Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
  • D21H11/12—Pulp from non-woody plants or crops, e.g. cotton, flax, straw, bagasse
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
  • D21B1/00—Fibrous raw materials or their mechanical treatment
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
  • D21B1/00—Fibrous raw materials or their mechanical treatment
  • D21B1/02—Pretreatment of the raw materials by chemical or physical means
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H25/00—After-treatment of paper not provided for in groups D21H17/00 - D21H23/00
  • D21H25/04—Physical treatment, e.g. heating, irradiating
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H25/00—After-treatment of paper not provided for in groups D21H17/00 - D21H23/00
  • D21H25/02—Chemical or biochemical treatment

Definitions

• the invention relates to a manufacturing process of a paper substrate intended to be vulcanised or parchmentised. Thus, it also relates to the substrate obtained with the vulcanising or parchmentising process.
• the vulcanising is an operation consisting in treating a paper substrate by immersing it into a zinc chloride solution
• the parchmentising is a similar operation, in which the zinc chloride is replaced by sulphuric acid.
• the present invention does not relate to the actual vulcanising and parchmentising operations, but it relates to the manufacturing process of webs that can be treated with the operations of these two types.
• the ability of a substrate to be treated by vulcanising or parchmentising depends mainly, if not exclusively, on the reactivity of the cellulose fibres making up the web with regard to the zinc chloride or sulphuric acid solutions.
• the reactivity of a fibrous web depends on several factors, one of which is especially the degree of polymerisation (DP) of the cellulose making up the fibre, the latter corresponding to the number of repetition units, which form the cellulose polymer. In general, it looks like the weaker the DP is, the more reactive is the fibre.
• DP degree of polymerisation
• the efficiency of the vulcanising or of the parchmentising is controlled by evaluating the barrier level of the obtained vulcanised or parchmentised paper according to a technique, which will be made clear in the examples.
• the number of webs intended to be vulcanised is manufactured from textile waste coming especially from the “jeans industry”, the jeans consisting 100% of long cotton fibres (staple), the size of which is between 20 and 50 mm.
• the jeans manufacturing clippings or rags are in the form of a bale, which is then opened and the size of the rags is reduced by different operations such as cutting and shredding.
• the shredded pieces of jeans are cooked in a solution of soda concentrated to 7% in a closed reactor, under pressure, at a temperature of about 150° C. Then follows the tiresome step, in which the cooked fibres are washed with water in order to eliminate all of the cooking liquor. All these necessary operations of this discontinuous process may lead to duration of about 24 hours.
• Soda cooking step allows both opening of the cotton fibres and reducing the degree of polymerisation of the cellulose.
• this degree is only about 600, as far as vulcanising and parchmentising are concerned, immediately after the cooking step.
• the value of 600 seems in fact sufficient for obtaining reactivity, and consequently a satisfactory ability of the base paper to vulcanising or parchmentising.
• the clusters of cooked fibres are processed in an aqueous environment so as to separate the fibres from each other, after which the individual fibres are refined, i.e. their structure is subjected to a deformation by mechanical action, allowing optimising the accessibility of the fibre.
• the suspension of the individual cotton fibres obtained right after these steps is then deposited on the wire of the paper machine, in the presence, or not, of fibres having different kind or same kind of nature such as e.g. wood fibres, so as to form in a known manner a web, which is then drained and dried until the actual paper substrate is obtained.
• the cooking step allowing obtaining this result has, however, some inconveniences.
• the capital costs of an industrial chemical reactor are relatively high.
• the cooking consumes a lot of chemicals, in the case in question, soda.
• the cooking leads to the formation of coloured effluents of concentrated soda having a pH of 13,5, the elimination of which is especially difficult and polluting.
• These operations of cooking and washing the rags take place generally with a yield in the order of 85% meaning a loss of the raw material of about 15%.
• the invention tends to solve the problem by developing a clean and economical high yield (over 85%) manufacturing process of paper substrates intended to be vulcanised or parchmentised, which would be at least as reactive with regard to the zinc chloride or sulphuric acid solutions as the substrates obtained by the processes using a chemical cooking step of the cellulose fibres with a high degree of polymerisation.
• the Applicant had the idea of substituting the cooking step in the concentrated soda solution with an energy radiation step, this radiation step being able to be performed, either, in a dry state, directly on the cellulose fibres, before the individualisation of the fibres and the refining in the aqueous environment, or in a dry state, on the final paper.
• the invention relates to a manufacturing process of a paper substrate intended to be vulcanised or parchmentised, comprising the steps of:
• homogenous fibre suspension denotes a suspension, in which the cellulose fibres are dispersed into an aqueous solution to a consistency of about 1 to 10% by weight. This suspension is called homogenous insofar as the fibres have been correctly individualized due to hydration and mechanical agitation operations, thus avoiding the clustering of fibres.
• the process consists first of all in lowering, with the energy radiation, in a dry state, the degree of polymerisation of the cellulose fibres, and once such a degree of polymerisation has been achieved, that the reactivity of the fibre is sufficient, separating the fibres in an aqueous environment and refining them, the fibre suspension next being settled on the wire of a paper machine to form a web, which is then drained and dried.
• the cellulose fibres are not exposed to energy radiation before the web formation, but thereafter, by the direct radiation of the final paper substrate intended to be vulcanised or parchmentised.
• the process comprises the steps of:
• cellulose fibres denotes fibres formed by definition of cellulose, such as cotton fibres or any other annual plant fibres (flax, abaca etc.), wood fibres, these fibres of different origin distinguishing from each other by the structural characteristics such as the shape, the cross-section and thickness of the walls and the average degree of polymerisation (DP) of the cellulose making them up.
• DP average degree of polymerisation
• the energy radiation is carried out before obtaining the sheet
• the fibre suspension containing the cellulose fibres being exposed to energy radiation, cellulose fibres of the same origin, exposed to energy radiation or not, and/or cellulose fibres of different origin, exposed to energy radiation or not, and/or synthetic and/or mineral non-cellulose fibres.
• the cellulose fibres treated with energy radiation are advantageously annual plant fibres and especially of cotton and represent at least 20%, advantageously at least 50% by weight, of the fibre suspension.
• the cellulose fibres contained in the paper are irradiated by electron beams, regardless of their origin. It is clear that the mixture of fibres may further contain cellulose fibres, synthetic and/or mineral non-cellulose fibres.
• the cellulose fibres represent at least 20%, preferably at least 50% by weight, the most preferably 100% by weight of the fibre composition. In an advantageous embodiment, the cellulose fibres consist exclusively of cotton fibres.
• the cotton fibres may have two essential sources.
• the cotton fibres may be virgin cotton fibres, advantageously long fibres, the length of which is between 20 and 50 mm.
• these cotton fibres are received by the paper manufacturer in a dry state, either in the form of sheets, or in the form of compressed pulp thus comprising 100% of cotton fibres.
• the energy radiation is in the form of a radiation by an electron beam or an X-ray beam.
• the penetration of the radiation is sufficient so that the cotton pulp is directly treated in a bale of about 1 m 3 .
• the dry defibering of the sheet or of the compressed pulp starts prior to the radiation step and this, is done in such a way that the material passing under the beam is of low density ( ⁇ 0,6) and thin (in the order of a centimetre) so that the cotton fibres are treated in a homogenous and efficient manner.
• the paper substrates intended to be vulcanised or parchmentised can also advantageously be obtained from cotton fibres coming from textile industry waste.
• the cotton fibres coming to the composition of the fibre suspension come from jeans industry.
• the raw material is in the form of jeans manufacturing rags compacted in the form of bales.
• the bale is first opened, the jeans rags are cut, possibly sorted to remove the foreign objects e.g. of metallic particle type, and finally shredded.
• the cellulose fibres obtained after the shredding are separated and the refined in an aqueous environment.
• the fibres obtained from shredded rags are stored again in the form of a bale, which is opened, and the cellulose fibres are separated and finally refined in an aqueous environment.
• the radiation treatment can be performed either immediately after the cutting step and prior to the shredding step or immediately after the shredding step.
• the radiation is an X-radiation performed directly on the bale containing the cut and shredded rags of jeans.
• the Applicant has noticed that for a same reactivity level, the DP of a cellulose fibre absorbing a given dose of irradiation before the sheet formation was higher than that of the same fibre having absorbed the same dose from the final paper.
• the degree of polymerisation of a cooked fibre intended to be vulcanised is in the order of 600, it is necessary, for obtaining a reactivity of at least equal to the same fibre treated by energy radiation, to reduce this degree of polymerisation to a value between 350 and 500, advantageously equal to 450.
• the irradiation dose absorbed by the cotton fibres is between 10 and 30 kGy.
• the degree of polymerisation of a cellulose fibre treated by cooking and intended to be parchmentised is about 1000.
• the absorbed irradiation dose necessary to the cellulose fibre for obtaining an optimal reactivity of the substrate with regard to vulcanising and parchmentising depends on the treatment conditions and in particular of the type of equipment used.
• the degree of polymerisation of the fibres making up the paper sheet obtained is less than 700, advantageously between 200 and 300, preferably 250.
• the Applicant has noticed that the irradiation dose absorbed by the cotton fibres should be between 10 and 50 kGy.
• these values can be applied only to vulcanising.
• the degree of polymerisation of the fibres making up the paper sheet obtained is between 400 and 600, advantageously 500.
• the Applicant has noticed that the irradiation dose absorbed by the cotton fibres should be between 5 and 30 kGy.
• the manufacturing processes of the paper substrate of the invention can be carried out continuously or discontinuously.
• the process is a discontinuous process consisting in cutting the textile waste, removing the foreign bodies and shredding the pieces before forming a bale.
• This sequence of steps is made continuously on suitable cutting, sorting and shredding machines, known to those skilled in the art.
• the baling step makes it easier to store the ready-made raw material for a subsequent dispersion step of the fibres in an aqueous environment.
• the paper manufacturer takes again the jeans waste bale, he opens it in a dry state so that the bale is broken.
• the pieces of the jeans are then separated, defiberized and then refined in an aqueous environment, the obtained fibre suspension then being deposited on a paper machine, which assures, after draining and drying, the manufacturing of the final paper.
• the obtained shredded pieces of jeans after the dry disintegration of the bale, are subjected to a cooking step in a cooker at the temperatures of about 150° C. in soda solutions concentrated to 7%, the matter obtained being washed and defiberized, and finally refined in an aqueous environment.
• this cooking and washing step is replaced by a radiation step by electron beams.
• This irradiation step can be performed on the cotton fibres before manufacturing the paper and this, either immediately after the sorting step or immediately after the shredding step, or directly on the finished sheet.
• a paper intended to be vulcanised is produced containing 100% of cotton fibres treated either by cooking or by irradiation before the sheet formation.
• the degree of polymerisation of the cooked cotton fibres or those exposed to radiation by an electron beam has been determined before transformation operation of the paper by vulcanising, as well as the reactivity of the final sheet has been determined after the vulcanising.
• the degree of polymerisation of the cotton fibres is determined by calculations from the viscosity measurements of a solution based on cupriethylenediamine (CED), into which the cellulose fibres are dissolved.
• CED cupriethylenediamine
• the reactivity of the paper (DL) is evaluated after the vulcanising by measuring the barrier level with a coloured solvent. The test is done as follows:
• the reactivity of a paper is consequently estimated by the barrier level of the final product obtained.
• DP DL 1 Cooked cotton fibres 600 3 2 Paper irradiated with 50 250 3 kGy 3 Fibres irradiated with 30 390 3 kGy
• the examples 2 and 3 of the table reveal the difference due to raw material irradiation before manufacturing of the paper in comparison with an irradiation on the finished paper. For the same paper transformation level after vulcanising, that is to say for the same reactivity level of the paper, a much more important dose of irradiation has to be applied to the finished paper than to the raw material.
• a paper intended to be parchmentised is manufactured, containing 100% of cotton fibres treated by irradiation before the sheet formation.
• the samples are characterized by the degree of polymerisation of the cotton fibres exposed to radiation by an electron beam, before the transformation operation of the paper by parchmentising, as well as by the reactivity of the sheet with regard to the parchmentising.
• the degree of polymerisation DP of the cotton fibres is determined by calculation from the measurements of the viscosity of a solution based on cupriethylenediamine (CED), in which the cellulose fibres are dissolved.
• CED cupriethylenediamine
• the reactivity of the paper (DL) is evaluated after the parchmentising, by measuring its barrier level with a coloured solvent.
• B/ Measurements Dose in kGy DP DL 0 2010 1 10 640 5 30 400 5 50 320 5

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Paper (AREA)
• Chemical Or Physical Treatment Of Fibers (AREA)
• Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)

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Cited By (8)

Citations (3)

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• 2003
  • 2003-03-17 FR FR0303229A patent/FR2852612B1/fr not_active Expired - Fee Related
• 2004
  • 2004-03-15 WO PCT/FI2004/000147 patent/WO2004083519A1/en active Search and Examination
  • 2004-03-15 JP JP2006505620A patent/JP2006520857A/ja active Pending
  • 2004-03-15 RU RU2005131946/12A patent/RU2338022C2/ru not_active IP Right Cessation
  • 2004-03-15 US US10/548,205 patent/US20060169427A1/en not_active Abandoned
  • 2004-03-15 EP EP04720634A patent/EP1611280A1/en not_active Withdrawn
• 2008
  • 2008-03-06 US US12/043,725 patent/US20080149290A1/en not_active Abandoned

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