Classifications

• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
  • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
  • D04H1/58—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives
  • D04H1/64—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives the bonding agent being applied in wet state, e.g. chemical agents in dispersions or solutions
  • D04H1/645—Impregnation followed by a solidification process
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
  • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
  • D04H1/58—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives
  • D04H1/587—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives characterised by the bonding agents used
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M15/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment
  • D06M15/19—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with synthetic macromolecular compounds
  • D06M15/21—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D06M15/285—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds of unsaturated carboxylic acid amides or imides
  • D06M15/29—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds of unsaturated carboxylic acid amides or imides containing a N-methylol group or an etherified N-methylol group; containing a N-aminomethylene group; containing a N-sulfidomethylene group

Definitions

• This invention relates to non-woven fibrous materials, and concerns a binding composition intended for use in binding non-woven fibrous materials, for example paper and viscose, use of the binding composition and the resulting product.
• Non-woven fibrous material comprises a consolidated mass of fibres which may be laid down by mechanical, chemical, pneumatic, electrical or vacuum means and deposited in a desired flat shape, for example as webs, mats or sheets, or in a three dimensional form.
• the fibres may be natural or synthetic or a combination. In general the fibres to be used will be selected to suit the desired end use of the non-woven product.
• fibres may be derived from wood, i.e. cellulose, or may be cotton, glass, asbestos, rayon, wool, viscose etc.
• the fibres may be deposited in a random manner, or may be positioned or aligned along particular axes.
• the non-woven product may contain layers of fibre oriented in a cross-layered manner to provide a uniform strength across the product.
• binding the product usually it is necessary to submit the product to a binding step to ensure the product maintains its physical integrity.
• One route to binding the product is to introduce a binding composition during or after formation of the product. Some of the binding composition will coat the fibres but a portion will be concentrated at the positions where the fibres touch. Subsequent treatment, usually by the application of heat, dries the binding composition and gives structural integrity to the product.
• the non-woven product may be impregnated with the binding agent by dipping or immersing the fabric in the agent to provide sufficient pick-up.
• the wetted non-woven product in a form of a web can then be passed between a pair of pressure rollers to ensure the impregnation is uniform and so to control the amount of binding agent applied.
• Bound non-woven fibre products are useful e.g. as curtains, in furniture, as drapes, filters, packaging, wiping cloths, fabric interlining for clothes, and industrial sealing material such as gaskets.
• a particular market is in the use of non-woven padding as absorbents in, e.g., babies nappies (diapers), female sanitary products etc.
• copolymer emulsions As binding compositions for non-woven fibrous materials.
• a particularly suitable base for binding compositions is copolymer emulsions obtained by polymerising unsaturated monomers in an emulsion system. Suitable copolymer emulsions may be obtained by means of processes performed at ambient pressure or under elevated pressure, e.g. up to 120 bars.
• Copolymer emulsion compositions suitable for this purpose will usually contain a monomer capable of cross- linking in a post-polymerisation step. Thus the copolymer emulsion will be applied to the non-woven product and first subjected to heating to remove the water. Then in a further heating step the cross-linkable monomer cross-links to provide a three dimensional copolymer network with strength sufficient to provide structural integrity.
• the cross-linkable monomer used is required to have an appropriate cross-linking efficiency, appropriate wet and dry strengths and, where appropriate, sufficient tensile strength when the resulting non-woven product is subjected to solvent or other chemical contact. Additionally there has been a general desire to reduce the content of fomaldehyde in some non-woven products, in particular those designed for human contact e.g. babies nappies.
• Formaldehyde may be present in the fibrous components of the non-woven product and may also be generated by the cross- linking reaction.
• one cross-linkable monomer widely used for this purpose is N-methylolacrylamide (NMA) , but the cross-linking reaction of this monomer generates formaldehyde.
• NMA N-methylolacrylamide
• a binding composition for non-woven fibrous materials comprising a copolymer emulsion in which at least about 30% by weight of the monomer content is vinyl C1 to C4 alkanoate and an amount of N-(n-butoxymethyl) acrylamide effective to act as a post polymerisation cross-linking agent is present.
• N-(n-butoxymethyl) acrylamide (NBMA) as the post- polymerisation cross-linking monomer in place of NMA in a binding composition for non-woven fibrous materials, it is possible to produce non-woven fibrous products having reduced levels of formaldehyde.
• the copolymer emulsion solids are required to include an amount of the cross-linkable monomer (NBMA) effective to provide the necessary strengthening of the copolymer solids and thereby structural integrity of the non-woven body.
• the effective amount of cross-linkable monomer will be from about 0.5% to about 10% by weight, typically below about 5% by weight, of the total monomer content.
• Preferably not more than 90% by weight, more preferably between 60 and 80% by weight, of the monomer content is vinyl C1 to C4 alkanoate, with the preferred material being vinyl acetate.
• the copolymer emulsion may include a C2 to C4 alkylene monomer, e.g., ethylene, typically in an amount from 5% to 40% by weight of total monomer.
• Another possible comonomer is selected from the alkyl (C2 to C10) (meth) acrylate class e.g., butylacrylate or 2 ethyl hexyl acrylate, which will preferably be present in an amount of from about 10% to about 60% by weight of total monomer.
• alkyl (C2 to C10) (meth) acrylate class e.g., butylacrylate or 2 ethyl hexyl acrylate, which will preferably be present in an amount of from about 10% to about 60% by weight of total monomer.
• a further class of possible functional comonomer is carboxyl group-containg monomers, e.g. acrylic acid, methacrylic acid, crotonic acid, itaconic acid etc.
• Hydroxy alkyl (meth) acrylate monomers e.g. hydroxy ethyl acrylate, may also be included.
• Sodium vinyl sulphonate and acrylamide are further examples of functional monomers that may be included.
• use of sodium vinyl sulphonate has been found useful for improving mechanical stability of the composition in use and so providing good runnability.
• One or more surfactants may be included as appropriate.
• copolymer emulsion can be prepared using generally conventional techniques, which are well known and well characterised in the literature. Polymer synthesis (vols I & II) by Sandier & Karo (Academic Press 1974) and Preparative Methods of Polymer Chemistry (2nd Ed) by Sorensen & Campbell (Interscience 1968) provide preparative information. Methoden der Organischen Chemie (Houben- eyl) Band XIV published by Geog Thie e Verla Stuttgart (1961) also provides preparative descriptions.
• Any suitable initiator system can be used, but it is preferred not to use formosul (sodium formaldehyde sulphoxylate) as this produces formaldehyde. It is preferred to us a thermal polymerisation, with no reducing agent, e.g. using ammonium or alkali metal persulphates. Redox intiation may also be used, with a persulphate, hydrogen peroxide or an organic peroxide as the oxidising agent and with the reducing agent typically being ascorbic acid or sodium metabisulphite.
• the binding composition of the invention can be used for binding non-woven fibrous materials in generally conventional manner, e.g. by dipping, soaking, or spraying or by use of rollers and a bath.
• the present invention provides a process of binding a non-woven fibrous material, comprising impregnating the material with a binding composition in accordance with the invention; drying the copolymer emulsion; and subjecting the impregnated material to thermal treatment to provide cross-linking.
• the invention also includes within its scope the resulting non-woven fibrous material or product.
• Viscosity This was measured in centipoise using a Brookfield viscometer (ERV type) at 25°C with spindle 2 at 20 rpm.
• Tensile Strength This was measured for dry, wet and solvent (acetone) treated samples using a Lloyd Tensometer. Latices were diluted to 20% solids and impregnated on to
• the solids pick-up was 20%.
• the cross-linking reaction was catalysed by citric acid, (1% w/w on polymer solids for Examples 1 to 8 and 10, 2% w/w for Example 9).
• Curing was at 165°C on a rotary iron for 12 seconds for filter paper and light viscose web and 24 seconds for heavy viscose web. strips of impregnated substrate of dimensions 200 x 50 mm were stretched at a speed of 100 mms " .
• the breaking load, F, in Newtons, (N), and the strain, (e as %), at break were measured.
• Formaldehyde Content (in ppm) : A 1g sample of impregnated substrate was extracted with deionised water, (20ml), for 1 hour at 40°C and then filtered. 1.0ml of the extract was diluted with 2.7ml of water, then 0.3ml of a 1% w/v chromotropic acid solution and 6.0ml of cone, sulphuric acid were added. The solution was cooled and the 580nm absorption was measured.
• a monomer mixture consisting of 126.0g of vinyl acetate, 115.9g of n-butyl acrylate, 9.23g of N-(n- butoxymethyl) acrylamide (NBMA) and 2.52g of 80/20 methacrylic acid/methyl methacrylate mix, and catalyst solutions comprising 2.58g of sodium persulphate in 25.Og of water and 1.57g of sodium metabisulphite in 25.Og of water, were begun to last for 2 hours at constant rate. When the slow additions were complete the temperature was held at 50°C for 15 minutes.
• the temperature was reduced to 45°C, 0.34g of t-butylhydroperoxide was added, followed by a solution of sodium metabisulphite, (0.34g in 1.66g of water).
• the medium was allowed to exotherm to 50"C, maintained there for 15 minutes and then cooled.
• the pH was adjusted to 4.5-5.0 with ammonia and the emulsion was filtered through 250 mesh nylon to remove any coagulum. This resulted in a latex with a solids content of 49.01% and a viscosity of 42 centipoise, measured as described above.
• Example 2 used the procedure of Example 1 except that sodium metabisulphite was replaced by sodium tartrate, to produce a latex with a solids content of 45.53% and a viscosity of 40 centipoise.
• a surfactant solution consisting of 16.0g of Synperonic NP30, (70% active), and 0.56g of Gafac RE610 in 80.Og of water plus 2.58g of 1N sodium hydroxide solution was prepared. 10% of this surfactant solution was added to a 700ml reactor containing 146.5g of deionised water.
• a monomer mixture consisting of 14.0g of vinyl acetate, 12.9g of n-butyl acrylate and 0.28g of an 80/20 methacrylic acid/methyl methacrylate blend was charged to the reactor.
• the temperature was reduced to 45°C, 0.34g of t- butylhydroperoxide was added, followed by a solution of sodium metabisulphite, (0.34g in 1.66g of water).
• the medium was allowed to exotherm to 50°C, maintained there fo 15 minutes and then cooled.
• the pH was adjusted to 4.5-5.0 with ammonia and the emulsion was filtered through 250 mesh nylon to remove any coagulum. This resulted in a latex wit a solids content cf 49.42% ⁇ nd a viscosity of 31 centipoise.
• NMA N-methylolacrylamide
• the temperature was reduced to 45°C, 0.34g of t- butylhydroperoxide was added, followed by a solution of formosul, (0.34g in 1.66g of water).
• the medium was allowed to exotherm to 50"C, maintained there for 15 minutes and then cooled.
• the pH was adjusted to 4.5-5.0 with ammonia and the emulsion was filtered through 250 mesh nylon to remove any coagulum. This resulted in a latex with a solids content of 49.17% and a viscosity of 146 centipoise.
• a solution of 103g of Synperonic NP30, (70% active), in 750g of deionised water and a monomer mixture consisting of 67g of vinyl acetate and 0.45g of acrylic acid were charged to a 4 litre stainless steel reactor. The temperature was raised to 30°C, then the reactor was purged twice with nitrogen and once with ethylene. The reactor was charged with ethylene to a pressure 52 bar, and then heated to a temperature of 70°C. At this temperature 10% of a solution of sodium persulphate, (7.5g in 300g of water), was added to the reactor.
• a monomer mixture consisting of 1294g of vinyl acetate, 30.0g of N-(n-butoxymethyl) acrylamide and 8.6g of acrylic acid was added at a constant rate over 5 hours.
• Ethylene was charged to the reactor during the first four hours of these additions to maintain the pressure at 62 bar. The temperature was maintained at 70°C throughout the slow additions and for a further 30 minutes.
• the temperature was reduced to 50 C C an solutions of t-butylhydroperoxide, (3.6g in 70g of water), ' and sodium metabisulphite, (3.6g in 70g of water), were added over 30 minutes while cooling to 30°C.
• the emulsion was discharged from the reactor and filtered through 250 mesh nylon to remove coagulum.
• the resultant latex had a solids content of 52.59%, viscosity of 87 centipoise, and an ethylene content by infra-red analysis of 22.5%.
• a solution of 10.5kg of Synperonic NP30, (70% active), in 98kg of deionised water and a monomer mixture consisting of 7.0kg of vinyl acetate and 0.56kg of acrylic acid were charged to a 50 gallon reactor.
• the reactor was purged three times with nitrogen and once with ethylene.
• the reactor was charged with ethylene (12.5kg), to a pressure of 40 bar, then 15% of a solution of sodium persulphate, (0.92kg in 19kg of water), was added to the reactor.
• the temperature was raised to 70"C, and then allowed to exotherm to 75 G C.
• the temperature was reduced to 50°C and solutions of t-butylhydroperoxide, (0.37kg in 6 kg of water), and sodium metabisulphite, (0.37kg in 6kg of water), were added over 30 minutes while cooling to 30°C.
• the emulsion was discharged from the reactor and filtered through 250 mesh nylon to remove coagulum.
• the resultant latex had a solids content of 55.38%, viscosity of 108 centipoise, and an ethylene content by infra-red analysis of 23.0%.
• a solution of 320g of Synperonic NP30, (70% active), and 12.4g of Perlankrol PA cone in 2700g of deionised water and a monomer mixture consisting of 220g of vinyl acetate and 1.4g of acrylic acid were charged to a 12 litre stainless steel reactor.
• Perlankrol PA is the ammonium salt of nonylphenol ethoxylate with 4 ethylene oxide units and one sulphate group, obtainable from Harcros Chemicals UK Limited.
• the reactor was purged twice with nitrogen and once with ethylene. The temperature was raised to 75°C while charging the reactor with ethylene to a pressure of 62 bar. 15% of a solution of sodium persulphate, (28g in 800g of water), was added to the reactor.
• a monomer mixture consisting of 4120g of vinyl acetate, 91.0g of N-(n- butoxymethyl) acrylamide and 26.6g of acrylic acid was added at a constant rate over 4 hours 30 minutes.
• Ethylene was charged to the reactor during the first three hours of these additions to maintain the pressure at 62 bar, adding a total of 1148g. The temperature was maintained at 75°C throughout the slow additions and for a further 30 minutes.
• the temperature was reduced to 50°C and solutions of t-butylhydroperoxide, (11.2g in 100g of water), and sodium metabisulphite, (7.3g in 100g of water), were added over 30 minutes while cooling to 30°C.
• the emulsion was discharged from the reactor and filtered through 250 mesh nylon to remove coagulum.
• the resultant latex had a solids content of 54.11%, viscosity of 230 centipoise, and an ethylene content by infra-red analysis of 21.3%.
• Example 6 used the procedure of Example 6, except that the surfactant solution originally charged to the reactor also contained 0.41kg of Perlankrol PA cone.
• the resultant latex had a solids content of 55.37%, viscosity of 83 centipoise, and an ethylene content by infra-red analysis of 23.1%.
• a solution of 103g of Synperonic NP30, (70% active), and 4.0g of Perlankrol PA cone, in 750g of deionised water and a monomer mixture consisting of 67g of vinyl acetate and 0.45g of acrylic acid were charged to a 4 litre stainless steel reactor. The temperature was raised to 30°C, then the reactor was purged twice with nitrogen and once with ethylene. The reactor was charged with ethylene to a pressure of 52 bar, and then heated to a temperature of 75°C. At this temperature 15% of a solution of sodium persulphate, (9.0g in 300g of water), was added to the reactor.
• the temperature was reduced to 50°C and solutions of t-butylhydroperoxide, (3.6g in 70g of water), and sodium metabisulphite, (3.6g in 70g of water), were added over 30 minutes while cooling to 30°C.
• the emulsion was discharged from the reactor and filtered through 250 mesh nylon to remove coagulum.
• the resultant latex had a solids content of 54.00%, viscosity of 91 centipoise, and an ethylene content by infra-red analysis of 21.2%.
• NMA N-methylolacrylamide
• a monomer mixture consisting of 1274g of vinyl acetate and 8.45g of crotonic acid and a solution of 120g of N-methylolacrylamide, (45% aq.), and 5.0g of ammonia in 205g of water were added at a constant rate over 5 hours.
• Initiator solutions comprising 7.2g of ammonium persulphate in 300g of water and 2.2g of formosul in 300g of water were added at double rate for 20 minutes, normal rate for 4 hours 20 minutes and double rate for 1 hour to give a total addition time for initiators of 5 hours 40 minutes.
• the temperature was slowly raised to 60°C during the first 3 hours of additions and maintained until the monomer addition was complete, then it was raised to 70°C until the initiator additions were complete.
• the temperature was reduced to 50°C and solutions of t-butylhydroperoxide, (3.6g in 35g of water), and sodium metabisulphite, (3.6g in 35g of water), were added over 30 minutes while cooling to 30°C.
• the emulsion was discharged from the reactor and filtered through 250 mesh nylon to remove coagulum.

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• 1991
  • 1991-11-13 CA CA 2073693 patent/CA2073693A1/en not_active Abandoned
  • 1991-11-13 WO PCT/GB1991/002002 patent/WO1992008835A1/en not_active Application Discontinuation
  • 1991-11-13 EP EP19910919665 patent/EP0510153A1/de not_active Withdrawn

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