baber/WOPTO huggingface dataset:
Patent WO-03068682-A1 (WO)
Title: Nanoskaliger rutil oder nanoskaliges oxid sowie verfahren zu dessen herstellung
Inventor: NONNINGER RALPH
IPC: C01G25/02
Filed: 2002-08-30
Abstract: Nanoskalige Rutil-oder Oxidpulver sind dadurch erhältlich, dass man zunächst ein amorphes TiO2 herstellt, durch Versetzen einer alkoholischen Lösung mit einem Titanalkoholat und mit einem Aluminiumalkoholat unter Zugabe von Wasser und Säure. Das amorphe, aluminiumhaltige TiO2 wird durch Entfernung des Lösungsmittels isoliert, und in Wasser bei Gegenwart eines Zinnsalzes redispergiert. Eine thermische oder hydrothermale Nachbehandlung führt zu einem auf Primärteilchengrösse redispergierbaren Rutil oder Oxid. Mit einer Primärteilchengrösse zw. 5 und 20 nm kann dieser n-Rutil oder das erhaltene Oxid transparent in alle organische Matrizes eingearbeitet werden. Durch eine Gitterdotierung mit dreiwertigen Ionen wird die photokatalytische Aktivität unterdrückt. Wird die amorphe Vorstufe in Alkohol redispergiert, oder nicht isoliert, sondern direkt kristallisiert, entsteht ein auf Primärteilchengrösse redispergierbarer Anatas. Durch Variation der Alkoholate sind ebenfalls darstellbar: ZrO2, ZnO, SnO2, ATO, In2O3, ITO, Y2O3, BaO, CaO, MgO, CeO2, und BaTiO3.
Patent WO-03046305-A1 (WO)
Title: Stirnseitige stossverbindung zwischen zwei dachblechelementen eines flachdachs und hierzu geeignetes dachblechelement
Inventor: ZAHN HARALD
IPC: E04D3/362
Filed: 2002-11-14
Abstract: Die Erfindung betrifft eine Stirnseitige Stossverbindung zwischen zwei Dachblechelementen eines Flachdachs und ein hierzu geeignetes Dachblechelement (1), das in seinen Profilwandungen (6, 7) eingeformte Hinterschneidungen, Nuten oder Taschen (8, 9) besitzt. In diesem Bereich sind die Taschen mindestens eines Dachblechelements durch Schlitze (11) oder eine Ausklinkung (15) weitestgehend ausgespart wobei auch der Blechscheitel eines Blechs entfernt werden kann. Die Bleche können ineinander eingeschoben werden oder aufeinander aufgelegt werden, ohne dass sich die Taschen oder Nuten gegenseitig behindern. Insbesondere dann, wenn die Schlitze oder die Ausklinkung so ausgeführt sind, dass diese die Taschen nahe des Obergurtes nahezu halbieren, umgreifen die restlich verbleibenden Taschen die Taschen des darunter liegenden Blechs. Das obere Blech ist dabei im Schlitzbereich soweit elastisch, dass dieses nahezu in den Obergurt des unteren Bleches einklippst. Die Dachblechelemente können z.B. im Bereich der sich überlappenden Obergurte oder mit ihren auf der Pfette aufliegenden Blechflächen entweder miteinander und/oder auf der Pfette befestigt werden. Die Erfindung stellt sicher, dass die Dachblechelemente trotz ihrer ausragenden Taschen spaltfrei überlappend gestossen werden können.
Patent WO-03045671-A1 (WO)
Title: Verfahren und vorrichtung zur herstellung von faserverstärkten kunststoffbauteilen
Inventor: LORENZ TORSTEN
IPC: B29C70/34
Filed: 2002-11-13
Abstract: Herstellungsvorrichtung und Verfahren zur Herstellung von faserverstärkten Kunststoffbauteilen aus einem Prepreg-Halbzeug und einem trockenen Textil-Halbzeug mit einer Be- und Entlüftungskammer (A) und einer in diese mündenden Abzugsleitung (25) zur Herstellung von Unterdruck und einer Textil-Halbzeug-Kammer (C) zur Aufnahme eines trockenen Textil-Halbzeugs (1), in die eine Injektionsleitung (20) zum Einbringen von Harz mündet, wobei eine Prepreg-Kammer (B) zur Aufnahme eines Prepreg-Halbzeugs (2) vorgesehen ist, wobei die Prepreg-Kammer (B) luftdurchlässig und die Textil-Halbzeug-Kammer (C) mittels einer Membran zumindest bereichsweise luftundurchlässig und harzdurchlässig an der Be- und Entlüftungskammer (A) gelegen ist, wobei ein Unterdruck in der Be- und Entlüftungskammer (A) durch die luftdurchlässigen Membranen einen Unterdruck sowohl in der Prepreg-Kammer (B) als auch in der Textil-Halbzeug-Kammer (C) bewirkt.
Patent WO-03066498-A1 (WO)
Title: Treibscheibenaufzug
Inventor: KUENTSCHER DIETMAR
IPC: B66B11/00
Filed: 2003-01-25
Abstract: Bei einem Treibscheibenaufzug mit einem zwischen Schienen geführten Fahrkorb, mit über Eck zu den Fahrkorbschienen angeordneten Schienen für die Führung einer Gegenlast, mit einem Satz von Tragseilen, an denen der Fahrkorb und die Gegenlast in loser Rolle aufgehängt sind, und mit einer zumindest aus einem getriebelosen Motor, einer Treibscheibe für die Tragseile und einer Bremse gebildeten Antriebseinheit, deren axiale Länge grösser als ihr Durchmesser ist, sowie vorzugsweise einer Gegenscheibe für eine doppelte Tragseilumschlingung der Treibscheibe ist die Antriebseinheit (4) lediglich einerseits an der inneren Fahrkorbschiene (2i) und andererseits an der äusseren Gegenlastschiene (3a) befestigt, wobei die Antriebseinheit (4) im lichten Raum zwischen diesen beiden Schienen (2i, 3a) liegt.
Patent DE-1801730-A1 (DE)
Title: Purification of fluids
Inventor: LUETTICH GERHARD
IPC: D06N7/00
Filed: 1968-10-08
Abstract: Vibrating screen for mechanical separation of impurities from liquid suspensions incorporates means for preventing tabular particles from passing the screen in edge-on attitude, and for prevention of foaming due to inspirated air, in the form of a deflector plate which is suspended at the entry to the screen frame, and is spaced above the screen fabric and parallel to it.
Patent DE-1808016-A1 (DE)
Title: Sulphamylanthranilic acids prepared from nitrobenzoic
Inventor: NAHM DR HELMUT
IPC: C07C311/37
Filed: 1968-11-09
Abstract: Prepn. of sulphamylanthranilic acids of formula (I) by the method given under 'PREPARATION'. Hal = Cl, Br R = benzyl, thienyl, furfuryl (I) are diuretic and saluretic agents. A mixt. of 3-sulphamyl-4-chloro-6-nitrobenzoic acid (10 g) and benzylamine (40 ml) is stirred at 100-110 deg. for 1 hr. and the hot mixt. poured into 2N-HCl (400 ml). The recovered product is dried, powdered, extd. several times with CH2Cl2 and then purified by charcoal treatment in aq. NaHCO3 soln. to yield 3-sulphamyl-4-chloro-6-benzylaminobenzoic acid (65%). m.p. 240 deg.
Patent DE-1816229-A1 (DE)
Title: Lime burning and sintering
Inventor: STINGEL EGON
IPC: F27B1/00
Filed: 1968-12-20
Abstract: Lime or dolomite chips, particularly smaller than 40 mm. are treated in a shaft furnace in which about 80% of half-burnt gas from the combustion chamber is drawn horizontally through the charge in the firing zone and burnt outside the furnace with air rising from the cooling zone, and is then returned to the firing zone higher up to join the remaining 20% rising through the furnace, and continue up to the preheating zone.
Patent DE-1950329-A1 (DE)
Title: Anti-trichomonas pharmaceuticals
Inventor: DOMASCHKE LOTHAR DR
IPC: C07D231/16
Filed: 1969-10-01
Abstract: New 4-nitro-N1-pyrazolyl cpds. such as 4-nitro-N1-pyrazolyl-(acetic acid methyl ester) are produced, in an example, by adding chloroacetone to boiling solution of 4-nitro-pyrazol in triethylamine and acetonitrile to obtain 4-nitro-pyrazol-acetone. Products are pharmaceuticals used, for example, against trichomonas vaginalis.
Patent DE-1951360-A1 (DE)
Title: Shrink resistant wool textiles
Inventor: BERNHEIM WILLY DR
IPC: D06M15/423
Filed: 1969-10-11
Abstract: Textiles made partly or completely of wool are made shrink resistant by soaking in a aqs. dye bath containing the salt of a volatile acid with a condensation product obtained by (1) reacting 1 mole polyamine with at least 3:1 degrees and/or 2 degrees amino grps. with 0.5-1.5 moles of a 3-10C dicarboxylic acid (deriv) or with 0.2-2 moles dicyandiamide or with 0.4-4 moles cyanamide. (2) reacting the resulting basic condensation product with a cpd. contg. an aliphatic or aromatic epoxy gp. and (3) terminating reaction with a volatile acid water and/or lower alkanol in presence of or after further reaction with formaldehyde. The textiles are then dried and finished in known manner.
Patent DE-1966311-A1 (DE)
Title: 1 subst 4 amino 6 pyridazones with herbicidal - activity
Inventor: FISCHER ADOLF DR
IPC: C07D237/22
Filed: 1969-03-13
Abstract: 1-Subst-4-amino-6-pyridazones with herbicidal activity Title cpds. are 1-R-4-X-5-Y-6-pyridazones where R is phenyl or aralkyl (opt. subst. by halogen, alkyl, alkoxy or haloalkyl) or cyclohexyl (opt. subst by halogen, or alkyl), Y is H, halogen, alkoxy or mercaptoalkyl and X is cyclopropanecarboxamido, (m-alkanoylaminophenoxy) carbonylamino, (m-alkoxycarbonylaminophenoxy)carbonylamino, N'-cycloalkyl-N'-hydroxy-ureido or N'-chlorosulphonyl-ureido; X can also be NH2 or acetamido when Y is H or is aralkyl. The cpds. may be prepd. by reacting corr. 4-isocyrindopyridazines with m-acylaminophenols or hydroxylamines, by reacting 4-aminopyridazones with chlorosulphonyl isocyanate or cyclopropanecarboxylic acid chloride, by reacting 4,5-dihalopyridazones with NH3, or by reacting 4-amino-5-chloropyridazones with hydrogen.
Patent DE-2002363-A1 (DE)
Title: Strontium carbonate from crude phosphate
Inventor: GRAMS GERHARD DR
IPC: C01F11/18
Filed: 1970-01-20
Abstract: The residue separated from the solution after dissolving the crude phosphate in nitric acid is washed with nitric acid to remove the remainder of the digestion product. It is then mixed to a suspension with H2O and ammonia led in at 40-110 degrees C.M preferably 80-100 degrees C., to give pH >2.0, preferably 4.0-7.0. The solid material is separated from the liquid and into the latter are passed NH3 +CO2 in a molar ratio 2 : 1, at 30-100 degrees C., preferably 60-65 degrees C., until precipitation of strontium carbonate is complete.
Patent DE-2004429-A1 (DE)
Title: Sand slinger
IPC: B22D41/02
Filed: 1970-01-31
Abstract: A method of filling a material in an at least semiplastic or mouldable condition into a tubular space defined between an outer, female, wall surface and an inner, male surface having its periphery spaced from the female surface, and having a closed bottom comprising dividing the material into continually produced similar slugs; projecting the slugs as produced in a constant flow stream into the tubular space towards its bottom, while continuously advancing the stream in repeated circuits around the closed circumference of the tubular space and while maintaining a rough parallelism of the average centreline of the stream relative to a fixed central axis, rapidly deflecting the stream in an oscillatory manner, transverse to the direction in which the stream is advancing to shift the point of stream impact continually to and fro between the inner and outer surface; this procedure being carried on through sufficient repeated circuits of the stream until the space is filled.
Patent DE-2008293-A1 (DE)
Title: Metal foil coated with vapour barrier for building elements
IPC: E04D5/10
Filed: 1970-02-23
Abstract: Metal foil is coated, pref. on both sides, with liquid plastic, then its surface is scarified to remove the metal oxide coating (e.g. while in a plastic bath) and increase the bonding area, then it is passed through a heater and coated with short fibres or granules, then passed through a further heater.
Patent DE-2047564-A1 (DE)
Title: Tenter with rotatable pin holders - to allow easy uptake of verticall presented fabric
IPC: D06C3/02
Filed: 1970-09-28
Abstract: A tenter has its pins supported in rotatable holders that are themselves attached to the links of the tenter chain. At the cloth take-up point the pins are held in the horizontal plane by a suitable spring. After the pins have penetrated the vertically presented fabric they are rotated by a cam until they hold the fabric with the pins in the conventional vertical position. The pin holders are held in this position by a latch device that is unlatched at the delivery end of the tenter to allow the pins to be withdrawn from the fabric. This device could be used in the slitting and flat setting of tubular fabrocs.
Patent DE-2050448-A1 (DE)
Title: Plastic cable protecting cover - manufactured in one piece with and/or nylon lattice reinforcement
IPC: H02G9/02
Filed: 1970-10-14
Abstract: The protective cover, esp. for underground cables has a lattice work of two intersecting wire and/or strong filament systems. Pref. the filament material is nylon and the intersections of the latticework are fixed by plastic. The wires are worked into the flat plastic before it is shaped into a 'pointed roof', semi-circular or flat construction.
Patent DE-2055600-A1 (DE)
Title: Laminated packing material
IPC: B65D65/40
Filed: 1970-11-12
Abstract: A multi-layered flexible packing material consists of (a) an outer layer of polypropylene, (b) an intermediate layer of polyvinyl alcohol with a moisture content of 3-7%, bonded to the polypropylene layer by an adhesive, and (c) an inner layer of polyethylene laminated to the polyvinyl alcohol layer. Bags of such material are partic. used for ground roast coffee, or other substances which are sensitive to oxidation. The packing material is flexible and resistant to rough handling; it can be heat-sealed. The polypropylene layer can be printed.
Patent DE-2065681-A1 (DE)
Title: Compound piezo electric transducer - is for bi-directional vibration and has an angled centre junction carrying two vibrators
Inventor: KLOZ EDUARD
IPC: A61B18/00
Filed: 1970-11-03
Abstract: The transducer centrepiece is fitted with two vibrator aggregates which are fixed by means of steel bolts to outward angled faces to form a trapezoid combination. The centrepiece incorporates a fixing socket for the attachment of a vibration transmitter at right angles to the plane of the vibrators. A variety of tools or instruments such as drills, cutters, grinders, can be attached to the transmitter. The vibrators and transmitter are arranged to vibrate at half of the ultrasound wavelength in opposing phases by polarity reversal of the supply current. The configuration induces vibrations both axially and transversely for increased efficiency. This mode of operation also facilitates the insertion of long flexible probes or catheters in medical applications.
Patent DE-2105465-A1 (DE)
Title: Protective creams for rubber - for use in tyre fitting contg glycerol glycols fatty alcohols and silica
IPC: C09K23/00
Filed: 1971-02-05
Abstract: The compsns. contain (A) 10-50wt.% glycerol, (B) 0.25 to 4 times the wt. of (A), of diethylene glycol or higher-molecular liq. polyethylene glycol, (C) 5-10wt.% of 16-18C fatty alcohols, (D) opt. 0.1-5wt.% of emulsifier, (E) 0.2-3% of metal oxide inert to rubber, with mean particle size of 5-50 mu and BET-surface area of 100-300 m2/g., and (f) remainder water. (D) is pref. a fatty alcohol sulphate and (E) is silica, alumina or magnesia, pref. silica with pH 6.5, BET surface area of 230 m2/g. and average size of primary particles 18 m mu and of secondary particles 10 mu. The compsns. have a creamy, paintable consistency and are suitable for application to tyres to assist fitting, prevent movement of the tyre on the rim in use and assist removal.
Patent DE-2135827-A1 (DE)
Title: Forming oxidic ceramic - metal joints - by superficial reduction of ceramic material by active metals
Inventor: SCHMIDT-BRUECKEN HEINRICH DIPL
IPC: C04B37/02
Filed: 1971-07-17
Abstract: According to DT 2,047,056, composite bodies are produced by compressing together an oxidic ceramic material and a base metal alloyed with an activating metal, and heating the assembly to a temp. below the m.pt. of the metal alloy; firm bonds are formed as a result of superficial chemical reduction of the oxide(s); suitable activating metals are those whose oxidation heat is equal to or larger than that of the ceramic material. The range of activating materials is now extended to metals whose oxide-formation enthalpy is smaller than that of the ceramic oxides, but larger than that of the incidentally saturated (e.g., by adsorption of gases) surface valences of the ceramic material. Thus, for example, very strong joints (about 1100 kg/cm2) can be formed between alumina and gold foils contg. 0.5-2% of Si, V, Cr or Ga.
Patent DE-2136768-A1 (DE)
Title: Polyethylene cable fitting - heat sealed to the polyethylene cable casing by an intermediate heating element
Inventor: GANSER ALFONS
IPC: H02G15/013
Filed: 1971-07-22
Abstract: The cable fitting around the cable inlet is formed with thickened walls so that edges are formed in the axial and radial direction to the cable which maintain the natural rigidity of the polyethylene fitting during heating and oppose the pressure from the heat expanding polyethylene fitting so that the heated polyethylene is forced radially into the parts. Pref. the wall thickness of the fitting at the inlet point is double the width of the heating element.
Patent DE-2149997-A1 (DE)
Title: Removal of arsenic cpds - from hydrocarbon mixts using palladium or platinum gp metals on porous carriers or in suspen
IPC: C07C7/148
Filed: 1971-10-07
Abstract: Hydrogen mixts contg As are brought into contact with hydrogenating metals, pref. Ni or metals of the Pd and/or Pt gps. esp Pd. The hydrocarbon may be in the liq or gaseous phase, and the metal may be dispersed on a porous carrier or in an aq. suspension, the As being retained on the carrier or in the suspension. As levels are reduced to below the detection levels of 1 in 109 parts making the hydrocarbons suitable for subsequent catalytic processes. The olefin content is not reduced by polymsn and corrosion problems associated with the use of silica gel contg H2SO4 to remove As are eliminated.
Patent DE-2153014-A1 (DE)
Title: Alpha-aminoacetonitriles - from benzyl alkyl ketones by treatment with hydrazine and activated aluminium and benza
Inventor: KLOSA JOSEF DIPL CHEM DR RER N
IPC: C07C255/24
Filed: 1971-10-21
Abstract: Alpha-Aminoacetonitriles of formula: (in which R is H, CH3, halogen, pref. Cl, or an alkoxy gp., pref. methoxy; and R1 is an arylalkyl gp., such as alpha-phenylisopropyl, in which phenyl can be substd. with e.g. a halogen, esp. Cl or F; and R3 is an alkyl, esp. CH3 or C2H5) are produced by treating R2C6H4-CH2-CO-R3 (in which R2 is H or a halogen, esp. Cl or F; and R3 is an alkyl, esp. CH3 or C2H5) with hydrazine hydrate and then with metallic Al opt. activated with HgCl2 in a solvent or diluent, pref. a lower alcohol; subsequently, the product is reacted with an aldehyde of the benzaldehyde series and an alkali cyanide; the resulting alpha-aminoacetonitrile is ppted. with water. The products are pharmaceuticals, e.g. 'Amphetaminil' (RTM); they can also be used as starting materials for the prodn. of alpha-amino acid amides and alpha-amino acids.
Patent DE-2156468-A1 (DE)
Title: Sulphuric acid purification - from mercury by cathodic deposition esp in electrolytic chamber with concentric electrodes
Inventor: KOLA ROLF
IPC: C01B17/90
Filed: 1971-11-13
Abstract: Sulphuric acid of >78 wt.% concn., e.g. produced by processing SO2 from roasting of sulphide ores, is purified by cathodically depositing Hg by electrolysis carried out esp. below decompsn. voltage of H2SO4. Electrolytic sepn. takes place esp. with a 4-30 (6-15) mm. electrode distance, at 1.1-6 (1.5-3) V, pref. in a chamber formed of 2 concentrically placed electrodes.
Patent DE-2162027-A1 (DE)
Title: Thioether prepn - from olefinic cpds and mercaptans re-treated with hydrogen sulphide
IPC: C07C321/16
Filed: 1971-12-14
Abstract: H2S is dissolved in mercaptans, pref. to saturation limit, before free radical-promoted reaction of mercaptans with olefinic cpds. in presence of an initiator, in process for prodn. of thioethers. No H2S need be present during radical reaction and residual H2S may be removed from mercaptans by heating under reduced press. Dissolved H2S reduces metallic mercaptides and disulphides formed in presence of impurities, e.g. Cu, Fe, Ni, Cr and Zn, and restores addn. reactivity of mercaptans with olefinic double bonds.
Patent DE-2215618-A1 (DE)
Title: Continuous chipboard press - has two endless belts running along roller paths
Inventor: ENGELS KASPAR
IPC: B30B5/06
Filed: 1972-03-30
Abstract: A continuously operating press for making endless chipboard or fibreboard, for subsequent cutting to length, comprises a pair of opposed pressing elements which pass through the pressing zone; these elements comprises upper and lower endless belts guided along the opposed faces of upper and lower fixed tables; between each, belt and its associated table is an endless series of rollers, which travel around a (non-circular) path in the manner of a roller bearing.
Patent DE-2218050-A1 (DE)
Inventor: GLITZ EKKEHARD
IPC: G10L25/90
Filed: 1972-04-14
Abstract: 1433351 Bandwidth compression LICENTIA PATENT - VERWALTUNGS GmbH 13 April 1973 [14 April 1972] 17933/73 Heading H4R In speech bandwidth compression in which spaced sections of the speed signal are selected for transmission, voiced sections are of a length equal to a whole pitch period or to a portion extending between the zero crossing before the energy rich start of a pitch period and a zero crossing before the next pitch period, and unvoiced sections are of a length equal to a mean of the voiced pitch period, the sections being transmitted as delta modulations and being stretched to fill the gaps between sections. The modulated speech 1 is read alternately into stores 3, 4 associated with counters 31, 41 recording which store stages are occupied, at a rate determined by zero crossing detector 21 and read-out at a slower rate for multiplexed transmission 8. A pitch extractor 2 produces a pitch pulse at the start of each word and these pulses are monitored to produce a voicedunvoiced decision for encoded transmission. Characters identifying the start of words and representing the basic pitch frequency are also encoded for transmission, the latter occupying every 40th time slot for synchronization and level control at the receiver. Word storing is only effected when a zero crossing pulse is followed by a pitch pulse, otherwise the stores are reset, and the amount of voiced speech stored (typically 2/3) is controlled by the duration of the pitch period. The various characters are assembled at 7 in the required order for transmission. A signal representing the near pitch period may also be transmitted during unvoiced speech. At the receiver (Fig. 2, not shown) the data is demultiplexed at (18) and read-in to stores (13,14) when a new word character (e.g. 1100 ... 1100) is confirmed. The word is repetitively read-out to fill-in the gaps arising from expansion at the transmitter. The fundamental or mean pitch frequency or a frequency containing random pulses is generated at (12) corresponding to voiced or unvoiced speech. The read-out rate may be controlled according to pitch period signals received to automatically prevent overlaps or gaps in the read-out.
Patent DE-2229644-A1 (DE)
Title: Rubber vulcanisation accelerator - comprising bis-amino-methane with di-substd amino gps
Inventor: DISTLER HARRY DR
IPC: C07D295/02
Filed: 1972-06-19
Abstract: Vulcanisation of rubber is carried out in the presence of bis-amino-methane cpds. (I), with disubstd. amino gps. of formula R1R2N-CHR5-NR3R4 (where the R gps. are each aliphatic, cyclo-aliphatic, araliphatic or aromatic gps; or R1 and R2 and/or R3 can be -R6-NR2-CHR5-NR3R4; R6 is an aliphatic or aromatic gp.; or R1 and R2 together with the N atom can be The use of (I) provides applicability over a wide range of operating conditions and rubber goods. 0.5-3.0 (1-2) pts. (I)/100 pts. rubber may be used. Best results are obtd. in the vulcanisation of natural rubber with S, but the process is also suitable for use with synthetic rubbers and other vulcanising agents.
Patent DE-2308144-A1 (DE)
Title: Inhomogeneously constructed contact lens - incorporating a pharmaceutically active ingredient
Inventor: KINKEL HEINZ-JOACHIM DR
IPC: G02C7/04
Filed: 1973-02-19
Abstract: A contact lens has a pharmaceutically active ingredient (e.g. an antibiotic), incorporated in swellable material. The marginal portion of the lens comprises a porous matrix. The lens may be made of a rel. hard material e.g. PMMA, or a soft gel e.g. polyglycolmonomethacrylate. It is mfrd. by applying a pure plastic powder onto the centre portion of a moulding press. piston whilst a mixt. of plastics powder and a sol. or volatile substance is placed around it to form, after moulding a porous ring around the non-porous centre portion of the lens.