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
  • D21H11/14—Secondary fibres
• • 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

Definitions

• the present invention relates to paper material made from a fibrous pulp of industrial textile waste and exhausted sugarbeet pulp; to a method of industrially producing such a pulp from said waste raw materials; and to a method of preserving the damp exhausted beet pulp used in the fabrication method according to the invention.
• a method of producing paper material from industrial textile and agricultural waste characterized by comprising the steps of:
• the present invention is based on the discovery that a fibrous pulp suitable for paper manufacture may be obtained easily and cheaply by mixing waste textile fibers, of acknowledged physical-mechanical properties, directly and in the right proportions with whole exhausted sugarbeet pulp resulting from diffusion extraction of sucrose, providing the exhausted pulp is used in the damp state.
• the exhausted beet pulp must contain a minimum of 40-50% by weight of humidity, and use is preferably made of pressed exhausted pulp in which the dry substance is limited to 22-28%, and more preferably 24-26%, of the total weight of the product.
• yet a further basis of the present invention is the possibility of preserving the damp exhausted beet pulp for long periods of time to prevent the formation of mold or similar (which would impair and contaminate the raw material) or any chemical or morphological alteration in the solid structure of the pulp (pectins, hemicellulose, cellulose) due to degradation or the use of chemical preservatives.
• the pulp is preserved by inducing lactic fermentation in anaerobic conditions to achieve and maintain in the damp pulp a pH of 4 to 4.5.
• the pulp may even be preserved for over a year, thus enabling it to be stored safely and easily, and to be used as raw material all the year round despite being produced on a strictly seasonal basis.
• damp exhausted pulp also eliminates the drying process, thus greatly reducing production cost as compared with known processes also employing exhausted beet pulp.
• the method according to the present invention also comprises the step of conditioning the damp exhausted sugarbeet pulp and waste textile fibers.
• the conditioning step is performed simultaneously with said mixing step, by performing the mixing step in a known Bi-VisTM machine capable of inducing a high shear rate in the mixed materials, and by operating in an aqueous suspension with a concentration of 2 to 20% by weight of solid substance, and in the presence of a strong base, preferably NaOH, dissolved in water to a concentration of 0.1 to 10 gr/l.
• a strong base preferably NaOH
• said conditioning step is performed prior to said mixing step, by hot treating both the damp exhausted pulp and the waste textile fibers in an autoclave, and instantaneously releasing the pressure.
• Such a treatment though used for entirely different materials, is known as "steam explosion".
• the autoclave treatment is performed by placing the materials separately inside a respective reactor made of stainless steel or other material resistant to an aggressive acid environment and high temperature, and presenting a large release valve at the bottom; supersaturated steam is then fed into the reactor at 20 to 30 bar pressure to bring the material to within a given temperature range and keep it there for a given length of time; at which point, the pressure is reduced instantaneously to ambient pressure by expelling the steam and materials simultaneously through said valve at the bottom of the reactor used as an autoclave.
• the waste textile fibers are treated at a temperature of 190 to 230°C for 2 to 10 minutes; whereas the damp exhausted beet pulp is treated less severely, at a temperature of 170 to 200°C for 2 to 6 minutes.
• the fiber structure and the supramolecular structure of both the textile fibers and the polysaccharide organic material in the pulp used in the method according to the invention are therefore so modified as to permit mixing using normal paper manufacturing methods.
• a similar variation in textile fiber structure is also obtained operating simultaneously with the mixing step according to the first embodiment described above, wherein the material for mixing, strongly diluted in soda water, is fed into mixers capable of developing very high shear rates, e.g. Bi-VisTM machines.
• mixers capable of developing very high shear rates, e.g. Bi-VisTM machines.
• the "conditioning" to which the materials for mixing are subjected enables any other raw materials, such as conventional wood pulp, to be eliminated, unlike other known processes employing agricultural and/or industrial waste.
• the waste cellulosic textile fibers used in the method according to the invention are selected from a group comprising: cotton fibers and waste from the production of cotton or cotton yarn; linen fibers and waste from the production of linen or linen yarn; hemp fibers and waste from the production of hemp or hemp yarn; synthetic cellulosic fibers, particularly waste from the production of viscose yarn; and mixtures thereof. Waste cotton fiber from the manufacture of cotton products is, however, preferred.
• additives compatible with said paper manufacturing technique may be added to the pulp mixture to obtain specific characteristics of the finished paper material.
• limited amounts about 2% by weight, calculated on the total weight of dry pulp, i.e. not taking into account the weight of the water
• limited amounts about 2-20% by weight, calculated on dry pulp
• inorganic fillers such as calcium carbonate, china clay, etc.
• any other known additive such as sizing agents, adhesives (synthetic or rosin-based), and bleaching agents may be added to the paper pulp according to the invention.
• the method according to the invention also comprises the step of "bleaching" the mixture of beet pulp and fibers, which is preferably done during the mixing step in a Bi-Vis machine, by adding to the mixture 3-5% by weight (calculated on dry pulp only, i.e. without calculating the water) of hydrogen peroxide (or any other non-chlorine-based oxidizing bleaching agent, such as ozone, peracids, etc.), which provides for obtaining an excellent degree of whiteness of 70 to 75% (measured to ISO standards).
• hydrogen peroxide or any other non-chlorine-based oxidizing bleaching agent, such as ozone, peracids, etc.
• chlorine-based bleaching agents may also affect the cellulosic fiber structure of the beet pulp, and are therefore to be avoided.
• the paper pulp obtained using the method according to the invention comprises water, 2 to 50% of beet pulp, and, say, up to 80% of industrial waste cotton fiber or other cellulosic fibers.
• the present invention therefore also relates to a paper pulp which may be produced exclusively from cellulosic and fibrous raw materials in the form of industrial waste, characterized by comprising a mixture of 2 to 50% of exhausted sugarbeet pulp, and 88 to 40% of waste textile fibers selected from a group comprising: cotton fibers and waste from the production of cotton or cotton yarn; linen fibers and waste from the production of linen or linen yarn; hemp fibers and waste from the production of hemp or hemp yarn; synthetic fibers, particularly waste from the production of viscose yarn; and mixtures thereof.
• the present invention also relates to an ecological paper material, characterized by comprising textile fibers mixed with a cellulosic matrix exclusively comprising exhausted sugarbeet pulp.
• the fibrous pulp according to the present invention may be used for producing widely different types of paper, by virtue of featuring a mixture of materials with complementary and synergic structural and morphological characteristics; and the invention also provides for a new ecological, low-energy paper manufacturing method capable of meeting the requirements of leading ecological brands.
• Beet pulp preparation and preservation - Sugarbeet pulp from the diffusion extraction of sucrose is partially dehydrated by pressing it to obtain a dry substance content of 22 to 28% (preferably 24 to 26%) by weight.
• the residual sucrose content may vary from 1.1 to 3% (on average, from 1.5 to 2%) by weight, calculated on dry pulp; the temperature of the pulp just after pressing is about 50°C; and the content of antifermenting products (such as formaldehyde, glutaraldehyde, quaternary ammonium salts, etc.) must not exceed the normal amount remaining in exhausted pulp following normal antiseptic diffusion treatment.
• the damp exhausted beet pulp is ensiled anaerobically.
• the pressed ensiled pulp with correct lactic fermentation presents the following average composition: dry substance 25-27 % of total weight raw fiber 21-22 % of total weight pH 3.8-4.1 lactic acid 5.0-5.5 % by weight of dry pulp acetic acid 1-2 % by weight of dry pulp propionic acid ⁇ 0.01 % by weight of dry pulp L-butyric acid ⁇ 0.01 % by weight of dry pulp n-butyric acid ⁇ 0.01 % by weight of dry pulp valeric acid ⁇ 0.01 % by weight of dry pulp ethanol 0.1-0.20 % by weight of dry pulp In the above conditions, the damp pulp is preserved perfectly for long periods, even for over a year.
• the preservation method according to the invention was also tested, and gave the same results, using cold pressed exhausted pulp (at ambient temperature of, on average, 10 to 25°C).
• the sucrose content must be controlled and, if necessary, integrated to keep it at least equal to 1.5-2% by weight of dry pulp. If below this value, a sufficient amount of sugar, usually molasses, is added to the pulp, or Lactobacillus delbgurll is inoculated to reach the above value. Since oxygen encourages the formation of mold and yeast, anaerobic conditions must be guaranteed during ensilage. For this reason, the third method described above, using plastic bags, is preferable, and also presents the added advantages of ensuring the pulp is tightly packed, thus assisting fermentation, and of reducing storage cost by requiring no building work.
• Paper production using the Bi-Vis method Cotton waste and waste from other industrial textile processes (spinning, weaving, manufacture) are mixed - as they are or carded beforehand - with exhausted beet pulp preserved damp as in Example 1. Mixing is performed initially in a normal pulper equipped with a screw mixer, and in the presence of an aqueous solution of NaOH with a concentration of 4% by weight of dry pulp. The mixture, diluted with water to a concentration of 2% by weight of dry pulp, is then fed at the rate of 7 kg/h into a standard semiindustrial Bi-VisTM facility.
• the paper die cycle comprises: dispersion in water, addition of additives, mixing, cloth draining, damp pressing, and drying on a plate heated to 105°C, at the end of which, the paper sheet presents a residual humidity of 5-10% by weight.
• the sheets of different substance so formed are then conditioned in a conditioned chamber maintained at a temperature of 23°C and 50% relative humidity, and then subjected to mechanical and technological testing to ISO/UNI standards. The results are shown in comparison Table 1.
• the values relative to the sheets produced from the pulp according to the invention are comparable with the normal values of paper produced from conventional chemical pulp with a cellulosic content derived entirely from wood. Moreover, the pulp containing absolutely no beet pulp results in paper of slightly poorer properties, and above all with excessively high permeability values.
• Paper production using the steam explosion method -Waste cotton of the same type as in Example 2 is first steam explosion treated in a pilot facility. Supersaturated steam is used, and the cotton fibers maintained at a temperature of 210°C for about 4 minutes.
• the beet pulp in Example 1 is pretreated in the same facility at a lower temperature (170°C) for 2 minutes.
• the fibrous material so formed is mixed in varying proportions (% by weight) in the Example 2 pulper, and, operating as in Example 2, is subjected to a standard paper die cycle to produce 200 cm 2 sheets using the same facility as in Example 2.
• the physical-mechanical characteristics are shown in Table 2 and, as can be seen, are fully comparable with those of Example 2.
• white 200 cm 2 sheets of paper are produced by adding to the mixture, as it is mixed in a Bi-VisTM machine, from 3 to 5% by weight, calculated on dry pulp (odp), of 12-volume hydrogen peroxide.
• the physical-mechanical properties are the same as in Table 1.
• the degree of whiteness of the finished paper is assessed to ISO standards and found to range from 70 to 75%, which is more than enough to enable the paper according to the invention, and with the addition of normal bleaching agents, to be used in applications requiring a high degree of whiteness (writing and printing paper, etc.).

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• 1995
  • 1995-05-19 IT IT95TO000395A patent/IT1279744B1/it active IP Right Grant
• 1996
  • 1996-05-15 EP EP96107793A patent/EP0743393A3/de not_active Withdrawn

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