IE880842L

IE880842L - Manufacturing paper

Info

Publication number: IE880842L
Application number: IE880842A
Authority: IE
Original assignee: Atochem
Priority date: 1987-03-23
Filing date: 1988-03-22
Publication date: 1988-09-23
Also published as: DK154788D0; FR2612961A1; ES2029522T3; FI881369A; NO173887B; ATE73184T1; FI94972B; GR3004804T3; DK170686B1; PT87044B; EP0285487A1; PT87044A; IE60052B1; FR2612961B1; EP0285487B1; NO881029L; DK154788A; NO173887C; NO881029D0; FI881369A0

Abstract

Papermaking process characterised in that the following are added to the suspension containing the cellulose fibres before the sheet is formed: calcium carbonate, a sizing agent such as a dimeric alkylketene or a carboxylic acid anhydride, cationic starch and a basic aluminium polychlorosulphate.

Description

! t 6 C 0 5 2 The present invention relates to an improvement to processes for manufacturing paper.

Haw paper pulp, consisting essentially of cellulose fibres, is made into a dilute aqueous suspension which is 5 carried to the flow box of the papermaking machinee whence it is distributed onto a filtering cloth on which the sheet of paper is formed. This sheet is then wrung and subsequently dried. The qualities and properties of the paper obtained are determined, in particular, by the 10 conditions of operation of the papermaking machine, the raw pulp, the different additives which are added to the suspension before the formation of the sheet and also the products which are coated onto the sheet of paper produced on the filtering cloth.

The present invention relates more especially to the products which are added before the formation of the sheet. Thus, inorganic fillers such as calcium carbonate and titanium dioxide are added. These fillers make the sheet of paper opaque, thereby facilitating writing and printing. A 20 sizing agent can also be added in order to make the sheet resistant to liquids, that is to saye, the sised sheet of paper may be used for writing and printing. It is also necessary to add a retention systsme Mhich precipitates the sizing agent on the cellulose fibres and enables the 25 inorganic fillers to be retained in the sheet of paper. The retention system is frequently a mixture of several products. Products for improving the mechanical qualities of the paper,, colorants, end the likee, are also added.

All these products do not have a 11 specified action in respect of a single characteristic of the paper, 5 but act more or lass jointly and in respect of several parameters. When acid-sensitive fill-srs, for example calcium carbonate, are used, it is important that the sising agent and the retention system do not produce an acidic aqueous suspension as this causes a decomposition of the 10 carbonate and foams- Products, and calcium carbonate in particular, are frequently coated onto the sheet of paper. A portion of the coated paper can also be recycled to the start of the manufacturing process? before the formation of the sheet, 15 thereby carrying carbonate into the suspension before the papermaking machine, even if fillers other than carbonate have been introduced into the suspension. For this reason, it is preferable to use sizing agents and retention systems which do not lead to an acidic suspension; this is referred 20 to as sizing in neutral medium The article "Papermaking Additives", pages 803 to 825, volume 16, of KIRK—OTBHER, 3rd edition, ed John Wiley 1981, describes (pages 811-812) sizing agents of the dimeric alkvlketene family which may be used in neutral medium, but 25 does not specify the retention system.

JP-&-031P519 of 21st February 1985 refers to sising in neutral medium. The filler is calcium carbonate, and aluminium polychloride and a high molecular weight retention t agent are added.

GB-A-2,015,614 describes processes for ^ manufacturing paper and cardboard in which a basic aluminium polychlorosulphate is added to the suspension before the formation of the sheet. However, either sizing is omitted, or colophony is used, and it is known that colophony must be used in acidic medium: see KIRK-OTHMER already cited, page 10 810.

A process for manufacturing paper has now been found, according to the present invention, characterised in that the following are added to the suspension containing the cellulose fibres, before the formation of the paper sheets 15 a) an inorganic filler, b) a sizing agent which is chosen from dimeric alkylketenes and/or derivatives thereof, and/or anhydrides of carboxylic acids containing a fatty chain, c) cationic starch, and d) aluminium polychloride.

The suspension containing the cellulose fibres can be raw or bleached pulp, or a mixture of raw pulp and bleached pulp, or a pulp already containing additives.

The nature of the inorganic filler is not critical 25 but is preferably clay, calcium carbonate, silica, hydrated i alumina, talc or titanium dioxide.

These products are desirably introduced into the suspension in finely divided form, or in the form of a paste or solution. It is preferable to use calcium carbonate- The calcium carbonate can be introduced in any quantity, but is generally at most 40 parts, and preferably from 10 to 25, per 5 100 parts of cellulose fibres. This quantity does not take into account the fillers present in the paper that is recycled to the input of the manufacturing process, in the suspension.

The sizing agent is one or more dimeric 10 alkylketenes and/or their derivatives, and/or anhydrides of fatty-chain carboxylic acids. It is preferable to use a sizing agent which is employed in neutral medium. The quantity to be used depends on the properties desired in the paper. Advantageously, the quantity does not exceed 10 15 parts, and is preferably 0.1 to 2 parts, per 100 parts of cellulose fibres.

The cationic starch is usually a mixture of one or more products marketed under the generic name of "cationic starch". These products include those described in KIRK-20 OTHMER, 3rd edition, vol. 21 page 503. The quantity is advantageously not more than 5 parts per 100 parts of cellulose fibres, and preferably less than 2.

The term "aluminium polychloride", as used herein? denotes the products that are customarily referred to as "aluminium polychloride", "basic aluminium polychloride" and 5 "basic aluminium polychlorosulphate", and is preferably one or more of the following products? 1/ the salts of formula: Al (OH) CI, (I) n m j n — jti in %;hich m and n are positive integers, n having any value 10 and 3n-m being positive; such salts can contain? in addition, a polyvalent anion Y, e.g. an anion of sulphuricp phosphoric, polyphosphoric, silicic, chromic,, carboxylic or sulphonic acid, the mole ratio Y;Al preferably being from 0=015:1 to 0.4:1; 2/ the salts of formula: (II) in which k, m and n are positive integers, 3n > m + 2k,, the basicity sn/3n is front 0.3 to 0.7 and k/n = 0„01 to 0.3.

This product may be prepared according to the process 20 described in US-A.-3 „ 929 f 666 ,• 3/ the salts of formula: [Al (OH) , CI,(SO,)d] s (III) n 3 n — sa — 2 p ra 45 p in which k, m, n and p are integers and z is at least 1 such that (3n-m-2p)/3n = 0.4 to 0.7; p ™ 0.04 to 025n ; m/p « 8 5 to 35. These products are described in GB-a-2,128,977; and 4/ basic aluminium chlorosulphates of formula: ',Cl3„-.-2» IIV) in which the basicity or the mole ratio m x 100 is 3n from approximately 40% to 65% and which has an Al 10 equivalent/Cl equivalent ratio of from 2.8 to 5„ and an apparent molecular mass AM, measured by conventional light scattering, and apparent hydrodvnamic diameters 0Z and 0W, measured by quasi-elastic light scattering, of the following values: AM 35000 0Z o (A) 2500 0M O (A) 1200 These products are described in French Patent 2,584,699.

The quantity of aluminium polychloridet, expressed as 20 Al203, to be used is advantageously not more than 0.5 part, and is preferably from 0.05 to 0.2 partsP per 100 parts of cellulose fibres.

The products a to d can be added separately or as a , mixture, or partially mixed and in anv order. Kowever„ it P is preferable to add the aluminium polychloride after the others. It is also preferable that the aluminium 5 polychoride be added at a point as close as possible to the flow box. The cationic starch and the aluminium polychloride are not normally described as a retention system; as stated above, it is believed that all products added to the suspension before the formation of the sheet of 10 paper act together. The present invention consists in adding the products a to d to the suspension, and we have found that the joint use of these products has many advantages. The present invention is especially useful for manufacturing paper sized in neutral medium. The process of 15 the present invention enables the paper to be charged with acid-sensitive products such as calcium carbonate.

Another advantage of the invention is good retention of the fillers., and consequently a large decrease in the suspended matter in the water obtained during the formation 20 of the sheet.

Another advantage of the invention is greater productivity of the papermaking machine and better internal cohesion.

Other products,, such as colorants and agents for 25 mechanical strengthening of the sheet,, can also be added to ^ the suspension of cellulose fibres before the formation of the sheet.

According to another embodiment of the invention,, it is also possible to add, in addition to the products a to d, one or more polyacryl amides, poly (ethyleniraines), carboxymethylcellulose, urea-formaldehyde resins,, melaaine-formaldehyde resins, aminopolyamide-epichlorohydrin resins and polyamide-epichlorohydrin resins. Advantageously, these products are used in addition to cationic starch and in the same quantities.

The following Examples further illustrate the present invention; EXAMPLE 1 (not according to the invention) Manufacture of a paper for printing and writing, designed to be coated.

Composition of the aqueous suspension, before the formation of the sheet, referred to as the "flow box composition": Fibres bleached chemical pulp = recycled coated 60 parts paper CaC03 parts Fillers parts Sizing agents dimeric alkyl- ketene 0.15 part Operating characteristics of the machines Wire mesh, useful web width 3.5 m Basic weight of the paper: 180 g/m2 Nature of the paper: coating base pape r, followed by surface applicat ion of dextrinized or enzyae~ treated er oxidized starch by press.

Cationic starch CO-3 part for 100 parts of fibre and 420 a/tonne of fibres of poly(ethylenioine) are added.

A production rate of 207 m/sin, a 772 retention of the fillers arad a 92% total retention are obtained™ The internal cohesion, measured by the so-called "pendulum" apparatus, is 87„ The pendulum apparatus used is the INTERNAL BOND IMPACT TESTER H0DEL B supplied fey GCA/PRECISX0N SCIENTIFIC, 373? W_ Cortland Street, CH1CAGO, USA» The pH of the suspension during the formation of the sheet is 7.4„ The suspended scatter £SM5 in the clarified back-Mater Is 170 mg/U EXAMPLE 2 Caccording to the invention) Tine procedure is as in E xaeap le 1 but, instead of polyCethyleni*ine), an aluminium polychloride oi formula (II) Is added in the proportion of 0.1 part (expressed as MgDjS for 100 parts ef cellulose fibres.

A product ion rate ef 221 m/min, an 86* retention of the fillers and a 95.5% total retention are then obtained.

The internal cohesion becomes 110, the SS in the clarified backwater 100 mg/l and the pH in the flow box V Despite its acidic nature, alueiniuB polychloride keeps the medium in the pH region that is conpat ible with J the use of calc iua carbonate. It brings about a gain in the total retention of 3.5 po int$, and in the retention 5 of the fillers of 9 points- The machine speed could be increased by IX. The content of suspended natter in the water under the cloth decreased markedly. A gain in internal cohesion is noted.

EXAMPLE 3 (not according to the invention) 10 Flow box cssipos i i i on: fibres : bleached chemical pulp : 69 parts bleached nechanical pulp : 15 parts Filters : CaC©3 : 16 parts Size : dluetic alkyt- ketene : 0.10 part Operat ing characteristics of the machine: &ouble cloth, useful seb width 2«7 ■ 2 Basis weight s 60 g/m ■ Nature of the papers offset printing fallowed by surface application ©f starch by press. 0.4 part of cationic starch for 100 parts of .) fibres and 400 g/tonne of fibres of poll yacryt amide of 7 molecular weight above 10' are addled.

The following are ©htairaed;; A machine speed : 502 na/®n Total retention : 55., IX Retention of the fillers: 36.4% pH (in the flow box) : ?_6 EXAMPLE 4 (according to the invent ■ion) The procedure is as in Example 3 but, instead of polyacrylanide, aluminiua polychloride of foraula (IS) is used ir? the proportion of 0.1 part^ expressed as AI2O3, for 100 parts of fibres- TEie following are obtained: Hach ine speed : S28 n/nn Total retention : 57% Retention of the fillers: 401 pH I in t he flow box 5 : ?.6 EXAMPLE S (not according to the inventions Flow boss composition: Fibres : bleached cheaical pylps 85 parts Fillers s CaC©3 : 15 parts Size : anhydride of fatty-chain carboxylic acid 0-2 part Operafcing characteristics of the nachine: Mire aesh, useful web widths 2.6 ■ 2 Basis weight : SO g/a H a t u r e ©f the paper : reprography Coating by surface application of starch fey press 0.5 part of cationic starch for 100 parts of fibres and 500 g p©ILyacryla«ide/t of fibres are added™ The following are obta ined: Machine speed s 495 n/ran Total retention - 73*5% Retention of the f i HI® rs : 42 . SS S l»H (in flow box) : 7.S EXAMPLE 6 ^according to the invention) The procedure is as in ExaejptLe 5but less poly ac ryI am i de is i nt reduced, 100 g/1 instead of 500 g/1, and an aluniniusj polychlor ide of formula "(IIS is added in the 10 proportion of 0.1 part,, expressed as A12^3^ for parts of fibres.

The following results are obtained: Machine speedl ; 501 sa/esn Total retention : 81% Retention of the fillers: 48S pH Cin flow bos) : 7.8

Claims

- 14 -CLAIMS

1. Process for manufacturing paper, in which the following are incorporated in the suspension containing the cellulose fibres, before the formation of the paper 5 sheet: (a) an inorganic filler, (b) a sizing agent which is chosen from dimeric alkylketenes and/or derivatives thereof, and/or anhydrides of carboxylic acids containing a fatty chain, 10 (c) cationic starch, and (d) aluminium polychloride (as hereinbefore defined).

2. Process according to claim 1, in which (d) is a basic aluminium polychlorosulphate. 15

3. Process according to claim 1 or 2, in which (a) is calcium carbonate.

4. Process according to any one of claims 1 to 3, in which not more than 4 0 parts of (a) are incorporated per 100 parts of cellulose fibres. 20

5. Process according to claim 4, in which from 10 to 25 parts of (a) are incorporated.

6. Process according to any one of claims 1 to 5, in which not more than 10 parts of (b) are incorporated per 100 parts of cellulose fibres. 2 5

7. Process according to claim 6 in which 0.1 to 2 parts of (b) are incorporated.

8. Process according to any one of claims 1 to - 15 - 7, in which not more than 5 parts of (c) are incorporated per 100 parts of cellulose fibres.

9. Process according to claim 8, in which not more than 2 parts of (c) are incorporated. 5

10. Process according to any one of claims 1 to 9, in which not more than 0.5 parts of (d), expressed as A1203, are incorporated per 100 parts of cellulose fibres.

11. Process according to claim 10 in which 0.05 to 0.2 parts of (d), expressed as A1203, are incorporated. 10

12. Process according to any one of claims 1 to 11, in which at least one polyacrylamide, poly-(ethylenimine) , carboxymethylcellulose, urea-formaldehyde resin, melamine-formaldehyde resin, aminopolyamide-epichlorohydrin resin or polyamide-epichlorohydrin resin is 15 also incorporated.

13. Process according to any one of the preceding claims in which (d) is incorporated after (a), (b) and (c).

14. Process according to claim 1 substantially 20 as described in any one of Examples 2, 4 and 6.

15. Paper whenever manufactured by a process as claimed in any one of the preceding claims. F. R. KELLY & CO., AGENTS FOR THE APPLICANTS. J