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
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/03—Non-macromolecular organic compounds
  • D21H17/05—Non-macromolecular organic compounds containing elements other than carbon and hydrogen only
  • D21H17/14—Carboxylic acids; Derivatives thereof
  • D21H17/15—Polycarboxylic acids, e.g. maleic acid
  • D21H17/16—Addition products thereof with hydrocarbons
• • 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
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/21—Macromolecular organic compounds of natural origin; Derivatives thereof
  • D21H17/24—Polysaccharides
  • D21H17/28—Starch

Definitions

• the present invention relates to a method for producing an alkenyl succinic anhydride (ASA) emulsion in an aqueous solution of cationic starchy material, it being understood that the oily phase is constituted by ASA, the starchy solution acting as a carrier of said emulsion.
• aqueous solution of cationic starchy material is meant a composition containing at least one cationic starch in aqueous solution.
• the process described in the present application does not implement a recirculation loop of the product at the emulsification unit, and carries out a dilution of the emulsion once it is manufactured: a product with granulometry both fine, monodisperse, and stable over time.
• This provides an efficient method, easy to implement, especially at a papermaking production site, to deliver an emulsion that can be stored during the shutdown of the paper machine for cleaning or maintenance operations.
• ASA alkenyl succinic anhydride
• This chemical species which is not miscible in water must be emulsified in order to be advantageously used in the form of a liquid product: this allows a good contact between the ASA and the cellulose fibers.
• the emulsion in question is an ASA emulsion in an aqueous solution of cationic starchy material; in the rest of the application, it may also be referred to simply as an emulsion.
• aqueous solutions of cationic starchy materials of different natures the starchy material being optionally modified; the function of such compositions is to prevent the coalescence of the ASA particles by positive ionization of the surface of the particles, and to bring the ASA particles closer to the fibers by an ionic mechanism.
• a dry weight ratio of cationic starchy material / ASA of between 0.2 and 4 is used.
• the ASA emulsion in the aqueous solution of cationic starchy material must have a number of characteristics. In particular, it must have a great fineness of particle sizes, as well as a narrow spectrum of distribution of these sizes ("monodisperse" product). As explained in WO 97/35068 A1, these parameters condition the effectiveness of the bonding composition vis-à-vis the hydrophobicity properties it is supposed to confer.
• the Applicant has recently developed a method of manufacturing an ASA emulsion in a composition of cationic starchy material, leading to a narrow particle size distribution and centered on an interval of between 1 ⁇ and 1, 5 ⁇ and this, without temperature rise of the emulsion, a phenomenon that accelerates the hydrolysis of ASA.
• the resulting emulsions indeed confer excellent hydrophobizing properties on the papers in which they are intended to be used.
• the key to this process is based on a step of emulsifying an ASA / aqueous cationic amylaceous material in a single pass (that is to say without recirculation loop as in the prior art), while by adjusting the dry matter content of the initial aqueous solution of cationic starch material to between about 7% and 12% of its total weight.
• the emulsions thus manufactured do not exhibit a stable particle size distribution. It has thus been found that the average diameter of said particles is rapidly changing over time, sometimes to values of greater than 4 ⁇ : it therefore deviates substantially from the optimum value sought by the papermaker and as defined above, with a view to get an effective collage of the sheet of paper. However, it is not uncommon for the paper machine to be stopped for several minutes, or even hours, for cleaning or maintenance operations. In this respect, it is essential that the particle size distribution of the particle sizes of the emulsion does not vary.
• a first object of the present invention is a process for producing an ASA emulsion in an aqueous solution of cationic starch material, comprising the steps of: a) producing an aqueous solution of cationic starchy material having a content of dry matter is between 7% and 12% of its total weight,
• step b) mixing ASA and the aqueous solution of cationic starchy material from step a), so as to obtain a cationic starch / ASA dry weight ratio of less than 1,
• step c) producing in a single pass in an emulsification unit an emulsion from the mixture resulting from step b) and without a recirculation loop, d) diluting the emulsion from step c) in a factor of between 1.5 and 3.5 with respect to the dry cationic starch content relative to water.
• Step d) is therefore the crucial step of the process that is the subject of the present invention.
• the dilution of the emulsion is carried out by adding water thereto, from all the means well known to those skilled in the art.
• the dilution factor is therefore between 1, 5 and 3.5; dilution is understood to mean the dilution of the cationic starchy material with respect to the water contained in said emulsion.
• the particle size of the emulsion is less stable over time if a dilution factor of between 1.5 and 3.5 is applied.
• the examples demonstrate that the dilution of the initial solution of cationic starchy material does not constitute a satisfactory response: it leads to emulsions whose average diameter is too large (of the order of 2 ⁇ ).
• emulsions whose average diameter is too large (of the order of 2 ⁇ ).
• Those skilled in the art will be able to adapt the dilution factor, in particular as a function of the dry matter content of the initial aqueous solution of cationic starchy material: it will seek to dilute it, so as to obtain a solids content between 4% and 6% by weight of cationic starchy material.
• Step a) of producing the aqueous solution of cationic starchy material either consists in providing an aqueous solution of cationic starchy material, as commercially available, or else in diluting it with water, in order to obtain the desired dry matter content.
• cationic starchy material designates a starchy material obtained by any of the known methods of cationisation in an aqueous medium, in a solvent medium or in a dry phase, since this process allows a or more nitrogen group (s) of electropositive nature to bind to said starchy material.
• s nitrogen group
• Step b) consists, from conventional mixing means, in particular for controlling the mass concentrations of the constituents, to achieve mixing between the aqueous solution of cationic starch material from step a) and the ASA.
• the dry weight ratio cationic starchy material / ASA is preferably between 0.2 and 0.6, and very preferably between 0.3 and 0.5. Said mixture and the ASA are brought to a mixer which is ideally a static mixer, but may also consist of a dynamic mixer, or a mixer called "venturi", according to the expression well known to those skilled in the art .
• Step c) consists of circulating in a single pass the mixture which has been obtained in step b), in an emulsification unit.
• This unit designates all the devices well known to those skilled in the art, and having in particular mechanical means whose purpose is to micronize and disperse homogeneously the liquid that is to be emulsified.
• Such devices are in particular the Process Pilot DR 2000/4 (IKA®) or Ytron Z (YTRON®) materials.
• the unit in which the aqueous solution of cationic starchy material (a '), the mixer (b'), the emulsification unit (c ') and the dilution devices (d') are all made classic, interconnected ideally by pipes, allowing the flow of different liquids.
• the apparatus within the meaning of the present invention must be understood as devices capable of implementing the method according to the invention, on an industrial scale.
• the manufacture of the emulsion consumes at least 5 liters of ASA per hour, preferably at least 10 liters of ASA per hour.
• the process according to the present invention is also characterized in that the ASA is a product preferably of synthetic origin; these are modified oils that result from C16-C18 cuts.
• Chemsize® A 180 CHEMEC®
• This process is also characterized in that the aqueous solution of cationic starchy material has a fixed nitrogen content of less than 3.5%, preferably between 0.3% and 3.5%, very preferably between 0.7% and 2% by dry weight of nitrogen relative to the total weight of cationic starchy material.
• This cationic starchy material may optionally be modified from an operation chosen from hydrolysis, chemical and physical, mechanical, thermomechanical or even thermal transformations.
• a hydrolysis operation very directly aimed at reducing the molecular weight and, in most cases, reducing the viscosity, can be conducted by various means such as chemical, commonly by the action of an acid, a base or an oxidizing agent or by an enzymatic action, most commonly by amylase.
• the common chemical modifications are of different types such as oxidation, especially with hypochlorite, esterification, such as acetylation, etherification, for example by cationization, carboxymethylation or hydroxypropylation.
• thermomechanical means such as extrusion or pregelatinization
• thermal such as those known to those skilled in the art as Hot Moisture Treatment (HMT) or Annealing.
• HMT Hot Moisture Treatment
• Another object of the present invention is a device comprising: a) a storage unit of an aqueous solution of cationic starch material, b ') a mixing unit of ASA and aqueous cationic starch material, connected with unit a '),
• This device is in particular adapted to the implementation of the method according to the invention.
• the subject of the present invention is therefore in particular a method for producing an ASA emulsion in an aqueous solution of cationic starchy material, as described before, which is produced in a device consisting of:
• an emulsification unit c ') of the mixture of ASA and of the aqueous solution of cationic starchy material connected with the unit b') and free of a recirculation loop, for carrying out step c),
• a unit for diluting the emulsion connected with the unit c '), for carrying out step d).
• Another subject of the present invention consists of an emulsion of ASA in an aqueous solution of cationic starchy material, having:
• a dry weight ratio of cationic starchy material / ASA of less than 1, preferably of between 0.2 and 0.6, and very preferably of between 0.3 and 0.5,
• a particle size distribution such that at least 80% by volume of said particles have a diameter of less than 2 ⁇ , and a mean diameter of between 1 ⁇ and 1.5 ⁇ as determined by laser particle size distribution by means of a device marketed by MALVERN® under the name Mastersizer® 2000,
• a dry matter content of cationic starch material of between 4% and 6% relative to the water contained in said emulsion.
• This emulsion is also characterized in that the ASA it contains is a product preferably of synthetic origin. It is also characterized in that the cationic starch material which it comprises has a fixed nitrogen content of less than 3.5%, preferably between 0.3% and 3.5%, very preferably between 0.7% and 2% by dry weight of nitrogen relative to the total weight of cationic starchy material.
• Said cationic starchy material may optionally be modified from an operation selected from hydrolysis, chemical and physical, mechanical, thermomechanical or thermal transformations as previously indicated.
• Another object of the present invention is a sizing composition containing the ASA emulsion in an aqueous solution of starchy material as described above.
• a final object of the present invention is the use of said emulsion in a gluing operation of a sheet of paper or cardboard.
• the particle size of the emulsions is analyzed from a laser granulometer marketed by MALVERN® under the name Mastersizer® 2000, with the following parameters:
• - Particle shape model spherical
• This example is intended to illustrate the manufacture of ASA emulsion in an aqueous solution of cationic starchy material in the context of a device according to the invention free of a recirculation loop at the unit level. emulsification, and with a device according to the prior art. It also aims to illustrate the influence of the dry matter content of the initial aqueous solution of cationic starchy material on the particle size of the emulsion produced.
• ASA which is the Chemsize® A180 product marketed by CHEMEC®, is also used. This product contains 0.5% by weight sodium dioctyl sulfosuccinate as surfactant (also called "DOSS").
• the water supply is from an existing distribution network.
• the transfers and assays of the ASA and the aqueous solution of cationic starchy material to this emulsification platform are made from their mobile container or respective storage tank, by means of hoses and volumetric pumps, whose speeds of rotation are subject to the desired flow rate and target ratio cationic starch (dry) / ASA.
• the aqueous solution of cationic starchy material is diluted in line.
• the dilution water flow rate is regulated by the flow rate of the aqueous solution of commercial cationic starchy material, depending on the desired solids content.
• a static mixer makes it possible to homogenize this dilute aqueous solution.
• the ASA is then introduced online in the dilute and homogeneous aqueous solution of cationic starchy material.
• This mixture "aqueous solution of cationic starchy material / ASA” is then conveyed via a pipe to the emulsifier.
• This single-pass and continuous emulsification system has a series of 3 consecutive rotors / stators, each rotor and stator of which consists of 3 rows of concentric serrated crowns.
• This process operates at variable speed; the speed of rotation depends on the hydraulic flow rate, the nature of the constituents and their proportions, the pressure in the emulsion chamber, as well as the fineness of the desired emulsion.
• the output of the emulsifier is provided with a temperature sensor, a pressure sensor, a valve for maintaining a pressure of 3 bars in the process, and a flow meter.
• the dry matter content of the aqueous solution of cationic starchy material was varied from 3% to 20%, the dry cationic starch content / ASA ratio from 0.3 to 0.5, the flow rate at the outlet of the emulsifier from 80 to 140 kg / h, the peripheral speed of the rotor of the emulsifier being set at 40 m / s.
• the temperature T ⁇ C of the emulsion at the outlet of the emulsification unit is measured, and a granulometric analysis is carried out according to the protocol already explained, so as to determine the average diameter as well as the parameter % ⁇ 2 ⁇ .
• the emulsion at the outlet of the emulsification unit is recovered, and according to test No. 6, the emulsion is recirculated at least once more in the said emulsion. unit.
• MA / ASA dry weight ratio cationic starchy material / ASA
• T ° (° C) temperature of the final emulsion at the exit of the emulsifier
• Tests Nos. 1 to 4 demonstrate that, at two given MA / ASA ratios and for a dry extract of cationic starchy material that is too low (3% and 5%), the result is a too large average diameter (in particular much greater than 2 ⁇ for tests n ° 3 and 4) and / or at a value of% ⁇ 2 ⁇ too low.
• An optimal quantity of particles whose diameter is between 1 ⁇ and 1.5 ⁇ is therefore not available, which means that particles of larger size are generated which can cause fouling problems.
• tests No. 6 and 7 carried out with a large dry extract of starchy material do not give the desired particle size.
• Example 2 In this example, it is placed under the optimum conditions according to Example 1, namely, use of an aqueous solution of cationic starch material whose dry matter content is equal to 8%, in combination with ASA so as to obtain a ratio by dry weight cationic starch material / ASA equal to 0.3.
• Emulsions are produced under the same operating conditions as before. We are interested here in the evolution of the average diameter of the emulsion over time, depending on whether the emulsion is diluted or not. The hydrophobicity of a paper made with a diluted or non-diluted emulsion is measured after various storage times.
• the emulsion is manufactured under conditions identical to those described in Example 1.
• the flow rate at the outlet of the emulsifier is 120 kg / h, the peripheral speed of the rotor of the emulsifier being set at 40 m / s.
• emulsion 1 Part of the manufactured emulsion is stored: this product is called “emulsion 1".
• the other part is diluted by a factor of 2 as regards the dry cationic starch content relative to water: this product is called “emulsion 2”.
• Each emulsion is stored at room temperature.
• the value of the average diameter of each emulsion 1 and 2 is determined according to the method already indicated.
• a portion of each emulsion (diluted or not) is also taken in order to produce sheets of paper. laboratory, and to measure the degree of hydrophobicity (Cobb60).
• these sheets of laboratory paper also known as formettes, are manufactured from a FRET (retention form) device marketed by TECHPAP.
• FRET retention form
• Such forms have characteristics close to the industrial customer paper, especially with regard to flocculation and retentions.
• the method of manufacturing the formette uses a pulp which is a pulp of virgin fibers (50% resinous, 50% hardwood) with a refining level of 35 ° Schopper (° SR). 35% (by dry weight relative to the total weight of the dough) of natural calcium carbonate marketed by OMYA® under the name of Omyalite® 50 is added. The filled fibrous suspension has a concentration of 2.5 g / l. . 0.3% (dry equivalent / paper) of a HICAT® 5163AM (ROQUETTE®) glue is then added. Finally, 0.35% (relative to the paper) of the ASA emulsion is added. This produces a form having a grammage of 70 g / m 2 .
• the form After manufacture of the form, it is placed between 2 blotters and the set is passed twice in a TECHPAP brand roller press. The form is then separated from the blotters and is placed on a TECHPAP brand dryer for 5 minutes at 100 ° C. A ripening of the forms is then performed, placing them for 30 minutes in an oven at 110 ° C, to allow the bonding agent to give the paper its hydrophobic character. The forms are then placed for a minimum of 24 hours in a room conditioned at 23 ⁇ (+/- 1 ' ⁇ ) and 50% relative humidity (+/- 2%) (ISO 187: 1990 and Tappi T402 sp-08 standards). ).
• the diluted product (emulsion 2) still has a diameter which is quite stable after 3 hours (the same is true for the value corresponding to Cobb60); the average diameter begins to change after 4 hours as well as the degree of hydrophobicity of the paper sheet. After 5 hours, these evolutions are notable but remain nevertheless much lower than that observed beyond 1 hour for the undiluted product.

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