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
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/46—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/47—Condensation polymers of aldehydes or ketones
  • D21H17/49—Condensation polymers of aldehydes or ketones with compounds containing hydrogen bound to nitrogen
  • D21H17/51—Triazines, e.g. melamine
• • 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
  • D21H21/18—Reinforcing agents
  • D21H21/20—Wet strength agents

Definitions

• a melamine-formaldehyde resin colloid is a product which is obtained by continuously mixing a 40-80% strength aqueous solution of an optionally modified methylolmelamine with water and acid in a mixing zone under turbulent flow, a temperature of 40 to 110 ° C, a pH of 2 to 4 and a residence time from the mixing zone to the point of addition to the paper stock of 1 to 300 seconds has been obtained, the solids content of the melamine-formaldehyde resin colloid solution being 5 to 20% by weight. -%.
• methylol melamines usually, for the preparation of methylol melamines, an aqueous solution of melamine is heated to temperatures between 70 and 95 ° C. and formaldehyde, for. B. formalin or paraformaldehyde.
• the pH of the reaction mixture is generally adjusted to between 7.5 and 11.
• the methylolmeiamines are stable in the alkaline pH range. They can be etherified very easily with alcohols in the acidic pH range. Methanol, ethanol and n- or iso-propanol or n- or iso-butanol are preferably used for the etherification. Etherification with methanol is particularly simple and therefore also preferred. It is possible to partially or completely etherify the methylolmelamines.
• the resulting products can contain 1 to 6, preferably 2 to 5 ether groups.
• the pH of the aqueous solution is adjusted to above 7 so that condensation is prevented.
• the optionally etherified methylolmelamines are already produced in high concentration, e.g. B. as a 40 to 80% aqueous solution. They can also be obtained by concentrating dilute solutions.
• the highly concentrated modified methylol melamine solutions can also be modified with alkali sulfites, alkali bisulfites or with amines.
• the molar ratio of methylolmelamine to sulfite or bisulfite is preferably in a range from 1: 0.5 to 1 5.
• the main amines are ammonia, primary and secondary alkylamines, di- and polyamines and, for. B. mono-, di- and triethanolamine in question.
• the molar ratio of methylolmelamine to amine is preferably in a range from 1: 0.5 to 1: 5.
• the concentrated aqueous solution of the optionally modified methylolmelamine is continuously mixed in a mixing zone by adding water and an acid - it being possible for a reactant to be premixed in the water - at a temperature of 40 to 110 ° C., preferably 70 to 90 ° C. , so that a downstream also continuously flowed dwell time, the polycondensation of the optionally modified methylolmelamine takes place within a very short time. At temperatures above 100 ° C, pressure equipment must be used.
• a homogeneous solution - without concentration gradients - has to be prepared in a very short time, because due to the high reaction acceleration in the range of low acid concentrations this may be the case would polymerize modified methylol melamine to an insoluble resin within a few seconds.
• the mixing of the reaction components with the water is preferably carried out in a jet mixer, which opens out into a downstream period of use, designed as a reaction tube or container.
• the water preferably the methylolmelamine solution, optionally modified with the water, is used by using it as a driving jet with turbulent flow at speeds of 5 to 50 m / s, preferably 10 to 20 m / s the jet of the jet mixer is given.
• the energy density in the mixing zone is at least 20 kW / m 3 and is preferably above 50 kW / m3.
• the resin solution if it is not already premixed with the water, as well as the acid required to start the condensation reaction, can be passed through the nozzle - which in this case is designed as a multi-component nozzle - as well as with separate inlet pipes next to the nozzle or be fed to the side of the mixing tube at the height of the nozzle.
• the impulse exchange between the propellant jet and the reaction solution surrounding it results in a rapid and intensive mixing of the mixing space designed as a tube.
• the components leave the tube homogeneously mixed. Due to the short mixing time and the high energy density of 50 to 7000, preferably 50 to 2000 kW / m 3 entered with the mixing devices, it is possible to achieve the required reaction time until optimal ripening by setting suitable reaction conditions (pH from 3 to 4, temperature from 40 to 110 ° C) to 1 to 300 seconds, without getting disruptions due to flocculation if the condensation is too advanced or due to loss of effectiveness if the dwell time is too short.
• suitable reaction conditions pH from 3 to 4, temperature from 40 to 110 ° C
• the ripening - polycondensation of the optionally modified methylolmelamine - takes place in the mixing zone and in the subsequent dwell period, preferably in a reaction tube which is integrated with the jet mixer and has a turbulent flow.
• the homogeneously mixed solution - regardless of the mixing device used - passes through a tube or additionally a container in which the desired residence time is achieved.
• the required residence time is from a few seconds to several minutes, preferably from 15 seconds to 1 minute.
• the acids used are preferably hydrochloric acid and phosphoric acid or carboxylic acid, such as formic acid, acetic acid and propionic acid.
• a highly effective melamine-formaldehyde resin colloid solution with a solids content of about 5 to 20% by weight is obtained, which is metered in directly to the paper stock or, after a further continuous or discontinuous dilution with water in a weight ratio of 1 10 to 1:20, is added to the paper stock suspension .
• the colloid solutions prepared in this way are effective and are preferably used directly after leaving the mixing apparatus. They can also be stored for a few hours, but lose their effectiveness as a wet setting agent after a long time.
• the components were mixed intensively and quickly into a homogeneous solution.
• the energy density in the mixing room was 470 kW / m 3 .
• a residence time in the form of a reaction tube was connected to the mixing tube.
• the reaction tube had an inner diameter of 10 mm and a length of 30 m.
• the residence time of the reaction mixture in the mixing zone and the downstream reaction tube to the point of addition to the paper stock was 30 seconds, the temperature was 75 ° C. and the pH of the mixture was 3.0.
• the stirrer was then switched off and the mixture was aged at a temperature of 40 ° C. for 3 hours.
• the pH of the mixture was 2.2.
• the resin colloid was obtained in an amount of 150 g / min (corresponding to 5%). added to the paper stock on dry fiber material.
• the pH of the stock suspension was adjusted to 4.5 with 2% aluminum sulfate and additionally with dilute sulfuric acid.
• This stock suspension with a freeness of 35 ° SR was dewatered on the paper machine described in Example 1 at a speed of 66 m / min. Approx. 3 kg / min of a paper made from bleached sulfite pulp with a basis weight of 60 g / cm 2 were thus produced.
• the properties of the paper are given in the table.
• Comparative example 1 was repeated with the exception that 300 g / min corresponding to 10%, based on the fiber material, of the 10% melamine-formaldehyde resin colloid solution were used for the paper stock.
• the properties of the paper thus obtained are given in the table.

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Paper (AREA)
• Phenolic Resins Or Amino Resins (AREA)
• Replacement Of Web Rolls (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

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ID=6114904

Family Applications (1)

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Family Cites Families (5)

• 1980
  • 1980-10-22 DE DE19803039762 patent/DE3039762A1/de not_active Withdrawn
• 1981
  • 1981-09-15 FI FI812880A patent/FI66943C/fi not_active IP Right Cessation
  • 1981-09-21 DE DE8181107478T patent/DE3161038D1/de not_active Expired
  • 1981-09-21 EP EP81107478A patent/EP0050223B1/de not_active Expired
  • 1981-09-21 AT AT81107478T patent/ATE4826T1/de not_active IP Right Cessation
  • 1981-10-21 NO NO813548A patent/NO160666C/no unknown
  • 1981-10-21 ES ES506403A patent/ES506403A0/es active Granted

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