GB2186895A

GB2186895A - Pitch control aid

Info

Publication number: GB2186895A
Application number: GB08600506A
Authority: GB
Inventors: Thord Gustav Gunnar Hassler
Original assignee: WR Grace AB
Current assignee: WR Grace AB
Priority date: 1986-01-09
Filing date: 1986-01-09
Publication date: 1987-08-26
Also published as: FI88814B; FI870072A0; ATE59068T1; EP0232015A1; GB2186895B; FI88814C; FI870072L; ES2019376B3; GB8600506D0; JPH07113200B2; EP0232015B1; CA1306570C; JPS62223394A; DE3766623D1

Abstract

A method for the control of pitch in an aqueous system used in pulp or paper making is disclosed which comprises adding to the system, or to the pulp making or paper making machinery, a water soluble polymer derived from (a) an epihalohydrin, a diepoxide or a precursor of an epihalohydrin or diepoxide, (b) an alkyl amine having a functionality with respect to an epihalohydrin of 2 and (c) an amine which has a functionality with respect to an epihalohydrin greater than 2 and which does not possess any carbonyl groups.

Description

GB2186895A 1

SPECIFICATION

Pitch control aid This invention relates to the control of pitch in the manufacture of pulp and paper. 5 It is well known that---pitch-can accumulate in paper making and also in the manufacture of pulp, causing significant problems.---Pitch-is the term used to describe the sticky materials which appear in paper making; these originate from the wood from which the paper is made.

However, nowadays when more recycled paper is used,---pitch-is now used as a general term for all material soluble in organic solvents but not soluble in water, for example the ink or 10 adhesive present in recycled paper. The pitch can accumulate at various points in the system.

For example, it can block the felt and thus hinder drainage of the paper web. In addition, it can adhere to the wires or drying cylinders causing it to pick holes in the paper. Deposits may also build up at any earlier stage in the papermaking process. When these deposits break loose they may form a defect in the paper such as a spot or a hole. Such defects may even create a 15 weakness in the paper sufficient to induce a breakage in the paper during the producti,on resulting in unappreciated production down-time.

Many materials have been used in an attempt to eliminate these problems. Such materials include inorganic treatments such as talc and anionic dispersants. However, conventional disper sants can be ineffective in a closed system as there can be a build-up of -pitch-. In such 20 systems the pitch particles have to be removed from the water system in a controlled way without being allowed to accumulate on the felt or rolls or, for example, the pipe work used in the paper making machinery. These products have also been found to give a limited effect and there is a need for further improved treatments.

It has now been found, according to the present invention, that certain water soluble poly- 25 quaternary amines are particularly effective for this purpose. Accordingly, the present invention provides a method for the control of pitch in an aqueous system used in pulp or paper making which comprises adding to the system or to the pulp making or paper making machinery, a water soluble polymer derived from (a) an epihalohydrin, a diepoxide or a precursor of an epihalohydrin or diepoxide, (b) an alkyl amine having a functionality with respect to an epihalohy- 30 drin of two, and (c) an amine which has a functionality with respct to an epihalohydrin greater than two.

A special feature of the products used in the present invention is that they may combine with dissolved anionic material originating from the wood from which the pulp and paper is produced, providing a method of removing these anionic materials thereby lowering the concentration of 35 such materials in the process water.

Component (a) is preferably an epihalohydrin, especially epichlorohydrin or epibromohydrin, but dihalohydrins, preferably dichlorohydrins or dibromohydrins, having three to twenty, especially three to ten, carbon atoms per molecule may also be used. Typically dihalohydrins which may be used include the following: 40 CH,CICHCICH20H CH2CICH,(01-1)CH2C1 CH3CHCICHCICH20H CH3CI-ICICH(O1-1)CH2C1 45 CH,CH2CHCICHCICH20H CH,Cl-ICICHOCH(OffiCH3 CH,Cl-1,Cl-iCICH(O1-1)C1 CH3CH,CH(OH)CHCICH2C' CH3CHOCH(O1-1)CI-ICICH3 50 CH3 1 CH3CCI-ICICH2C1 1 55 OH CH3 1 CH2CICCHCICH3 and 60 1 OH 2 GB 2 186 895A 2 CH3 1 CH,(OH)C-CHCICH, 1 cl 5 As regards component (b) the alkyl amine may be a compound possessing two tertiary amino groups such as N,N,N',N-tetramethyleneethylenediamine. Details of the preparation of products derived from such component (b) and component (a) can be found in UK-A-1 486 396. However, component (b) is preferably a dialkylamine in which the alkyl groups individually contain one to 10 three atoms. Dimethylamine is especially preferred.

As previously indicated, component (c) is an amine which possesses a functionality greater than two with respect to epihalohydrin; it can therefore act as a branching agent. A primary amino group is capable of reacting with three molecules of epihalohydrin so that a simple primary amine possesses a functionality of three. Likewise, a simple secondary amine will 15 possess a functionality of two and a simple tertiary amine a functionality of one. Accordingly, component (c) is typically ammonia, a primary amine, a primary alkylene polyamine having four to twenty-five, preferably four to twelve, carbon atoms and at least one, preferably one to six, primary amino groups per molecule including polyglycolamines as well as ariomatic and heteroar omatic diamines and polyamine-polybasic acid condensation products. Preferred materials include 20 ammonia, diethylaminobutylamine, dimethylaminopropylamine and ethylenediamine, the latter two being especially preferred.

If desired, the polymer may also be derived from a further component which generally has the ability to act as a---end-capping- agent. In general, these materials will also be amines or other material having reactivity towards epichlorohydrin and which also possess some other functional 25 group and which possess a functionality less than two, such as a simple tertiary amine such as a trialkylamine, especially trimethylamine or a hydroxyalkylamine, typically triethanolamine.

The polymers used in the present invention may be prepared by first reacting components (a) and (b) to obtain a -coupling agent- and then reacting this with component (c) and, if desired, the fourth component. Preferred polymers for use in the present invention include those in which 30 the coupling agent is derived from epichlorohydrin and dimethylamine, which is subsequently reacted with ethylenediamine or octadecylamine and, if desired, also with trimethylamine or triethanolamine.

The polymers may also be prepared by reacting a mixture of components (b) and (c) with component (a). The preferred raw materials for such a process are the same as those given 35 above.

In general, the reaction is carried out in an aqueous medium, typically maintaining the reaction temperature at 5 to 125'C, preferably 30 to 95'C. The equivalent ratio of component (b) to component (c) is suitably 1:0.009 to 1.0 and preferably 1:0.02 to 0.5 while the equivalent ratio of component (a) to components (b) and (c) may vary widely depending on the amount and 40 nature of component (b). Generally, the ratio of component (c) to component (a) and component (b), together should be selected so that the viscosity of the aqueous polymer solution is at least Cps at 50% dry content. Typically, the ratio is from 1:0.22 to 2.5 and preferably 1:0.25 to 1.3. In general, the reaction can be continued until the desired viscosity, and therefore molecular weight, has been achieved although acid can be used to reduce the pH and thereby terminate 45 the reaction. A pH of 1 to 7.5, especially 2 to 6.5, is generally preferred for the final solution.

The upper viscosity limit is not critical provided it is consistent with having a workable solution; the upper limit is normally about 2000 Cps.

Further details regarding the polymers which can be used and their preparation is to be found in, inter alia, UK-A-2 085 433, US-A-3 855 299 and US Patent Re-Issue 28 808 and, for certain 50 polymers, in -Polyelectrolytes for Water and Wastewater Treatment-, ed W L K Schwoyer, CRC Press Inc, pages 26-35. A particularly preferred polymer for use in the present invention is formed by reacting ethylenediamine with a precondensate of dimethylamine and epichlorohydrin, and reacting the product with triethanolamine to form a water-soluble reaction product. Another preferred product is formed by reacting a mixture of dimethylamine and ethylenediamine or 55 dimethylaminopropyla mine with epichlorohydrin to form a water-soluble reaction product.

The polymer is generally added to the aqueous system with the furnish containing the paper pulp but it is possible to add it at different points in the system depending on the precise nature of the problem.

The amount of polymer required will, of course, depend to some extent on the nature of the 60 wood or other material used to prepare the paper pulp. Also, some polymer once added will tend to recirculate in the system thus requiring a lower addition rate. In general, however, from 0.1 to 20 ppm of polymer by weight based on the aqueous medium is suitable. Preferably, the amount is 1 to 10 plam. This corresponds in the normal case to an addition of 10 to 2,000 grams, preferably 100 to 1,000 grams, polymer per tonne fibre. 65 3 GB2186895A 3 Sometimes it can be preferred to spray the reaction product used in this invention onto a particular part of the pulp- or paper-making machinery such as the wire or press felts. In such cases, the polymer is preferably pre-diluted with water, generally to a concentration below 10% by weight and preferably 1 to 5% by weight.

In some instances, it will be convenient to add the polymer together with a biocide. Examples 5 of suitable biocides include those in the following classes:

(i) a substituted 5- or 6-membered ring heterocyclic compound in which the heterc, atom or atoms are one or more of nitrogen, oxygen or sulphur and the substituent is an alkyl group, a keto group or a hydroxyl group or a halogen atom, such compounds include isothiazolones, and in particular, those having the formula: 10 wherein R represents hydrogen or chlorine. A blend of these two isothiazolones is commercially available, the weight ratio of the chloro-sub-stituted compound to the unsubstituted compound being about 2.66: 1; 20 (ii) a phenol or chlorinated phenol such as pentachlorophenol; (iii) an amine or amide including 2,2-dibromo-3-nitrilopropionamide; (iv) an organic cyanide or thiocyanate, particularly methylene bis(thiocyanates); (v) a sulphone including halosulphones, particularly hexachlorodimethyisulphone; (vi) a straight chain aliphatic aldehyde, particularly glutaraldehyde; 25 (vii) a triazine, particularly thio and/or amino-substituted alkyl triazines; (viii) bis bromo acetoxy butene; and (ix) a dithioca rba mate, especially the monomethyl, dimethyl, monoethyl and diethyl derivatives, typically in the form of sodium salts.

The polymer is generally compatible with the usual pulp and paper making additives including 30 starch, for example potato or corn starch, titanium dioxide, a defoamer such as a fatty acid alcohol, a size, for example a rosin size based on abietic acid, a neutral size based on alkyl ketene dimer or a succinic acid anhydride based size and a wet strength resin such as, if neutral, an epichlorohydrin polyamide or, if acid, a melamineor urea- formaldehyde resin.

The precise nature of the pH of the system is unimportant since the effectiveness of the 35 polymer is substantially unaffected by changes in pH.

Some of the polymers used in the present invention are commercially available, typically as aqueous solutions containing a concentration of 40 to 50% per cent. Typically, the compositions used in the present invention will possess from 1 to 70%, especially 10 to 30%, by weight of the polymer. 40 The following examples further illustrate the present invention.

EXAMPLE 1

Into a reaction flask fitted with reflux condenser, mechanical stirrer and thermometer were placed 183.5 g of 32.7% dimethylamine and 270g of water. 76.04 g of 36% hydrochloric acid 45 was added while maintaining a temperature maximum of 3WC by cooling. 208. 12 g epichlorohy drin was added during 30 minutes. Cooling was applied to keep the temperature not above 4WC. This temperature was maintained for two hours to produce a stock solution of so-called 1 coupling agent---. 176.9 9 of the aqueous solution of the coupling agent was, using the same equipment, heated to WC. 5.94 g of ethylenediamine was added dropwise over a 30 minute 50 period. The temperature was then kept at WC for one hour. The reaction mixture was heated to WC and 32.48 g of 30% trimethylamine was added during ten minutes; WC was then maintained for two hours and the reaction mixture cooled to room temperature. This reaction mixture had a total solids content of 40.7%.

55 EXAMPLE 2

Using the equipment described in Example 1, 25.35 9 of 36% hydrochloric acid was added to a mixture of 68.81 9 of 32.7% dimethylamine solution and 121.4 9 water. The temperature was kept below WC by cooling. 83.25 9 epichlorohydrin was added at such a rate that temperature was maintained at 4WC. This temperature was then kept for one hour. The reaction mixture was 60 heated to WC and 7.5 9 ethylene diamine was added over 15 minutes while maintaining the temperature at WC. This temperature was kept for another 30 minutes. The reaction mixture was heated to WC and 37.25 9 triethanolamine was added dropwise over 30 minutes. This temperature was maintained for a further two hours to complete the reaction. The total solids content was 44.6%. 65 4 GB2186895A 4 EXAMPLE 3

The products prepared in Examples 1 and 2 were evaluated using essentially the method described in 1977 TAPPI paper makers Conference p 23-32 by Ch E Farley. This method is built on TAPPI Standard Method RC324 which is a recognised method for evaluating depositabil- 5 ity of pitch. The standard pitch solution was prepared as described in the above references. A synthetic pitch emulsion/dispersion was prepared by adding one litre volume of deionised water at WC to the synthetic pitch to reach a 1200 ppm concentration.

A solution of calcium chloride was added to reach a hardness of 340 ppm expressed as calcium carbonate. The pH was adjusted to 8.0. To evaluate the products as pitch control 10 agents, the products were added to obtain a concentration of polymer as specified in Table 1.

The depositability of the pitch was evaluated according to the procedure in the above refer ences. The test duration was always five minutes. The results are presented in Table 1 (mg deposited pitch).

15 TABLE 1

PRODUCT CONCENTRATION (PPM) DEPOSITED PITCH (MG) Blank - 280 20 Example 1 2 252 Example 1 10 2 Example 2 2 255 Example 2 10 28 25 COMPARATIVE EXAMPLE 1 An aminoplast resin was prepared essentially according to Example Ill in US Patent 3 582 461 for comparison.

84 9 (1 mole) of dicyandiamide, 196 (2.4 moles) of 37% by weight inhibited aqueous 30 formaldehyde solution, 126 g (mole) of 85% active formic acid were charged into a 1 litre four neck flask equipped with an agitator, thermometer and condenser. The mixture was agitated for 0.5 hours at room temperature. External heat was applied to the reaction mixture and the mixture was heated to WC over a 0.5 hour period. The reaction temperature was gradually raised from WC to the boiling point of the mixture. The exothermic reaction, which occurred 35 when the temperature was raised above WC, was controlled by intermittent cooling. The boiling point of the reaction mixture was reached after three hours heating. The mixture was boiled for 15 minutes and then coled rapidly to WC. 42 9 of methanol was added to etherify free methylol groups and the mixture was agitated for 2.5 hours and then cooled to 2WC. The resulting reaction product was a water soluble dicyandiamide-formaidehyde condensate in the 40 form of a clear water soluble syrup containing 40% by weight solids.

This resin was evaluated according to procedure in Example 3 with the following results.

Concentration (ppm) Deposit (mg) Blank 299 45 2 ppm 293 ppm 80 COMPARATIVE EXAMPLE 2 Some other products with potential as pitch control agents were evaluated following the 50 procedure of Example 3 with the following results.

Product Concentration Deposit (mg) 55 Blank - 299 Polyacrylate 100 ppm 212 Cationic starch 100 ppm 94 Paper makers' alum 100 ppm 41 60 EXAMPLE 4

To a mixture of 68.81 9 of 32.7% dimethylamine and 121.4 9 water was added 25.35 g of 36% hydrochloric acid dropwise over 30 minutes. The temperature of the reaction mixture was not allowed to exceed WC; some cooling was required. 83.25 g of epichlorohydrin was added 65 GB2186895A 5 at such a rate that the temperature of the reaction mixture was maintained at 4WC. After the exothermic reaction was completed the solution was maintained at 4WC until it became clear (1 hour). After heating to WC, 7.5 g of ethylenediamine was added quickly over 5 minutes. The reaction mixture was maintained at WC for a further hour. The reaction mixture was then cooled to room temperature. To 97.42 g of this solution was added 22.56 g octadecylamine (2 5 moles) and 7.5 9 2-methoxy ethanol. This slurry was slowly heated to 7WC and maintained at this temperature for 30 minutes. Further heating to 7WC produced a highly exothermic reaction which required external cooling to maintain a temperature of 7WC. After completion of the exothermic reaction, the mixture was heated at 90C for 2 hours. The product, which was in the form of a creamy emulsion, had a total solid content of 18%. 10 EXAMPLE 5

The product of Example 4 was evaluated using the method described in Example 3, but a different synthetic pitch was used. This time a pitch solution was made by adding a mixture of 2.0 g tall oil and 20.0 g glycerol ester of rosin to 10.5 g 5% potassium hydroxide to form an 15 emulsion. This was then diluted with 187.5 9 isopropanol and 110 g acetone to form a clear pitch solution. 15 mi of this solution was added to one litre water at 2WC and a hardness of ppm expressed as calcium carbonate. The pH was adjusted to 3.0 using concentrated hydrochloric acid and the test was carried out over three minutes.

20 Concentration (ppm) Deposit (mg) Blank 250 2 72 3.5 23 7.5 Nil 25 COMPARATIVE EXAMPLE 3 Polydiallyl dimethyl ammonium chloride (poly DADMAC) is another poly quaternary resin sug gested at a pitch control agent, in European Patent Application 58 621. This resin was tested following the procedure in Example 5. 30 Concentration (ppm) Deposit (mg) 2 193 45 10 27 35 COMPARATIVE EXAMPLE 4 The preferred type of quaternary compound for control of pitch deposition in US-A-3 619 351 is a methyltriethanolamine. This material was synthesized from triethanolamine and dimethyl sulphate to form quaternary ammonium methyl triethanolamine monomethyl sulphate. This ma- 40 terial was evaluated using the procedure in Example 3 with the following results:

Concentration (ppm) Deposit (mg) Blank 130 10 ppm 166 45 ppm 102

Claims

1. A method for the control of pitch in an aqueous system used in pulp or paper making which comprises adding to the system, or to the pulp making or paper making machinery, a 50 water soluble polymer derived from (a) an epihalohydrin, a diepoxide or a precursor of an epihalohydrin or diepoxide, (b) an alkyl amine having a functionality with respect to an epihalohy drin of 2 and (c) an amine which has a functionality with respect to an epihalohydrin greater than 2.

2. A method according to claim 1 in which component (a) is epichlorohydrin or epibromohy- 55 drin.

3. A method according to claim 1 or 2 in which component (b) is a dialkyl amine in which the alkyl groups individually contain 1 to 3 carbon atoms.

4. A method according to claim 3 in which component (b) is dimethylamine.

5. A method according to any one of the preceding claims in which component (c) is a 60 primary amine or a primary alkylene polyamine.

6. A method according to claim 5 in which component (c) is diethylaminobutylamine, dime thyla m inopropyla mine or ethylene diamine.

7. A method according to any one of the preceding claims in which the polymer is also derived from a tertiary amine or a hydroxy alkyl amine. 65 6 GB2186895A 6

8. A method according to claim 7 in which the polymer is also derived from trimethyl amine or triethanol amine.

9. A method according to any one of the preceding claims in which the polymer is one formed by reacting ethylene diamine with a precondensate of dimethyl amine and epichlorohydrin and reacting the product with triethanolamine to form a water soluble reaction product. 5

10. A method according to any one of claims 1 to 8 in which the polymer is one formed by reacting a mixture of dimethylamine and ethylene diamine or dimethylamino propylamine with epichlorohydrin to form a water soluble reaction product.

11. A method according to any one of the preceding claims in which the polymer is added to the aqueous system with the furnish containing the paper pulp. 10

12. A method according to any one of claims 1 to 10 in which the polymer is sprayed onto at least a part of the pulp or paper making machinery.

13. A method according to any one of the preceding claims in which a biocide is also added to the aqueous system.

14. A method according to claim 1 substantially described in any one of Examples from 1 to 15 4.

15. A composition suitable for use in pulp or paper making which comprises a polymer as defined in any one of claims 1 to 10 and a biocide.

16. A composition according to claim 15 which contains 1 to 70% by weight of the polymer. 20

17. A composition according to claim 16 which contains 10 to 30% by weight of the polymer.

18. A composition according to claim 15 substantially as hereinbefore described.

Printed for Her Majesty's Stationery Office by Burgess & Son (Abingdon) Ltd, Dd 8991685, 1987.

Published at The Patent Office, 25 Southampton Buildings, London, WC2A 1 AY, from which copies may be obtained.

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