WO1999002577A1

WO1999002577A1 - Modified phenol-formaldehyde resin and process of making the same

Info

Publication number: WO1999002577A1
Application number: PCT/SE1998/001281
Authority: WO
Inventors: Stig Ohlsson
Original assignee: Perstorp AB
Current assignee: Perstorp AB
Priority date: 1997-07-07
Filing date: 1998-06-30
Publication date: 1999-01-21
Anticipated expiration: 2000-01-07
Also published as: SE509778C2; SE9702606D0; AU8362398A; SE9702606L

Abstract

Modified phenol-formaldehyde resin and a process of making said resin. the resin comprises cationic groups and has a cationicity of 2-95 %, preferably 15-60 %. The resin is suitably a modified resole made from a phenolic compound, such as a phenol, a cresole, an alkylphenol and/or a sulphur derivative thereof, and formaldehyde at a molar ratio of 1:1 to 1:3.5, a temperature of 40-100 °C and a pH exceeding ≈ 8. The process is carried out in an aqueous medium and in the presence of ammonia or an amine as combined catalyst and reactant, whereby anionic groups are introduced into the resin.

Description

MODIFIED PHENOL-FORMALDEHYDE RESIN AND PROCESS OF MAKING THE SAME

The present invention relates to a modified phenol-formaldehyde resin comprising cationic groups, and in a further aspect to a process of making said resin.

Phenol-formaldehyde resins, resoles as well as novolacs, are since the beginning of this century well known in the art. Phenolic resins are disclosed and discussed inter alia in Kirk-Othmer "Encyclopedia of Chemical Technology", vol. 17, 1982, pp. 384-416. Normally, phenol-formaldehyde resins do not comprise cationic groups. Said resins include for instance moulding compound resins, laminate resins, foundry resins and resins for coatings and glues as well as a large number of speciality applications as disclosed in for instance the Canadian Patent no. 1 ,044,782. Said Patent discloses the use of a combination of a phenol-formaldehyde resin and a polyethylene oxide for improved retention in dewatering of cellulose fibre slurries. Furthermore, the Swedish Patent Application no. 8604975-6 teaches improved filling retention in dewatering of cellulose fibre slurries by addition of a phenol-formaldehyde resins and a high molecular polyethylene oxide in combination with a cationic derivative of starch or cellulose. Improved filling retention is also known from the U.S. Patent no. 5,516,405, which teaches a method of improving the first pass filler retention of a papermaking pulp slurry. The method comprises adding an organic cationic fixative, a promoter and a polyethylene oxide to a filler containing slurry to increase the first pass retention of said filler. The organic fixative is selected from the group consisting of polyethylene amides, polydiallyl dimethylammonium chlorides and polyethylene imines and the promoter consists of for instance a phenol-formaldehyde resin.

Although improved retention is obtained by the use of a combination of phenol-formaldehyde resin and polyethylene oxide, the requirement for further improved retention is significant. The method of U.S. Patent no. 5,516,405 exemplifies the efforts of obtaining further improved retention. The addition of a cationic fixative implies, however, increased costs and decreased process accuracy due to for instance extensive analyses and calculations for determination of when, where and how much to add.

The present invention relates to a modified phenol-formaldehyde resin which can be used for instance in combination with polyethylene oxide to improve, compared to ordinary phenol-formaldehyde resins as discussed above, the retention in dewatering of cellulose fibre slurries.

It has through the present invention quite surprisingly been possible to obtain a modified phenol-formaldehyde resin fulfilling the requests for improved retention. The resin of the present invention is characterised in that it comprises cationic groups and that it has a cationicity of approximately 2-95%, such as 5-85% or preferably 15-60%.

The phenol-formaldehyde resin corresponds, besides the content of cationic groups, to ordinary phenol-formaldehyde resins used in retention systems within the papermaking and pulp industry. The resin is accordingly a condensation product obtained by subjecting at least one phenolic compound and formaldehyde to a condensation reaction. The resin of the present invention is preferably a resole, which is a reaction product between a phenolic compound and formaldehyde in excess. Novolacs can of course also be prepared and used. The resin is in suitable or preferred embodiments a water diluted or waterborne cationic phenol-formaldehyde resins.

The cationic groups in the phenol-formaldehyde resin of the invention can either be introduced during the condensation or by addition to a processed resin. The invention is not limited to any specific cationic group. The cationic group is, however, in preferred embodiments an amine group derived from ammonia or a primary, secondary or tertiary amine. The amine group can in certain embodiments be attached to the resin by means of a linking group. Preferred amines include for instance ethanolamine, «-propylamine, dibutylamine, triethylamine and diethylethanolamine.

The phenolic compound is in various embodiments a phenol, a cresol, an alkylphenol, such as nonylphenol, or a combination thereof. The phenolic compound can also suitably be a sulphur derivatised phenol, cresole, alkylphenol or a combination thereof, such as a pre-condensate between sulphur and for instance said phenol, cresole, alkylphenol or said combination thereof.

The cationicity is the ratio between the cationic groups and the anionic groups (phenolic groups). The latter is normally a part of the resin. A cationicity of 0% means that the phenol-formaldehyde resin only contains the normally present anionic phenolic groups and that it does not contain any cationic groups. The concentration of anionic phenolic groups can in many resins be exemplified by the figure « 24 μequivalents/g dry resin. A cationicity of 20% means that the concentration of cationic groups corresponds to 20% of the anionic groups, which using above figure corresponds to « 5 μequivalents/g dry resin. A cationicity of 35% accordingly corresponds to « 8 μequivalents/g dry resin. A suitable method for determination of cationicity is disclosed in "Charge Titration for Selection and Dosage of Flocculants" by Lydia Bley, published March 1994 in Miitek Application 1501 -e, Miitek Analytic GmbH, Germany.

In a further aspect, the present invention relates to a process of making a modified phenol-formaldehyde resin as disclosed above. The process comprises subjecting a number of monomers consisting of or comprising at least one phenolic compound and formaldehyde to a condensation reaction at a molar ratio phenolic compound to formaldehyde of 1 : 1 to 1 :3.5, preferably 1.2, at a reaction temperature of 40-100°C, preferably 50-90°C, at atmospheric or reduced pressure and at a pH exceeding « 8. The condensation reaction is performed in an aqueous medium in the presence of ammonia, a primary, secondary or tertiary amine or a mixture thereof as combined catalyst and reactant introducing cationic amino groups into the phenol-formaldehyde resin. The condensation reaction is, furthermore, maintained until a high molecular resin having a cationicity of 5-85%, preferably 15-60% is obtained. The condensation reaction is suitably maintained until all monomers are consumed. Obtained resin is subsequently treated with an aqueous solution of at least one alkali or alkaline earth metal hydroxide, such as sodium, potassium and/or calcium hydroxide, whereby a resin solution comprising a cationic phenol-formaldehyde resin, which resin at a pH of less than » 7 can be precipitated as small particles, is yielded. The formaldehyde is suitably employed as an aqueous solution having a formaldehyde content of 30-55% by weight. The phenolic compound is in various embodiments preferably a phenol, a cresol, an alkylphenol, such as nonylphenol, or a combination thereof. The phenolic compound can, furthermore, be a sulphur derivatised phenol, cresole, alkylphenol or a combination thereof, such as a pre-condensate between sulphur and for instance said phenol, cresole, alkylphenol or said combination thereof.

The process of the present invention can advantageously commence with a mixing and pre-heating of the phenol and the ammonia or amine, which mixing and pre-heating is followed by a gradual addition of the formaldehyde.

The ammonia or amine compound can in alternative embodiments of the process be mixed into a finished phenol-formaldehyde resin, thus providing a certain cationicity in said resin. These and other objects and the attendant advantages will be more fully understood from the following detailed description, taken in conjunction with embodiment examples 1-12. Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilise the present invention to its fullest extent. The following preferred specific embodiments are, therefore, to be construed as merely illustrative and not limitative of the remainder of the disclosure in any way whatsoever.

- Examples 1 -5 and 7-9: Preparation of resole resins, in accordance with the invention, wherein amino groups are reacted into said resin.

- Example 6: Comparative example beyond the scope of the invention. Preparation of a reference resole resin without amino groups.

- Example 10: Addition of amine to a resole resin.

- Example 1 1 : Preparation of a novolac resins, in accordance with the invention, wherein amino groups are reacted into said resin.

- Example 12: Evaluation of the resins according to Example 5 compared to a conventional resin as retention agent in dewatering of a cellulose fibre slurry. The resins were used together with polyethylene oxide.

Example 1

5.87 moles (552 g) of phenol and 1.39 mole (200 g) of ammonia were charged in a 2 litres reaction flask and carefully heated to « 75°C and 1 1.29 moles (678 g) of an aqueous methanol free formaldehyde solution (50% by weight of formaldehyde) was gradually, under stirring and controlled cooling, added during « 25 minutes (exothermic reaction). The reaction temperature was after a further 30 minutes raised to 85°C. The reaction was allowed to continue until the molecular weight of the resole resin had increased to yield a water insoluble and precipitated resin. The reaction mixture was now cooled and 3.56 moles (310 g) of an aqueous sodium hydroxide solution (46% by weight of sodium hydroxide) was added to yield a water soluble resin. 15.28 moles (275 g) of water was also added.

The cationicity of obtained resole was determined to be 27% in comparison to a standard resole resin prepared without amino groups (Example 6).

Example 2

4.74 moles (446 g) of phenol and 0.86 mole (51 g) of the primary amine n-propylamine were charged in a 2 litres reaction flask. The mixture was heated to « 75°C and 8.72 moles (524 g) of an aqueous methanol free formaldehyde solution (50% by weight of formaldehyde) was gradually added. The reaction temperature was after « 30 minutes raised to 100°C. The reaction was now allowed to continue a precipitation of water insoluble reaction product was obtained and all reactants were consumed. The reaction mixture was then cooled and 3.94 moles (343 g) of an aqueous sodium hydroxide solution (46% by weight of sodium hydroxide) and 38.89 moles (700 g) of water were added.

The cationicity of obtained resole was determined to be 40% in comparison to a standard resole resin prepared without amino groups (Example 6).

Example 3

4.53 moles (426 g) of phenol and 0.85 mole (1 10 g) of the secondary amine dibutylamine were charged in a 2 litres reaction flask. The mixture was heated to « 75°C and 8.72 moles (524 g) of an aqueous methanol free formaldehyde solution (50% by weight of formaldehyde) was gradually, under stirring and controlled cooling, added during « 15 minutes (exothermic reaction). The reaction temperature was raised to 100°C and the reaction was allowed to continue for a further 25 minutes. A phase separation had then occurred. The reaction mixture was after determination of completed condensation cooled and 2.97 moles (258 g) of an aqueous sodium hydroxide solution (46% by weight of sodium hydroxide) and 38.89 moles (700 g) of water were added.

The cationicity of obtained resole was determined to be 36% in comparison to a standard resole resin prepared without amino groups (Example 6).

Example 4

4.53 moles (426 g) of phenol and 0.86 mole (87 g) of the tertiary amine triethylamine were charged in a 2 litres reaction flask. The mixture was heated to « 75°C and 8.72 moles (524 g) of an aqueous methanol free formaldehyde solution (50% by weight of formaldehyde) was gradually, under stirring and controlled cooling, added during « 20 minutes (exothermic reaction). The reaction temperature was raised to 100°C and the reaction was allowed to continue for a further 25 minutes. The reaction mixture was after determination of completed condensation cooled and 2.97 moles (258 g) of an aqueous sodium hydroxide solution (46% by weight of sodium hydroxide) and 38.89 moles (700 g) of water were added. The cationicity of obtained resole was determined to be 42% in comparison to a standard resole resin prepared without amino groups (Example 6).

Example 5

4.53 moles (426 g) of phenol and 1.7 mole (200 g) of the tertiary amine diethylethanolamine were charged in a 2 litres reaction flask. The mixture was heated to « 75°C and 8.72 moles (524 g) of an aqueous methanol free formaldehyde solution (50% by weight of formaldehyde) was gradually, under stirring and controlled cooling, added during « 20 minutes (exothermic reaction). The reaction temperature was raised to 100°C and the reaction was allowed to continue for a further 25 minutes. The reaction mixture was after determination of completed condensation cooled and 2.97 moles (258 g) of an aqueous sodium hydroxide solution (46% by weight of sodium hydroxide) and 38.89 moles (700 g) of water were added.

The cationicity of obtained resole was determined to be 28% in comparison to a standard resole resin prepared without amino groups (Example 6).

Example 6

4.53 moles (426 g) of phenol, 2.3 moles (200 g) of an aqueous sodium hydroxide solution (46% by weight of sodium hydroxide) and 22.22 moles (400 g) of water were charged in a 2 litres reaction flask and heated to « 100°C. 8.72 moles (524 g) of an aqueous methanol free formaldehyde solution (50% by weight of formaldehyde) was then gradually, under stirring and controlled cooling, during 20 minutes charged (exothermic reaction). The cooling lowered the reaction temperature to 85°C and the reaction was allowed to continue for a further « 25 minutes. The reaction mixture was after determination of completed condensation cooled and 0.98 mole (58 g) of an aqueous sodium hydroxide solution (46% by weight of sodium hydroxide) and 16.67 moles (300 g) of water were added.

Obtained resole, which was used as reference, had a cationicity of 0%.

Example 7

4.53 moles (426 g) of phenol and 0.16 mole (200 g) of the tertiary amine diethylethanolamine were charged in a 2 litres reaction flask. The mixture was heated to « 75°C and 8.72 moles (524 g) of an aqueous methanol free formaldehyde solution (50% by weight of formaldehyde) was gradually, under stirring and controlled cooling, added during « 20 minutes (exothermic reaction). The reaction temperature was raised to 100°C and the reaction was allowed to continue for a further 25 minutes. The reaction mixture was after determination of completed condensation cooled and 2.97 moles (258 g) of an aqueous sodium hydroxide solution (46% by weight of sodium hydroxide) and 38.89 moles (700 g) of water were added.

The cationicity of obtained resole was determined to be 50% in comparison to a standard resole resin prepared without amino groups (Example 6).

Example 8

4.53 moles (426 g) of phenol and 0.44 mole (51.1 g) of the tertiary amine diethylethanolamine were charged in a 2 litres reaction flask. The mixture was heated to « 75°C and 8.72 moles (524 g) of an aqueous methanol free formaldehyde solution (50% by weight of formaldehyde) was gradually, under stirring and controlled cooling, added during « 20 minutes (exothermic reaction). The reaction temperature was raised to 100°C and the reaction was allowed to continue for a further 25 minutes. The reaction mixture was after determination of completed condensation cooled and 2.97 moles (258 g) of an aqueous sodium hydroxide solution (46% by weight of sodium hydroxide) and 38.89 moles (700 g) of water were added.

The cationicity of obtained resole was determined to be 20% in comparison to a standard resole resin prepared without amino groups (Example 6).

Example 9

A phenol-sulphur pre-condensate was prepared by reacting 4.53 moles (426 g) of phenol with 1.69 mole (54 g) of sulphur at a temperature of 1 15°C and in the presence of NaOH (aq) as catalyst.

The pre-condensate according to above and 0.66 mole (77.1 g) of the tertiary amine diethylethanolamine were charged in a 2 litres reaction flask. The mixture was heated to « 75°C and 8.72 moles (524 g) of an aqueous methanol free formaldehyde solution (50% by weight of formaldehyde) was gradually, under stirring and controlled cooling, added during « 20 minutes (exothermic reaction). The reaction temperature was raised to 100°C and the reaction was allowed to continue for a further 15 minutes. The reaction mixture was after determination of completed condensation cooled and 2.97 moles (258 g) of an aqueous sodium hydroxide solution (46% by weight of sodium hydroxide) and 38.89 moles (700 g) of water were added.

The cationicity of obtained resole was determined to be 10% in comparison to a standard resole resin prepared without amino groups (Example 6).

Example 10

4.53 moles (426 g) of phenol and 2.3 moles (200 g) of an aqueous sodium hydroxide solution (46% by weight of sodium hydroxide) were charged in a 2 litres reaction flask. The mixture was heated to « 100°C and 8.72 moles (524 g) of an aqueous methanol free formaldehyde solution (50% by weight of formaldehyde) was gradually, under stirring and controlled cooling, added during 20 minutes (exothermic reaction). The reaction temperature was reduced to 85°C and the reaction was allowed to continue for a further 25 minutes. The reaction mixture was after determination of completed condensation cooled and 0.98 mole (58 g) of an aqueous sodium hydroxide solution (46% by weight of sodium hydroxide) and 16.67 moles (300 g) of water were added. 16.2 moles (190.8 g) diethylethanoamine was now mixed into obtained resin.

The cationicity of obtained resole mixed with amine was determined to be 10.8% in comparison to a standard resole resin prepared without amino groups (Example 6).

Example 11

5 moles (470.55 g) of phenol and 0.4 mole (46.86 g) of diethylethanolamine and 15 moles (225.22 g) of an aqueous methanol free formaldehyde solution (50% by weight of formaldehyde) were charged in a 2 litres reaction flask and heated to 100°C. The reaction was at 100°C allowed to continue for 5.5 hours. 3 moles (260.4 g) of an aqueous sodium hydroxide solution (46% by weight of sodium hydroxide) and 1552.4 g of water were now added.

Obtained product was a novolac wherein the molar ration phenol:formaldehyde:diethylethanolamine was 1 :0.75 :0.1 1. The cationicity of obtained novolac was determined to be 27% in comparison to a standard resin prepared without amino groups (Example 6).

Example 12

Below evaluation was performed using a so called Britt Jar (BDDJ) from Paper Research Materials Inc., USA, provided with a 75 mesh sieve (60M). The equipment is disclosed in TAPPI Test Method T261 cm-90. A thermomechanic pulp (TMP) made from coniferous wood was when required diluted with tap water. The non-volatile content, pH and temperature of the furnish were adjusted to the processing conditions of used paper maker machine. The diluted furnish was pre-heated to correct temperature and pH was adjusted prior to use.

500 ml of the furnish was used in each BDDJ test. Used chemicals were added (diluted to 15-20 ml) under stirring at 1000 rpm. The resin was added 20 seconds before addition of polyethylene oxide (PEO) after which the foot-valve immediately was opened. The first 25 ml of filtrate was discarded and the total retention was determined on the following 100 ml. The total retention was calculated as the ration between the amount of suspended substances in the filtrate (according to SCAN Test Method C 17:64 - paper filter no. 3) and the non-volatile content of the furnish, TS (retention in % = (1 -(suspended substances/TS)) x 100)). Dewatering was determined in the same equipment by measuring the time for outflow of the subsequent 280 ml of filtrate.

Used polyethylene (PEO) had a molecular weight of 7 x 10 , a density of 1210 kg/m³ and a viscosity of 6000-10000 mPas at 25°C.

The evaluation was performed using a furnish consisting of 100% TMP made from coniferous wood, which furnish had a non-volatile content of 0.92% by weight. The result is given in Table 1.

The total retention was, as can be seen from Table 1 , substantially improved by the modified phenol-formaldehyde resin of the present invention compared to a conventional phenol-formaldehyde resin. Table 1

Claims

1. Modified phenol-formaldehyde resin, which resin is a condensation product obtained by subjecting at least one phenolic compound and formaldehyde to a condensation reaction ch aracterised in, that it comprises cationic groups and that it has a cationicity of 2-95%.

2. Modified phenol-formaldehyde resin according to Claim 1 ch aracteris ed in, that the cationicity is 5-85%.

3. Modified phenol-formaldehyde resin according to Claim 1 ch aracterised in, that the cationicity is 15-60%.

4. Modified phenol-formaldehyde resin according to any of the Claims 1-3 ch aracterised in, that the cationic groups are amine groups.

5. Modified phenol-formaldehyde resin according to Claim 4 ch aracterised in, that the amine groups are derived from ammonia, a primary, secondary or tertiary amine or a mixture thereof.

6. Modified phenol-formaldehyde resin according to any of the Claims 1-5 ch aracterised in, that the phenolic compound is a phenol, a cresol, an alkylphenol or a combination thereof.

7. Modified phenol-formaldehyde resin according to any of the Claims 1-5 characterised in, that the phenolic compound is a sulphur derivatised phenol, cresol, alkylphenol or a combination thereof.

8. Modified phenol-formaldehyde resin according to any of the Claims 1-7 ch aracterised in, that the phenol-formaldehyde resin is a resole resin.

9. Modified phenol-formaldehyde resin according to any of the Claims 1-8 ch aracterised in, that the phenol-formaldehyde resin is water diluted or waterborne.

10. Process of making a modified phenol-formaldehyde resin by subjecting monomers comprising one or more phenolic compounds and formaldehyde to a condensation reaction at a molar ratio phenolic compound to formaldehyde of 1:1 to 1:3.5, at a reaction temperature of 40-100°C, at atmospheric or reduced pressure and at a pH exceeding 8 ch aracterised in, that the condensation reaction is performed in an aqueous medium in the presence of ammonia, a primary, secondary or tertiary amine or a mixture thereof as combined catalyst and reactant introducing cationic amino groups into the phenol-formaldehyde resin, said condensation reaction being maintained until a cationicity of 5-85% is obtained, which resin subsequently is treated with at least one aqueous alkali or alkaline earth metal hydroxide solution, whereby a resin solution comprising a cationic phenol-formaldehyde resin, which resin at a pH of less than 7 can be precipitated as small particles, is yielded.

11. Process according to Claim 10 ch aracteris ed in, that the molar ratio phenolic compound to formaldehyde is 1:2.

12. Process according to Claim 10 or 11 ch aracterised in, that the reaction temperature is 50-90°C.

13. Process according to any of the Claims 10-12 ch aracterised in, that the alkali or alkaline earth metal hydroxide solution is an aqueous solution of sodium, potassium or calcium hydroxide or a combination thereof.

14. Process according to any of the Claims 10-13 characterised in, that the condensation reaction is maintained until a cationicity of 15-60% is obtained.

15. Process according to any of the Claims 10-14 ch aracterised in, that the formaldehyde is employed as an aqueous solution having a formaldehyde content of 30-55% by weight.

16. Process according to any of the Claims 10-15 ch aracterised in, that the phenolic compound is a phenol, a cresol, an alkylphenol or a combination thereof.

17. Process according to any of the Claims 10-15 ch aracterised in, that the phenolic compound is a sulphur derivatised phenol, cresol, alkylphenol or a combination thereof.

18. Process according to any of the Claims 10-17 ch aracterised in, that the process commences with a mixing and heating of the phenolic compound and the ammonia or amine, which mixing and heating is followed by a gradual addition of the formaldehyde.