WO1996036432A1 - Produit et procede de post-traitement - Google Patents

Produit et procede de post-traitement Download PDF

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Publication number
WO1996036432A1
WO1996036432A1 PCT/US1996/005174 US9605174W WO9636432A1 WO 1996036432 A1 WO1996036432 A1 WO 1996036432A1 US 9605174 W US9605174 W US 9605174W WO 9636432 A1 WO9636432 A1 WO 9636432A1
Authority
WO
WIPO (PCT)
Prior art keywords
sizing agent
process according
aqueous medium
solvent
carbon atoms
Prior art date
Application number
PCT/US1996/005174
Other languages
English (en)
Inventor
Bertil Johansson
Tommy Lindgren
Stig Johnson
Original Assignee
Betzdearborn Inc.
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Betzdearborn Inc. filed Critical Betzdearborn Inc.
Priority to AU56638/96A priority Critical patent/AU5663896A/en
Publication of WO1996036432A1 publication Critical patent/WO1996036432A1/fr

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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
    • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
    • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
    • D21H21/16—Sizing or water-repelling agents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/34—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping with one or more auxiliary substances
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/54—Preparation of carboxylic acid anhydrides
    • C07C51/573—Separation; Purification; Stabilisation; Use of additives

Definitions

  • the present invention generally relates to sizing agents, i.e., agents which are primarily used for paper and board products in order to prevent the penetration of liquids into the paper structure and to improve the surface bonding strength thereof.
  • sizing agents are typically manufactured in the presence of an organic liquid as a solvent which means that the manufactured sizing agent contains residual amount of said organic solvent.
  • the present invention relates to a post-treatment process for the removal of the organic solvent in a very simple, highly efficient and reliable way. Also encompassed by the invention is the sizing agent with substantially eliminated content of organic solvent as obtained from said process .
  • Sizing agents are widely used in order to control properties of paper and board products, such as the penetration of liquids into the paper structure.
  • One main group of such sizing agents is the so called cellulose-reactive sizing agents, which react with the cellulosic fibers thereby rendering the fiber surface hydrophobic .
  • the sizing agent per se is insoluble in water and is generally added to the paper stock as a cationic aqueous dispersion. Said dispersion is also usually stabilized by the addition of a cationic starch.
  • Products of this general type are disclosed in for example EP 353 212.
  • the sizing agents as obtained by the common procedures for the manufacture thereof contain residual amounts of organic solvents, as it is not practical by conventional evaporation to distill off the last tenths of percent of solvent therein.
  • the requirements as to residual organic solvents are strict, which in practice means that the amounts thereof have to be reduced further from parts of percents down to a few ppm or even lower.
  • the only method for practical use today for reduction of solvent content is the use of a thin film evaporator. Such a method is, however, typically limited in practice to residual solvent concentrations of about 10 ppm or more. Furthermore, it is rather sensitive and requires a high vacuum which also makes it expensive.
  • one object of the invention is to provide a process for post-treatment of a sizing agent, by means of which it is possible to reduce the amount of residual solvent and other volatile organic compounds down to ppm levels or even lower.
  • Another object of the invention is to provide a process which is very simple and thereby economical .
  • Still another object is to provide a process which is robust and reliable.
  • One more object of the invention is to provide a process which is of such a nature that it does not adversely affect the favorable properties of the sizing agent.
  • One further object of the invention is to provide a process which is automatically temperature controlled.
  • a process for post-treatment of a sizing agent containing residual amounts of organic solvent from the manufacture of said sizing agent to substantially eliminate the solvent or to substantially reduce the amount thereof, preferably to trace amounts only which process is characterized by adding a substantially aqueous medium to the sizing agent, subjecting the mixture of aqueous medium and sizing agent thus formed to an intense mixing operation by means of a dispersing mixer, and evaporating the aqueous medium from the mixture at atmospheric or sub-atmospheric pressure and at a temperature where the sizing agent is in a molten state, the evaporating aqueous medium entraining said organic solvent and other volatile organic compounds to remove the same from the sizing agent.
  • the sizing agent subjected to the process according to the invention is generally of the hydrophobic cellulose-reactive type.
  • the process should be applicable to the removal of residual solvent from any high-boiling compound which is insoluble or sparingly soluble in water.
  • aqueous medium which is preferably pure water, e.g., deionized water.
  • aqueous medium is utilized in the common sense, i.e., a medium the major ingredient of which is water.
  • the entrainment operation used in the invention is a common use of water as an entrainer for an organic substance.
  • the organic substance firstly dissolves to some extent in the water. From the aqueous phase, water and the organic substance are then distilled off and as a consequence of the high activity factor of the organic substance in the water a larger amount thereof is evaporated than can be expected from its boiling point and concentration. For substances forming an azeotrope with water this is called an azeotropic evaporation.
  • For residual amounts of solvents in a sizing agent it is highly unlikely that such a mechanism could work, since the amount of solvent in the water would be extremely small.
  • the process according to the present invention would work and furthermore works in a very efficient way.
  • the amount of aqueous medium added to the sizing agent is generally selected as a function of the effect aimed at.
  • the degree of reduction of the contents of the organic solvent is directly proportional to the amount of added water, i.e., addition of more water gives a more reduced content of residual solvent. Therefore, it is difficult to generalize the limits of the water addition, which limits are, however, rather easily determined by a person skilled in the art from case to case. Generally, it can also be said, however, that excessive amounts of water should be avoided as there should be no extract benefits from using more water or aqueous medium than what is needed to obtain the desired degree of reduction.
  • the aqueous medium is added in a ratio of at least 1:5, preferably at least 1:4, expressed as weight ratio of aqueous medium: sizing agent. More preferably the aqueous medium is added in a ratio of from 1:4 to 2:1, even more preferred from 1:3 to 1:1, and most preferred from 1:2 to 1:1, expressed on the same weight basis.
  • the amount of added aqueous medium can be much smaller, the effect or advantage of the invention still being utilized.
  • Another essential feature of the process of the invention is that the mixture of aqueous medium and sizing agent is subjected to an intense mixing operation. Said operation is performed by means of a dispersing mixer, which is generally a mixer that causes a dispersion or rather an emulsion or at least a mixture behaving similar to that of an emulsion.
  • a dispersing mixer which is generally a mixer that causes a dispersion or rather an emulsion or at least a mixture behaving similar to that of an emulsion.
  • the invention is, however, not bound by any theory in this respect, i.e., as to the mechanism of the process. Rather, it should be the effect of the mixing operation that is decisive for the scope of the invention.
  • the mixing apparatus used is, however, a turbine mixer.
  • the process claimed is performed at atmospheric or sub-atmospheric pressure, atmospheric pressure being allowable in such cases where the sizing agent can withstand around 100°C without being decomposed. Generally this means that the evaporation is accomplished at a pressure within the range of from 10 mbar absolute up to atmospheric pressure, preferably 30-750 mbar absolute. In this context it should also be added that the process is performed at a constant pressure or preferably at a decreasing pressure.
  • the process is performed with an initial pressure in the range of 100-1013 mbar absolute and with a final pressure in the range of 10-200 mbar absolute.
  • the pressure is maintained in the range of 30-500 mbar absolute, especially 30-300 mbar absolute, the range of 30-220 mbar absolute often being the optimum range, said ranges referring to constant pressures or decreasing pressures within said ranges .
  • the temperature is controlled to a level where the sizing agent is in a molten state.
  • the lower temperature limit is 45°C, preferably 55°C.
  • the upper temperature limit generally is the temperature at which the sizing agent starts decomposing. Generally said upper limit is 95°C, preferably 90°C.
  • the general temperature ranges are 45-95°C, preferably 55-90°C.
  • a most preferred temperature range is 60-80°C, especially 65-75°C.
  • the temperatures referred to are the temperatures utilized throughout the main portion of the evaporation operation and that a temperature rise may have to be accepted in the final stage of said evaporation to distill off the final traces of the aqueous medium.
  • the temperature of the liquid phase during the evaporation is primarily dependent on the boiling point of the aqueous phase, at least as long as the aqueous phase is fairly large.
  • the boiling potion of the aqueous phase is in turn dependent of the pressure of the gaseous phase.
  • the pressure may have to be reduced to maintain the desired temperature.
  • the pH value of the mixture of aqueous medium and sizing agent should be acidic.
  • the solvent contained in the starting sizing agent generally is an aromatic solvent, since aromatic solvents are preferred in the manufacture of the most common group of sizing agents, viz. hydrophobic cellulose-reactive sizing agents.
  • An especially preferred aromatic solvent in this respect is toluene.
  • the process according to the invention is especially preferable in connection with aromatic solvents as the demands from e.g., the food and beverage industries are extremely strict with reference to this group of solvents .
  • the initial sizing agent may also contain other volatile organic compounds, such as residual reactants from the manufacture of the sizing agent, and such volatile compounds are also entrained by the added aqueous medium in the process according to the invention.
  • the process according to the invention is applicable to any sizing agent used in the paper and pulp industry, provided that it is not decomposed in the presence of said aqueous medium.
  • a sizing agent selected from the group consisting of: a) acid anhydrides of the formula:
  • R 1 and R 2 are the same or different and each represents hydrocarbon radicals containing 7-30 carbon atoms: b) cyclic dicarboxylic acid anhydrides of the formula: 0
  • R 3 contains 2 or 3 carbon atoms and R, is a hydrocarbon radical having 7-30 carbon atoms; c) ketene dimers of the formula:
  • R 5 which are the same or different, is a hydrocarbon radical having 6-30 carbon atoms; and d) isocyanates of the formula:
  • R 6 is a hydrocarbon radical having 7-30 carbon atoms .
  • the sizing agent is a ketene dimer of the formula given in section c) , wherein R 5 is alkyl having 6-22 carbon atoms, especially alkyl having 14-22 carbon atoms.
  • the process according to the invention is utilized to reduce the amount of solvent in the sizing agent from a value of the order of magnitude of some tenth of a percent or similar, such as from 0,5%, for instance 0,4% or from 0,3%, expressed as percent by weight based on the weight of the sizing agent.
  • a value of the order of magnitude of some tenth of a percent or similar such as from 0,5%, for instance 0,4% or from 0,3%, expressed as percent by weight based on the weight of the sizing agent.
  • the process according to the present invention enables the manufacture of a sizing agent containing extremely low residual amounts of organic solvents, such as less than 1 ppm. This does not mean, however, that it is in any way restricted thereto. Thus, if higher amounts of organic solvents are accepted, the process can of course be operated to accomplish a final product having any ppm level or even percent level of residual organic solvent thereabove, the easiest way of accomplishing this being an adjustment of the added amount of aqueous medium.
  • the invention also relates to the sizing agent per se as obtained from the above-defined process .
  • the invention also relates to a sizing agent with substantially reduced or eliminated amount of organic solvent whenever post-treated as defined above.
  • the term "post- treatment" in connection with the process should be interpreted in a broad sense. That is, the process claimed need not necessarily be performed as a treatment separated from the process for the preparation of the sizing agent per se. Rather it should be preferable to add the treatment process according to the present invention as a final step of a conventional process for the manufacture of a sizing agent.
  • One advantage with such a final step should be that the starting sizing agent is already in a warm, molten state when starting the post-treatment according to the invention.
  • the process claimed is a very rapid process. Thus, from the working examples below it can be gathered that typically the treatment time is of the order of a few hours to reach ppm levels.
  • the apparatus schematically shown comprises a tank
  • the tank 1 wherein the post-treatment process according to the invention is to be performed, a condensor 2, a vacuum pump 3 and a recovery vessel 4 for water plus organic solvent.
  • the tank 1 is also provided with a dispersing mixer 5, heating means 6, a feed line 7 for starting sizing agent, a feed line 8 for water, and a drain line 9 for purified sizing agent.
  • the function of said apparatus can be described as follows .
  • the starting sizing agent which has been subjected to a conventional evaporation operation (not shown) is fed to the tank 1 via the feed line 7 and deionized water is fed to the same tank 1 via the feed line 8.
  • the pressure within said tank 1 is adjusted to the desired level by means of a control loop (not shown) and the vacuum pump 3, while the mixture of sizing agent and water therein is heated by means of steam through the heating means 6 and is subjected to intense mixing by means of the dispersing mixer 5.
  • Water and organic solvent is then distilled off to the recovery vessel 4 via the condensor 2 cooled by cooling water and the charge remaining in said tank 1 after said distillation, i.e., the pure sizing agent, is cooled.
  • the tank 1 is then pressurized and the charge is drained therefrom through line 9.
  • Deionized water in varying amounts (for details see the Table below) was added thereto.
  • the pressure of said tank 1 was adjusted to 220 mbar and the charge was heated by means of steam of 0,8 bar, which was subsequently reduced to 0,6 bar.
  • a mixer with Scaba 4SRGT turbines was used. When water and toluene distilled off to the vessel 4, the pressure was reduced to 100 mbar.
  • the temperature in said tank 1 was about 70°C during most of the distillation period but rose at the end thereof. At about 85°C the pressure was reduced to about 35 mbar.
  • At 95°C the steam was shut down.
  • the charge was maintained at 95°C and said reduced pressure for 20 minutes .
  • the total distillation time was typically 3 hours .
  • the charge was then cooled and the tank pressurized and the final AKD wax was drained therefrom and analyzed as to any decomposition and amount of toluene remaining.
  • 1,1 1500 92,8 3 averages
  • the results within the respective groups are comparable to each other.
  • the series with different amount of water is based on a sizing agent manufactured in exactly the same way.
  • the AKD percentages typically vary up to 2% between identical charges, which might be due to the analytical method.
  • Example 2 In order to examine the decomposition of the AKD agent at different pH values the following test was performed:

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Paper (AREA)

Abstract

Procédé permettant le post-traitement d'une colle contenant des quantités résiduelles de solvant organique provenant de la fabrication de ladite colle, pour sensiblement réduire le solvant qu'elle contient ou l'en éliminer, dans lequel un milieu pratiquement aqueux est ajouté à la colle, le mélange ainsi formé étant soumis à une opération de mélange intense au moyen d'un mélangeur disperseur (1), le milieu aqueux étant évaporé du mélange à la pression atmosphérique ou subatmosphérique et à une température à laquelle la colle est à l'état fondu, le milieu aqueux en cours d'évaporation entraînant ledit solvant organique et d'autres composés organiques volatils pour les enlever de la colle. L'invention décrit également une colle soumise à un post-traitement, obtenue par lesdits procédés de post-traitement.
PCT/US1996/005174 1995-05-17 1996-04-09 Produit et procede de post-traitement WO1996036432A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU56638/96A AU5663896A (en) 1995-05-17 1996-04-09 Post-treatment process and product

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP95850094 1995-05-17
EP95850094.4 1995-05-17

Publications (1)

Publication Number Publication Date
WO1996036432A1 true WO1996036432A1 (fr) 1996-11-21

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ID=8222105

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1996/005174 WO1996036432A1 (fr) 1995-05-17 1996-04-09 Produit et procede de post-traitement

Country Status (2)

Country Link
AU (1) AU5663896A (fr)
WO (1) WO1996036432A1 (fr)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3409500A (en) * 1966-10-28 1968-11-05 American Cyanamid Co Method of sizing paper with cationic polyamine and carboxylic anhydride
US3990939A (en) * 1973-08-31 1976-11-09 Hercules Incorporated Paper sized with ketene dimer modified water-dispersible thermosettable cationic resins
US4786330A (en) * 1986-01-24 1988-11-22 Atochem Diurethane latex and processes
US4964915A (en) * 1988-06-22 1990-10-23 W. R. Grace & Co.-Conn. Sizing composition, a method for the preparation thereof and a method of use
WO1994019306A1 (fr) * 1993-02-22 1994-09-01 Eka Nobel Ab Procede de production de dimeres de cetene
US5370774A (en) * 1992-11-20 1994-12-06 Wacker-Chemie Gmbh Process for isolating pure diketene with recovery of materials of value

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3409500A (en) * 1966-10-28 1968-11-05 American Cyanamid Co Method of sizing paper with cationic polyamine and carboxylic anhydride
US3990939A (en) * 1973-08-31 1976-11-09 Hercules Incorporated Paper sized with ketene dimer modified water-dispersible thermosettable cationic resins
US4786330A (en) * 1986-01-24 1988-11-22 Atochem Diurethane latex and processes
US4964915A (en) * 1988-06-22 1990-10-23 W. R. Grace & Co.-Conn. Sizing composition, a method for the preparation thereof and a method of use
US5370774A (en) * 1992-11-20 1994-12-06 Wacker-Chemie Gmbh Process for isolating pure diketene with recovery of materials of value
WO1994019306A1 (fr) * 1993-02-22 1994-09-01 Eka Nobel Ab Procede de production de dimeres de cetene

Also Published As

Publication number Publication date
AU5663896A (en) 1996-11-29

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