EP0009322B1 - Absorbierendes Papier und Verfahren zu seiner Herstellung - Google Patents

Absorbierendes Papier und Verfahren zu seiner Herstellung Download PDF

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Publication number
EP0009322B1
EP0009322B1 EP79301669A EP79301669A EP0009322B1 EP 0009322 B1 EP0009322 B1 EP 0009322B1 EP 79301669 A EP79301669 A EP 79301669A EP 79301669 A EP79301669 A EP 79301669A EP 0009322 B1 EP0009322 B1 EP 0009322B1
Authority
EP
European Patent Office
Prior art keywords
fibres
amino
weight
formaldehyde resin
absorbent paper
Prior art date
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
Application number
EP79301669A
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English (en)
French (fr)
Other versions
EP0009322A1 (de
Inventor
Richard George Cleveland Henbest
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Imperial Chemical Industries Ltd
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Imperial Chemical Industries Ltd
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Filing date
Publication date
Application filed by Imperial Chemical Industries Ltd filed Critical Imperial Chemical Industries Ltd
Priority to AT79301669T priority Critical patent/ATE2233T1/de
Publication of EP0009322A1 publication Critical patent/EP0009322A1/de
Application granted granted Critical
Publication of EP0009322B1 publication Critical patent/EP0009322B1/de
Expired legal-status Critical Current

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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
    • 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
    • D21H5/20—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials of organic non-cellulosic fibres too short for spinning, with or without cellulose fibres

Definitions

  • This invention relates to absorbent papers: such papers find a variety of uses, such as facial or other hygienic tissues, towelling ana biutting paper. Depending on the desired use, other factors besides absorbency, for example bulk, softness, and strength may also be of importance.
  • Paper is generally made by a wet-laid process wherein a slurry of fibres in water is formed into sheet form, e.g. by deposition of the slurry on to a moving porous surface, e.g. the wire of a Fourdrinier paper making machine, and removing the water, initially by drainage through the porous surface and subsequently by passage of the drained fibrous web through a suitable drier.
  • a moving porous surface e.g. the wire of a Fourdrinier paper making machine
  • the average length of the fibres should be below 10 mm.
  • the fibres used to make the paper are usually cellulosic: cellulosic pulps are of two main types viz lignin free, e.g.
  • the degree of beating or refining of the pulp in general the greater the degree of beating the stronger and less bulky is the resultant paper.
  • the degree of beating is conveniently assessed by measuring the freeness of the pulp. In this specification freeness refers to the freeness measured by the Canadian Standard Freeness test procedure: the higher the freeness, the less well beaten is the pulp.
  • the absorbency of the paper is also affected by the freeness: generally the higher the freeness, i.e. the less well beaten, the greater the absorbency.
  • absorbent papers may be obtained by making the paper from certain mixtures of cellulose pulp and fibres formed from an amino-formaldehyde resin such as a urea-formaldehyde (UF) resin.
  • an amino-formaldehyde resin such as a urea-formaldehyde (UF) resin.
  • Paper formed from mixtures of UF resin fibres and cellulose pulps have been described in FR-A-2382542. In that specification the cellulose pulp had a Canadian Standard Freeness of less than 400 ml (chemical pulp) or 120 ml (mechanical pulp).
  • absorbent papers can be made using amino-formaldehyde resin fibres mixed with cellulose pulps having somewhat higher freenesses. Also, where the proportion of amino-formaldehyde resin fibres is high, absorbent papers can be made with cellulosic pulps having lower freenesses.
  • absorbent paper we mean that the paper has a water-absorption capacity exceeding 3: this may be determined by saturating a weighed quantity of air dry paper with water, lightly shaking to remove excess water followed by reweighing. The absorption capacity is calculated as the weight of water absorbed per unit weight of the air dry paper.
  • absorbent papers according to the invention have a greater water-absorption capacity than the most absorbent paper that can be made, under the same paper-making conditions, from the cellulose pulp employed.
  • an unbeaten or very lightly beaten chemical wood pulp may have a freeness of about 600 ml and paper made therefrom may have a water absorption capacity of about 3.
  • the water absorption capacity may be increased to about 3.4.
  • stronger papers may be made: thus by beating the cellulose pulp to a freeness of about 450 ml prior to blending with the 20% of UF fibres, a paper can be made that is stronger than the most absorptive pure cellulose pulp paper achievable from this cellulose pulp and yet has similar absorption characteristics.
  • an absorbent paper product formed from a blend of fibrous constituents comprising 5 to 95% by weight of amino-formaldehyde resin fibres which are insoluble in cold water and have an average length between 1 and 10 mm and a mean diameter between 1 and 30 ⁇ m, and, correspondingly, 95 to 5% by weight of cellulose pulp, provided that, where the Canadian Standard Freeness of the cellulose pulp is below 310 x + 140 ml (where x is the proportion by weight of lignin free pulp in said cellulose pulp) the proportion of amino-formaldehyde resin fibres in the blend is such that the Canadian Standard Freeness of the blend is above 220 x + 400 ml.
  • the pulp should have a freeness above 450 ml.
  • absorbent papers can be made with blends containing sufficient amino-formaldehyde resin fibres to give a blend of freeness above 620 ml.
  • the cellulose pulp is wholly a lignin containing, e.g. mechanical, pulp, i.e.
  • absorbent papers can be made with blends containing sufficient amino-formaldehyde resin fibres to give a blend of freeness above 400 ml.
  • the amino-formaldehyde resin used to make the fibres is a condensate of an amino compound, preferably a polyamine such as urea or melamine, with formaldehyde.
  • the amino compound is preferably urea, alone or in admixture with up to 5% by weight of melamine.
  • the molar ratio of formaldehyde to amino groups is preferably between 0.6:1 and 1.5:1, particularly between 0.7:1 and 1.3:1.
  • the amino-formaldehyde resin fibres may be made by any suitable fibre forming technique such as wet or dry spinning and are preferably formed by a centrifugal spinning process, for example as described in our DE-A-2810535, which gives, as is preferred, substantially straight and unbranched fibres.
  • the amino-formaldehyde resin fibres should have an average length, weighted by length, of between 1 and 10 mm, preferably between 2 and 6 mm. Preferably substantially all the amino-formaldehyde resin fibres have a length within the range 1 to 10 mm.
  • the amino-formaldehyde resin fibres should have a mean diameter between 1 and 30 ⁇ m, preferably between 2 and 20 ,um, and particularly between 5 and 15 um. Preferably substantially all the amino-formaldehyde resin fibres have a diameter between 1 and 30 um.
  • the amino-formaldehyde resin fibres preferably have an average strength of at least 50 MNm- 2 (which corresponds approximately to 33 Nmg -1 ), particularly at least 100 MNm -2 ( ⁇ 67 Nmg -1 ).
  • the amino-formaldehyde resin fibres should be cured to such an extent that they are insoluble in water: thus their solubility in water at 25°C should not exceed 1.5% by weight.
  • Cellulose fibres that may be used include mechanical wood pulp, chemical wood pulp, such as is produced by the sulphate or sulphite pulping processes, thermomechanical and semichemical wood pulps.
  • the cellulose pulp may be cotton linters, linen fibres derived from rags, or other cellulose fibres conventionally used in paper making. Depending on their source and method of production they may or may not contain substantial quantities of lignin. Thus cotton linters are substantially free of lignin.
  • the absorbent papers may be made by the conventional wet laid process, e.g. as hereinbefore described, after preparation and blending of the fibrous ingredients into a paper-making fibrous stock.
  • the absorption capacity and bulk of the paper can be increased if the conventional step of pressing the wet paper sheet prior to drying is omitted.
  • Papers containing a high proportion of amino-formaldehyde resin fibres tend to have relatively poor strengths.
  • the strength of such papers may be increased by incorporating a binder into the paper: the binder can be added to the aqueous slurry of the fibrous constituents or can be incorporated in a subsequent impregnation or coating stage.
  • the binder may be sprayed on to the wet web or it may be coated on the dry or partly dried paper.
  • Different methods are appropriate to different binder systems, as is well known to those skilled in the paper making art.
  • Binders may also advantageously be incorporated in papers containing lesser proportions of amino-formaldehyde resin fibres.
  • Suitable binders include starch or modified starch, polymer latices, water soluble polymers such as poly(ethylene imine), poly(acrylamide), and poly(vinyl pyrrolidone).
  • the binder is preferably treated to render it cationic in water.
  • Particularly favoured are cationic binders added with the fibres-including, in addition to those binders already mentioned, cationic starch and urea - or melamine-formaldehyde resins, as conventionally used to achieve increases in paper wet strength.
  • the amount of binder employed is from 0.01 to 10%, preferably 0.1 to 5%, by weight of the fibrous ingredients.
  • the paper products of the present invention contain 5-95% by weight of amino-formaldehyde resin fibres and correspondingly 95-5% by weight of cellulose fibres.
  • the properties of the paper will vary considerably as the proportions of the respective fibres are varied: thus as the proportion of amino-formaldehyde resin fibres increases, absorbency and bulk increases.
  • the proportion of amino-formaldehyde resin fibres increases so the freeness of the cellulose pulp should be reduced in order to obtain adequate strength, although it will be appreciated that for some applications strength is not important, for example in highly absorbent products where an absorbent paper layer is attached. e.g. by an adhesive or stitching, to a supportiny web.
  • the paper products preferably contain at least 15%, and preferably less than 80%, by weight of amino-formaldehyde resin fibres.
  • the paper products may be creped, by conventional means, as a way of increasing their bulk and also, incidentally, to improve their stretch. Creping may not be necessary with papers comprising predominantly amino-formaldehyde resin fibres but in the latter case it may be desirable to incorporate one or more of the aforementioned binders. Where the amount of amino-formaldehyde resin fibres is relatively low, i.e. below about 35% by weight, the paper will be soft and bulky and may require creping on conventional equipment to produce a paper acceptable for absorbent applications. However, because of the higher bulk conferred by the amino-formaldehyde resin fibres, the severity of the creping process may be reduced as compared with conventional papers.
  • the papers may be acceptable for some absorbent applications, but for others may require to be creped.
  • amino-formaldehyde resin fibres also confer advantages in processing. It is possible, for example, to increase the dilution of the stock, while maintaining machine speed, and so improve the even formation of the sheet. This may be of particular importance with light weight tissue products.
  • the invention is illustrated by the following examples in which all percentages ae by weight.
  • the amino-formaldehyde resin fibres employed were urea-formaldehyde (UF) fibres made by centrifugal spinning.
  • An aqueous solution of a urea-formaldehyde resin having a formaldehyde:urea ratio of 2:1, a solids content of 65%, and a viscosity of 45 poise (4.5 Pa s) was mixed continuously with 10% of a solution containing 1.66% poly(ethylene oxide) of weight average molecular weight 600,000 and 6.66% ammonium sulphate.
  • the resulting mixture was fed at a rate of 200 g/min. to a 13 cm diameter spinning cup rotating at 10,000 rpm.
  • the resin was spun as fibres from the cup into an atmosphere of air at 150°C, and then the fibres were removed therefrom and cured by heating for 3 hours at 120°C to render them insoluble in cold water.
  • the resultant fibres were shredded and further disintegrated in a laboratory Valley beater.
  • the shredded, beaten, fibres had an average fibre length of about 3 mm an an average diameter about 1 ⁇ ⁇ nn.
  • Substantially all the fibres had a length within the range 1-10 mm and a diameter within the range 3-20 ,um.
  • the strength of the fibres, measured by short span testing of a loose mat of the fibres, was approximately 120 MNm- 2 .
  • the UF fibres were blended, in specified quantities expressed on a dry fibre basis, with cellulose pulps that had been beaten in a Valley beater to specified freenesses.
  • the resultant blends were made into paper handsheets of substance about 60g m- 2 using a British Standard handsheet former. Except where indicated, the papers were wet pressed.
  • starch was added to the fibrous mixture from which the papers were made.
  • the cellulose pulp was a birch sulphate pulp beaten to a freeness of 484 mi.
  • starch free systems of similar blend freeness and UF content in Example 1 e.g. compare run 2.3 with run 1.6 and run 2.4 with run 1.9, it is seen that adding starch improves both the absorbency and burst index.
  • Example 1 The procedure of Example 1 was repeated using a commercially available unbleached mechanical wood pulp in place of the birch sulphate pulp. In one case, run 3.7, the paper was made omitting the wet pressing step. The results are shown in the following Table.
  • absorbent papers can be made with low freeness cellulose pulps.
  • Example 1 The procedure of Example 1 was repeated using as the cellulose pulp a mixture of 70% bleached pine sulphate and 30% bleached birch sulphate. In some cases 3%, on fibre weight, of starch was added and, in all these runs, the wet pressing step was omitted.
  • the water absorption time quoted is the time taken to absorb 0.1 ml of water rather than 1 ml as in the previous examples.
  • Example 2 The procedure of Example 1 was repeated using as the cellulose pulp a birch sulphate wood pulp of freeness 425 ml. The results are shown in the following Table, together with data for a commercial blotting paper and a commercial absorbent paper towelling. The papers of runs 5.1 to 5.9 all had absorption capacities in excess of 3.

Landscapes

  • Paper (AREA)
  • Absorbent Articles And Supports Therefor (AREA)
  • Orthopedics, Nursing, And Contraception (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)

Claims (13)

1. Saugfähiges Papierprodukt, gebildet aus einer Mischung von faserigen Bestandteilen, die aus 5 bis 95 Gew.-% in kaltem Wasser unlöslichen Amino-Formaldehyd-Harz-Fasern mit einer durchschnittlichen Länge zwischen 1 und 10 mm und einem riittleren Durchmesser zwischen 1 und 30 um und entsprechend 95 bis 5 Gew.-% Zellstoff bestehen, wobei vorausgesetzt ist, daß die Amino-Formaldehyd-Harz-Fasern in der Mischung in einem solchen Anteil enthalten sind, daß der Mahlgrad (Canadian Standard Freeness) der Mischung über 220 x + 400 ml liegt, wenn der Mahlgrad (Canadian Standard Freeness) des Zellstoffs unter 310 x + 140 ml liegt (wobei x der Gewichtsanteil des ligninfreien Zellstoffs in dem Zellstoff ist).
2. Saugfähiges Papierprodukt nach Anspruch 1, bei dem die faserigen Bestandteile aus 15 bis 80 Gew.-% der Amino-Formaldehyd-Harz-Fasern und entsprechend 85 bis 20 Gew.-% des Zellstoffs bestehen.
3. Saugfähiges Papierprodukt nach Anspruch 1 oder Anspruch 2, enthaltend 0,01 bis 10 Gew.-% auf das Gewicht der faserigen Bestandteile bezogen, eines Bindemittels.
4. Saugfähiges Papierprodukt nach Anspruch 3, bei dem die Amino-Formaldehyd-Harz-Fasern mehr als 75 Gew.-% der faserigen Bestandteile bilden.
5. Saugfähiges Papierprodukt nach einem der Ansprüche. 1 bis 4, das gekreppt worden ist.
6. Saugfähiges Papierprodukt nach Anspruch 5, bei dem die Amino-Formaldehyd-Harz-Fasern weniger als 35 Gew.-% der faserigen Bestandteile bilden.
7. Saugfähiges Papierprodukt nach einem der Ansprüche 1 bis 6, bei dem die Amino-Formaldehyd-Harz-Fasern Fasern aus einem Harz sind, das durch Kondensieren von Formaldehyd mit Harnstoff und 0 bis 5 Gew.-%, auf das Gewicht des Harnstoffs bezogen, Melamin gebildet worden ist.
8. Saugfähiges Papierprodukt nach einem der Ansprüche 1 bis 7, bei dem das Molverhältnis des Formaldehyds zu den Aminogruppen in dem Amino-Formaldehyd-Harz zwischen 0,6:1 und 1,5:1 liegt.
9. Saugfähiges Papierprodukt nach einem der Ansprüche 1 bis 8, bei dem die Amino-Formaldehyd-Harz-Fasern eine durchschnittliche Länge im Bereich von 2 bis 6 mm haben, wobei im wesentlichen alle Fasern eine Länge im Bereich von 1 bis 10 mm haben.
10. Saugfähiges Papierprodukt nach einem der Ansprüche 1 bis 9, bei dem die Amino-Formaldehyd-Harz-Fasern einen mittleren Durchmesser im Bereich von 2 bis 20 µm haben, wobei im wesentlichen alle Fasern einen Durchmesser im Bereich von 1 bis 30 µm haben.
11. Verfahren zur Herstellung eines saugfähigen Papierprodukts nach einem der vorhergehenden Ansprüche, bei dem aus den faserigen Bestandteilen ein wäßriger Brei gebildet, der Brei unter Ausbildung einer Blattform geformt und das Wasser entfernt wird.
12. Verfahren nach Anspruch 11, bei dem das Blatt vor dem Trocknen nicht gepreßt wird.
13. Verfahren nach Anspruch 11 oder Anspruch 12, bei dem das Blatt nach dem Trocknen gekreppt wird.
EP79301669A 1978-09-01 1979-08-15 Absorbierendes Papier und Verfahren zu seiner Herstellung Expired EP0009322B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT79301669T ATE2233T1 (de) 1978-09-01 1979-08-15 Absorbierendes papier und verfahren zu seiner herstellung.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB7835310 1978-09-01
GB3531078 1978-09-01

Publications (2)

Publication Number Publication Date
EP0009322A1 EP0009322A1 (de) 1980-04-02
EP0009322B1 true EP0009322B1 (de) 1983-01-12

Family

ID=10499398

Family Applications (1)

Application Number Title Priority Date Filing Date
EP79301669A Expired EP0009322B1 (de) 1978-09-01 1979-08-15 Absorbierendes Papier und Verfahren zu seiner Herstellung

Country Status (6)

Country Link
EP (1) EP0009322B1 (de)
JP (1) JPS5536397A (de)
AT (1) ATE2233T1 (de)
AU (1) AU5017379A (de)
CA (1) CA1109709A (de)
DE (1) DE2964483D1 (de)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0045135B1 (de) * 1980-07-29 1984-01-18 Imperial Chemical Industries Plc Verfahren zur Herstellung eines laminierten Bahnmaterials
US4468428A (en) * 1982-06-01 1984-08-28 The Procter & Gamble Company Hydrophilic microfibrous absorbent webs
JPS61163086U (de) * 1985-03-29 1986-10-09
US4902564A (en) * 1988-02-03 1990-02-20 James River Corporation Of Virginia Highly absorbent nonwoven fabric
FR2647128B1 (fr) * 1989-05-18 1991-12-27 Aussedat Rey Procede de fabrication d'un substrat plan, fibreux, souple, difficilement dechirable et substrat obtenu
JP2843454B2 (ja) * 1991-05-23 1999-01-06 川崎重工業株式会社 細粒のための振動ふるい

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB572962A (en) * 1942-05-25 1945-10-31 Sylvania Ind Corp Paper products and methods of making the same
FR87511E (fr) * 1964-11-10 1966-08-26 Cta Papiers absorbants résistants à l'état mouillé, à base de fibres artificielles en cellulose régénérée
FI41620B (de) * 1967-10-20 1969-09-01 Neste Oy
DE2024831A1 (de) * 1969-05-30 1970-12-03 Mölnlycke AB, Göteborg (Schweden) Für Kompressen, insbesondere für Menstruationsbinden und Windeln bestimmter saugfähiger Körper aus entfasertem Zellstoff
SE401697B (sv) * 1976-09-21 1978-05-22 Sunden Olof Halvsyntetiskt papper pa ureabas samt sett for dess framstellning
GB1573114A (en) * 1976-12-08 1980-08-13 Ici Ltd Paper
GB1573115A (en) * 1977-03-11 1980-08-13 Ici Ltd Fibre containing products in sheet form

Also Published As

Publication number Publication date
DE2964483D1 (en) 1983-02-17
JPS5536397A (en) 1980-03-13
EP0009322A1 (de) 1980-04-02
ATE2233T1 (de) 1983-01-15
AU5017379A (en) 1980-03-06
CA1109709A (en) 1981-09-29

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