NO118821B - - Google Patents
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- Publication number
- NO118821B NO118821B NO158416A NO15841665A NO118821B NO 118821 B NO118821 B NO 118821B NO 158416 A NO158416 A NO 158416A NO 15841665 A NO15841665 A NO 15841665A NO 118821 B NO118821 B NO 118821B
- Authority
- NO
- Norway
- Prior art keywords
- peroxide
- sodium
- hydrogen peroxide
- mixture
- phosphoric acid
- Prior art date
Links
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 36
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 24
- PFUVRDFDKPNGAV-UHFFFAOYSA-N sodium peroxide Chemical compound [Na+].[Na+].[O-][O-] PFUVRDFDKPNGAV-UHFFFAOYSA-N 0.000 claims description 22
- 238000004061 bleaching Methods 0.000 claims description 13
- 238000004519 manufacturing process Methods 0.000 claims description 13
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 12
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 12
- 239000000203 mixture Substances 0.000 claims description 12
- 239000007788 liquid Substances 0.000 claims description 9
- 238000000034 method Methods 0.000 claims description 9
- 229910019142 PO4 Inorganic materials 0.000 claims description 8
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 6
- 238000004821 distillation Methods 0.000 claims description 6
- 239000010452 phosphate Substances 0.000 claims description 6
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims description 6
- 239000002253 acid Substances 0.000 claims description 5
- 239000001488 sodium phosphate Substances 0.000 claims description 5
- 229910000162 sodium phosphate Inorganic materials 0.000 claims description 5
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 claims description 5
- 239000001913 cellulose Substances 0.000 claims description 4
- 229920002678 cellulose Polymers 0.000 claims description 4
- 239000010440 gypsum Substances 0.000 claims description 4
- 229910052602 gypsum Inorganic materials 0.000 claims description 4
- 229910052586 apatite Inorganic materials 0.000 claims description 3
- 239000007789 gas Substances 0.000 claims description 3
- VSIIXMUUUJUKCM-UHFFFAOYSA-D pentacalcium;fluoride;triphosphate Chemical compound [F-].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O VSIIXMUUUJUKCM-UHFFFAOYSA-D 0.000 claims description 3
- 150000002978 peroxides Chemical class 0.000 claims description 3
- 239000002367 phosphate rock Substances 0.000 claims description 3
- OJMIONKXNSYLSR-UHFFFAOYSA-N phosphorous acid Chemical compound OP(O)O OJMIONKXNSYLSR-UHFFFAOYSA-N 0.000 claims description 3
- 239000011541 reaction mixture Substances 0.000 claims description 3
- LSNNMFCWUKXFEE-UHFFFAOYSA-L sulfite Chemical compound [O-]S([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-L 0.000 claims description 3
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 2
- 239000011575 calcium Substances 0.000 claims description 2
- 229910052791 calcium Inorganic materials 0.000 claims description 2
- 238000000605 extraction Methods 0.000 claims description 2
- 238000001914 filtration Methods 0.000 claims description 2
- 239000000463 material Substances 0.000 claims description 2
- 239000011574 phosphorus Substances 0.000 claims description 2
- 229910052698 phosphorus Inorganic materials 0.000 claims description 2
- 239000002002 slurry Substances 0.000 claims description 2
- 239000007858 starting material Substances 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 2
- 230000004048 modification Effects 0.000 claims 2
- 238000012986 modification Methods 0.000 claims 2
- 239000000706 filtrate Substances 0.000 claims 1
- 238000006386 neutralization reaction Methods 0.000 claims 1
- 238000000926 separation method Methods 0.000 claims 1
- 235000021317 phosphate Nutrition 0.000 description 7
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 6
- 229910052739 hydrogen Inorganic materials 0.000 description 6
- 239000001257 hydrogen Substances 0.000 description 6
- OUUQCZGPVNCOIJ-UHFFFAOYSA-M Superoxide Chemical compound [O-][O] OUUQCZGPVNCOIJ-UHFFFAOYSA-M 0.000 description 5
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 4
- 230000029087 digestion Effects 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 239000003513 alkali Substances 0.000 description 3
- DMLAVOWQYNRWNQ-UHFFFAOYSA-N azobenzene Chemical compound C1=CC=CC=C1N=NC1=CC=CC=C1 DMLAVOWQYNRWNQ-UHFFFAOYSA-N 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 239000001506 calcium phosphate Substances 0.000 description 2
- 229910000389 calcium phosphate Inorganic materials 0.000 description 2
- 235000011010 calcium phosphates Nutrition 0.000 description 2
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 2
- QORWJWZARLRLPR-UHFFFAOYSA-H tricalcium bis(phosphate) Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O QORWJWZARLRLPR-UHFFFAOYSA-H 0.000 description 2
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 229910001854 alkali hydroxide Inorganic materials 0.000 description 1
- 150000008044 alkali metal hydroxides Chemical class 0.000 description 1
- 239000001110 calcium chloride Substances 0.000 description 1
- 229910001628 calcium chloride Inorganic materials 0.000 description 1
- 239000001175 calcium sulphate Substances 0.000 description 1
- 235000011132 calcium sulphate Nutrition 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- MJGFBOZCAJSGQW-UHFFFAOYSA-N mercury sodium Chemical compound [Na].[Hg] MJGFBOZCAJSGQW-UHFFFAOYSA-N 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 229910001023 sodium amalgam Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J17/00—Mechanisms for manipulating page-width impression-transfer material, e.g. carbon paper
- B41J17/02—Feeding mechanisms
- B41J17/14—Automatic arrangements for reversing the feed direction
Description
Fremgangsmåte for fremstilling av peroksydoppløsninger for blekning av celluloseholdig materiale. Method for producing peroxide solutions for bleaching cellulose-containing material.
Det er siden lenge kjent at man kan It has long been known that you can
bleke kjemisk masse og slipemasse med natriumperoksyd henholdsvis vannstoffsuperoksyd eller en blanding av begge. Vanligvis anvendes 1—2 pst. peroksyd (beregnet som bleaching chemical compound and abrasive compound with sodium peroxide or hydrogen peroxide or a mixture of both. Usually 1-2 percent peroxide is used (calculated as
vannstoffperoksyd) på tørr masse. Når blekningen bør skje i alkalisk miljø, må ved anvendelsen av bare vannstoffperoksyd natriumhydroksyd tilsettes, hvilket selvfølgelig øker blekningsomkostningene. Ved anvendelsen av bare natriumperoksyd blir derimot alkaliteten for høy, hvorfor syre, f. eks. svovelsyre, må tilsettes. hydrogen peroxide) on dry mass. When the bleaching should take place in an alkaline environment, when only hydrogen peroxide is used, sodium hydroxide must be added, which of course increases the bleaching costs. When using only sodium peroxide, on the other hand, the alkalinity becomes too high, why acid, e.g. sulfuric acid, must be added.
Ved anvendelse av en blanding av natriumperoksyd og vannstoffsuperoksyd kan den ønskede alkalitet oppnås uten ekstra kjemikalietilsetning. Da vannstoffsuperoksyd er dyrt i forhold til natriumperoksyd, blir en slik fremgangsmåte uøkonomisk. By using a mixture of sodium peroxide and hydrogen peroxide, the desired alkalinity can be achieved without additional chemical addition. As hydrogen peroxide is expensive compared to sodium peroxide, such a method becomes uneconomical.
Formålet med nærværende oppfinnelse The object of the present invention
er på en mere økonomisk måte å fremstille en blekevæske av ovennevnte art, som ved anvendelse av en ny kombinasjon av hittil fra teknikkens forskjellige områder i og for seg kjente fremgangsmåter, hvilken kombinasjon egner seg særlig for anvendelse i forbindelse med sulfitcellulosefrem-stilling, hvor de herskende betingelsene lar seg overraskende lett tilpasse i overens-stemmelse med den nevnte kombinasjon. is in a more economical way to produce a bleaching liquid of the above-mentioned kind, which by using a new combination of methods known in and of themselves up to now from the various areas of the art, which combination is particularly suitable for use in connection with sulphite cellulose production, where the the prevailing conditions can be surprisingly easily adapted in accordance with the aforementioned combination.
Fremgangsmåten etter oppfinnelsen karakteriseres ved en sådan kombinasjon at fosforholdig utgangsmateriale, som fosforit og apatit oppsluttes med svovelsyre, hensiktsmessig fremstilt av SOa-holdige gasser fra syreavdelingen ved sulfitcellu-losefremstilling, at utfallende gips fjernes f. eks. ved filtrering, at med således erholdt fosforsyre vannstoffsuperoksyd fremstilles av natriumperoksyd, under destillasjon av reaksjonsblandingen og herved erholdt vannstoffsuperoksyd anvendes for fremstilling av den for blekningen bestemte blandingen av natriumperoksyd og vannstoffsuperoksyd, mens destillasjonsresten viderebearbeides for utvinnelse av natriumfosfat. Herved erholdes således natriumfosfat som et verdifullt biprodukt, likeså gips, som kan anvendes som fyllstoff ved papirfabrikasjon eller for andre i og for seg kjente formål. Fordelaktig er å gjøre bruk av fosforsyre, som erholdes ved fremstilling av alkali-og kalsiumfosfat på kjent måte, slik at en vannoppslemming av råfosfat oppsluttes med en blanding av salt-syre og svovelsyre, hvor forholdet mellom syrene er valgt i avhengighet av det forhold mellom alkalifosfat og kalciumfosfat, som man ønsker å oppnå og i et slikt forhold til råfosfatmengden at ved oppslutningen fås en oppslutningsvæske, som inne-holder kalciumklorid, fosforsyre og kal-ciumsulfat. Fra denne væske filtreres gip-sen bort, hvoretter væsken med unntagelse av en andel som tilsvarer den for vann-stoffsuperoksydfremstillingen nødvendige fosforsyremengde nøytraliseres for erhol-delse av fosfatene med alkalihydroksyd eller -karbonat. Naturligvis kan væsken og-så nøytraliseres i sin helhet for oppnåelse av fosforsyre, men med fordel bare så langt at kalcium og dermed skadelige forurens-ninger faller ut. Når den nødvendige fosforsyremengde er uttatt, sluttnøytraliseres resten av væsken for videre utvinning av alkalifosfat. Den for oppslutningen anvendte syre fremstilles med fordel fra selve råfosfatoppslutningsvæsken ved å innlede til samme gjennom klorkalkalielektrolyse erholdt klorgass samt svoveldioksyd eller svoveldioksydholdige gasser enten samtidig eller hver for seg under bortledning og kondensering av de oppstående saltsyre-dampene. The method according to the invention is characterized by such a combination that phosphorus-containing starting material, such as phosphorite and apatite, is digested with sulfuric acid, appropriately produced from SOa-containing gases from the acid department during sulphite cellulose production, that precipitated gypsum is removed, e.g. by filtration, that with phosphoric acid thus obtained, hydrogen superoxide is produced from sodium peroxide, during distillation of the reaction mixture and the hydrogen superoxide thus obtained is used to produce the mixture of sodium peroxide and hydrogen superoxide determined for the bleaching, while the distillation residue is further processed for the recovery of sodium phosphate. Sodium phosphate is thus obtained as a valuable by-product, as well as gypsum, which can be used as a filler in paper manufacture or for other purposes known in and of themselves. It is advantageous to make use of phosphoric acid, which is obtained by producing alkali and calcium phosphate in a known manner, so that a water slurry of raw phosphate is dissolved with a mixture of hydrochloric acid and sulfuric acid, where the ratio between the acids is chosen depending on the ratio between alkali phosphate and calcium phosphate, which one wants to achieve and in such a ratio to the amount of raw phosphate that a digestion liquid is obtained which contains calcium chloride, phosphoric acid and calcium sulphate. The gypsum is filtered away from this liquid, after which the liquid, with the exception of a proportion corresponding to the amount of phosphoric acid required for the production of hydrogen peroxide, is neutralized to obtain the phosphates with alkali hydroxide or carbonate. Naturally, the liquid can also be neutralized in its entirety to obtain phosphoric acid, but with advantage only to the extent that calcium and thus harmful contaminants precipitate out. When the required quantity of phosphoric acid has been withdrawn, the rest of the liquid is finally neutralized for further extraction of alkali phosphate. The acid used for digestion is advantageously produced from the raw phosphate digestion liquid itself by introducing into it chlorine gas obtained through chloralkali electrolysis as well as sulfur dioxide or sulfur dioxide-containing gases either simultaneously or separately while conducting away and condensing the hydrochloric acid vapors that arise.
Takkket være de ved fremgangsmåten ifølge oppfinnelsen erholdte biprodukter kompenseres vannstoffsuperoksydets ellers høye pris, som har gjort blekningen ved hjelp av natriumperoksyd og vannstoffsuperoksyd mer eller mindre uøkonomisk. Selvfølgelig reguleres den for fremstilling av vannstoffsuperoksyd anvendte mengde natriumperoksyd, under iakttagelse av at best mulig økonomisk resultat oppnås herved, hvilket som regel turde bety at bare den for fremstilling av blekningsblandin-gen nødvendige mengde vannstoffsuperoksyd fremstilles fra natriumperoksyd, mens hovedmengden av oppslutningspro-duktene tilgodegiøres på tidligere kjent måte. Selv ved destillasjonen av vann-stoffsuperoksydet holder man seg naturligvis til de i økonomisk henseende mest gun-stige konsentrasjonene. I alminnelighet turde en konsentrasjon på 3—10 pst. være egnet. Fremstillingen av vannstoffsuper-oksydet fra natriumperoksyd ved hjelp av fosforsyre skjer, som kjent, hensiktsmessig under kjøling av reaksjonsblandingen. Thanks to the by-products obtained by the method according to the invention, hydrogen peroxide's otherwise high price is compensated, which has made the bleaching using sodium peroxide and hydrogen peroxide more or less uneconomical. Of course, the amount of sodium peroxide used for the production of hydrogen peroxide is regulated, taking into account that the best possible economic result is achieved thereby, which as a rule should mean that only the amount of hydrogen peroxide required for the production of the bleaching mixture is produced from sodium peroxide, while the main amount of the decomposition products is accounted for in a previously known manner. Even in the distillation of the hydrogen superoxide, one naturally sticks to the economically most advantageous concentrations. In general, a concentration of 3-10 percent would be suitable. The production of the hydrogen superoxide from sodium peroxide by means of phosphoric acid takes place, as is known, expediently while cooling the reaction mixture.
I mange tilfelle turde det være til-strekkelig at for fremstilling av en for blekning bestemt natriumperoksyd- og vannstoffsuperoksydblanding en oppløs-ning av natriumperoksyd i egnet konsentrasjon, eventuelt erholdt direkte fra na-triumperoksydfremstilling fra f. eks. azo-benzol, ved reduksjon med natriumamal-gam, tilsettes en nødvendig mengde fosforsyre, hensiktsmessig erholdt ved spaltning av fosfater med svovelsyre, eller ved den foran beskrevne oppslutningsmetode. Herved bør det observeres at den erholdte blanding av natriumperoksyd og vannstoffsuperoksyd også kommer til å inneholde natriumfosfat i oppløsning. Ved denne fremgangsmåte slipper man destillasjonen. In many cases, it would be sufficient for the preparation of a sodium peroxide and hydrogen peroxide mixture intended for bleaching, a solution of sodium peroxide in a suitable concentration, possibly obtained directly from sodium peroxide production from e.g. azo-benzene, by reduction with sodium amalgam, a necessary amount of phosphoric acid is added, conveniently obtained by splitting phosphates with sulfuric acid, or by the digestion method described above. Hereby, it should be observed that the resulting mixture of sodium peroxide and hydrogen peroxide will also contain sodium phosphate in solution. In this method, distillation is avoided.
Det for fremstilling av vannstoffsuper- That for the production of hydrogen super-
oksydet og fremstillingen av blekningsvæ-skeblandingen nødvendige natriumperoksyd fremstilles med fordel ved reduksjon av autoksydable, organiske forbindelser, som azobensol og azotoluol osv. the oxide and the production of the bleaching liquid mixture, the necessary sodium peroxide is advantageously produced by reducing autoxidable organic compounds, such as azobenzene and azotoluene, etc.
Claims (3)
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US376630A US3334585A (en) | 1964-06-22 | 1964-06-22 | Electro-mechanical apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| NO118821B true NO118821B (en) | 1970-02-16 |
Family
ID=23485811
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| NO158416A NO118821B (en) | 1964-06-22 | 1965-06-09 |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US3334585A (en) |
| AT (1) | AT265707B (en) |
| BE (1) | BE665700A (en) |
| CH (1) | CH443362A (en) |
| DE (1) | DE1436658A1 (en) |
| GB (1) | GB1114783A (en) |
| NO (1) | NO118821B (en) |
| SE (1) | SE308729B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3901479A (en) * | 1971-12-13 | 1975-08-26 | Western Gear Corp | Traction type hoist |
| US3902585A (en) * | 1973-05-07 | 1975-09-02 | Data Products Corp | Electric switch actuated printer ribbon reversing mechanism |
| US4177731A (en) * | 1976-07-26 | 1979-12-11 | Printronix, Inc. | Printer system ribbon drive having constant ribbon speed and tension |
| JPS60165278A (en) * | 1984-02-09 | 1985-08-28 | Toshiba Corp | Image forming apparatus |
| US4685818A (en) * | 1985-09-16 | 1987-08-11 | Printronix, Inc. | Ribbon fault detection system |
| DE19514599C2 (en) * | 1995-04-20 | 2001-09-06 | Meto International Gmbh | Printer for printing on a recording medium |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE518934C (en) * | 1931-02-21 | Heinrich Scheidig | Device on typewriters for displaying the last line of sheets to be written on | |
| US2199556A (en) * | 1938-10-07 | 1940-05-07 | Ibm | Paper feeding device |
| US2400447A (en) * | 1940-04-25 | 1946-05-14 | American Mach & Foundry | Web-registering device |
| US2705639A (en) * | 1949-12-16 | 1955-04-05 | James A Kennedy | Magnetic type recorder and play back unit |
| US2821284A (en) * | 1954-03-15 | 1958-01-28 | Lamson Paragon Ltd | Carbon transfer material with alarm means for an imprinting machine |
| US3077830A (en) * | 1961-06-05 | 1963-02-19 | Burroughs Corp | High speed print mechanism |
| US3156181A (en) * | 1961-08-03 | 1964-11-10 | Telechrome Mfg Corp | Type wheel printer |
| US3185083A (en) * | 1961-09-21 | 1965-05-25 | Control Data Corp | Ribbon drive mechanism |
-
1964
- 1964-06-22 US US376630A patent/US3334585A/en not_active Expired - Lifetime
-
1965
- 1965-06-03 GB GB23825/65A patent/GB1114783A/en not_active Expired
- 1965-06-09 NO NO158416A patent/NO118821B/no unknown
- 1965-06-18 SE SE8103/65A patent/SE308729B/xx unknown
- 1965-06-19 DE DE19651436658 patent/DE1436658A1/en active Pending
- 1965-06-21 CH CH862765A patent/CH443362A/en unknown
- 1965-06-21 BE BE665700D patent/BE665700A/xx unknown
- 1965-06-22 AT AT564365A patent/AT265707B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| SE308729B (en) | 1969-02-24 |
| GB1114783A (en) | 1968-05-22 |
| BE665700A (en) | 1965-10-18 |
| US3334585A (en) | 1967-08-08 |
| AT265707B (en) | 1968-10-25 |
| DE1436658A1 (en) | 1968-11-14 |
| CH443362A (en) | 1967-09-15 |
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