Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
  • B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
  • B07B1/00—Sieving, screening, sifting, or sorting solid materials using networks, gratings, grids, or the like
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
  • B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
  • B07B13/00—Grading or sorting solid materials by dry methods, not otherwise provided for; Sorting articles otherwise than by indirectly controlled devices
  • B07B13/14—Details or accessories
  • B07B13/18—Control
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
  • B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
  • B07B4/00—Separating solids from solids by subjecting their mixture to gas currents
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
  • B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
  • B07B7/00—Selective separation of solid materials carried by, or dispersed in, gas currents

Definitions

• the invention relates to the preparation of selected viscosity polyvinyl acetals by fractionation of crude polyvinyl acetal based on its particle size distribution.
• polyvinyl acetals in particular polyvinyl butyral
• acid-catalyzed acetalization of polyvinyl alcohol has been commercially used in many variants for several decades, such as. In DE 2838025 . US 5187217 . EP 1384731 described, performed.
• Common feature of these methods is that polyvinyl alcohol is successively acetalized in a homogeneous aqueous solution, the resulting polyvinyl acetal is insoluble in water with increasing degree of acetalization and precipitates in the form of particles from the reaction solution.
• the polyvinyl acetal particles are filtered off after completion of the reactions, washed and dried.
• the polyvinyl alcohol used is present as a radical polymer of vinyl acetate with a relatively large polydispersity of 2.5 to 4.5. Accordingly, the resulting polyvinyl acetals are a mixture of polyvinyl acetals of different chain length and sometimes different degree of acetalization.
• the properties determined macroscopically on the polyvinyl acetal such as degree of acetalization, residual polyvinyl alcohol content, degree of polymerization and viscosity, accordingly represent averages over all fractions.
• the present invention therefore provides a process for fractionating crude polyvinyl acetal into at least two fractions containing polyvinyl acetals having different viscosities by sifting the crude polyvinyl acetal into at least two fractions having different mean particle sizes.
• the process according to the invention can be carried out independently of the absolute viscosity and mean particle size of the crude polyvinyl acetal. By screening in at least two, preferably in three and particularly preferably in four or five fractions with different average particle size, a corresponding number of fractions having different viscosities is obtained.
• screening in fractions of different particle size includes the separation of crude polyvinyl acetal in fractions, which due to the selectivity of the Sighting technique technically overlapping areas may have.
• the process according to the invention is carried out in a first embodiment in which the crude polyvinyl acetal is prepared by sifting the crude polyvinyl acetal into two fractions, the first fraction comprising all crude polyvinyl acetal particles having a mean particle diameter smaller than 50 and the second fraction all raw polyvinyl acetal.
• crude polyvinyl acetal is split by screening of the crude polyvinyl acetal in two fractions, the first fraction, all crude polyvinyl acetal particles having an average particle diameter smaller than d 40 and the second fraction, all crude polyvinyl acetal particles having an average particle diameter greater than 40 contains.
• crude polyvinyl acetal is divided into two fractions by sifting the crude polyvinyl acetal, the first fraction comprising all crude polyvinyl acetal particles having an average particle diameter less than 30 and the second fraction all crude polyvinyl acetal particles having an average particle diameter greater than 30 contains.
• crude polyvinyl acetal is divided into two fractions by sifting the crude polyvinyl acetal, wherein the first fraction contains all the crude polyvinyl acetal particles having an average particle diameter smaller than d 20 and the second fraction contains all the crude polyvinyl acetal particles having an average particle diameter greater than d 20 .
• crude polyvinyl acetal is divided into two fractions by sifting the crude polyvinyl acetal, the first fraction comprising all crude polyvinyl acetal particles having a mean particle diameter less than d 10 and the second fraction all crude polyvinyl acetal particles having an average particle diameter greater than 10 contains.
• crude polyvinyl acetal is split by screening of the crude polyvinyl acetal in two fractions, the first fraction, all crude polyvinyl acetal particles having an average particle diameter smaller than d 90 and the second fraction, all crude polyvinyl acetal particles having an average particle diameter greater d 90 contains.
• a separation of the crude polyvinyl acetal is realized in fractions having different average molecular weights.
• the viscosities and molecular weights of the fractions depend on the average particle size and the molecular weight distribution, as well as their width of the crude polyvinyl acetal.
• crude polyvinyl acetal is classified into fractions having the following size distributions d 50 using the process according to the invention: 51 - 300 microns 50 - 1 microns
• the process according to the invention uses crude polyvinyl acetal in fractions with the following Size distributions d 50 sighted. 1 - 10 microns 11 - 20 microns 21 - 30 microns 31 - 300 microns
• crude polyvinyl acetal is classified into fractions having the following size distributions d 50 using the process according to the invention. 110 - 300 microns 21 - 109 microns 9 - 20 microns 1 - 8th microns
• the fractionation according to the invention can be carried out by techniques such as sieving, centrifugation or air classification.
• the crude polyvinyl acetals used according to the invention preferably have a polyvinyl alcohol content of 12 to 27% by weight and in particular 12 to 18% by weight, 18 to 21%, 21 to 24% by weight and 24 to 27% by weight.
• the residual acetate content is preferably less than 20 mol% and in particular of 16-6.5 mol%, or less than 4 mol%.
• the polyvinyl acetals used according to the invention have a polydispersity of from 15 to 1, preferably from 10 to 1.5 and particularly preferably from 7 to 2.
• Polyvinyl acetals whose weight average molecular weight Mw is greater than 10,000 g / mol, preferably Mw greater than 20,000 g / mol and / or whose solution viscosity is between 14 mPas and preferably 17 mPas and 90 mPas (measured on a 10% strength solution) are preferably used for the fractionation from PVB in EtOH: H 2 O (95: 5) at 20 ° C).
• the weight-average molecular weight Mw should not exceed 150000 g / mol and / or a solution viscosity (measured on a 5% solution of PVB in EtOH: H 2 O (95: 5) at 20 ° C.) of 300 mPas.
• the crude polyvinyl acetal preferably has a particle size distribution d 50 of from 30 to 150 ⁇ m.
• the molecular weight M w or the solution viscosity is measured as indicated in the examples by means of gel permeation chromatography (GPC) or at 10% or 5% solution of the polyvinyl acetals in ethanol / water (95: 5) at 20 ° C.
• the raw polyvinyl acetals used in the preparation of the crude polyvinyl acetals according to the invention are obtained by the known methods by reacting polyvinyl alcohols having a corresponding molecular weight and residual acetate content with one or more aldehydes.
• Polyvinyl acetal used is in particular polyvinyl butyral obtainable by reacting polyvinyl alcohol with butyraldehyde.
• the absolute molecular weight or solution viscosity can be controlled by using appropriate polyvinyl alcohols for the preparation of the polyvinyl acetals.
• the polyvinyl alcohols used for the preparation of the polyvinyl acetals preferably have a solution viscosity of more than 2.7 mPas, measured as 4% aqueous solution at 20 ° C.
• the polyvinyl alcohols can be used in the context of the present invention purely or as a mixture of polyvinyl alcohols with different degree of polymerization or degree of hydrolysis. If mixtures of polyvinyl alcohols are used, their solution viscosity is According to the invention above 2.7 mPas and does not exceed 60 mPas.
• terpolymers of hydrolyzed vinyl acetate / ethylene copolymers can be used in the present invention in addition to copolymers of vinyl alcohol and vinyl acetate. These compounds are usually hydrolyzed to greater than 98% and contain from 1 to 10 wt. Ethylene-based units (e.g., "Exceval" type from Kuraray Europe GmbH).
• the polyvinyl alcohol used can also be hydrolyzed copolymers of vinyl acetate and at least one further ethylenically unsaturated monomer.
• aldehydes having 2-10 carbon atoms and their branched isomers, preferably with acetaldehyde, butyraldehyde, isobutyraldehyde, valeraldehyde, or mixtures thereof.
• the polyvinyl acetals used according to the invention have an increased molecular weight and an increased solution viscosity by crosslinking via carboxyl groups, by polyaldehydes, glutaric dialdehyde or glyoxylic acid.
• Crosslinked polyvinyl acetals are obtainable, for example, via an intermolecular crosslinking of carboxyl-substituted polyvinyl acetals. These can be prepared, for example, by the co-acetalization of polyvinyl alcohols with polyaldehydes, glutaric dialdehyde or glyoxylic acid.
• the polyvinyl acetals obtained in this way particularly preferably have the lower limits for molecular weight M w or solution viscosity already described on. 0.001 to 1% of the OH groups originally contained in the polyvinyl acetal react preferentially through the crosslinking.
• the crosslinked polyvinyl acetals should have a similar solubility behavior as the uncrosslinked polyvinyl acetals.
• Suitable crosslinking possibilities for polyvinyl acetals are, for example, in EP 1527107 B1 and WO 2004/063231 A1 (thermal self-crosslinking of carboxyl-containing polyvinyl acetals), EP 1606325 A1 (polyvinyl acetals crosslinked with polyaldehydes), EP 1622946 A1 (Glutardialdehyd cross-linked polyvinyl acetals) and WO 03/020776 A1 (Crosslinked with glyoxylic polyvinyl acetals) described. The disclosure of these patent applications is fully incorporated by reference. The crosslinking of the polyvinyl acetal is perceived macroscopically via an increased molecular weight and an increased viscosity of an ethanolic solution.
• polyvinyl acetals In the preparation of polyvinyl acetals, a mixture of polyvinyl alcohol and aldehyde (s) or polyvinyl alcohol and an acid such as e.g. HCl and reacted by addition of an acid or aldehyde (s) at a temperature of -6 to 40 ° C with precipitation of the polyvinyl acetal (precipitation phase).
• the precipitation phase begins with the addition of the last component (acid or aldehyde) and usually lasts between 5 and 360 minutes, preferably between 5 and 240 minutes.
• the precipitation phase ends with the start of heating to the final temperature.
• the beginning of heating is the start of the heating phase. Subsequently, the reaction is completed at a final temperature of 20 to 80 ° C, after which the reaction mixture is cooled and the polyvinyl acetal separated u. worked becomes.
• the heating phase ends when the cooling starts and usually lasts between 0 and 300 minutes.
• the polyvinyl acetate content of the crude polyvinyl acetals used according to the invention is preferably less than 14% by weight, more preferably less than 10% by weight or less than 5% by weight and in particular less than or equal to 4% by weight.
• the degree of acetalization can be determined by calculation.
• the polyvinyl alcohol and polyvinyl alcohol acetate content of the polyvinyl acetals was determined according to ASTM D 1396-92.
• the calibration of the detectors was carried out by means of PVB calibration standards whose absolute values were determined by means of static light scattering.
• the solution viscosity of the polyvinyl acetals was measured according to DIN 53015 at 20 ° C. in a mixture of 95 parts of ethanol and the like. 5 parts water.
• the solids content of the viscosity solution was 10% by weight, or 5% by weight in the case of highly viscous compounds.
• the solution viscosity of the polyvinyl alcohols was measured according to DIN 53015 at 20 ° C. in water.
• the solids content of the viscosity solution was 4% by weight.
• the particle size of the PVB powder was measured by laser diffraction according to ISO 13320: 2009.
• the laser used to measure the particle size is diffracted at the particles to be measured and gives a specific diffraction pattern on the basis of which the particle size can be determined according to the so-called Fraunhofer or Mie theory.
• Fraunhofer or Mie theory the result is idealized and the measured particles considered to be ideal spherical.
• Common measuring systems are from Sympatec (Rodos), Malvern (Mastersizer 2000/3000) etc.
• the separation of the grain size classes is done by so-called wind views.
• particles are classified according to their size and density by means of a constant air flow, wherein the principle of gravity separation is utilized.
• various classifier geometries are used as standard, whereby the air can be introduced horizontally or vertically.
• Common classifier systems originate, for example, from PMT Jetmill GmbH or Hosokawa Alpine Aktiengesellschaft.
• Examples 1 and 2 show by way of example the synthesis of a crude PVB with lower or higher viscosity. It can already be seen that the production of low-viscosity PVBs higher demands on cooling capacities, etc. required, at the same time lower yield per batch.
• PVB having a polyvinyl alcohol content of 19.6% by weight and a polyvinyl acetate content of 1.8% by weight was obtained.

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• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
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Citations (9)

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• 2012
  • 2012-11-07 EP EP12191563.1A patent/EP2730591A1/fr not_active Withdrawn
• 2013
  • 2013-11-07 JP JP2013230899A patent/JP2014095078A/ja active Pending

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