IE60052B1

IE60052B1 - Improvement to processes for manufacture paper

Info

Publication number: IE60052B1
Application number: IE84288A
Authority: IE
Original assignee: Atochem
Priority date: 1987-03-23
Filing date: 1988-03-22
Publication date: 1994-05-18
Also published as: ATE73184T1; FI881369A0; FI94972C; IE880842L; CA1312708C; JPS63256796A; NO881029L; DK154788D0; DE3868659D1; DK154788A; PT87044A; EP0285487B1; NO173887B; FR2612961A1; ES2029522T3; PT87044B; FR2612961B1; NO173887C; NO881029D0; FI94972B

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

The present invention relates to an improvement to processes for manufacturing paper. f Raw paper pulp, consisting essentially of cellulose fibres, is made into a dilute aqueous suspension which is carried to the flow box of the papermaking machine, 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 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 ©nd titanium dioxide are added. These fillers make the sheet of JO paper opaque, thereby facilitating writing and printing. A sizing agent can also be added in order to make the sheet resistant to liquids, that is to say, the sized sheet of paper may be used for writing and printing. It is also necessary to add a retention system, which orecioirates the r sizing agent on the cellulose fibres and enables the 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, and the like, are also added.

All these products do not have a well specified action in respect of a single characteristic of the paper, but act more or less jointly and in respect of several parameters, when acid-sensitive fillers, for example calcium carbonate, are used, it is important that the sizing agent and the retention system do not produce an acidic aqueous suspension as this causes a decomposition of the 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, 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 to as sizing in neutral medium.

The article ’Papermaking Additives, pages 803 to 825, volume 16, of XIRK-OTHHBR, 3rd edition, ed John Wiley 1981, describes (pages 811-812) sizing agents of the dimeric alkylketene family which may be used in neutral medium, but does not specify the retention system.

JP-A-031,519 of 21st February 1985 refers to sizing in neutral medium. The filler is calcium carbonate, and aluminium polychloride and a high molecular weight retention 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 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 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, 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 but is preferably clay, calcium carbonate, silica, hydrated ί 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 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 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 KIRK20 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 basic aluminium polychlorosulphate, and is preferably one or more of the following products: 1/ the salts of formula: Al (OH) Cl, n ' m 3 n - m (I) in which m and n are positive integers, n having any value and 3n-m being positive; such salts can contain, in addition, a polyvalent anion Y, e.g. an anion of sulphuric, 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: Al (OH) Cl, m ,. n ' ia 3 n - 01- 2 k (SO,) (II) in which k, m and n are positive integers, 3n > m - 2k, the basicity m/3n is from 0.3 to 0.7 and k/n = 0.01 to 0.3.

This product may be prepared according to the process described in US-A-3,929,666; 3/ the salts of formula: !Al.’0H>3. — 2Pcl.(s°<’pl 2 The quantity of aluminium polychloride, expressed as Al2O3, to be used is advantageously not more than 0.5 part, and is preferably from 0.05 to 0.2 parts, per 100 parts of cellulose fibres.

The products a to d can be added separately or as a mixture, or partially mixed and in any order. However, it is preferable to add the aluminium polychloride after the others. It is also preferable that the aluminium 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 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 the present invention enables the paper to be charged with acid-sensitive produets 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 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 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 polyacrylamides, poly(ethylenimines), carboxymethylcellulose, urea-formaldehyde resins, melamineformaldehyde 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 parts ~ recvcled coated paper Fillers ··= CaCO3 Sizing agents ~ dimeric alkylketene parts 20 parts 0.15 part Operating characteristics of the machine: Wire mesh, useful web width 3.5 m Basic weight of the paper: 180 g/m2 Nature of the paper: coating base paper, followed by surface application of dextrinized or enzyae~ treated er oxidized starch by press» Cationic starch £0-3 part for WO parts of fibres) and 420 §7 tonne ibres of loo ly Cethylen iss ine) are added» A production rate of 207 e/siii, a 77S retention e fillers and a 92S total retention are obtained» ;e-e of Th® internal cohesion, Measured by ’’pendulum apparatus, is 87» Th® pendulua apparatus used is the INTERNAL BOND IMPACT TESTER MODEL B supplied by 6CA/PRECISI0N SCIENTIFIC, 3737 W. Cortland Street, CHICAGO, MSA» The pH of th® suspension during the formation of the sheet is 7»4,., The suspended Matter CSS) in the clarified backwater is 170 «g/l.

EXAMPLE 2 (according to the invention) The procedure is as in Example 1 but, instead of pelyCethylenixine), sn alueiniu· polychloride of formula Cil) is added in the proportion of (3.1 part (expressed as AlgISj) for 100 parts of cellulose fibres» Λ productiem rate of 221 /io, an S«SX retention of the fillers and a 95·5Χ total retention are then obtained.

Tbe internal cohesion becomes 110, the SH in the clarified backwater 100 eg/l and the pH in tbe flow box 7.3. - 11 Despite its acidic nature^ aluminium polychloride keeps the medium in the pH region that is compatible with th® use of calcium carbonate. It brings about a gain in the total retention of 3.5 points^ and in the retention of the fillers of 9 points. The machine speed could be increased by TX. The content of suspended matter in the water under the cloth decreased ear feed I y., A gain in internal cohesion is noted.

EXAMPLE 3 (not according to the invention) Flow box coBipos i t ions bleached chemical Fillers Size s 09 parts bleached mechanical pulp ϊ 15 parts ; CaiC©3 : 1-5 parts : dimeric alkylketene : 0.10 Operating characteristics of the machine: Bouble eleth^ useful web width 2.7 par Basis wei? 6C g/i Nature of th® papers offset printing followed 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 [Polyacrylamide of T molecular w©ight above W are The following are obtained:; A machine speed : 502 ns/mn Total retention ; 55.,IX Retention of the fillers; 36.4S pH (in the flow box) : 7.6 EXAMPLE 4 (according to the invention) The procedure is as in Exaaple 3 but, instead of polyacrylamide, aluminium polychloride ef formula (IS) is used in the proportion of 0.1 part, expressed as AlpOjj, for 100 parts of fibres.

The following are obtained; Machine speed 528 l®Zen Total retention : 57X Retention of the fillers: 4GX pH (in the flow box) ; 7.6 EXAMPLE 5 (net according to th® Invention) Flew box composition: Fibres : bleached e he·1s aI palps ®5 parts Fillers : CaCOj ϊ 115 parts $>Ize ; anhydride ef fatty-chain carboxylic aeid 0.2 part ©perat ing character I st I es of the machines Wire iiiesih, useful web widths 2.6 Basis weight : 80 g/m Mature ef the paper : reprography Coating by surface applIcation of starch by press. 0.3 part of cationic starch for TOO parts of fibres and 300 g polyacrylamide/t of fibres are added.

The following are obtained: Machine speed s 495 μ/βπ Total retention : 73.5* Retention of the fillers: 42„52 S e»H (in flow box) : 7.® EXAMPLE ά (according to the invention) The procedure is as in Exanple 5, but less polyacrylamide is introduced, 100 g/t instead of 300 g/1, and an aluminium polychloride of formula ’€ II > is added in the proportion of 0.1 part, expressed as AI2O3, for 100 parts of fibres.

The following results are obtained: Machine speed : 501 sa/mn Total retention : 81X Retention of the fillers: 4SX pH (in flow box) : 7.8

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 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, (c) cationic starch, and (d) aluminium polychloride (as hereinbefore defined).

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

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 40 parts of (a) are incorporated per 100 parts of cellulose fibres.

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.

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 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.

10. Process according to any one of claims 1 to 9, in which not more than 0.5 parts of (d), expressed as A1 2 O 3 , 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 A1 2 O 3 , are incorporated.

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, aminopolyamideepichlorohydrin resin or polyamide-epichlorohydrin resin is 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 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.