Abstract:
A process for inhibiting unwanted free-radical polymerization of acrylic acid present in a liquid phase P whose acrylic acid content is at least 10% by weight and which, based on the weight of the acrylic acid present therein, additionally comprises at least 100 ppm by weight of propionic acid and at least 100 ppm by weight of glyoxal, in which at least one chemical compound of the element copper is added to the liquid phase P, and the resulting liquid phases P to which a chemical compound of the element copper has been added.
Abstract:
A method is disclosed for transferring heat to a liquid F containing dissolved monomeric acrylic acid, acrylic acid oligomers obtained by Michael addition, and acrylic acid polymer with the help of an indirect heat exchanger to which the liquid F is fed at a temperature T F ≥ 150°C and a heat transfer fluid W is fed at a temperature T w > T F . In said method, gas bubbles or thin layers of liquid F bordering a gas phase are generated in the liquid F while said liquid F flows through the heat exchanger.
Abstract:
The invention relates to a method for separating acrylic acid, contained as the main constituent and glyoxal, contained as a by-product from a gaseous product mixture of a partial gas phase oxidation of a C 3 precursor compound of acrylic acid. According to said method, a liquid phase P is created, 70 % of the total weight of which consists of acrylic acid and which contains at least 200 mol ppm of glyoxal in relation to the contained molar quantity of acrylic acid. The glyoxal is separated from the acrylic acid by crystallisation from the liquid phase P.
Abstract:
The invention relates to a composition containing at least one piperidine compound of formula (I) as a stabiliser. In said formula (I) the variables R1, R2, R3, R4, R5, R6, R7, R8,Y and the index n have the meanings cited in claim 1 and the description. Said composition also comprises a polymer component and a colouring agent. The invention further relates to a method for producing pigment-containing polymer compositions and to the use of the compounds of formula (I) as dispersing auxiliary agents.
Abstract:
The invention relates to a composition containing at least one piperidine compound of formula (I) as a stabiliser. In said formula (I) the variables R1, R2, R3, R4, R5, R6, R7, R8,Y and the index n have the meanings cited in claim 1 and the description. Said composition also comprises a polymer component and a colouring agent. The invention further relates to a method for producing pigment-containing polymer compositions and to the use of the compounds of formula (I) as dispersing auxiliary agents.
Abstract:
The invention relates to a method for transporting a liquid monomer phase, which has been removed from a storage container, in a tanker lorry or tanker ship, said phase containing up to ≥ 90 % by weight methacryl monomers. According to said method, the liquid monomer phase is subjected to an isolation operation for isolating polymer contained in dissolved form in the liquid monomer phase from the monomer as said phase is removed from the storage container and transferred to the tank of a tanker lorry or a tanker ship.
Abstract:
A process for production of acrylic acid includes preparing a product gas mixture by a catalytic gas-phase oxidation of a C3 precursor; cooling and contacting the cooled product gas mixture in an absorption column having at least two cooling loops in countercurrent with an absorbent to obtain an absorbate A, containing the absorbent and absorbed acrylic acid; condensing a high boiler fraction of the product gas mixture in a first cooling loop; condensing a low boiler fraction of the product gas mixture in a second cooling loop; maintaining a temperature of the absorbate A in the second cooling loop at a value of at least 56° C.; removing an acid water stream comprising glyoxal from the absorption column at a side take-off located above the second cooling loop; and removing a stream F of absorbate A from the absorption column at a side take-off, located at a height of the absorption column between the first cooling loop and the second cooling loop.