Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
  • C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
  • C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B9/00—Making granules
  • B29B9/10—Making granules by moulding the material, i.e. treating it in the molten state
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2/00—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
  • B01J2/22—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic by pressing in moulds or between rollers
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C31/00—Saturated compounds having hydroxy or O-metal groups bound to acyclic carbon atoms
  • C07C31/18—Polyhydroxylic acyclic alcohols
  • C07C31/20—Dihydroxylic alcohols
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2033/00—Use of polymers of unsaturated acids or derivatives thereof as moulding material
  • B29K2033/04—Polymers of esters
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
  • B29K2995/0037—Other properties
  • B29K2995/0063—Density

Definitions

• the present invention relates to a process for the production of neopentyl glycol pellets, the process comprising at least the process steps: a) providing a bed of NPG flakes; b) compressing the bed in a mold to form a compact, the compression taking place at a pressure of greater than or equal to 0.5 MPa and less than or equal to 7.5 MPa. Furthermore, the present invention relates to NPG compacts.
• Neopentyl glycol (NPG, 2,2-dimethylpropane-1,3-diol) is an important diol that is used in large quantities to produce polyesters and polyurethanes, for example.
• the industrial production of NPGs usually starts with isobutylaldehyde, which is reacted with formaldehyde and the reaction product is then catalytically hydrogenated.
• the NPG is a hygroscopic, crystalline compound which has a melting point of approx. 129°C.
• the diol is offered in the form of smaller flakes, which are produced by solidifying an NPG melt using a crystallization or cooling belt and then breaking it up into individual, more or fewer, irregular platelets.
• the NPG scales are then suitably packaged and delivered in big bags of greater than or equal to 250 kg or in sacks of greater than or equal to 25 kg.
• the scales can cake together in the form of larger aggregates over time.
• the unregulated Agglomeration can result in the formation of very large, compact clumps of NPG, which tend to reduce the product's ability to flow freely. This effect can go so far that the entire contents of a big bag are caked, making it no longer possible to efficiently empty the big bag for further processing.
• US Pat. No. 4,435,603A teaches the addition of tertiary amines in concentrations of 0.25-0.5% by weight as anticaking agents in the production of polyol flakes, in particular neopentyl glycol flakes.
• anticaking agents in the production of polyol flakes, in particular neopentyl glycol flakes.
• experience teaches that even the addition of such anti-caking agents does not reliably prevent the formation of material caking, coarse nodules and lumps or large-volume product caking, especially when storing palletized sacks or big bags.
• DE 3 522 359 A1 describes a process for processing organic materials that are crystalline under normal conditions, in which the materials are processed in a powdered and/or molten state in a self-cleaning, twin-screw machine with screw shafts rotating in the same direction, through at least one narrowed passage into a zone of low pressure, cooled and comminuted into particles, characterized in that the materials are heated during discharge through the restricted passage to form a melt film.
• EP 0 829298 A2 discloses a process for the production of hydroxypivalic acid neopentyl glycol ester granules by applying a hydroxypivalic acid neopentyl glycol ester melt to a cooling surface on which the melt solidifies, characterized in that the melt contains at least 3% by weight, based on the total amount of hydroxypivalic acid neopentyl glycol ester , of hydroxypivalic acid neopentyl glycol ester crystals.
• EP 1 268 378 B1 also describes a process for preparing neopentyl glycol by cooling, crystallizing and comminuting a neopentyl glycol melt and then packing the resulting neopentyl glycol particles in storage or transport containers.
• the melt is cooled at the beginning of cooling for at least 1/10 minute without using a coolant or using a coolant having a temperature ranging from 50 to 120°C and packed at a temperature below 30°C.
• the object is achieved according to the invention by a process for the production of neopentyl glycol pellets, the process comprising at least the process steps a) providing a bed of NPG flakes; and b) compressing the bed in a mold to form a compact, wherein the compression occurs at a pressure of greater than or equal to 0.5 MPa and less than or equal to 7.5 MPa.
• the compacts that can be produced by means of the process also show a lower tendency to sublime and, particularly surprisingly, their dissolvability in different solvents is only insignificantly restricted for large-scale industrial processing.
• the synergistic advantages result from high mechanical resilience, low sublimation tendency, lower caking tendency with a relatively good dissolving capacity through the use of NPG flakes within a mechanical pressing process with relatively low pressures, with a mechanically very stable but nevertheless easily dissolvable into its components by means of solvents.
• the process according to the invention is a process for the production of neopentyl glycol pellets.
• the compacts are shaped bodies which are obtained by compressing material in a compression mold.
• the compacts are characterized by a regular shape, which results from the geometry of the mold used. For example, balls, cuboids or briquettes in different designs and sizes can be produced by selecting the press form.
• the compacts are shaped essentially the same, so that, for example, different compacts differ in their weight by less than 25% by weight, preferably less than 15% by weight and further preferably by less than 10% by weight.
• the compact is a neopentyl glycol compact in those cases where greater than 90%, further greater than 95%, and more preferably greater than 97% by weight of the compact is NPG.
• the process can be carried out using conventional presses in the form of extruder presses, roll presses or in the press chamber process.
• the method comprises method step a), in which a bed of NPG flakes is provided.
• the NPG pellet is made from a bed of NPG flakes. This bed is a statistical distribution of irregularly broken NPG particles.
• the NPG flakes have a thickness and size distribution that is a function of the manufacturing process.
• NPG particles in the form of small grains or NPG dust can also be present in the bed.
• the dust content of the NPG fill is also a function of the manufacturing process.
• scales in the form of flat platelets with an irregularly broken edge are predominantly present in the bed.
• the size distribution of the NPG flakes can be determined by mechanical action on the NPG that has solidified on a cooling belt.
• the composition of the NPG scales can be freely selected in certain proportions.
• the NPG bed can preferably consist of pure NPG. However, it is also possible for the scales to have other substances as additional components.
• the weight fraction of the NPG in the flakes is preferably greater than or equal to 80%, further preferably greater than or equal to 90% and further preferably greater than or equal to 95%.
• the method comprises method step b), in which the bulk material is compressed in a mold to form a compact.
• the compression takes place at a pressure greater than or equal to 0.5 MPa and less than or equal to 7.5 MPa.
• the bed of NPG flakes filled into one or more molds is subjected to the above pressure range by contacting the two mold halves.
• This process can be carried out, for example, using a manual press or continuously using rotating pressing tools.
• the pressing process can optionally take place within a conditioned environment. However, it is not mandatory for the ambient air or temperature to be preconditioned accordingly.
• the pressing process can expediently be carried out at room temperature.
• the pressing tools can be preheated to a specific temperature range, for example between greater than or equal to 10°C and less than or equal to 40°C.
• the time it takes to press a single mold can vary. That's how she can Bed of NPG flakes remain in the pressing tool, for example, for greater than or equal to 1 second, more preferably greater than or equal to 2 and further preferably greater than or equal to 5 seconds.
• the application of the pressing pressure over a longer period of time is unnecessary.
• connecting pieces can also be formed between the compacts, which result from the fact that material from the fill has also been deposited between the individual compacts. This additional material does not form the compacts in the sense of the invention and can be sheared off or screened off prior to further processing of the compacts, for example by applying slight mechanical pressure.
• the NPG flakes can have a bulk density of greater than or equal to 0.5 g/cm 3 and less than or equal to 0.6 g/cm 3 .
• the bulk density of the NPG bed in the range specified above.
• the bulk density in particular also seems to be decisive for the preferred porosity of the compacts. Smaller bulk densities can be disadvantageous since the mechanical strength of the compacts can be insufficient in these cases. Higher bulk densities, on the other hand, can be disadvantageous, since in these cases the dissolution rate of the compact is reduced too much.
• the bulk density can be measured according to DIN ISO 697 or DIN ISO 60, for example.
• the NPG flakes can have a fines content of less than or equal to 6 mm, determined by sieving, of greater than or equal to 80% by weight and less than or equal to 90% by weight.
• the NPG flakes used in the NPG fill have a specific size distribution.
• a higher proportion of small flakes, indicated here as fines with a size of less than 6 mm can result in both the mechanical strength and the dissolving power of the compact being improved.
• the NPG flakes may have a thickness greater than or equal to 0.75 mm and less than or equal to 5 mm.
• the thickness of the flakes can expediently be determined by the height of the NPG melt on the cooling belt used for production. Smaller thicknesses of the NPG flakes can be disadvantageous, since in these cases the mechanical strength of the pellet that can be obtained can be reduced. Higher thicknesses can be disadvantageous, since in these cases unfavorable mechanical properties of the compact can also be obtained. Without being bound by theory, this relationship is likely due to the fact that the individual flakes are more resistant to deformation in the press and as such reduced interaction between the individual flakes is induced by the pressing process.
• the thickness of the NPG flakes can be determined, for example, using calipers.
• the thickness of the flakes can be greater than or equal to 1 mm and less than or equal to 4 mm, furthermore preferably greater than or equal to 1.5 mm and less than or equal to 3 mm.
• the NPG flakes can have a D50 quantile, determined by sieving, of greater than or equal to 2 mm and less than or equal to 8 mm.
• NPG flakes with the quantile specified above have proven to be particularly suitable for the production of particularly mechanically stable and quickly dissolving pellets. This size range of the NPG flakes with a high proportion of rather smaller particles, together with a relatively low pressing pressure and a relatively short pressing time, can result in particularly suitable interactions being produced between the individual particles to be pressed. A very homogeneous pellet is formed, which dissolves well in a relatively short time when it comes into contact with a solvent.
• the NPG flakes can have a D95 quantile, determined by screening, of greater than or equal to 7.5 mm and less than or equal to 10 mm.
• the use of NPG flakes with a relatively small proportion of flakes over 10 mm can also lead to particularly homogeneous compacts being obtainable, which are characterized by only a small proportion of fragments even under greater mechanical stress.
• the compression can take place at a pressure of greater than or equal to 1.0 MPa and less than or equal to 4 MPa.
• the pressing pressure indicated above has proven to be particularly suitable. Sufficient stability and very rapid dissolution behavior of the compacts can be achieved in particular in the area of relatively low compaction pressures.
• method step b) can take place in a temperature range of greater than or equal to 5°C and less than or equal to 40°C.
• the temperature range specified above has proven to be particularly suitable for obtaining particularly uniform compacts and for preventing caking in the compression molds.
• Higher temperatures can be disadvantageous, since unwanted thermodynamic phase transformations of the NPG can be induced in these areas.
• higher temperatures in the process can lead to production material unintentionally sticking to the walls of the press in the course of continuous production, which is not removed from the mold independently during the pressing process.
• Lower temperatures during pressing can be disadvantageous, since in these cases the individual particles are only insufficiently pressed together due to the lower pressing pressure.
• the NPG flakes can have a water content of greater than or equal to 0.05% by weight and less than or equal to 3% by weight.
• the NPG flakes can have a defined water content.
• the water content of the fill can also have an impact on the producibility of the compacts. In particular, it can happen that the mechanical press molds have to be cleaned more frequently if the water content is too high.
• the water content of the NPG scales can be determined using known methods such as Karl Fischer.
• an NPG compact wherein the compact has a density of greater than or equal to 0.9 g/cm 3 and less than or equal to 1.02 g/cm 3 .
• compacts can be obtained which, starting from the NPG used and starting from the use as NPG flakes, have a very small specific density range.
• there are mechanically very stable pellets which show only a very low tendency to cake even under unfavorable storage conditions.
• the pellets still show good solubility in the usual solvents for NPG, such as water.
• the density of the pellets can be determined using methods known to those skilled in the art, for example by measuring and weighing the pellets.
• the compact may have a volume greater than or equal to 2.5 cc and less than or equal to 15 cc .
• the volumes indicated above have proven to be particularly suitable for the individual compact. Smaller compacts can have too large a surface, which can lead to a too high proportion of fines during storage due to increased sublimation from the surfaces of the individual compacts. Larger pellet volumes, on the other hand, can be disadvantageous since in these cases the dissolution rate of the pellets, for example in water, is reduced too much.
• the compact may have a density greater than or equal to 0.95 g/cm 3 and less than or equal to 1.05 g/cm 3 .
• the density of the resulting NPG pellets can be determined based on the bulk density of the NPG flakes and the pressure applied during manufacture. These parameters make it possible in particular to obtain compacts which have a density in the range specified above. This very narrow range of material density for the NPG compacts can lead in particular to mechanically very stable compacts being obtained, which show a particularly rapid dissolution in the solvents suitable for this. In addition, this density range can mean that the final mechanical strength of the compacts is obtained after a relatively short time.
• the compact can have a surface area to mass ratio greater than or equal to 0.4 m 2 /kg and less than or equal to 0.6 m 2 /kg.
• compression molds with a basic geometry which have the surface-to-mass ratio indicated above. This geometry shows only a small amount of mass loss (sublimation) during storage, leads to only low abrasion on the individual compacts even under heavy mechanical stress and these shapes can also be processed with standard equipment in an industrial environment.
• the surface-to-mass ratio can be determined by weighing and determining the compact size, for example using calipers.
• the compact can have an NPG content of greater than or equal to 98% by weight.
• the NPG content in the compact can be greater than or equal to 98.5% by weight, more preferably greater than or equal to 99.5% by weight and more preferably greater than or equal to 99.9% by weight.
• the compact can also consist of 100% NPG.
• the proportion by weight of the NPG in the pellets can be determined quantitatively, for example, by means of an HPLC analysis, neglecting the proportion of water.
• the compact can have a compressive strength of greater than or equal to 80 N and less than or equal to 400 N.
• the pressings according to the invention are characterized by a relatively high breaking strength, which surprisingly can be obtained with only a relatively low pressing pressure during production.
• the breaking strength of the individual compacts is determined 24 hours after production and storage at room temperature. Within this period of time, the compact as such can still post-cure and develop higher breaking strengths.
• the compressive strength is determined using a compression strength tester from Erichson (model 469 E4).
• the upper and lower plates each have a diameter of 80 mm.
• the diameter of the measuring body is 10mm (horizontal) and the speed of the measuring body is 8mm/min.
• the compact can have a cuboid geometry.
• the compacts For handling in industrial packaging and transport processes, it has been found to be particularly suitable that the compacts have a cuboid geometry. This geometry can contribute to a particularly low caking tendency and to a particularly low level of abrasion, even under heavy mechanical stress during transport.
• the compact can have an exact cuboid geometry or else a geometry which is based on a cuboid. This definition refers to briquettes in the usual sense as well as egg charcoal or egg briquettes, which have a cuboid basic geometry with rounded corners.
• the cuboid geometry can also be a cube.
• the compacts can also have a press seam, for example a circumferential press seam, and other features, such as a logo or the like, on the surface.
• the ratio of the average length and width to the height of the cuboid compact determined as (length + width) / 2 divided by the height, greater than or equal to 1.25 and less than or equal to 3, amount to 5. Due to the fact that the compacts are not properly layered during industrial production, but are provided in a disorderly pile in bags or big bags, the above-mentioned ratio of the height and width of the cuboid compact has turned out to be particularly suitable. This aspect ratio of the compact can mean that even under unfavorable storage conditions and under high mechanical stress, only a small proportion of breakage is obtained in the bulk compact. In addition, due to the specified asymmetry of the cuboid compact, a suitable dissolution rate of the compact in the usual solvents can also be achieved.
• beds of neopentyl glycol compacts that are resistant to caking, the proportion of fine particles ⁇ 1 mm in the beds being less than 10%. These fills can be distinguished by a particularly low proportion of caking, even under unfavorable storage and transport conditions.
• NPG scales consist (ignoring the water content) of 100% NPG. No additional anti-caking, binding or disintegrating agents are added to the NPG flakes or the NPG itself.
• the scales were examined using a sieve analysis with the following size classes (in mm): > 20, 20-10; 10-8; 8-6.3; 6:3-5; 5-4; 4-3:15; 3:15-2; 2-1; 1-0.5; 0.5-0.25; 0.25-0.125 and 0.125-0mm.
• the result is a D50 quantile of 3.45 mm and a D95 quantile of 8.7 mm.
• the density of the NPG fill is 0.525 g/cm 3 .
• the pressing is carried out at a pressing pressure of 1 MPa.
• the briquettes are then screened to separate the fines (particles smaller than 6.3 mm). Without fines, the yield of the pressing process is over 90%.
• the briquettes are stored for 24 hours at room temperature and a relative humidity of 85%. Under these storage conditions, no change in the briquette mass due to hygroscopic behavior was observed.
• the compressive strength of the compacts improves significantly after 24 h storage.
• the compressive strength determined by a compressive strength measurement (“Compression Strength of Briquettes”, measured with a machine type 469 ERICHSEN) is >100 N. After storage for 24 hours under the conditions specified above, the compressive strength can be increased again.
• Typical compressive strength values are after storage for the smaller briquettes at 109N and for the larger briquettes at 155N.
• the briquettes also pass a 2m drop test. After 2 runs on unstored briquettes, approx. 90% intact briquettes could still be determined for both briquette sizes. These results of the drop tests also improved after the freshly produced compacts had been stored for 24 hours.
• the briquettes are placed in a fume hood and the mass loss is monitored over 49 days.
• the briquettes show linear sublimation behavior, with the mass loss after 49 days being approx. 10% for the 10cm 3 and 11% for the 5cm 3 compact.
• the mass loss of NPG scales under these conditions is approximately 18%.
• Tests are also carried out with regard to pellet hygroscopy under a defined humidity level in a desiccator.
• the briquettes are placed in an open bowl in a desiccator containing various saturated salt solutions.
• Saturated NaCl solution provides a relative humidity of 74%, while using saturated LiCl solution achieves a lower humidity of 11%.
• the weight and water content of the pellets are noted after two weeks. Storage at a relative humidity of 11% means that no significant increase in the water content or loss of mass of the pellets can be observed.
• a water content of 1.3% (10cm 3 briquettes) or 1.6% (5cm 3 compact) was measured after 2 weeks.
• the pellets show a significantly lower hygroscopicity.
• NPG scales show a significantly higher proportion of caking and agglomerations. Even sticking briquettes can be easily separated from each other again by using little force. After 4 weeks of storage, a similar picture emerges for the pellets compared to the NPG scales. The degree of adhesion increases for both the NPG flakes and the pellets, but the proportion of caked material in the flakes is significant. In addition, pressings that are sticking can be easily separated from one another by applying little force. The adhering NPG scales cannot be completely separated from each other, even by higher forces.
• NPG flakes and pellets To compare the dissolution behavior of NPG flakes and pellets, a 25% by weight NPG solution in water is prepared with stirring. Surprisingly, the dissolving behavior of the briquettes is practically independent of the compact size used. The dissolution rate of the compacts is approx. 12:20 min for the 5 cm 3 and 12:40 min for the 10 cm 3 compacts. NPG scales disintegrate in about 2:53 min under the same experimental conditions. Looking at the difference in the surface area available for dissolving the flakes and pellets, it can be estimated that the surface area of the flakes is at least 10 times higher than that of the pellets.
• the flake surface can be approximated by assuming cylindrical particles with the flake height used as the height and a diameter corresponding to the D50 quantile of the flakes. This approach ignores the considerable proportion of very small fragments in the scales and leads to a very conservative estimate of the scale surface.
• the pellets detach less easily by a factor of 4-5, although the difference in the available surface area factor is definitely higher than 10. In this respect, the pellets come off much better than could have been expected. Without being bound by theory, this is based on the specific gravity of the pellets returned, indicating that no compact NPG pellet is present. Due to the use of NPG scales and the application of only low pressure, the compacts also contain a significant proportion of pores or air in the compact, which apparently facilitates the diffusion of solvents and thus the dissolution.

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• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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Citations (4)

• 2021
  • 2021-12-23 EP EP21217297.7A patent/EP4201918A1/de active Pending
• 2022
  • 2022-12-14 WO PCT/EP2022/085738 patent/WO2023117601A1/de not_active Ceased
  • 2022-12-14 JP JP2024537920A patent/JP2024546176A/ja active Pending
  • 2022-12-14 KR KR1020247024948A patent/KR20240129191A/ko active Pending
  • 2022-12-14 CN CN202280084824.4A patent/CN118434706A/zh active Pending
  • 2022-12-14 US US18/721,623 patent/US20250050544A1/en active Pending
  • 2022-12-15 TW TW111148119A patent/TWI874858B/zh active

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