EP0117884B1 - Bleifasern, ein Verfahren zur Herstellung derselben und Strahlenschutzmaterialien die solche enthalten - Google Patents

Bleifasern, ein Verfahren zur Herstellung derselben und Strahlenschutzmaterialien die solche enthalten Download PDF

Info

Publication number
EP0117884B1
EP0117884B1 EP83102162A EP83102162A EP0117884B1 EP 0117884 B1 EP0117884 B1 EP 0117884B1 EP 83102162 A EP83102162 A EP 83102162A EP 83102162 A EP83102162 A EP 83102162A EP 0117884 B1 EP0117884 B1 EP 0117884B1
Authority
EP
European Patent Office
Prior art keywords
lead
fibers
tin
lead fibers
radiation shielding
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP83102162A
Other languages
English (en)
French (fr)
Other versions
EP0117884A1 (de
Inventor
Hisataka Shoji
Shigehiro Ouchi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toray Industries Inc
Original Assignee
Toray Industries Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Toray Industries Inc filed Critical Toray Industries Inc
Priority to EP83102162A priority Critical patent/EP0117884B1/de
Priority to DE8383102162T priority patent/DE3367867D1/de
Publication of EP0117884A1 publication Critical patent/EP0117884A1/de
Application granted granted Critical
Publication of EP0117884B1 publication Critical patent/EP0117884B1/de
Expired legal-status Critical Current

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/005—Continuous casting of metals, i.e. casting in indefinite lengths of wire
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/06—Metallic powder characterised by the shape of the particles
    • B22F1/062—Fibrous particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
    • B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying
    • B22F9/10—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying using centrifugal force
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F3/00—Shielding characterised by its physical form, e.g. granules, or shape of the material

Definitions

  • the present invention relates to lead fibers melt-spun of lead containing tin as well as to a method of melt-spinning such lead fibers.
  • the present invention further relates to radiation shielding materials for X-rays comprising these lead fibers.
  • the prior art teaches methods of melt-spinning lead. These lead fibers are mainly used as radiation and sound shielding materials.
  • the diameter of lead fibers made by conventional melt-spinning methods ranges from 150 to 200 microns. Fibers having a considerably smaller diameter are not available.
  • Fibers with smaller diameters cannot by produced because when the fine lead fibers are extruded the small holes clog within a very short time, or the output decreases sharply. This problem is particularly noticeable in the process of spinning high-purity lead, such as lead with a purity of more than 99.9%.
  • Japanese Patent Application No. 49-16168 discloses a method of avoiding the above-mentioned difficulties involved in the spinning of lead fibers. According to this method, the spinneret holes are prevented from clogging by the addition of alloy elements to the lead. Considerable amounts of an alloy element are used, namely 0.1 to 40% (by weight) of tin.
  • the present invention is based on the concept that lead fibers with very small fiber diameters can be produced by melt-spinning the fibers of lead containing minimal amounts of tin only. This leads to high purity lead fibers with conspicuous advantages.
  • the lead fibers according to the invention melt-spun of lead containing tin, are characterized in that the tin content of the lead is within the range of 50 to 500 ppm.
  • the average fiber diameter is preferably less than 60 microns.
  • the radiation shielding materials according to the invention comprise such lead fibers in which the tin content of the lead is within the range of 50 to 500 ppm.
  • the lead fibers according to the invention are extremely flexible due to their very small diameter, and are therefore suitable for a variety of applications.
  • the fibers are also highly resistant to corrosion:
  • the lead fibers can be produced without any problems to do with the spinneret holes clogging up, which is a benefit of the low tin content.
  • Figures 1 to 3 show X-ray photographs of Sheets A, B and C, respectively, made according to Example 7.
  • the lead fibers of the present invention contain 50 to 500 ppm tin, and preferably 100 to 200 ppm tin.
  • the lead fibers are produced by melt-spinning. Tin is added to the lead so that the amount of tin is within the range of 50 to 500 ppm. Since tin melts at about 232°C the mixture can be melted completely at 327°C, the melting point of lead. The fluid mixture is spun into fibers by being passed through spinneret holes having a desired diameter.
  • spinneret holes can be prevented from clogging by the small amount of tin, holes with a very small diameter can be used without any problem.
  • lead fibers with a diameter of 60 or 50 microns or even preferably below 30 microns can easily be spun.
  • the lead fibers produced are extremely resistant to corrosion due to the characteristics of the tin.
  • the lead fibers contain more than 500 ppm of tin, the advantageous effect as mentioned above is not increased, but the higher amount of tin is disadvantageous in view of the generation of characteristic X-rays.
  • the tin can be mixed with the lead either in elemental form or as a compound.
  • the lead fibers according to the invention since they are very fine and flexible, are especially suitable for radiation shielding material.
  • the lead fibers can easily be fabricated into sheets which may be thin, thick, dense or coarse in their composition.
  • the sheets are extremely resistant to corrosion and provide easy handling due to their flexibility.
  • the lead fibers according to the invention are also especially suitable for producing composite materials comprising the lead fibers in chopped form and resin. It has been found that the extremely fine lead fibers according to the invention should be used in shorter length, preferably with an average fiber length of between 0.5 and 1.3 mm, compared to conventional thick lead fibers because the fine fibers entangle easily and form lumps, leading to non-uniform dispersion in the composite material.
  • the fibers easily aggregate and form lumps when slightly pressed during production. During the mixing process with the resin, these fibers also form lumps resulting in a very poor dispersibility. On the other hand, when the fibers have an average length of less than 0.5 mm the fibers fly up in the air easily and are thus very inconvenient to handle.
  • the spun fibers are cut immediately after solidification during spinning, using a rotary cutter next to the spinning facilities. They are then filtered through a sieve adjacent to the rotary cutter and only those lead fibers having the predetermined length are selected.
  • the fibers of the present invention are extremely well-suited for use in radiation shielding material, having extremely high X-ray shielding power in spite of the thin fabric construction.
  • garments or aprons as commercially available are made up of a number of X-ray shielding sheets which contain powder of lead metal or a lead compound dispersed in a high polymer.
  • a fine powder of lead or a lead compound cannot be blended into a resin to achieve a specific gravity greater than 0.2. If more powder is added the sheets become too weak to be used properly.
  • the lead equivalent amounts only to a value of 0.08 (mm Pb) at the thickness of 0.5 mm, according to the JIS Z-4501 standard test method. This value is too low for proper shielding of X-rays.
  • a composite material mainly used for sound shielding which comprises lead fibers with diameters extending from a minimum of 100 microns upwards, and normally in the range of 200 to 500 microns. Compared to lead powder, these fibers allow a significantly higher lead content to be achieved when incorporated in a high polymer, so that values of 5.5 of specific gravity can be reached.
  • the radiation shielding material according to the present invention being preferably a composite material composed of lead fibers blended with synthetic resin, wherein the lead fibers have an average diameter of less than 60 microns and the composite material has a minimum specific gravity of 4.0, does not show such a pin-hole effect.
  • the lead equivalent is often used to compare X-ray shielding powers of various materials, whereby the lead equivalent is represented by "the thickness of lead substrate to which the X-ray shielding power is equivalent". The greater the lead equivalent is, the higher the X-ray shielding power is.
  • the lead equivalent value In order to obtain maximum X-ray shielding power, the lead equivalent value must be increased by providing material with higher specific gravity and especially the X-ray absorbing material, which is the lead, must be uniformly dispersed.
  • the uniform dispersion is essential because even if the lead equivalent value is increased, if there are pin-holes which allow the X-rays to penetrate the shielding sheet locally, such sheet is fatally defective for X-ray shielding purposes.
  • the extremely fine lead fibers of the present invention can easily be homogeneously dispersed into resin and, even though a large amount of the lead fibers is added, the strength and the flexibility of the sheet remain unaffected.
  • the diameter of the lead fibers exceeds 60 microns, the homogeneous dispersibility is lower, which then leads to a number of pin-holes which allow the X-rays to penetrate easily the shielding sheet itself.
  • thermoplastic and thermosetting resins that are usually applicable for conventional composite materials may also be used with the lead fibers of the present invention.
  • thermosetting resins include, for example: epoxy, phenol, unsaturated polyester and polyimide resins.
  • Crosslinking agents, catalysts or any other additives may be used with any of these resins.
  • thermoplastic resins are, for example: polyvinyl chloride, polyolefin, polyamide and polyester. Any suitable additives such as plasticizers, fillers, thermostabilizers, flame retarders, pigments, etc. may be used with these resins.
  • the composite materials comprising chopped lead fibers and resin of the present invention normally have a specific gravity of more than 4.0 and particularly more than 4.5.
  • the lead fibers are homogeneously dispersed.
  • the lead equivalent values measured by the JIS Z-4501 standard test method were significantly higher than those measured for any of the conventional lead powder blended composite material, and yet the composite material comprising the lead fibers is totally free of pin-holes which would allow X-rays to penetrate.
  • thermosetting resins Even a composite material comprising any of the thermosetting resins, if made into a very thin sheet having a thickness of less than 0.5 mm, provides sufficient shielding power against X-rays. In addition, it is very easy to handle owing to its excellent flexibility. Thus, a vast variety of applications is possible.
  • Preferred radiation shielding sheets can, for example, be made by any of the following methods, without being limited thereto.
  • the lead fibers are mixed, for example, with polyvinyl chloride resin in any desired proportion.
  • a suitable plasticizer is added before the mixture is completely blended, thereby using a Banbury mixer.
  • the blended material is pressed between rolls that are provided with a predetermined gap so that the blended material can be shaped into a sheet.
  • woven, knitted or spun-bonded fabric composed of either the natural fiber or a man-made fiber to be laminated on or in the composite material so that the sheet strength can be increased.
  • Tin metal (Sn shot, made by Fukuda Kinzoku Hakufun Kogyo KK) was added to molten lead metal of 99.9% minimum purity.
  • the sum of the content of Sb and Sn was less than 10 ppm so that the amount of the Sn in the lead fiber had the values as shown in the following table.
  • the mixed metals were melted at 385°C and fed to spinning equipment provided with a spinneret comprising five holes each having a diameter of 0.05 mm.
  • the material was then extruded through the spinneret at 380°C by pressurized inert gas. Lead fibers with a diameter of 30 to 40 microns were produced in this manner.
  • lead fibers having very high purity can stably be produced although a very minimal amount of tin is present.
  • tin metal was added to lead metal with a minimum purity of 99.9%, whereby the sum of the content of Sb and Sn was less than 10 ppm at 345°C so that the Sn content became 100 ppm.
  • the melted metal was then spun through holes each having a diameter of 0.05 mm.
  • This mat was then rolled onto a pipe with a diameter of 10 cm. Owing to its high flexibility, the mat could be tightly rolled onto the pipe. This high flexibility is very advantageous because such sheets can be used for radiation shielding of radioactive pipes.
  • a light metal mixture was prepared for spinning according to Example 4. After being melted at 345°C, the fluid metal was spun using a spinneret having holes with a diameter of 0.05 mm. With these lead fibers having a diameter of 30 to 40 microns, a web with a weight of 7.5 kg/m 2 was produced.
  • Very fine lead fibers having a diameter of 30 to 40 microns produced according to Example 4 were cut by a cutter in order to obtain chopped fibers. Chopped fibers of several lengths were produced by varying the diameter of the cutter screen.
  • lead fibers having an average length in the range of 0.5 to 1.3 mm show excellent dispersibility and are good to handle.
  • a mixture was first prepared by adding the fibers to polyvinyl chloride resin. After adding a plasticizer, the mixture was sufficiently stirred by a Banbury mixer. The mixture was then extruded through a gap between rollers, whereby two sheets having a specific gravity of 4.2 (sheet A) and 4.7 (sheet B) were produced.
  • the JIS Z-4501 standard test method revealed a lead equivalent of 0.14 (sheet A) and 0.17 (sheet B).
  • Photographs were made by 100 KVP X-ray tube voltage. They showed that the sheets were of a homogeneous quality without containing any pin-holes at all and providing totally effective radiation shielding characteristics.
  • lead fibers having a diameter of 70 microns and a length of 1 mm were mixed with polyvinyl chloride resin and a sheet having a thickness of 0.5 mm was prepared (sheet C).
  • the specific gravity was 4.7 and the lead equivalent value 0.14.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Nanotechnology (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Nonwoven Fabrics (AREA)

Claims (8)

1. Bleifasern, aus Zinn enthaltendem Blei schmelzgesponnen, dadurch gekennzeichnet, daß der Zinngehalt des Bleis innerhalb des Bereichs von 50 bis 500 ppm liegt.
2. Bleifasern nach Anspruch 1, dadurch gekennzeichnet, daß der Zinngehalt des Bleis innerhalb des Bereichs von 100 bis 200 ppm liegt.
3. Bleifasern nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die durchschnittliche Faserdurchmesser kleiner als 60 um ist.
4. Bleifasern nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß die durchschnittliche Faserlänger zwischen 0,5 und 1,3 mm liegt.
5. Verfahren zum Schmelzspinnen von Bleifasern von Zinn enthaltendem Blei, dadurch gekennzeichnet, daß die Fasern aus geschmolzenem Blei gesponnen werden, das 50 bis 500 Zinn enthält.
6. Verfahren nach Anspruch 5, dadurch gekennzeichnet, daß die Fasern mit einem Faserdurchmesser von weniger als 60 11m gesponnen werden.
7. Verfahren nach Anspruch 5 oder 6, dadurch gekennzeichnet, daß die Fasern mit einer durchschnittlichen Faserlänge von zwischen 0,5 und 1,3 mm gesponnen werden.
8. Strahlenschutzmaterialien für Röntgenstrahlen, dadurch gekennzeichnet, daß sie Bleifasern nach einem der Ansprüche 1 bis 4 enthalten.
EP83102162A 1983-03-04 1983-03-04 Bleifasern, ein Verfahren zur Herstellung derselben und Strahlenschutzmaterialien die solche enthalten Expired EP0117884B1 (de)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP83102162A EP0117884B1 (de) 1983-03-04 1983-03-04 Bleifasern, ein Verfahren zur Herstellung derselben und Strahlenschutzmaterialien die solche enthalten
DE8383102162T DE3367867D1 (en) 1983-03-04 1983-03-04 Lead fibers, a method of producing same and radiation shielding materials comprising same

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP83102162A EP0117884B1 (de) 1983-03-04 1983-03-04 Bleifasern, ein Verfahren zur Herstellung derselben und Strahlenschutzmaterialien die solche enthalten

Publications (2)

Publication Number Publication Date
EP0117884A1 EP0117884A1 (de) 1984-09-12
EP0117884B1 true EP0117884B1 (de) 1986-11-26

Family

ID=8190331

Family Applications (1)

Application Number Title Priority Date Filing Date
EP83102162A Expired EP0117884B1 (de) 1983-03-04 1983-03-04 Bleifasern, ein Verfahren zur Herstellung derselben und Strahlenschutzmaterialien die solche enthalten

Country Status (2)

Country Link
EP (1) EP0117884B1 (de)
DE (1) DE3367867D1 (de)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DK444985A (da) * 1984-10-08 1986-04-09 Johnson Matthey Plc Fremgangsmaade ved fremstilling af metalliske materialer
ATE383649T1 (de) * 2001-08-28 2008-01-15 Jl Goslar Gmbh Strahlenschutzformkörper und seine verwendung

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3967739A (en) * 1971-11-24 1976-07-06 Itogihan Company, Ltd. Apparatus for supplying thin, flat articles
US3845805A (en) * 1972-11-14 1974-11-05 Allied Chem Liquid quenching of free jet spun metal filaments
DE2461243A1 (de) * 1974-12-23 1976-06-24 Kernforschung Gmbh Ges Fuer Bleimatte zum abschirmen von gammastrahlen
US4190095A (en) * 1976-10-28 1980-02-26 Allied Chemical Corporation Chill roll casting of continuous filament
US4170257A (en) * 1978-03-03 1979-10-09 National Standard Company Method and apparatus for producing filamentary articles by melt extraction

Also Published As

Publication number Publication date
DE3367867D1 (en) 1987-01-15
EP0117884A1 (de) 1984-09-12

Similar Documents

Publication Publication Date Title
US4485838A (en) Methods for manufacturing lead fiber and radiation shielding material using the same
US4619963A (en) Radiation shielding composite sheet material
DE1902036C3 (de) Material für eine Schutzkleidung sowie Verfahren zu seiner Herstellung
DE69614403T2 (de) Verbundfäden mit hoher schneidfestigkeit für schweren einsatz
DE68916382T2 (de) Ein Verfahren zur Herstellung eines Polstermaterials.
DE69629191T2 (de) Nicht verstreckte, zähe, dauerhaft schmelzklebende, thermoplastische macrodenier-multikomponentfilamente
DE602004004792T2 (de) Flammfeste fasergemische mit modacrylfasern sowie daraus hergestellte textile flächengebilde und kleidungsstücke
DE3200959C2 (de)
DE1540949A1 (de) Neuartiges Erzeugnis
DE69014777T2 (de) Spaltfasern, damit hergestellte Artikel und Verfahren zu deren Herstellung.
DE2754929A1 (de) Mischfasermatte und verfahren zum verformen von faserverstaerkten verbundstoffen
DE69902010T2 (de) Kardierbare doppelglasfasermischung
DE3888573T2 (de) Monofasern, Verfahren zur Herstellung derselben und damit hergestellte Gewebe.
DE2727690A1 (de) Polyamidgrundmischung
WO1995026432A1 (de) Abriebfeste polyester-polyurethan-mischung mit erhöhter verarbeitungssicherheit und monofilamente daraus
DE69009560T2 (de) Vliesstoff zur Verstärkung von Kunstharz und diesen verwendende formbare Platte.
EP0117884B1 (de) Bleifasern, ein Verfahren zur Herstellung derselben und Strahlenschutzmaterialien die solche enthalten
DE2533017B2 (de) Aus einem Faservlies bestehendes elektrisches Isoliermaterial
JPS5831117A (ja) 中性子遮蔽性複合繊維材料の製造法
US4522868A (en) Neutron-shielding fabric and composite fiber and method of manufacture thereof
EP0599231A1 (de) Gefüllte Faser
CA1211258A (en) Method of manufacturing lead fiber and radiation shielding material using the same
JP3974189B2 (ja) 耐ｕｖ性エラストマーモノフィラメント
DE19520314C2 (de) Flammhemmende Trägereinlage, Verfahren zu deren Herstellung und deren Verwendung
JPS5860299A (ja) Ｘ線遮へい用複合材料

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Designated state(s): DE FR GB SE

17P Request for examination filed

Effective date: 19850215

17Q First examination report despatched

Effective date: 19860217

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE FR GB SE

ET Fr: translation filed
REF Corresponds to:

Ref document number: 3367867

Country of ref document: DE

Date of ref document: 19870115

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
EAL Se: european patent in force in sweden

Ref document number: 83102162.1

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 19950222

Year of fee payment: 13

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 19950309

Year of fee payment: 13

Ref country code: DE

Payment date: 19950309

Year of fee payment: 13

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: SE

Payment date: 19950315

Year of fee payment: 13

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Effective date: 19960304

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Effective date: 19960305

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 19960304

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Effective date: 19961129

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Effective date: 19961203

EUG Se: european patent has lapsed

Ref document number: 83102162.1

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST