US3729537A - Method of forming a fabric covered cellulose sponge strand and then compressing it in a plurality of directions - Google Patents

Method of forming a fabric covered cellulose sponge strand and then compressing it in a plurality of directions Download PDF

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Publication number
US3729537A
US3729537A US00067241A US3729537DA US3729537A US 3729537 A US3729537 A US 3729537A US 00067241 A US00067241 A US 00067241A US 3729537D A US3729537D A US 3729537DA US 3729537 A US3729537 A US 3729537A
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US
United States
Prior art keywords
sponge
rope
casing
strand
cellulose sponge
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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 - Lifetime
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US00067241A
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English (en)
Inventor
E Webster
D Jones
G Jowett
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Sponcel Ltd
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Sponcel Ltd
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Publication date
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2301/00—Characterised by the use of cellulose, modified cellulose or cellulose derivatives
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S604/00—Surgery
    • Y10S604/904—Tampons

Definitions

  • This invention concerns improvements in and relating to the manufacture of regenerated cellulose sponge material, and relates more especially to a process for the production of an elongated web or rope of regenerated cellulose sponge material having a relatively small crosssection of predetermined shape.
  • Regenerated cellulose sponge is conventionally produced by placing in a metal mould a mixture of viscose paste and sodium sulphate or other crystals with or without reinforcing fibres of hemp, flax or other material, and regenerating the cellulose from the viscose by heat and/or chemical action.
  • the crystals are removed by heating or by subsequent washing processes, thus leaving a porous mass absorbent to aqueous solutions.
  • This process is suitable for producing relatively large blocks of sponge material, pieces of sponge required to be of dimensions approximately 2 inches square or less being obtained by cutting from the larger blocks.
  • the present invention provides a process for the production of regenerated cellulose sponge material in strip form, wherein a sponge forming mixture comprising viscose paste is extruded into a flexible tubular reinforcing outer casing to form a web or rope of paste supported in said casing, and regeneration of the viscose paste is effected whilst maintaining the desired final cross-sectional shape of said web or rope.
  • the said outer casing may be removed after regeneration of the sponge material, so that the final sponge is left without external reinforcement, or may be left permanently in place as an outer reinforcing layer of the sponge.
  • the casing may comprise a membrane or film of suitable material, for example those polyolefines and other plastics which withstand the temperature at which regeneration is carried out, certain cellulose casings, polytetrafiuorethylene and the like.
  • the casing may comprise a knitted or woven fabric capable of becoming permanently bonded to the sponge material during the regeneration process. Such a knitted fabric could be formed in situ by a circular knitting machine arranged round the extrusion nozzle.
  • the casing may be seamless, for example an extruded tubular film or a circularly knitted fabric, or may be formed by seaming a fiat web into the form of a tube. Also a flat web may be applied directly to the extruded paste, without seaming of the web, by folding the web around the extrusion nozzle in a continuous manner so that the web is drawn from the nozzle in the form of a continuous folded tube.
  • the process according to the present invention has the advantage that strips of regenerated cellulose sponge of relatively small cross-section can be produced in crosssectional shapes that would be difficult to achieve by conventional means, for example by cutting from larger moulded blocks of sponge. Moreover such strips may have a woven or knitted outer reinforcing covering bonded securely thereto during the regeneration process.
  • Strip sponge material so produced is very useful for the production of articles such as catamenial tampons.
  • extrusion of the said mixture into the outer casing may be effected by extruding the mixture from a nozzle extending in the form of a pipe or horn, the casing being arranged in longitudinally collapsed form around the outer circumference of the pipe so that the pasty mixture issuing from the extrusion orifice fills the casing and draws the same from around the extrusion nozzle.
  • Uniform filling of the casing may be promoted by applying frictional contact with the outer surface of the casing, either manually or by an annular restraining means, in order to provide slight resistance to withdrawal of the casing from the nozzle.
  • the extrusion nozzle may incorporate a magazine in the form of a turret or sliding plate having a plurality of pipe or horn members for successive registration with an extrusion die in order to effect rapid changeover of outer casings as they become exhausted.
  • the web or rope may be shaped to the desired final cross-sectional shape, for example circular, rectangular or oval, prior to or during regeneration of the paste, for example by a member in the form of a sleeve of the desired cross-section through which the filled outer casing is arranged to pass, or by a pair of appropriately shaped nip rollers.
  • a member in the form of a sleeve of the desired cross-section through which the filled outer casing is arranged to pass or by a pair of appropriately shaped nip rollers.
  • a shaping means may in some cases be rendered unnecessary.
  • the sponge material produced by the above described method may be dried and compressed to cross-sectional dimensions substantially less than those in its moist relaxed state. This can be achieved by heating the material with hot air or other means and subsequently compressing it between heated platens or one or more pairs of rollers.
  • the rollers or platens may be shaped to impart a desired cross-sectional shape to the compressed sponge.
  • a particularly advantageous method of compressing the sponge material is by drawing it through a heated, tapering, tubular former. When re-moistened, the compressed sponge material in known manner regains its original dimensions in the moist relaxed state.
  • the sponge material may be cut into pieces of the desired length either before or after compression.
  • FIG. 1 is an elevation, in diagrammatic form of an arrangement for carrying out the process according to the invention
  • FIG. 2 is a sectional elevation showing a restraining means for retaining a supply of outer reinforcing casing around an extrusion nozzle
  • FIG. 3 is a section on the line III-III of FIG. 1, showing the shaping rollers for the web or rope of paste, and
  • FIG. 4 is an elevation, partly in section, of an arrangement for compression of the regenerated sponge strip.
  • a positive displacement extrusion pump 1 has an extrusion nozzle in the form of a pipe 2 around which is arranged a supply of shirred tubular reinforcing casing 3 for a web or rope 4 of viscose paste to be extruded.
  • the rope 4 is formed by extruding the paste of viscose containing reinforcing fibres and pore forming crystals into the casing 3 so that it draws the latter from the nozzle 2.
  • the casing 3 is held onto the nozzle, either manually or by a restraining ring 5 of nylon or like material (see FIG. 2), so that there is slight resistance to withdrawal of the casing from the nozzle 2 and the casing is uniformly filled with paste.
  • the rope 4 is passed directly into a conventional coagulating bath 6 referred to below, and then between two pairs of shaping rollers 7 at the surface of the bath. Between the pairs of rollers 7 and above the bath 6 is arranged an auxiliary spray bath 8 for spraying the upper side of the rope 4 with coagulating liquid. The rope 4 is finally removed from the bath 6 over a transfer roller 9.
  • rollers 7 and auxiliary spray bath 8 are such that at the point where the rope 4 meets the first pair of rollers it is partially regenerated, but is still capable of being shaped by the rollers 7. In this way the necessity for imparting a given cross-section to the rope 4 at the time of extrusion is avoided, unless the final shape departs radically from the extruded cross-section.
  • the rollers 7 are arranged to impart an elliptical final shape to the rope 4. Any other desired shape, for example a circular or rectangular cross section, may be imparted to the rope 4 in like manner.
  • a convenient method of estimating the point at which the rope 4 should be formed by the rollers 7 is as follows.
  • the viscose paste rope 4 When the viscose paste rope 4, is extruded directly into the bath 6 it initially sinks, owing to the fact that the mixture of paste and crystals is heavier than the liquid of the bath 6. As the crystals melt, however, the rope 4 becomes gradually lighter until it floats on the surface of the bath.
  • the spray bath 8 serves to supply coagulating liquid to the upper exposed side of the rope 4.
  • the rollers 7 may either be driven rollers or idler rollers.
  • the rope 4 may be formed of a conventional viscose paste sponge forming mix containing reinforcing fibres and pore forming crystals such as sodium sulphate crystals, the grade of mix preferably being such as to form a fine pore sponge.
  • the outer casing 3 is a woven fabric such that it becomes permanently bonded with the surface of the sponge. Suitable regeneration baths are illustrated in the following examples.
  • EXAMPLE 1 A rope of viscose paste as described above was formed by extrusion into a shirred tubular casing of woven cotton stockinet. The rope was passed directly into a liquid coagulating bath as described above and having a length of 40 feet. The bath was a heat regenerating bath comprising a solution of sodium sulphate at a temperature of 95 C. The extrusion rate of the rope and the corresponding rate of passage through the bath was 3 ft. per minute.
  • Example 2 The process of Example 1 was repeated, with an extruded rope formed by extrusion into an impermeable outer casing of polypropylene. In order to enable complete regeneration of the rope using the same bath, the extrusion rate was reduced to 1 ft. per minute.
  • EXAMPLE 3 An extruded rope was formed as described above by extrusion of a viscose paste mixture into an outer casing of woven cotton stockinet, and passed into a coagulating bath as described above and 40 ft. long.
  • the coagulating bath was an acid coagulating bath comprising a 3-5% solution of sulphuric acid with 500-700 grams per litre of Glaubers salt in solution at a temperature of 85 C.
  • the extrusion rate was 2-3 ft. per minute.
  • each extrusion pump preferably has a turret arrangement comprising a plurality of extrusion nozzles that can be interchanged to enable quick recharging of a supply of casing. This enables the process to be carried out continuously.
  • regeneration of the viscose paste is effected with the said web or rope freely suspended in a vertical position.
  • the web or rope is then self supporting in the desired cross sectional shape.
  • the sponge mixture may be extruded in a vertically upward or downward direction, into the tubular casing, the web or rope formed by the casing together with the sponge mixture being drawn from the extrusion nozzle by means of take up rollers located vertically above or below the nozzle and spaced therefrom, and that portion of the web or rope located between the extrusion nozzle and the take up rollers being subjected to a regeneration process so that the viscose paste becomes substantially completely regenerated to cellulose by the time the web or rope meets the take up rollers.
  • the take up rollers may be in the form of pulleys as described above defining between them the desired cross-sectional shape of the web or rope. If desired the web or rope may be guided by further similar take up rollers before and/or during regeneration of the viscose, the rollers serving to form or re-establish the desired cross-section of the web or rope whilst at the same time serving to transport and/or change the direction of movement of the web or rope. In this way the extrusion of the web or rope may be carried out in a horizontal direction and the web or rope may be subsequently transported in a vertical direction by said rollers.
  • FIG. 4 This comprises a tapering tubular stainless steel former 10 having a general cross-section corresponding to that of the rope 4.
  • the former has an annular external recess 10a in which is arranged an electrical resistance heating element 11 closely surrounding the tapering wall of the former 10.
  • the remainder of the recess 10a is filled with the heat insulating material 12, and the whole is closed by a cylindrical cover 13.
  • the angle of taper of the former 10 should be selected by experiment to provide effective compression of the sponge without the necessity of undue tension thereon.
  • the optimum temperature of the former for the effective compression of the sponge material is in the region of 130-150 C., the corresponding rate of throughput of the sponge material being adjusted by experiment.
  • a process for the manufacture of shaped vaginal tampons of regenerated cellulose sponge material which process comprises the steps of continuously extruding a sponge-forming material into a circumferentially continuous and flexible tubular reinforcing outer fabric casing to form said material into an elongated strand,

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Absorbent Articles And Supports Therefor (AREA)
  • Artificial Filaments (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
US00067241A 1967-07-19 1970-08-26 Method of forming a fabric covered cellulose sponge strand and then compressing it in a plurality of directions Expired - Lifetime US3729537A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB33095/67A GB1197611A (en) 1967-07-19 1967-07-19 Improvements in and relating to the Manufacture of Regenerated Cellulose Sponge Material.

Publications (1)

Publication Number Publication Date
US3729537A true US3729537A (en) 1973-04-24

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ID=10348505

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Application Number Title Priority Date Filing Date
US00067241A Expired - Lifetime US3729537A (en) 1967-07-19 1970-08-26 Method of forming a fabric covered cellulose sponge strand and then compressing it in a plurality of directions

Country Status (10)

Country Link
US (1) US3729537A (enExample)
BE (1) BE718372A (enExample)
CH (1) CH480162A (enExample)
DE (1) DE1769798A1 (enExample)
FI (1) FI52042C (enExample)
FR (1) FR1581708A (enExample)
GB (1) GB1197611A (enExample)
IE (1) IE32201B1 (enExample)
LU (1) LU56548A1 (enExample)
NL (1) NL6810113A (enExample)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109832262A (zh) * 2019-01-25 2019-06-04 袁隆平农业高科技股份有限公司 活体植物保存方法

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109832262A (zh) * 2019-01-25 2019-06-04 袁隆平农业高科技股份有限公司 活体植物保存方法

Also Published As

Publication number Publication date
FR1581708A (enExample) 1969-09-19
BE718372A (enExample) 1968-12-31
LU56548A1 (enExample) 1968-10-30
CH480162A (de) 1969-10-31
IE32201L (en) 1969-01-19
NL6810113A (enExample) 1969-01-21
FI52042C (fi) 1977-06-10
DE1769798A1 (de) 1971-11-11
IE32201B1 (en) 1973-05-16
FI52042B (enExample) 1977-02-28
GB1197611A (en) 1970-07-08

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