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
  • D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
  • D21H13/36—Inorganic fibres or flakes
  • D21H13/38—Inorganic fibres or flakes siliceous
  • D21H13/40—Inorganic fibres or flakes siliceous vitreous, e.g. mineral wool, glass 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
  • D21H5/00—Special paper or cardboard not otherwise provided for
  • D21H5/12—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials
  • D21H5/14—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials of cellulose fibres only
  • D21H5/141—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials of cellulose fibres only of fibrous cellulose derivatives
• • 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
  • D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
  • D21H13/36—Inorganic fibres or flakes
• • 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
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution

Definitions

• the invention relates to sheets based on cellulosic fibers produced by the papermaking process. More specifically, the invention relates to the improvement of certain properties of this type of product.
• the "hand” is a quality to which users are more and more sensitive. This specific property of paper is, in part, assessed subjectively. A paper with a good hand is appreciated as a quality paper. The hand corresponds to the mass volume of the sheet. With the same grammage, the hand is all the better as the thickness is greater. The user prefers a more "bulky” paper. Regardless of the subjective aspect, an improvement in the hand also results in better "rigidity" of the leaves. For relatively low grammages, the sheets while having sufficient mechanical strengths may be too flexible. It is important, even for these low grammages, to have a certain rigidity.
• the invention therefore proposes to provide new paper sheets having, in particular, an improvement in the hand and this while remaining in satisfactory cost conditions.
• the production of paper sheets according to the invention is carried out from a pulp based on cellulosic fibers containing a proportion which does not exceed 25% by weight of mineral wool, said wool being formed of fibers which have the dimensional characteristics of the fibers. produced for thermal insulation.
• Textile fibers are remarkable for their solidity which they owe to their regularity both in diameter and in length, both being linked to their mode of production. Textile fibers are also distinguished from mineral fibers produced under other conditions, in that their diameter remains relatively large. Typically, the diameter of the "textile" fibers is between 9 and 15 micrometers.
• a feature of the invention is to use mineral fibers such as those ordinarily produced according to techniques used for the formation of fibers intended for thermal insulation.
• An advantage of such fibers is that they are produced in large quantities and at relatively low costs.
• the insulation fibers are less regular in particular in length and are known to have a certain brittleness when they are subjected to mechanical forces. Account given, on the one hand the role which was expected from the mineral fibers previously incorporated in paper production, but also from the treatments to which the fibers are necessarily subjected during the preparation of the pulp and of the sheet, it is understood that the fibers insulation have so far been excluded from this type of application.
• the inventors have shown that the mineral fibers of the "insulation" type, incorporated into paper pulps, not only were not destroyed by the processing operations, but on the one hand are reduced to the dimensions most suitable for the uses considered. (less than a millimeter) and above all, on the other hand, were capable of giving the sheets produced an improved "hand" even when these fibers were introduced in small proportion.
• the length of the recovered fibers is usually several tens or even several hundred millimeters. It goes without saying that when it is introduced into the pulp preparation process, the mineral wool undergoes operations which break the original fibers into much shorter sections, that this introduction is made at the pulper level, from the refiner or even from the body.
• the mineral fibers that they contain preferably, have a length of at least 0.1 mm.
• the other characteristics of the fibers, in particular their diameter on the other hand the processing conditions, it is preferable that in the pulp used a high proportion of the mineral fibers have a length of between 0 , 2 and 0.6 mm. Under these conditions, the breakage of the fibers during the preparation of the dough is an advantage when starting from "insulation" fibers, in the sense that it is not necessary to carry out a cutting operation before incorporation into the dough.
• nodules previously prepared. from loose wool. These nodules, the dimensions of which are for example 0.5 to 5 mm, are obtained by a shredding operation of the loose wool followed by "nodulation" in a rotating drum. It should be clearly seen that this type of operation, even if it leads to cuts in the initial fibers, does not confer any regularity on them.
• the lengths of the fibers after the nodulation operation remain relatively large compared with those which are fixed when the cutting of continuous fibers (of the textile type) is carried out with a view to their incorporation into the dough. Both on the treated materials, but also under the conditions of implementation and the results obtained, these nodulation operations are not similar to those of cutting or cutting performed previously.
• the lengths of the fibers are partly the result of the processing of the pulp, another dimensional characteristic distinguishes the "insulation" fibers from the other mineral fibers used previously.
• the average diameters of the insulation fibers are traditionally included in a range of 3 to 8 micrometers and, more usually, in the range 4 to 6 micrometers.
• the insulation fibers used according to the invention are obtained by known techniques. It is techniques in which the molten mineral mass is subjected to a centrifugation operation. Depending on the case, centrifugation passes the material through calibrated orifices or only disperses the melt more randomly. To centrifugation is often added a drawing effect of the fibers by the action of gas streams.
• the preferred fibers come from techniques in which the centrifuge also acts as a die.
• the wool obtained by these techniques has the great advantage of being practically free of infibrated particles, that is to say particles of dimensions much greater than those of the fibrous mass proper.
• the fibers used generally have an average diameter of between 3 and 8 micrometers as we have seen, but for a given wool and a given average diameter, the fibers, taken individually, can deviate from these values medium. In all cases, whatever the average diameter of the fibers chosen, at least 80% by weight of the fibers constituting the wool have a diameter of between 3 and 8 micrometers. The differences between fibers of the same wool are more or less significant depending on the production method. The techniques indicated above lead to fibers whose histogram is relatively narrow. Thus, for a wool whose average diameter of the fibers is of the order of 5 micrometers, 90% by weight of the fibers have a diameter of between 3.5 and 7 micrometers.
• the introduction of mineral fibers into the paper composition is deliberately limited to a maximum of 25% by weight of the dry matter. It is possible to increase the quantity of mineral fibers but, in addition to the corresponding increase in cost, the paper obtained may have peculiarities not desired for printing. Too high a content of mineral fibers can thus lead to an undesirable increase in porosity.
• the mineral fiber content is between 2 and 15% by weight of the dry matter of the pulp used.
• the minimum quantity of fibers introduced according to the invention is therefore preferably such that the gain in hand is at least equal to 3% compared to the paper obtained with an identical pulp with the exception of the presence of these mineral fibers.
• the invention also relates to paper sheets based on cellulosic fibers and containing mineral fibers of the insulation type, sheets whose hand is improved.
• Such paper sheets are, in particular, those in the composition of which the only agent capable of improving the hand consists of these mineral fibers.
• other agents which have the role of increasing the mass volume. Among these are, in particular, what can be described as "lightening" fillers such as, for example, microspheres.
• the disadvantage of such agents, apart from their often high cost, is that they can lead to the very substantial lowering of certain mechanical properties such as resistance to bursting or resistance to tearing.
• a remarkable advantage of using insulation fibers for improving the hand under the conditions of the invention is that the mechanical properties in question are little affected.
• Samples are prepared from an unbleached Kraft pulp refined at 21 ° SR, incorporating various qualities and quantities of glass wool.
• the glass fibers are first soaked in water and then added to the paste with stirring. The mixture is passed to the Lhomargy shredder for 2 minutes.
• the sheets are made with Noble and Wood form in 150 g / m2, following standard NF Q 50-002.
• the tests are carried out by incorporating increasing amounts of fiber. A comparison is made using a control sheet.
• the sheets according to the invention (No. 2), in which the insulation fibers have an average diameter of 4 micrometers, are also compared to sheets prepared by incorporating microfibers whose diameter is 1 micrometer (No. 1).
• the addition of glass fibers under the conditions of the invention causes an increase in the hand even for a content of 2%.
• the gain in hand obtained by introducing the fibers of the insulation type according to the invention is advantageously compared with that corresponding to the microfibers. For 10% of the latter, the hand improvement remains lower than that obtained with only 2% of insulation fibers.
• the dough is a mixture of bleached Kraft pasta (66% Socel, 34% Iggesund) refined at 28 ° SR.
• the sheets are drawn in 80 g / m2 on Noble and Wood formulas.
• the fibers used are the same as in Example 1: microfibers (3), insulation fibers (4), insulation fibers with size of polyvinyl alcohol at 0.8% (5), insulation fibers with size starch at 0 , 8% (6).
• Example 1 The trends observed on the samples of Example 1 are confirmed on these sheets of another nature. The increase in hand is strong in all the samples corresponding to the invention (4, 5, 6) and remains very modest for the microfibers.
• the dimensional stability is improved mainly for the highest contents and the decrease in mechanical strength is less noticeable for the sheets obtained with the insulation fibers.
• Example 2 The tests of Example 2 are repeated with a mineral filler consisting of calcium carbonate (marketed under the name Hydrocarb 60).
• the mineral filler represents 10% of the mass of the dough.
• the dough is a mixture of bleached Kraft pasta (60% beech, 40% resinous) refined at 40 ° SR.
• the sheets are drawn in 70 g / m2 on a pilot paper line at a speed of 20 m / mm.
• the hand and dimensional stability measurements are grouped in the following table:
• test No. 8 show that the results obtained under the conditions of the invention (test No. 8) are better, as regards both the hand and the dimensional stability. This improvement is noted with respect to microfibers (test n ° 7) and with respect to textile fibers (test n ° 9).

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• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Paper (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (7)

Cited By (2)

Citations (2)

• 1989
  • 1989-11-28 FR FR8915602A patent/FR2655070A1/fr not_active Withdrawn
• 1990
  • 1990-11-22 EP EP90403298A patent/EP0430770A1/de not_active Withdrawn
  • 1990-11-23 CA CA002030688A patent/CA2030688A1/fr not_active Abandoned
  • 1990-11-26 KR KR1019900019180A patent/KR910010012A/ko not_active Withdrawn
  • 1990-11-26 NO NO90905110A patent/NO905110L/no unknown
  • 1990-11-27 FI FI905842A patent/FI905842L/fi not_active IP Right Cessation
  • 1990-11-28 JP JP2323436A patent/JPH03174089A/ja active Pending

Patent Citations (2)

Non-Patent Citations (1)

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