In this embodiment, if A is below 0.1, the films formed will generally be too brittle and may not be sufficiently flexible to form a freestanding, mechanically tough, flexible sheet that can be wrapped upon a conductive wire. Also in this embodiment, if A is above 0.9, the films formed therefrom may not be sufficiently corona resistant.
The polyamic acid casting solution mentioned above can optionally further comprise additional additives, including processing aids (e.g., oligomers), antioxidants, light stabilizers, flame retardant additives, anti-static agents, heat stabilizers, ultraviolet absorbing agents, inorganic fillers or various reinforcing agents. Common inorganic fillers include thermally conductive fillers, like granular metal oxides, and electrically conductive fillers like metals and electrically conductive polymers. Other common inorganic fillers include granular alumina, granular silica, fumed silica, silicon carbide, diamond, clay, boron nitride, aluminum nitride, titanium dioxide, dicalcium phosphate, and fumed metal oxides. Common organic fillers include polyaniline, polythiophene, polypyrrole, polyphenylenevinylene, polydialkylfluorenes, carbon black, and graphite.
In one embodiment, the polyamic acid casting solution is cast, or applied onto, a support such as an endless belt or rotating drum. A wet film then formed by heating the solution to remove some of the solvent. The wet film, sometimes called a 'green' film is converted into a self-supporting film by baking at an appropriate temperature where the solids are from 60, 65, 70, 75, 80, 85, and 90 weight percent. The green film is separated from the support, molecularly oriented tentering with continued thermal and radiation curing, to provide a fully cured polyimide film having a weight percent solids above 98.5%.
Other useful methods for producing polyimide films in accordance with the present invention can be found in U.S. Pat. Nos. 5,166,308 and 5,298,331 and are incorporated by reference into this specification for all teachings therein. Numerous variations are also possible such as:    (a) A method wherein the diamine monomers and dianhydride monomers are preliminarily mixed together and then the mixture is added in portions to a solvent while stirring.    (b) A method wherein a solvent is added to a stirring mixture of diamine and dianhydride monomers (contrary to (a) above).    (c) A method wherein diamines are exclusively dissolved in a solvent and then dianhydrides are added thereto at such a ratio as allowing to control the reaction rate.    (d) A method wherein the dianhydride monomers are exclusively dissolved in a solvent and then amine components are added thereto at such a ratio to allow control of the reaction rate.    (e) A method wherein the diamine monomers and the dianhydride monomers are separately dissolved in solvents and then these solutions are mixed in a reactor.    (f) A method wherein the polyamic acid with excessive amine component and another polyamic acid with excessive anhydride component are preliminarily formed and then reacted with each other in a reactor, particularly in such a way as to create a non-random or block copolymer.    (g) A method wherein a specific portion of the amine components and dianhydride components are first reacted and then residual dianhydride monomer is reacted, or vice versa.    (h) A method wherein the silane coated fumed alumina oxide particles are dispersed in a solvent and then injected into a stream of polyamic acid to form a filled polyamic acid casting solution and then cast to form a green film.    (i) A method wherein the components are added in part or in whole in any order to either part or whole of the solvent, also where part or all of any component can be added as a solution in part or all of the solvent.    (j) A method of first reacting one of the dianhydride monomers with one of the diamine monomers giving a first polyamic acid, then reacting the other dianhydride monomer with the other amine component to give a second polyamic acid, and then combining the amic acids in any one of a number of ways prior to film formation.
It is preferable to use a heating system having a plurality of heating sections or zones. It is also generally preferable that the maximum heating temperature be controlled to give a maximum air (or nitrogen) temperature of the ovens from about 200 to 600° C., more preferably from 350 to 500° C. By regulating the maximum curing temperature of the green film within the range as defined above, it is possible to obtain a polyimide film that has excellent mechanical strength, adhesive character, and thermal dimensional stability.
Alternatively, heating temperatures can be set to 200-600° C. while varying the heating time. Regarding the curing time, it is preferable that the polyimide films of the present invention be exposed to the maximum heating temperature for about 1, 2, 3, 5, 10, 15, 20, 25, 30, 35, 40, 45 or 50 seconds to about 60, 70, 80, 90, 100, 200, 400, 500, 700, 800, 900, 1000, 1100 or 1200 seconds. The heating temperature may be changed stepwise so as not to wrinkle the film by drying to quickly.
The thickness of the polyimide film may be adjusted depending on the intended purpose of the film or final application specifications. Depending upon the design criteria of any particular embodiment chosen, the film thickness can be in a range between (and including) any two of the following film thicknesses: 8, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 80, 100, 125, 150, 175, 200, 300, 400 and 500 microns. In one embodiment, the thickness is from about 12 to about 125 microns and is preferably from 25 to 75 microns.
As used herein, the term 'corona resistant' means a material possessing the physical property of being able to withstand a prolonged electrical plasma attack for a specific period. In the case of a film, corona resistance is typically measured using a film sample of film that is about one thousands of an inch thick (˜1.0 mil) or 25 microns. If the 1 mil (25 micron) film is capable of withstanding 750 volts of electricity (applied to the film using a copper probe measuring ¼″ in diameter) at 1050 Hz for a period of greater than 200 hours, the film is said to be 'corona resistant.' In one embodiment, the polyimide films of the present invention survived over 1000 hours of corona testing.
As used herein, the term 'dielectric strength' is a term used to describe the amount of voltage a material can withstand in short instance of time. Dielectric strength of one-mil thick, conventional, unfilled (non-corona resistant) polyimide film is typically about 7,800 volts/mil. Conventional corona resistant films generally provide a dielectric strength of about 7,400 volts/mil. In one embodiment, one class of films according to the present invention are defined as having a dielectric strength greater than 7400, 7500, 7600, 7700, 7800, 7900, or 8000 volts/mil.
As used herein, the term 'elongation' is used to describe a film's ability to stretch under physical pulling force without breaking. In an elongation test, a film sample is placed between two holding clamps. The clamps are pulled in opposite directions. The distance the clamps are able to travel before the material breaks determines the amount of mechanical elongation present in the film. A higher elongation in a film allows the film to wrap more easily around an electrical wire in an electrical insulation application. Typical one-mil thick polyimide generally has an elongation of about 90 to 100 percent (%). Typical corona resistant polyimide films, like DuPont KAPTON CR®, generally have a mechanical elongation of about 40-60 percent (%). In one embodiment, one class of corona resistant films according to the present invention have a mechanical elongation of greater than 60, 65 or 70 percent.
In accordance with the present invention, the corona-resistant films herein are used to wrap, or coat, electrical conductors or conductor wires. These films are also used to impregnate laminated electrical insulation, thus providing superior electrical insulating systems. Additionally, multiple strands of conductive wires wrapped with such corona resistant films are wound together to form turns and coils. In these applications and depending upon the particular embodiment selected, corona resistance can be at least 10 times greater than the conventional insulation used for this purpose. Still further, such novel coils have special utility in the construction of transformers and dynamoelectric machine rotor/stators.

Abstract: Surface area [m2/g] 50 to 150Tamped density [g/L] 25 to 130Drying loss [%]less than 5Loss on ignition [%]0.1 to 15 C content [%]0.1 to 15 pH value3 to 9is prepared by treating pyrogenically prepared aluminum oxide with a surface modifying agent.


One or more embodiments of the present invention pertain to an all solid-state microwave power module. The module includes a plurality of solid-state amplifiers configured to amplify a signal using a low power stage, a medium power stage, and a high power stage. The module also includes a power conditioner configured to activate a voltage sequencer (e.g., bias controller) when power is received from a power source. The voltage sequencer is configured to sequentially apply voltage to a gate of each amplifier and sequentially apply voltage to a drain of each amplifier.

Historically, the term microwave power module (MPM) is associated with a small fully integrated self-contained radio frequency (RF) amplifier that combines both solid-state and microwave vacuum electronics technologies. Typically, the output power of these MPMs is on the order of about 100 watts CW over an octave bandwidth. Because of their smaller size and lower mass compared to conventional traveling-wave tube amplifiers, these MPMs may have applications in electronic warfare systems.
The MPMs require both a solid-state amplifier at the front end and a microwave vacuum electronics amplifier at the back end. However, such MPMs cannot be utilized for communications because the MPMs are not optimized for linearity or efficiency. Also, the MPMs can be very expensive to manufacture, particularly when modules are produced in very small quantities for space applications. Also, a kilovolt (kV) class power supply is required to power the traveling wave tube amplifier, which is a part of the microwave vacuum electronics.

The United States of America as Represented by the Administrator of National Aeronautics and Space Administration


The invention relates to a receptacle with a plunger, which is displaceably arranged therein. The plunger comprises a plunger body with a flat face, whereby at least two encircling sealing lips are shaped onto the plunger body. Each sealing lip has slot-shaped notches at at least one location that, as soon as the plunger is inserted into the receptacle, permit a gas exchange between the inside of the receptacle and the outside atmosphere. The invention also relates to the use of the receptacle and of the plunger for storing and discharging, in particular, dental materials.

The invention relates to a slotted plunger, a receptacle containing the latter, and its use for closing receptacles containing dental material and for discharging the dental material from these receptacles.
From U.S. Pat. No. 5,129,825, a capsule for storing dental material is known, in which a plunger is displaceably arranged. For stabilizing the capsule when discharging very viscous dental material, the capsule is reinforced with exterior ribs. On one side, the interior of the capsule is sealed off by the plunger.
Plungers for sealing-off and for discharging dental material from capsules are also described in U.S. Pat. No. 5,083,921. It is stated that the plunger has the purpose of ensuring a largely complete discharge of dental material, in which case the penetrating of air is to be avoided.
U.S. Pat. No. 5,322,440 describes a receptacle for storing and discharging dental material, having a plunger which is displaceably arranged in the receptacle. An elastic sealing lip is molded to the plunger, which sealing lip has the purpose of, as it were, ensuring for a wiper blade that, when the plunger is moved forward, all dental material is discharged.
All these documents have in common that they provide devices which make it possible to largely completely discharge the masses packed into the receptacles.
In contrast, German Patent DE-C1-3915268 relates to a plug with sealing lips for the opening of a liquid receptacle disposed on a movable housing. The sealing lips have slot-shaped notches which are mutually offset by 180° on the circumference. On the one hand, the stopper prevents that liquid can flow out of the receptacle but, on the other hand, permits the unhindered flowing of air into the receptacle interior.
Because of its further development as a plug with a lid-type upper closing part, this plug is not suitable for discharging the liquid stored in the receptacle.
Finally, it was found in U.S. Pat. No. 5,624,260 that aqueous pasty dental materials are to be stored in receptacles whose material has a sufficiently high oxygen penetrability and a low water vapor penetrability. It is stressed that particularly the sealing ring, which may be mounted on the plunger, has to meet these definitions.
The parameters indicated in the document ensure that the stored dental material neither dries out nor polymerizes prematurely because, when radically hardenable dental materials are brought in contact with atmospheric oxygen, a beginning polymerization on the surface of the material is inhibited by the atmospheric oxygen.
The above-mentioned parameters for the oxygen penetrability and the water vapor penetrability, however, limit the available materials for producing plungers for the storing and discharging of dental material from cartridge-shaped receptacles.
It is therefore an object of the present invention to provide a plunger which, on the one hand, permits the discharging particularly of dental material from receptacles and, on the other hand, ensures that the characteristics of the stored material do not change during the storage process.
This object is achieved by providing a plunger and a receptacle containing this plunger and its use for the storage and for the discharge particularly of dental material, as described in the claims.
The invention has the following advantages: The presence of the sealing lips at the plunger results in a minimizing of the force to be applied during the discharge operation as a result of the reduced contact surface between the plunger and the interior wall of the receptacle.
The slot-shaped notches made in the sealing lips, on the one hand, as a result of the improved gas exchange with the surrounding atmosphere, permit a stabilization of the paste, and, on the other hand, as a result of the ventilation, facilitate the insertion of the plunger after the filling of the receptacle.
Despite the slot-shaped notches into the sealing lips, surprisingly, no mass flows out during the discharge operation by way of the face of the plunger although the plunger has no additional sealing devices in this area.
In addition, the molding of at least two sealing lips onto the plunger prevents a jamming of the plunger during the discharge operation.
The flat face ensures a uniform force transmission of from a forcer mounted on a discharge device to the plunger during the discharge operation.
The terms comprise and contain introduce non-exclusive listings of characteristics.
Plungers in the sense of the present invention are any shapes which can be displaceably inserted into a receptacle and are suitable, as a result of the displacement, to discharge the material situated in the receptacle by way of an opening from the receptacle.
In this context, the term "plunger" implies a sufficiently tight edge closure between the exterior surface of the plunger and the interior wall of the receptacle at least in the area in which the plunger is displaceable.
In the present case, this edge closure is achieved predominantly by the presence of sealing lips which are, for example, molded onto the plunger body.
In principle, the plunger may have any shape but preferably has a cylindrical or barrel-shaped construction. A shape with a cylindrical basic body to which a truncated cone is molded is also contemplated.
The term "barrel-shaped" applies to all geometrical shapes whose front and end area have a smaller circular section than the center area, in which case the cross-sectional change may take place continuously or in steps. Shapes are therefore also included which are obtained by joining two truncated cones to a cylinder. In this case, the two molded-on truncated cones must not necessarily have identical dimensions.
The angle of slope of the optionally molded-on truncated cones is normally in the range of from 70° to 88°, preferably in the range of from 80° to approximately 85°. The height of these truncated cones is normally in the range of from 0.3 mm to 2.0 mm, preferably in the range of from 0.5 mm to 1.5 mm.
A sufficiently tight edge closure means that it is ensured that, when the plunger moves forward, the material disposed in the receptacle, during the discharge operation, does not flow out against the forward movement over the face of the plunger.
The flat face of the plunger is the surface onto which pressure is normally exercised by means of a forcer which moves the plunger forward in the receptacle. This surface normally corresponds essentially to the interior cross-sectional surface of the receptacle at the point at which the plunger is introduced into the receptacle. The face is essentially oriented at a right angle with respect to the interior wall of the receptacle.
The term "receptacle" comprises any geometrical shape with an internal volume, the internal volume predominantly having a shape into which a plunger can be displaceably inserted. The internal volume preferably has a cylindrical shape.
The receptacles have a forward and a rearward opening, the ratio of the diameter of the forward opening to the rearward opening preferably being in the range of from 1:10 to 1:2, particularly in the range of from 1:8 to 1:5. The forward opening normally has a nozzle-type shape with a preferably constant inside diameter.
The forward opening of the receptacle is optionally provided with a cap or a displacement stopper which has a coding, preferably a color. It was found to be advantageous to dye this area to the color of the mass to be discharged.
In the dental field, such receptacles are normally called "computes"and have a volume in the range of from 0.1 to 2 cm3, preferably in the range of from 0.2 to 1.5 cm3.
Sealing lips are moldings onto the, or indentations at the, plunger which are to ensure a sufficiently tight edge closure between the plunger and the interior wall of the receptacle.
A cross-sectional shape of the sealing lips is preferable which ensures a minimal contact surface between the sealing lip and the interior surface of the receptacle. Here, wedge-shaped cross-sectional shapes were found to be advantageous which lead into a narrow plateau surface, the wedge-shaped tapering onto the plateau surface taking place from both sides of the sealing lip, but preferably only from one side.
The wedge-shaped areas normally have a slope in the range of from 20° to 50°, preferably in the range of approximately 30° to 40°.
It is particularly preferable for the sealing lip closest to the front surface to first rise perpendicularly in the cross-section, extend over a plateau surface and then drop off in a wedge-shape.
The following possibilities exist for the forming-on of the sealing lips: After the manufacturing of the central plunger body, the sealing lips may, for example, be shaped on by gluing or shrinking on.
Preferably, the sealing lips are molded to the central plunger body during the manufacturing of the plunger, particularly by injection molding through recesses in the injection mold die onto the central plunger body.
However, it is also possible to subsequently process the plunger by cutting methods, such as milling or shaving, in which case the sealing lips can be worked out by the removal of material.
The sealing lips are preferably made of a flexible material which facilitates the adaptation to unevennesses of the interior surface of the receptacle.
In this case, the outside diameter of the plunger measured in the area of the sealing lips is normally slightly larger than the inside diameter of the receptacle in order to ensure a uniformly narrow contacting of the contact surfaces.
The term "slot-shaped notches" comprises all interruptions in the sealing lip which prevent a tight edge closure between the sealing lip and the interior wall of the receptacle in this area. These may be notches, indentations or recesses.
Pasty masses are, for example, materials whose viscosity is such that, for discharging the mass from a small special steel tube (length 20 mm, diameter 2 mm) half filled with the mass, an average force in the range of from 20N to 300 N, preferably 50N to 150 N, has to be exercised upon a massive plunger.
Such masses are sufficiently stable so that they do not dissolve under their own force of gravity on a surface. These masses can be plastically deformed only under the effect of exterior pressure and can be pressed through an opening.
Examples of such masses in the dental field are particularly dental filler materials, such as composites, compomers and pasty glasionomer cements.
In the receptacles according to the invention, masses are preferably stored which are largely anhydrous and/or contain only constituents not easily volatilized under normal conditions.
The term "pasty masses" comprises all hardenable materials on an acrylate and/or epoxy resin base.
The ratio of the length of the plunger to the diameter averaged along the plunger length is normally in the range of from 1:1 to 2:1, preferably in the range of from 1.5:1 to 1.7:1. The plunger normally has a total length of from 3 mm to 15 mm, preferably from 5 mm to 10 mm.
The spacing of the at least two sealing lips with respect to one another is normally in the range of from 1 mm to 7 mm, preferably in the range of from 2 mm to 5 mm.
The plunger may optionally also have three, four or five sealing lips. The sealing lips are preferably uniformly distributed along the length of the plunger.
It was found to be advantageous for the plunger body to have a barrel-shaped construction. This facilitates the introducing of the plunger into the receptacle.
The discharge force to be applied, that is, the force which has to be applied in order to discharge the pasty mass from the receptacle, depends particularly on the following factors:
The viscosity of the mass to be discharged, the volume quantity of the mass to be discharged, the cross-section of the forward opening of the receptacle, the inside diameter of the receptacle in the area of the displaceable plunger, and the curvature radius or geometry during the transition from the cylindrical interior of the receptacle to the forward outlet opening.
With the number of the slot-shaped notches existing in the sealing lips, the gas exchange of the receptacle interior with the outside atmosphere is improved. Sealing lips with two, three or four slot-shaped notches respectively were found to be particularly advantageous when, on the one hand, a sufficient gas exchange is to be ensured and, on the other hand, the plunger has to still sufficiently seal off the receptacle toward the rearward opening. However, optionally, more than four slot-shaped notches may also be present in the sealing lip.
The danger of a flowing-out of mass to be discharged over the face of the plunger during the discharge operation can be additionally reduced if the slot-shaped notches of one sealing lip are arranged to be offset by 180° with respect to the slot-shaped notches of the other sealing lip.
An adaptation of the shape of the front face of the plunger to the face of the interior of the receptacle permits a largely complete discharge of the mass. Conical, step-shaped or oval front faces were found to be advantageous here.
If a largely optimal force transmission from the forcer, which presses on the face of the plunger, to the mass contained in the receptacle is to be ensured, it is advantageous when the front face of the plunger has a largely flat construction and the cross-sectional surface corresponds essentially to the inside diameter of the receptacle at its inlet opening.
The plunger and the receptacle are preferably manufactured from injection-moldable materials, such as PE, PP, POM, PA, PET, PBT, PTFE or fluoric polyolefines or mixtures of these polymers.
The material is preferably adapted to the mass to be stored in the receptacle or to the monomers contained therein. Nonpolar polyolefines are used when the diffusion of polar monomers from the mass to be stored into the receptacle or the plunger or through the receptacle is to be prevented. Polar polyolefines are preferably used for storing masses which contain nonpolar volatile constituents.
It may also be advantageous to coat the plunger with substances improving the sliding characteristics, such as fluoridated polyolefines, or to manufacture the plunger and/or the receptacle from these materials.
The face of the plunger can also be marked in color in order to facilitate the identification of the mass situated in the receptacle.
After the filling with the pasty mass to be stored and to be discharged, the receptacle according to the invention, for the use, is preferably placed in a pistol-type discharge device (for example, FIG. 1 of U.S. Pat. No. 5,083,921). During the discharge, force is in this case transmitted by way of a forcer of the discharge device to the face of the plunger, which leads to a forward movement of the plunger in the receptacle interior and to a displacement of the pasty mass through the forward opening of the receptacle.
Preferred embodiments are explained in detail in the following by means of the drawings.


A sensor assembly is provided that includes a skeletal frame comprising first and second portions configured to move relative to one another. At least one physiological sensor is attached to the frame. A coating is provided over the frame and the at least one physiological sensor to form the sensor assembly. The sensor may be placed on a patient's finger, toe, ear, and so forth to obtain pulse oximetry or other physiological measurements. Methods for manufacturing and using a sensor are also provided as is a method for manufacturing a sensor body.

1. Field of the Invention
The present invention relates generally to medical devices and, more particularly, to sensors used for sensing physiological parameters of a patient.
2. Description of the Related Art
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
In the field of medicine, doctors often desire to monitor certain physiological characteristics of their patients. Accordingly, a wide variety of devices have been developed for monitoring physiological characteristics. Such devices provide doctors and other healthcare personnel with the information they need to provide the best possible healthcare for their patients. As a result, such monitoring devices have become an indispensable part of modern medicine.
One technique for monitoring certain physiological characteristics of a patient is commonly referred to as pulse oximetry, and the devices built based upon pulse oximetry techniques are commonly referred to as pulse oximeters. Pulse oximetry may be used to measure various blood flow characteristics, such as the blood-oxygen saturation of hemoglobin in arterial blood, the volume of individual blood pulsations supplying the tissue, and/or the rate of blood pulsations corresponding to each heartbeat of a patient.
Pulse oximeters typically utilize a non-invasive sensor that is placed on or against a patient's tissue that is well perfused with blood, such as a patient's finger, toe, forehead or earlobe. The pulse oximeter sensor emits light and photoelectrically senses the absorption and/or scattering of the light after passage through the perfused tissue. The data collected by the sensor may then be used to calculate one or more of the above physiological characteristics based upon the absorption or scattering of the light. More specifically, the emitted light is typically selected to be of one or more wavelengths that are absorbed or scattered in an amount related to the presence of oxygenated versus de-oxygenated hemoglobin in the blood. The amount of light absorbed and/or scattered may then be used to estimate the amount of the oxygen in the tissue using various algorithms.
In many instances, it may be desirable to employ, for cost and/or convenience, a pulse oximeter sensor that is reusable. Such reusable sensors, however, may be uncomfortable for the patient for various reasons. For example, the materials used in their construction may not be adequately compliant or supple or the structural features may include angles or edges.
Furthermore, the reusable sensor should fit snugly enough that incidental patient motion will not dislodge or move the sensor, yet not so tight that it may interfere with pulse oximetry measurements. Such a conforming fit may be difficult to achieve over a range of patient physiologies without adjustment or excessive attention on the part of medical personnel. In addition, lack of a tight or secure fit may allow light from the environment to reach the photodetecting elements of the sensor. Such environmental light is not related to a physiological characteristic of the patient and may, therefore, introduce error into the measurements derived using data obtained with the sensor.
Reusable pulse oximeter sensors are also used repeatedly and, typically, on more than one patient. Therefore, over the life of the sensor, detritus and other bio-debris (sloughed off skin cells, dried fluids, dirt, and so forth) may accumulate on the surface of the sensor or in crevices and cavities of the sensor, after repeated uses. As a result, it may be desirable to quickly and/or routinely clean the sensor in a thorough manner. However, in sensors having a multi-part construction, as is typical in reusable pulse oximeter sensors, it may be difficult to perform such a quick and/or routine cleaning. For example, such a thorough cleaning may require disassembly of the sensor and individual cleaning of the disassembled parts or may require careful cleaning using utensils capable of reaching into cavities or crevices of the sensor. Such cleaning is labor intensive and may be impractical in a typical hospital or clinic environment.

Medical sensor and technique for using the same


A pocketformer apparatus for post-tension construction including an anchor member having a wedge-receiving cavity therein, a tubular member having a portion extending through the wedge-receiving cavity, a first securement member affixed to a first end of the tubular member, a cup member positioned over the tubular member, and a second securement member affixed to a second end of the tubular member. The cup member is interposed between the second securement member and the anchor member. The tubular member also extends through a hole in a form board. The second securement member is positioned on one side of the form board. The cup member and the anchor member are positioned on an opposite side of the form board. A tendon extends through the tubular member.

The present invention relates to post-tension anchor systems generally. More particularly, the present invention relates to pocketformers which are used for the creation of a pocket in concrete adjacent an end of the tendon in the anchor system. Additionally, the present invention relates to devices for securing the pocketformer in place at the end of the anchorage system.
For many years, the design of concrete structures imitated typical steel design of column, girder and beam. With technological advances in structural concrete, however, its own form began to evolve. Concrete has the advantages of lower cost than steel, of not requiring fireproofing, and of its plasticity, a quality that lends itself to free flowing or boldly massive architectural concepts. On the other hand, structural concrete, though quite capable of carrying almost any compressive (vertical) load, is extremely weak in carrying significant tensile loads. It becomes necessary, therefore, to add steel bars, called reinforcements, to concrete, thus allowing the concrete to carry the compressive forces and the steel to carry the tensile (horizontal) forces.
Structures ofreinforced concrete may be constructed with load-bearing walls, but this method does not use the full potentialities of the concrete. The skeleton frame, in which the floors and roofs rest directly on exterior and interior reinforced-concrete columns, has proven to be most economic and popular. Reinforced concrete framing is seemingly a quite simple form of construction. First, wood or steel forms are constructed in the sizes, positions, and shapes called for by engineering and design requirements. The steel reinforcing is then placed and held in position by wires at its intersections. Devices known as chairs and spacers are used to keep the reinforcing bars apart and raised off t he form work. The size an number of the steel bars depends completely upon the imposed loads and the need to transfer these loads evenly throughout the building and down to the foundation. After the reinforcing is set in place, the concrete, a mixture of water, cement, sand, and stone or aggregate, of proportions calculated to produce the required strength, is placed, care being taken to prevent voids or honeycombs.
One of the simplest designs in concrete frames is the beam-and-slab. This system follows ordinary steel design that uses concrete beams that are cast integrally with the floor slabs. The beam-and-slab system is often used in apartment buildings and other structures where the beams are not visually objectionable and can be hidden. The reinforcement is simple and the forms for casting can be utilized over and over for the same shape. The system, therefore, produces an economically viable structure. With the development of flat-slab construction, exposed beams can be eliminated. In this system, reinforcing bars are projected at right angles and in two directions from every column supporting flat slabs spanning twelve or fifteen feet in both directions.
Reinforced concrete reaches its highest potentialities when it is used in pre-stressed or post-tensioned members. Spans as great as 100 feet can be attained in members as deep as three feet for roof loads. The basic principal is simple. In pre-stressing, reinforcing rods of high tensile strength wires are stretched to a certain determined limit and then high-strength concrete is placed around them. When the concrete has set, it holds the steel in a tight grip, preventing slippage or sagging. Post-tensioning follows the same principal, but the reinforcing is held loosely in place while the concrete is placed around it. The reinforcing is then stretched by hydraulic jacks and securely anchored into place. Prestressing is done with individual members in the shop and post-tensioning as part of the structure on the site.
In a typical tendon tensioning anchor assembly in such post-tensioning operations, there is provided a pair of anchors for anchoring the ends of the tendons suspended therebetween. In the course of installing the tendon tensioning anchor assembly in a concrete structure, a hydraulic jack or the like is releasably attached to one of the exposed ends of the tendon for applying a predetermined amount of tension to the tendon. When the desired amount of tension is applied to the tendon, wedges, threaded nuts, or the like, are used to capture the tendon and, as the jack is removed from the tendon, to prevent its relaxation and hold it in its stressed condition.
In such post-tension construction, the tendons are anchored and cut off just inside the face of the structure in what are termed xe2x80x9cpocketsxe2x80x9d. The xe2x80x9cpocketsxe2x80x9d surrounding the tendon end are filled with a concrete grout. A xe2x80x9cpocketformerxe2x80x9d is placed in the concrete adjacent to the face of the structure and against an end of the terminal anchor. After the concrete is suitably hardened, a form board is removed and the pocketformer is removed so as to expose the pocket. The ends of the tendon extend outwardly of the pocket. After the tensioning has occurred, the pocket is then filled with a concrete grout so as to be flush with the face of the structure.
FIG. 1 shows a pocketformer 10 as used in the prior art. This pocketformer 10 has a frustoconical surface 12 formed on the exterior of the pocketformer 10. The frustoconical shape 12 will define the pocket. A central tubular member 14 is formed within the interior of the frustoconical portion 12. One end 18 of the tubular member 14 will extend into the central bore of the anchor. The interior 16 of the tubular member 14 will allow the tendon to extend therethrough. Struts 20 extend between the tubular member 14 and the frustoconical portion 12. The tubular member 14 is generally centered within the interior of the frustoconical portion 12. The surface of the anchor will abut the narrow end of the frustoconical portion 12. The wide end of the frustoconical portion will abut a surface of a form board. The tubular member 14 extends through a hole formed in the form board. As such, the tendon will extend outwardly of the form board during the formation of the concrete structure.
One of the problems with the pocketformer 10, as shown in FIG. 1, is the inability to properly secure the anchor relative to the pocketformer 10. In conventional practice, long threaded members will extend through holes in the anchor member and be attached to the form board. After the concrete is hardened, it will be necessary to remove the threaded members or nails. If these items are not removed, then corrosion can occur and rust patterns will form on the facing surface of the concrete structure. Furthermore, the use of nails or threaded members for securing the anchor relative to the form board is a time consuming and labor-intensive operation. As such, a need has developed so as to allow the anchor to be removably secured to the pocketformer during the installation of the pocketformer.
In the past, various patents have issued relating to pocketformers that serve to retain the pocketformer in place, against the form board, during the installation of the anchor. For example, U.S. Pat. No. 3,844,697, issued on Oct. 29, 1974 to H. J. W. Edwards describes an anchorage assembly including an anchor having a hollow housing and a means therein for engaging a stressing tendon passing therethrough. The hollow member is removably attached to the anchor housing and to the concrete formwork and fixing the relative position of the anchor housing to the formwork. The member surrounds the tendon between the anchor housing and the formwork and is adapted and arranged to be detached from the anchor housing after the concrete has set. A cavity forming spacer is provided which surrounds the member and is disposed between and seals against the anchor housing and the formwork to form a cavity in the concrete.
U.S. Pat. No. 3,956,797, issued on May 18, 1976 to Brandestini describes a pocketformer apparatus in which the pocketformer is initially threaded into the interior opening of a steel anchor. As such, the steel anchor will have internal threads which threadedly receive the external threads on the end of the pocketformer. The pocketformer includes an interior bore through which the tendon passes. On the opposite end of the pocketformer is a threaded section which extends on an opposite side of the form board from the anchor. A threaded nut is threadedly received by the threads of the pocketformer which extend on the opposite side of the form board.
U.S. Pat. No. 4,053,974, issued on Oct. 18, 1977 to Howlett et al. describes a method of forming a concrete structure with a recess to receive an anchorage. This method includes a tubular mounting means mounted to extend over the tendon and through an opening in a bearing or anchor plate in order to secure the bearing plate in a fixed position aligned in relation to the tendon for casting the bearing plate into the concrete member in a predetermined orientation. A spacing means is provided between the form board and the anchor plate so as to allow the anchor plate to be cast into a recess in the concrete member.
U.S. Pat. No. 4,363,462, issued on Dec. 14, 1982 to Wldodkowski et al. teaches a formwork for a concrete structural member. This device includes a recoverable formwork part. The recoverable part has an axially elongated sheath which closely encloses a tendon. A cup-shaped part is formed integrally with the sheath and is arranged to form at least a portion of the recess in the concrete member. When assembled on the formwork, one end of the sheath is arranged to be located within the concrete when it is poured and the other end is located on the exterior of the formwork. The cup-shaped part is located intermediate of the ends of the sheath and just inside the formwork. A member is engageable with the sheath for attaching it to the formwork.
U.S. Pat. No. 5,897,102, issued on Apr. 27, 1999 to the present inventor, describes a pocketformer apparatus for a post-tension anchor system. This pocketformer apparatus includes a tubularmember with an outwardly flanged end, a securement member affixed to the tubularmember, and a cup member having an interior opening such that the tubular member extends through the interior opening. The tubular member has an interior passageway extending from the flanged end to another end. The flanged end engages an anchor of the post-tension anchor system. The cup member is interposed between the flanged end and the securement member on the tubular member. The tubular member has an externally threaded area extending inwardly of the end opposite the flanged end. The securement member is threadedly received by the externally threaded area. An annular ring is formed on the flanged end of the tubular member so as to engage a receptacle formed in the encapsulation of the anchor. The securement member, the cup member and the tubular member are formed of a polymeric material.
Although the system described in U.S. Pat. No. 5,897,102 has performed well in actual usage, the system described in this patent is particularly adapted for use in association with an encapulated anchor. In particular, the flanged end of the tubular member engages the cap-receiving opening at the end of the encapsulation of the anchor member. In certain circumstances, certain construction requirements specify the use of a unencapsulated anchor. When such construction projects are specified, the system described in U.S. Pat. No. 5,897,102 cannot be adequately utilized. As such, a need has developed so as to provide a nailless pocketformer system whereby the system would accommodate unencapsulated anchorages.
U.S. Pat. No. 5,436,425, issued on Jul. 25, 1995 to the present inventor, describes a system whereby the tendon can be properly cut by using a plasma cutting torch. The present inventor is also the owner of U.S. application Ser. No.: 09/317,097, filed on May 23, 1999, for another system for the cutting of a tendon used in post-tension anchor systems. These systems utilize a plasma cutting torch which utilizes a positioning element for interconnecting the head of a plasma cutting torch with a tendon to be severed. The pocket into which the plasma cutting torch and positioning element are inserted has a particular configuration so as to allow enough space for the apparatus. In actual use, the product described in this patent and this patent application has been very successful. As such, a need has existed for the use of such a plasma cutting torch in association with unencapsulated anchor systems.
It is an object of the present invention to provide a pocketformer system which allows the anchor to be properly secured in place relative to the form board.
It is another object of the present invention to provide a pocketformer system whereby an unencapsulated anchor can be properly positioned relative to the form board without the use of nails.
It is a further object of the present invention to provide a pocketformer system whereby a pocket is formed which allows a plasma cutting torch and associated positioning elements to be used for the severing of the tendon in the pocket.
It is a further object of the present invention to provide a pocketformer system which eliminates the need for nails or threaded members for the attachment of the anchor relative to the form board.
It is still another object of the present invention to provide a pocketformer system which is easy to use, relatively inexpensive and easy to manufacture.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.
The present invention is a pocketformer apparatus for post-tension construction which comprises an anchor member having a wedge-receiving cavity, a tubular member extending through the wedge-receiving cavity, a first securement member affixed to a first end of the tubular member, a cup member extending over the tubular member, and a second securement member affixed to a second end of the tubular member. The cup member is interposed between the second securement member and the anchor member. The tubular member extends through a hole in a form board. The second securement member is positioned on one side of the form board. The cup member and the anchor member are positioned on an opposite side of the form board.
The second end of the tubular member extends outwardly of one side of the form board. The second securement member is affixed to the second end of the tubular member so as to have a surface in abutment with one side of the form board. The cup member has a wide end and a narrow end. The wide end of the cup member is in surface-to-surface contact with the opposite side of the form board. The narrow end of the cup member has positioning elements extending outwardly therefrom. The anchor member is received between the positioning elements such that the wedge-receiving cavity is in axial alignment with the interior opening of the cup member.
In the present invention, the anchor member is, preferably, an unencapsulated steel anchor.
In the present invention, the wedge-receiving cavity of the anchor member is tapered so as to have a narrow end adjacent to one side of the anchor member and a wide end adjacent an opposite side of the anchor member. The tubular member has a portion which is tapered so as to conform with the taper of the wedge-receiving cavity. The first securement member is of an annular configuration and is threadedly secured to the first end of the tubular member. The first securement member has a rim portion of greater thickness than a remainder of the first securement member.
In the present invention, a tendon extends through the tubular member. The second securement member is threadedly secured around the second end of the tubular member. In the preferred embodiment of the present invention, the cup member will have a double oval shape.
The present invention is also a method for the forming of a pocket in a concrete structure. This method comprises the steps of: (1) placing a tubular member through a wedge-receiving cavity of an anchor member such that a first end of the tubular member extends outwardly of a side of the anchor member; (2) affixing a first securement member onto the first end of the tubular member; (3) positioning a cup member over the tubular member such that a narrow end of the cup member faces an opposite side of the anchor member; (4) extending the tubular member through a hole in the form board such that a wide end of the cup member faces one side of the form board and such that a second end of the tubular member extends outwardly of an opposite side of the form board; (5) affixing a second securement member over the second end of the tubular member; (6) extending a tendon through the tubular members; (7) pouring concrete over an exterior of the anchor member and the cup member within one side of the form board; and (8) solidifying the concrete.
In particular, in this method, so as to completely form the pocket, the second securement member is removed from the second end of the tubular member and the form board and the cup member are also removed from the tubular member so as to expose a pocket, which is shaped like an exterior surface of the cup member. The tubular member is then pulled from the wedge-receiving cavity of the anchor member. This step of removing the tubular member from the cavity of the anchor member is accomplished by rotating the tubular member so as to threadedly detach the first end of the tubular member from engagement with the first securement member.

Pocketformer apparatus for a post-tension anchor system and method of using same